JP2885748B2 - 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 discharges toner particles by electrostatic force to perform recording on a recording medium.

[0002]

2. Description of the Related Art The non-impact recording method is excellent in that the generation of noise during recording is negligibly small, and has attracted particular interest in recent years. Among these recording methods, the ink jet recording method has an advantage that high-speed recording can be directly performed on a recording medium with a simple mechanism, and plain paper can be used as the recording medium, which is simple.

Various methods have been proposed as ink jet recording methods. One of them is to provide a plurality of recording electrodes on the front surface of the recording paper and one counter electrode on the back surface. The electrostatic force of the electric field generated when a voltage is applied between the plurality of recording electrodes and the counter electrode, such as ink There is an electrostatic ink jet recording method for recording by flying a color material. In this method, an ink in which charged toner particles are contained in a carrier liquid which is an insulating solvent is used.

A conventional recording head based on the electrostatic ink jet recording method will be described with reference to FIGS. FIG.
Is a perspective view showing a main part of a conventional recording head, and FIG.
FIG. 12 is an enlarged plan view showing the vicinity of the ink ejection port in FIG. 10, and FIG. 12 is a cross-sectional view taken along line XII-XII in FIG. The recording head includes a substrate 11 made of an insulator such as glass, and an upper cover 14 facing the substrate 11. A plurality of recording electrodes 12 are arranged on the surface of the substrate 11 in a direction perpendicular to the ink ejection direction. It is arranged in.

The plurality of recording electrodes 12 are formed by patterning a conductive material such as chromium sputtered on the entire surface of the substrate 11 by photolithography.
It is provided at a pitch of 00 dpi, that is, at an interval of about 85 μm.
The plurality of recording electrodes 12 are connected to a drive driver (not shown) provided on the printer main body side, and a high voltage pulse is selectively applied at the time of recording. A plurality of meniscus forming members 18 are arranged between the substrate 11 and the upper cover 14 so as to correspond to the recording electrodes 12. The meniscus forming member 18 is provided to form an ink meniscus 28 in the vicinity of the front end thereof, and is provided at a position slightly retreated from the front end of the recording electrode 12 so as to overlap with each recording electrode 12. The meniscus forming member 18 is formed by a photolithography method from a photosensitive polymer film laminated on the substrate 11. The thickness of the photosensitive polymer film is 30 μm, and the width of the meniscus forming member 18 is also about 30 μm.

The top end of the upper cover 14 is located further back than the front end of the meniscus forming member 18.
The upper cover 14 is made of an insulating material, and the upper cover 1
4 is provided with an ink supply port 15 and an ink discharge port 16. Between the substrate 11 and the upper cover 14 are formed slit-shaped ink discharge ports 17 partitioned by the recording electrodes 12 and the meniscus forming member 18. The rear end of the meniscus forming member 18 has the upper cover 1.
4 and form an ink flow path while supporting the upper cover 14 from below. An ink chamber 20 is formed by the rear end surface of the meniscus forming member 18, the substrate 11 and the upper cover 14. Behind the ink chamber 20, the electrophoresis electrode 2
1. A counter electrode 13 is provided on the back surface of the recording paper 25, respectively. The toner particles in the ink move due to the electrophoretic force of the electric field generated between the opposing electrode 13 and the migrating electrode 21, and concentrate near the tip of the meniscus forming member 18.

At the time of printing, a pulse voltage is selectively applied to the corresponding recording electrode 12. An electric field is generated from the recording electrode 12 toward the counter electrode 13, and an ink droplet 26 containing toner particles is discharged from the ink discharge portion near the tip of the meniscus forming member 18 toward the counter electrode 13, and is discharged onto the recording paper 25. Printing is performed.

[0008]

In the above-described conventional recording head, the recording electrode 12 is formed by patterning a conductive material sputtered on the entire surface of the substrate 11 by photolithography, and the recording electrode 12 is laminated on the substrate 11. The meniscus forming member 18 is formed by processing the resulting photosensitive polymer film by a photolithography method. These complicated steps make it difficult to reduce the manufacturing cost of the recording head.

In the above-mentioned conventional recording head, the ink discharge port 17 is formed as an extremely small slit in communication with the ink chamber 20. In the vicinity of the discharge port 17, the ink flow is suppressed low, and the ink overflows. Has been prevented. For this reason, at a position where the frequency of ink ejection is low in each of the ink ejection ports 17, the concentration of toner particles becomes excessively high due to excessively concentrated toner particles, and the viscosity of the ink rises. As a result, the printing quality of the recording paper 25 may be reduced.

In view of the above, it is an object of the present invention to provide an electrostatic ink jet recording head having a simple structure which can be manufactured at low cost. Still another object of the present invention is to provide an electrostatic ink jet recording head capable of obtaining good recording quality by stably supplying toner particles to an ink discharge section.

[0011]

In order to achieve the above object, an electrostatic ink jet recording head of the present invention supplies an ink containing charged toner particles in an insulating solvent from an ink tank, and supplies the ink to the ink. An electrostatic ink jet recording head that applies an electric field to the toner and discharges toner particles from an ink discharge unit by an electrostatic force generated, the head having an ink discharge unit and defining an ink chamber in which ink circulates between the ink tank and the ink tank A head block having a block main body and a base film supported by the head block main body, the base film having an opening in the ink ejection portion and having a plurality of protrusions protruding in a serrated shape from one edge of the opening into the opening. It is characterized by the following.

In the electrostatic ink jet recording head of the present invention, the main part of the recording head can be constituted by holding the base film provided with the serrated ink ejection projections on the head block main body. The process is simplified, and the manufacturing cost can be reduced.

Here, in the electrostatic ink jet recording head of the present invention, a plurality of recording electrodes are formed on the base film, and each of the plurality of recording electrodes passes through the plurality of protrusions and faces an edge. Is preferably bridged over the other edge of the slab. In this case, the ink can be smoothly circulated via each projection and the recording electrode,
Excess toner particles and counter ions are forcibly discharged from the vicinity of the recording electrode, and the toner particle concentration can be kept stable.

[0014]

The present invention will be described in more detail with reference to the drawings. FIG. 1 is a perspective view showing an electrostatic ink jet recording head according to an embodiment of the present invention. FIG.
It is a perspective view shown in the state where B tape was removed. The recording head 24 includes a head block 22 and a head block 2.
The head block 22 includes a head block main body 30 and a T block supported by the head block main body 30.
AB tape 40.

The ink jet printer equipped with the recording head 24 is provided with an ink tank (not shown) for storing an ink 34 (FIG. 5) containing charged toner particles in an insulating solvent. The ink tank communicates with a later-described ink chamber 33 provided in the recording head 24 via a tube. By providing a head difference of about 1 cmH ₂ O between the ink tank and the ink chamber 33, the ink 34 is forcibly circulated. Ink 3
No. 4 is produced by dispersing a charge control agent and colored thermoplastic resin fine particles (so-called toner particles) in a petroleum organic solvent (isoparaffin). The toner particles are made positive by the zeta potential. It has an apparent charge.

As shown in FIGS. 1 and 2, the head block main body 30 of the head block 22 is made of an insulating material such as plastic having a substantially quadrangular prism shape. It protrudes and forms a ridge extending in the horizontal direction. A first surface 30a that faces obliquely downward and a second surface 30b that faces obliquely upward extend from the protruding ridge, and an ink discharge portion of the ink chamber 33 is opened at a part of the ridge.

FIG. 3 is a plan view showing a TAB tape, and FIG.
FIG. 5 is an enlarged plan view showing the vicinity of an ink ejection portion formed by a TAB tape. FIG. 5 is a side view of the head block shown in FIG. 1 cut along a virtual plane A (FIG. 1) perpendicular to the ridge. FIG. 6 is a cross-sectional view taken along the line VI-VI of FIG. 5, and FIG. 7 is a schematic side view showing a state of an electrostatic potential by the recording head.

As shown in FIG. 2 and FIG.
At the rear end, a single electrophoresis electrode 39 is fixed in a state parallel to the ridge. The migrating electrode 39 applies a migrating voltage to the ink 34 to collect and concentrate the toner particles in the ink 34 by an electrophoretic phenomenon, and supplies the toner particles to the vicinity of the ink ejection unit. An ink supply port 36 and an ink discharge port 3 communicating with the ink tank are provided on the upper and lower surfaces of the head block body 30.
5 are formed. The ink chamber 33 has an ink inlet 36b communicating with an ink supply port 36 via an ink inflow path 36a, and an ink outlet 35 having an ink outlet 35.
and an ink outlet 35b communicating through a. The ink 34 is supplied from the ink tank to the ink supply port 3.
6, ink inflow path 36a, ink intake port 36b, ink chamber 33, ink outflow port 35b, ink outflow path 35a,
And, it circulates through the ink discharge port 35.

The head block body 30 has a first surface 30
a from the TAB (Tape Automated
Tape material (base film,
Hereinafter, referred to as a TAB tape) 40.
The TAB tape 40 is made of an insulating material such as polyimide having a rectangular shape as a whole, is formed to a thickness of about 50 μm, and has a first surface 3 of the head block body 30.
A first surface 40a corresponding to 0a and a second surface 40b corresponding to the second surface 30b are provided. The TAB tape 40 has a substantially rectangular opening 41 corresponding to the ink ejection port in a state where the TAB tape 40 is attached to the head block main body 30 and along a folding line Fo between the first surface 40a and the second surface 40b. Are formed.

At the edge of the opening 41 on the second surface 40b side, eight ink ejection projections 4 protruding into the opening 41 in a sawtooth shape.
2 are formed at a pitch corresponding to the resolution. Each of the protrusions 42 is formed by the TAB tape 40 on the head block body 30.
When bent at a position facing the ink chamber 33, the protruding portion of the head block body 30
To define the ejection position in the ink ejection section 37.

On the back surface of the TAB tape 40, each protrusion 42
, Eight recording electrodes 43 are formed integrally in the longitudinal direction of the TAB tape 40. 8 recording electrodes 4
3 is a conductive material such as copper on the TAB tape 40
They are pattern-plated with a thickness of 30 μm, and are arranged, for example, at a pitch of 300 dpi, that is, at intervals of about 85 μm. The eight recording electrodes 43 are bridged from one edge of the opening 41 to the other edge via the tips of the eight projections 42, respectively. Each recording electrode 43 has T
The AB tape 40 is alternately drawn out to the first surface 40a side and the second surface 40b side, and is connected to a drive driver via external electrodes. From the side edge of the first surface 40a to the second surface 40b
The four recording electrodes 43 extending upward are bridged from the side edge of the first surface 40a to the edge of the second surface 40b, and come into contact with every other eight projections 42. The four recording electrodes 43 extending from the side edge of the second surface 40b onto the first surface 40a
After the recording electrodes 43 from the side of the surface 40a contact the remaining four protrusions 42 that do not contact, the edge of the second surface 40B side to the first surface 4
It is bridged over the edge of Oa and is adhered on the first surface 40a.

The whole of the eight recording electrodes 43 including the bridge-shaped portion corresponding to the opening 41 is covered with an insulating coating member 45 formed by chemical vapor deposition of parylene resin, and is subjected to insulation treatment. In particular, the surface of the bridge-like portion of the recording electrode 43 is uniformly covered with an insulating coating member 45 having a thickness of about 10 μm or less, and is reliably insulated from the ink 34 that comes into contact. Further, when the TAB tape 40 is bent at the bending line Fo and attached to the head block main body 30, the bridge-shaped portion forms a bow shape from both edges of the opening 41 as shown in FIG. 5. It can be extended linearly without any.

In the electrostatic ink jet recording head having the above structure, when a voltage having the same polarity as the potential of the toner particles is applied to the migration electrode 39, an electric field from the migration electrode 39 to the counter electrode 32 is formed in the ink chamber 33. Occur. This electric field causes the toner particles in the ink 34 to move to the ink ejection unit 37 at an electrophoretic speed corresponding to the electric field. As a result, the ink 34 forms a meniscus 38 due to surface tension at the tip of the projection 42, so that the vicinity of the ink ejection unit 37 is always wet with the ink 34. This phenomenon is caused by the opening 4
A plurality of protrusions 42 corresponding to each recording electrode 43 are formed at one edge of the ink tank 3 and the ink tank 3 and the ink chamber 3.
This is caused by the fact that the ink 34 has an ink flow in the direction of the arrow 44 (FIG. 5) having a constant flow velocity due to the head difference between the ink flow rate and the ink flow rate.

The toner particles are supplied to the vicinity of the recording electrode 43 by forcible ink circulation by a pump. The toner particles further move due to the electrophoresis phenomenon, and the toner particle concentration in the vicinity of the ink ejection unit 37 is changed to the ink chamber 3.
3 is relatively higher than the toner particle concentration of the ink 34 on the inflow side. Counter ions having a charge having a polarity opposite to that of the toner particles are generated with the movement of the toner particles due to the electrophoresis phenomenon, move in the opposite direction to the toner particles, and are adsorbed on the migration electrode 39.

When a high-voltage pulse voltage having a predetermined width is applied to a specific recording electrode 43 in a state where an electric field is generated from the migrating electrode 39 toward the counter electrode 32, the electric field density around the ink ejection section 37 sharply increases. Increase. As a result, electrostatic force acts on the toner particles, and the toner particles move to and concentrate on the tip of the ink meniscus 38 due to the electrostatic force. After this,
The electrostatic force on the toner particles overcomes the surface tension and the viscous force of the ink meniscus 38 of each projection 42, so that the minute flying particles 47 including the toner particles face each projection 42 at a timing synchronized with the applied voltage. Electrode 3
Fly towards 2. From the ink tank to the ink chamber 33
The above operation is repeated while the ink 34 containing the excess toner particles is forcibly returned to the ink tank, and an image based on the print data is printed on the recording paper 25. You. This printed image is heated by the heater and fixed on the recording paper 25.

In the present recording head 24, the serrated projection 42
And a plurality of recording electrodes 43 are connected to a plurality of protrusions 42.
TAB tape 40 provided in the form of a bridge corresponding to
Is simply held in the head block body.
4 can be constituted. Therefore, the manufacturing process of the recording head 24 is simplified, and the manufacturing cost can be reduced. Further, since the ink 34 smoothly circulates through each projection 42 and the recording electrode 43, surplus toner particles and counter ions are forcibly discharged from the vicinity of the recording electrode 43, and the toner particle concentration is stably maintained. Can be kept.

FIG. 7 is a schematic side view showing the distribution of the electrostatic potential generated by the present recording head, and FIG. 8 shows a recording head of a comparative example in which the front portion of the ink chamber of the recording electrode has a gentler arc shape. FIG. 9 is a schematic side view showing the distribution of the electrostatic potential generated in the recording head of FIG. Other parts and elements in the recording head of FIG.
This is the same as the recording head in this embodiment.

As shown in FIG. 7, the present recording head 24
Since the TAB tape 40 is bent at one edge of the opening, and the acute projection 42 protrudes from the bent portion, when a voltage is applied to the recording electrode 43, the recording electrode 43
The electrostatic potential between the electrode and the opposing electrode 14 becomes denser on the protrusion 42 side, and becomes sparser toward the opposing electrode 32. On the other hand, in the recording head of the comparative example shown in FIG. 8, the electrostatic potential between the recording electrode 53 and the counter electrode 32 is reduced by the recording electrode 53 having a gentle arc shape at the ink ejection portion, as shown in FIG. As shown in (2), the distribution is substantially uniform both on the ink discharge unit side and on the counter electrode 32 side.

As can be understood from the comparison result between FIG. 7 and FIG. 9, in a recording head having an arcuate shape at the ink ejection portion, electric field concentration required for ink ejection hardly occurs at the ejection position. High voltage is required. Opening 4
There is also a problem that the arc-shaped recording electrode 53 formed in No. 1 has low mechanical strength. On the other hand, in the present recording head 24, the ink discharge position is clear, an electric field concentration required for ink discharge occurs, and the print head 24 can be driven at a practical low voltage, so that it can be manufactured at low cost. Further, the recording electrode 43 is linearly passed through the inside of the opening 41 and the mechanical strength at the ejection position is increased, so that the reliability is high.

Although the present invention has been described based on the preferred embodiment, the electrostatic ink jet recording head of the present invention is not limited to the configuration of the above-described embodiment, but is limited to the above-described embodiment. An electrostatic ink jet recording head obtained by making various modifications and changes from the configuration of the example is also included in the scope of the present invention.

[0031]

As described above, in the electrostatic ink jet recording head of the present invention, serrated ink ejection projections are provided, and a plurality of recording electrodes correspond to the plurality of ink ejection projections. The main part of the recording head can be constituted only by holding the base film provided in the head block main body in a bridge shape, so that the production process of the recording head is simplified and the production cost can be reduced.

[Brief description of the drawings]

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

FIG. 2 is a perspective view showing a head block of the recording head in a state where a TAB tape is removed from a head block main body.

FIG. 3 is a plan view showing a TAB tape.

FIG. 4 is an enlarged plan view showing the vicinity of an ink ejection portion formed by a TAB tape.

FIG. 5 is a cross-sectional view of the head block in FIG. 1 cut from a virtual plane A orthogonal to the ridge and viewed from the side.

FIG. 6 is a sectional view taken along the line VI-VI of FIG. 5;

FIG. 7 is a schematic side view showing a distribution of an electrostatic potential generated by the recording head.

FIG. 8 is a cross-sectional view illustrating a recording head of a comparative example in which the front portion of the ink chamber is formed in an arc shape.

FIG. 9 is a schematic side view showing a distribution of an electrostatic potential generated in the recording head of FIG.

FIG. 10 is a perspective view showing a main part of a conventional recording head.

FIG. 11 is an enlarged plan view showing the vicinity of an ink ejection port shown in FIG. 10;

FIG. 12 is a sectional view taken along the line XII-XII of FIG. 11;

[Explanation of symbols]

 Reference Signs List 22 head block 24 electrostatic ink jet recording head 25 recording paper (recording medium) 30 head block main body 32 counter electrode 33 ink chamber 34 ink 40 TAB tape (base film) 41 opening 42 ink ejection projection (projection) 43 recording electrode 45 Insulating coating material

──────────────────────────────────────────────────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-shi, Niigata Prefecture Inside Niigata Nippon Electric Co., Ltd. Inventor Tomoya Saeki 7546 Yasuda, Kashiwazaki-shi, Niigata Prefecture Niigata Nippon Electric Co., Ltd. (58) Field surveyed (Int.Cl. ⁶ , DB name) B41J 2/06

Claims (2)

(57) [Claims] An electrostatic ink jet that supplies an ink containing charged toner particles in an insulating solvent from an ink tank, applies an electric field to the ink, and discharges the toner particles from an ink discharge unit by generated electrostatic force. In the recording head, a head block main body having an ink discharge section and defining an ink chamber in which ink circulates between the ink tank and an ink discharge section having an opening supported by the head block main body and having an opening in the ink discharge section. An electrostatic ink jet recording head, comprising: a head block having a plurality of projections protruding into an opening from one edge into an opening and a base film having a plurality of recording electrodes. 2. The method according to claim 1, wherein the plurality of recording electrodes are bridged to the other edge of the opening facing the one edge via the plurality of projections, respectively. Electrostatic ink jet recording head.