JP2885744B2 - Electrostatic inkjet 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 electrostatic ink jet recording apparatus, and more particularly to an electrostatic ink jet recording apparatus 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 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.

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

FIG. 4 is a perspective view showing an example of this conventional electrostatic ink jet recording apparatus disclosed in, for example, Japanese Patent Application No. 7-120252. Referring to FIG.
The substrate 132 is an insulator such as glass, and a plurality of recording electrodes 125 are formed on the surface thereof. The recording electrodes 125 are obtained by patterning a conductive material such as chromium sputtered on the entire surface of the substrate 132 by photolithography, and are arranged, for example, at a pitch of 300 dpi, that is, at intervals of about 85 μm. The recording electrode 125 is connected to a driver (not shown), and this driver selectively applies a high voltage pulse to the recording electrode 125 during recording.

The meniscus forming member 128 is formed by processing a photosensitive polymer film laminated on a substrate 132 by photolithography, and is formed at a position slightly receded from the leading end of the recording electrode 125 so as to overlap with each recording electrode 125. Have been. The thickness of the photosensitive polymer film is 30μ
m, the width of the meniscus forming member 128 is also about 30 μm.

[0006] A cover 133 is mounted on the meniscus forming member 128 at a position further retracted from the tip of the meniscus forming member 128. Cover 133
Is an insulating member in which the ink supply port 126 and the ink discharge port 127 are processed in advance. The substrate 132 and the cover 133 form a slit-shaped ink ejection port 122, and a meniscus forming member 128 riding on the recording electrode 125 protrudes between the ink ejection ports 122. The meniscus forming member 128 supports the cover 133 and also has a purpose of forming the ink flow path 134, and thus partially extends below the cover 133. The meniscus forming member 128 forms an ink chamber 121 together with the substrate 132 and the cover 133.

Further, in order to concentrate the toner particles in the ink 120 and supply the concentrated toner particles to the vicinity of the ink ejection port 122 through the ink flow path 134, the electrophoresis electrode 1 is provided behind the ink flow path 134.
23 are provided. Electrophoresis electrode 123 and recording medium 12
4 The toner particles in the ink 120 move by the electrophoretic force due to the electric field between the counter electrode 129 provided on the back surface and concentrate near the ink ejection port 122. At this time, the recording electrode 1
By applying a pulse voltage to the toner particles 25, the toner particles fly toward the recording medium 124 as a flying particle group 131.

[0008]

However, a first problem of the above-mentioned conventional electrostatic ink jet recording apparatus is that the recording voltage applied to the recording electrodes cannot be reduced. The reason is that it is necessary to keep a sufficient distance between the recording medium and the recording electrode, and it is necessary to increase the voltage applied to the recording electrode in order to obtain sufficient electrostatic force to fly the toner particles in the ink. Because there is.

A second problem is that stable flying of the toner particles is hindered. The reason is that the electric field between the recording electrode and the counter electrode changes during the recording operation due to the thickness of the recording medium, floating of the recording medium during running, and the like, so that the force acting on the toner particles in the ink changes. That's why.

SUMMARY OF THE INVENTION [0010] An object of the present invention is to solve the above-mentioned problems, and an object of the present invention is to provide an electrostatic ink jet recording apparatus which discharges only toner particles in ink by an electrostatic field, in which an interelectrode between a recording electrode and a counter electrode is provided. By providing a third electrode, that is, a gate electrode, which is grounded by inserting a high resistance into the device, the distance between the recording electrode and the gate electrode is kept constant, and the toner flying is stabilized,
An object of the present invention is to provide a reliable low-cost multi-element recording head. Furthermore, since the gate electrode is grounded by inserting a high resistance, the potential of the gate electrode is always equal to the grounded potential, the electric field strength between the recording electrode and the gate electrode is kept constant, and stable toner ejection is performed. To do.

[0011]

According to the present invention, there is provided an electrostatic ink jet recording apparatus comprising: a base film having an insulating property;
A plurality of recording electrodes formed on the surface of the base film, one end of which is formed to protrude from the end of the base film and whose surface is covered with an insulating coating material, and sandwiches the base film so as not to cover the recording electrodes. An upper cover and a lower cover that supply and hold ink containing toner particles by passing the gap between the recording electrodes from the front surface to the back surface of the base film, and the ink at a position upstream of the recording electrode portion in the upper cover. An electrophoresis electrode disposed so as to be in contact with each other, an individual opening at a position corresponding to each of the recording electrodes, formed around the individual opening, and the other end is grounded via a high resistance of 1 MΩ or more . A gate electrode; and a counter electrode disposed at a position facing the gate electrode with the recording medium interposed therebetween.

Further, in the electrostatic ink jet recording apparatus according to the present invention, the gate electrode is connected to a common high resistance of 1 MΩ or more at the other end and is grounded.

[0013]

[0014]

Next, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a perspective view showing an embodiment of the present invention, and FIG. 2 is a plan view (FIG. 2 (a)) and a cross-sectional view taken along line AA (FIG. 2 (b)) of this embodiment.

Referring to FIGS. 1 and 2, an electrostatic ink jet recording apparatus according to this embodiment has a base film 10 having an insulating property, and one end formed on the surface of the base film 10. And a plurality of recording electrodes 2 formed so as to protrude from the ends of the base film 10 and covered with an insulating coating member 17, and the base film 10 is sandwiched between the recording electrodes 2 so as not to cover the recording electrodes 2. Cover 4 and lower cover 3 for supplying and holding ink 16 containing toner particles by passing through the gap between recording electrodes 2 from the back to the back.
And an electrophoretic electrode 11 disposed upstream of the recording electrode 2 in the upper cover 4 so as to be in contact with the ink 16.
A gate electrode 22 having an individual opening at a position corresponding to each recording electrode 2, formed around the individual opening, and the other end of which is grounded via a high resistance 20; And a counter electrode (not shown) disposed at a position facing the gate electrode 22 with the recording medium interposed therebetween.

The substrate 1 is an insulator such as plastic, and supports the base film 10 from the back side. The base film 10 is an insulator such as polyimide, has a thickness of about 50 μm, and has a plurality of recording electrodes 2 integrally formed on the surface thereof.

The recording electrodes 2 are formed by pattern-plating a conductive material such as copper on the base film 10 to a thickness of 20 to 30 μm, and are arranged, for example, at a pitch of 300 dpi, that is, at intervals 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 recording electrode 2 is uniformly covered with an insulating coating member 17 at a tip end surface with a thickness of 10 μm or less. In this embodiment, the base film 10
A tape-shaped recording head having a recording electrode 2 integrally formed thereon is used. Specifically, Tape Automated Bonding
The TAB tape used in the (TAB) technique is used, and the insulating coating member 17 is 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, and the space defined by the base film 10 and the upper cover 4 forms an ink chamber. The ink chamber is filled with ink 16 from the ink supply port 5 to fill the 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 8 is formed. ing. The lower cover 3 is an insulating member, and an ink discharge port 6 (not shown) is processed in advance. The space defined by the base film 10 and the lower cover 3 also forms an ink chamber, and the ink 16 passes from the ink chamber on the side of the upper cover 4 to the space between the recording electrodes 2 and from the vicinity of the ink ejection port 7 via the ink chamber. The ink is forcibly discharged from the ink discharge port 6 together with the surplus toner particles.

The electrostatic ink jet recording apparatus 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 16. . Ink 1
Reference numeral 6 denotes a dispersion of 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 positively charged by the zeta potential.

A migration electrode 11 is formed inside the upper cover 4 so as to be in contact with the ink 16. Electrophoresis electrode 11
A voltage of the same polarity as the potential of the toner is applied, and the toner in the ink 16 supplied from the ink supply port 5 is moved to 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 to the vicinity of the ink ejection port 7 due to the forced ink circulation by the pump, the toner concentration in the vicinity of the ink ejection port 7 due to the electrophoretic movement of the toner is reduced.
8 relatively higher than upstream.

The gate electrode 22 is a conductive substrate material manufactured by electroforming, that is, electroforming, and is disposed between the recording electrode 2 and a counter electrode (not shown).
The orifices 21 are individually located at positions facing each element of
have. Further, the gate electrode 22 has a connection pad 19 to the outside with a high resistance 20 interposed therebetween, and is grounded by connection means (not shown). here,
The diameter D of the orifice 21 individually formed in the gate electrode 22 is desirably the diameter D of the orifice 21 such that the relationship of L / 2 <D <L holds, where L is the distance between the gate electrode 22 and the recording electrode 2. .

The ink 16 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 in the ink chamber 18 and the recording electrodes 2 protrude from the base film 10, the upper cover 4 and the lower cover 3, the ink meniscus 8 is closer to the upper cover 4 when viewed from the side. Has a concave shape obliquely downward, and the lower cover 3 side has a symmetrical shape. Further, since each recording electrode 2 individually protrudes outside the ink ejection port 7, the ink meniscus 8 is formed individually corresponding to each recording electrode 2 when viewed from above.

When the gate electrode 22 is set to zero potential and a high voltage pulse is applied to an arbitrary recording electrode 2, an electric field is concentrated on the tip of the ink meniscus 8 protruding from the recording electrode 2. The charged toner in the ink 16 is applied to the gate electrode 2
Is guided from the tip of the ink meniscus 8 protruding from the tip of the ink meniscus 8, forming a toner group 9, and the individual orifice 2 of the gate electrode 22.
1 and facing the recording electrode 2 and the gate electrode 22
It flies in the direction of a recording medium (not shown), that is, at the same potential or at a lower potential. The toner adhering to the recording medium (not shown) and forming the recording dots is heated by a heater and fixed.

Since the gate electrode 22 is grounded via the high resistance 20, if ink 16 accumulates between the gate electrode 22 and the recording electrode 2 for some reason, the gap between the recording electrode 2 and the gate electrode 22 is lost. Therefore, even if a drive pulse voltage is applied to the recording electrode 2 in this state, no discharge or short circuit occurs between the recording electrode 2 and the gate electrode 22. The high resistance 20 inserted between the gate electrode 22 and the ground depends on the pulse voltage applied to the recording electrode 2, but is preferably about 1 MΩ or more.

The high resistance 20 may be added for each gate electrode 22 or may be added to each gate electrode 22.
May be added in common at the other end.

FIG. 3 is a schematic view of a TAB tape used in the electrostatic ink jet recording apparatus according to this embodiment. A method of manufacturing the TAB tape 12 will be briefly described. Flash plating is performed on a tape-like base film 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. Then, after pattern-plating copper or the like, the base film is etched to form the through holes 14. 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.

[0027]

As described above, the first effect of the electrostatic ink jet recording apparatus of the present invention is that stable flying of toner particles can be obtained. The reason is,
Since the gate electrode was provided between the recording electrode and the counter electrode,
The toner flight is determined by the potential difference between the gate electrode and the recording electrode. Even if the electric field between the recording electrode and the counter electrode changes during the recording operation due to the thickness of the recording medium or the floating of the recording medium during running, the ink jumps. This is because the force acting on the toner inside does not change.

The second effect is that stable recording can be performed. The reason is that the surface potential of the gate electrode can be maintained at the grounded potential even if the ink containing the charged toner flying from the recording electrode adheres to the gate electrode for some reason. Furthermore, even if ink accumulates between the gate electrode and the recording electrode for some reason and connects the recording electrode and the gate electrode, and a driving pulse voltage is applied to the recording electrode in this state, the recording electrode and the gate are not affected. This is because no discharge or short circuit occurs between the electrodes.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an embodiment of the present invention.

FIG. 2 is a plan view (FIG. 2A) and an AA cross-sectional view (FIG. 2B) of this embodiment.

FIG. 3 is a schematic view of a TAB tape used in the electrostatic ink jet recording head of the embodiment.

FIG. 4 is a perspective view of a conventional electrostatic ink jet recording apparatus.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 substrate 2 recording electrode 3 lower cover 4 upper cover 5 ink supply port 6 ink discharge port 7 ink ejection port 8 ink meniscus 9 toner group 10 base film 11 migration electrode 12 TAB tape 13 inner lead section 14 through hole 15 sprocket hole 16 ink 17 Insulating coating member 18 Ink chamber 19 Connection pad 20 High resistance 21 Orifice 22 Gate electrode

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Hitoshi Minemoto 7546 Yasuda, Kashiwazaki-shi, Niigata Niigata Nippon Electric Co., Ltd. (72) Inventor Hitoshi Takemoto 7546 Yasuda, Kashiwazaki-shi, Niigata Inside (72) Inventor Yoshihiro Hagiwara 7546 Yasuda, Kashiwazaki City, Niigata Prefecture Inside Niigata Nippon Electric Co., Ltd. Surveyed field (Int.Cl. ⁶ , DB name) B41J 2/06 B41J 2/385

Claims (2)

(57) [Claims] 1. A base film having an insulating property, a plurality of recording electrodes formed on the surface of the base film and having one end protruding from an end of the base film and covered with an insulating coating material, and the recording electrode; An upper cover and a lower cover for sandwiching the base film so as not to cover an electrode, passing the gap between the recording electrodes from the front surface of the base film to the back surface, and supplying and holding ink containing toner particles, and the lower cover in the upper cover. A migrating electrode disposed so as to be in contact with the ink at a position located upstream of the recording electrode portion, and an individual opening at a position corresponding to each of the recording electrodes, formed around the individual opening, and the other end is formed. a gate electrode via more high resistance 1MΩ is grounded, a position facing the gate electrode across the recording medium Electrostatic inkjet recording apparatus characterized by comprising a disposed a counter electrode. 2. The electrostatic ink jet recording apparatus according to claim 1, wherein the gate electrode is connected to a common high resistance of 1 MΩ or more at the other end and is grounded.