JP3514877B2 - Ink jet 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 ink jet recording apparatus, and in particular, a liquid ink in which a colorant is dispersed in a solvent is used, and the colorant component in this ink is aggregated and ejected onto a recording medium for recording. The present invention relates to an inkjet recording device.

[0002]

2. Description of the Related Art An apparatus for ejecting liquid ink as small droplets called ink particles on a recording medium to form recording dots and recording an image has been put into practical use as an inkjet printer. This ink jet printer has the advantages that it is less noisy than other recording methods and does not require processing such as development and fixing, and is attracting attention as a plain paper recording technology. Many methods of ink jet printers have been devised up to the present, but in particular, (a) a method of ejecting ink droplets by the pressure of steam generated by the heat of a heating element (for example, Japanese Patent Publication Nos. 56-9429 and 61-59).
911) or (b) a method in which an ink droplet is ejected by a mechanical pressure pulse generated by a piezoelectric element.

A recording head used in an ink jet printer is mounted on a carriage and is in a direction (main scanning direction) orthogonal to a recording paper conveyance direction (sub scanning direction).
A serial scanning type head is used in which recording is performed while moving to. It is difficult to increase the recording speed of this serial scanning head. Therefore, a so-called line scanning type head, which can increase the recording speed by using the recording head as a long head having the same size as the width of the recording paper, is also considered, but it is to realize such a line scanning type head. Not easy for the following reasons:

In the ink jet recording system, the concentration and concentration of the ink are likely to occur locally due to the evaporation and volatilization of the solvent, which causes the clogging of individual thin nozzles corresponding to the resolution. Further, in the method of using the pressure of vapor for forming an inkjet, insoluble matter is attached due to a thermal or chemical reaction with the ink, and in the method of using the pressure of a piezoelectric element, complicated ink flow paths and the like are complicated. The structure makes it easier to induce clogging. Line scanning heads that require thousands of nozzles, which are even more numerous than serial scanning heads that use several tens to hundreds of nozzles, are probabilistically clogged at a fairly high frequency and are reliable. It becomes a big problem in terms of sex.

Further, there is a problem that the conventional ink jet recording apparatus is not suitable for improving the resolution. That is, it is difficult to generate ink particles having a diameter of 20 μm or less (which corresponds to a recording dot having a diameter of about 50 and several μm on the recording paper) by the method using the pressure of vapor, and the pressure generated by the piezoelectric element is used. This is because in the method of using, the recording head has a complicated structure, and it is difficult to form a head with high resolution due to processing technology problems.

In order to overcome these drawbacks, an ink jet recording system has been devised in which a voltage is applied to a thin film electrode array and the electrostatic force is used to fly the ink or the colorant component therein from the liquid surface of the ink. Specifically, a method of ejecting ink by using electrostatic attraction (Japanese Patent Laid-Open No. 49-62).
No. 024, JP-A-56-4467, etc.) or a method in which ink containing a charged coloring material component is used to increase the density of the coloring material and fly (WO93 / 11866: PCT / AU92 / 00).
665) and the like have been proposed. In these methods, since the print head configuration is a slit nozzle configuration that does not require a nozzle for each individual dot, or a nozzleless configuration that does not require a partition of an ink flow path for each individual dot, line scanning This is effective in preventing and recovering from clogging, which was a major obstacle in realizing a mold recording head. The latter is particularly suitable for high resolution because it can stably generate and fly ink particles having a very small diameter.

In a conventional ink jet recording apparatus using such a method of flying a coloring material by electrostatic force, a recording head having an electrode array in which electrodes are arranged as described above is used, and a voltage is applied to each electrode of this electrode array. The ink is caused to fly by applying. Particularly, in the latter, when a voltage is applied, the colorant components aggregate, and the colorant components in the ink mainly fly. In this case, since it is not possible to separately control the agglomeration and the flight of the colorant component, in order to agglomerate the colorant component at a high concentration and to fly the agglomerated colorant component, the ink flow velocity and the applied voltage must be delicate. Adjustment is necessary.

Further, when a multi-nozzle head having a plurality of ink ejection ports such as a line scanning type recording head is constructed by using such an electrode array, when the voltage applied to the electrodes is high, electric field interference between adjacent electrodes occurs. It becomes a problem. In order to prevent the electric field interference between the adjacent electrodes, the distance between the recording head and the recording medium may be reduced to lower the applied voltage, but in that case, the electric field for aggregating the coloring material also decreases, There is a problem that the aggregated colorant component cannot be flown.

[0009]

As described above, in the recording head used in the ink jet recording system in which the coloring material component in the liquid ink is jetted by the electrostatic force in the related art, aggregation and flying of the coloring material component in the ink are caused. Since they cannot be separated and controlled, it is necessary to finely adjust the ink flow velocity and applied voltage in order to aggregate the colorant components in a high concentration and to fly the aggregated colorant components. If the distance between the recording head and the recording medium is reduced and the voltage applied to the electrodes is reduced to prevent electric field interference between them, the electric field required for the aggregation of the colorant components decreases, and stable image formation is achieved. There was a problem that it would be difficult. An object of the present invention is to provide an ink jet recording apparatus capable of optimally controlling by separating the aggregation of the colorant component in the ink and the flight onto the recording medium.

[0010]

According to the present invention, a colorant component in an ink in which a colorant charged to a predetermined polarity is dispersed in a solvent is aggregated, and the aggregated colorant component is ejected toward a recording medium. In an ink jet recording apparatus for performing recording by means of an ink jet recording apparatus, an aggregating electrode is provided in the ink transport path, and a DC voltage having the same polarity as the charging polarity of the coloring material is applied between the aggregating electrode and a ground potential point. Accordingly, there is provided an aggregating means for aggregating the colorant component by regulating the flow of the colorant component in the ink by the force of the electric field, and a flying electrode provided separately from the aggregating electrode. It is basically provided with a flying unit that applies a voltage according to an image signal between the electrode and the ground potential point to fly the colorant component aggregated by the aggregating unit toward the recording medium by the force of the electric field. Characterize.

[0011]

[0012]

According to the first aspect, the aggregating means has at least first and second aggregating electrodes provided in the ink transporting path at a predetermined interval in the ink transporting direction, and has a first upstream side in the ink transporting direction . of by applying a charging polarity identical to the polarity of the DC voltage of the colorant in the second coagulation electrode of the ink downstream side aggregation electrode as a reference, the flow of colorant components in the ink by the force of an electric field It is configured to regulate and aggregate the colorant components. The flying means has a flying electrode arranged in the vicinity of the aggregating electrode, and a voltage according to an image signal is applied between the flying electrode and the ground potential point to record the agglomerated colorant component with the force of an electric field. It is configured to fly toward the medium.

The second agglutinating electrode is used as a ground potential point .
By applying a DC voltage having the same polarity as the charging polarity of the colorant to the first aggregation electrode, the colorant component remaining between the first and second aggregation electrodes is caused to flow downstream in the ink transport direction. You may further provide the removal means which conveys to the side and removes.

In the second aspect, the aggregating means has at least one aggregating electrode provided in the ink chamber to which the ink is supplied, and has the same charge polarity of the coloring material between the aggregating electrode and the ground potential point. By applying a DC voltage of polarity to separate the colorant component in the ink from the aggregating electrode by the force of the electric field, the colorant component is aggregated, and the flying means aggregates.
The flying electrode is provided separately from the flying electrode.
Applying a voltage according to the image signal between the electrode and the ground potential point
Then, the colorant component aggregated by the aggregating means is caused to fly toward the recording medium by the force of the electric field.

Here, there may be further provided a collecting means for collecting the ink after the colorant components have been aggregated by the aggregating means , through a recovery port provided in the vicinity of the aggregating electrode.

In the third aspect, the aggregating means has a plurality of aggregating electrodes arranged in the ink chamber to which the ink is supplied, and these aggregating electrodes have the same polarity as the charging polarity of the coloring agent and the application timing. and at least one voltage value is configured to aggregate while transferring the coloring material component in the ink by applying different voltages to the array direction of the aggregated electrode by the force of the electric field, flying means is cohesive electrode A separate flight
An image is provided between the flight electrode and the ground potential point with a flight electrode.
A voltage corresponding to the signal is applied to cause the colorant component aggregated by the aggregating unit to fly toward the recording medium by the force of the electric field.

Further, in the engaged Louis inkjet recording apparatus of the present invention, ejecting unit applies a voltage to the flight electrode for jetting toward the recording medium with a force of an electric field the aggregated coloring material component by agglomeration means At the same time, it is desirable to bring the aggregated coloring material component into contact with the flying electrode.

[0019]

[0020]

As described above, according to the present invention, in the conventional method in which the colorant in the ink is aggregated and ejected, the electric field for aggregating the colorant component in the ink and the electric field for ejecting the aggregated colorant component are the same. In contrast to the generation at the electrode, the aggregation of the colorant component and the flight of the aggregated colorant component are performed separately.

[0021] In particular, for performing the agglomeration and flying color component together with a force of an electric field, it is possible to optimize the voltage and voltage for flight for aggregation, respectively. Therefore, even if the flying voltage is set to a low voltage that can prevent electric field interference between adjacent flying electrodes, the coloring agent component can be aggregated with a sufficiently high aggregation voltage, and a large number of ink ejection ports can be formed. When arrayed to form a multi-nozzle head, excellent recording can be performed without mutual interference between recording image points.

If a high electric field for agglomeration is formed by using a pair of agglomerating electrodes as in the first aspect , these agglomerating electrodes are provided in a flat portion receding from the end face of the head substrate. Therefore, the recording head can be easily realized by a planar process using a photolithography technique which has been conventionally used for IC manufacturing.

Further, by conveying and removing the ink flow by generating an electric field by applying a voltage of aggregation at the opposite aggregated coloring material component remaining after flying a pair of coagulating electrode, By constantly supplying new ink to the recording head, it is possible to prevent image deterioration such as blurring.

In the second aspect , the colorant component can be aggregated by the electrostatic repulsive force of the aggregating electrode while the ink is contained in the ink chamber, and the ink can be jetted by the flying electrode provided in the ink chamber.

In the third mode, the ink after the colorant components are aggregated by the electrostatic repulsion force of the aggregation electrode in this way is collected through the collection port provided in the vicinity of the aggregation electrode, and the color is recovered. Only ink having a low agent concentration can be efficiently recovered.

[0026] By performing the charge injection before flight by the flight electrode in agglutination was coloring material component, it is possible to perform flying color component efficiently at a low flying for a field, i.e. a low voltage.

[0027] be brought into contact with the coloring material component is aggregated with flight Sho electrodes, charge the coloring material components from flying electrode is by being injected, flight of coloring material component made easier.

[0028] By providing a pulse signal voltage controlled in accordance with at least one of the voltage value and pulse width to the image signal to the flight Sho electrode, by controlling the image dot density and image dots size, removing the fog be able to.

[0029]

Embodiments of the present invention will be described below with reference to the drawings. (First Embodiment) FIG. 1 is a sectional view showing the arrangement of a recording head portion of an ink jet recording apparatus according to the first embodiment of the present invention. This example uses an ink in which a coloring material charged to a predetermined polarity is dispersed in a solvent, and the flow of the coloring material component in this ink is regulated by the force of the electric field between the pair of aggregating electrodes to cause aggregation. The aggregating colorant component is caused to fly toward the recording medium by the force of the electric field generated by the flying electrode intersecting the aggregating electrode with the insulating layer sandwiched therebetween.

That is, in this embodiment, a glass layer is applied to the ink transport path 100 for transporting ink 1
An insulating head substrate 101 made of a ceramic substrate or a glass plate having a thickness of about mm is provided. On the head substrate 101, flying electrodes 102 having a width of about 100 μm corresponding to recording dots are perpendicular to the plane of the drawing. It is formed along the direction. 50 μ is on the flying electrode 102.
An insulating layer 104 made of, for example, glass is formed in a thickness of several μm to several tens of μm except for the recording image point forming region 103 having a size of about m.

On the insulating layer 104, a pair of aggregating electrodes 105 and 106 having a gap of about 100 μm for aggregating the charged colorant component in the ink are provided along the direction orthogonal to the flying electrode 102. It is formed. On these aggregating electrodes 105, 106, if necessary, several μm
By covering an insulating film (not shown) such as a SiO ₂ film described below, charge injection from the aggregating electrodes 105 and 106 into the ink solvent is prevented, and at the same time, the aggregating electrode 10 is formed.
Discharge between 5, 106 and the flying electrode 102 is prevented. The thickness of the flying electrode 102 and the aggregating electrodes 105 and 106 is about several thousand angstroms.

Next, the operation of aggregating and flying the colorant components in the ink conveyed to the ink conveying path 100 will be described with reference to FIGS. 1 (a) and 1 (b). FIG. 1A shows a step of aggregating the colorant component in the ink. The ink 107 used here is a colloidal coloring agent in which a pigment and a control agent for positive charging are mixed with a binder in an ink solvent made of insulating kerosene or isoparaffin of 10 ⁸ Ωcm or more which is a kind of petroleum. Dispersed and suspended in
The colorant is charged in a positive polarity. The electrification of the coloring material may be of negative polarity, in which case the electrode 10
The voltages applied to 2, 105 and 106 may all have opposite polarities.

As described above, the ink 107 having the coloring agent charged in the positive polarity in the ink solvent is the ink transport path 10.
0 is carried on the head substrate 101 along the direction of the solid arrow 108 by a constant amount. In order to aggregate the charged colorant components in the ink 107, the aggregation electrode 105 on the upstream side in the transport direction of the ink 107 is set to the ground potential, and the aggregation electrode 1 on the downstream side in the transport direction of the ink 107.
By applying an aggregating voltage of, for example, plus 50 V from the aggregating voltage source 109 to 06, a high electric field (...
2 × 10 ⁴ V / cm) is formed.

Due to the high electric field formed between the aggregating electrodes 105 and 106, the charged coloring material component in the ink 107 is regulated so as to resist the flow of the ink 107, and the aggregating electrode 105 of the flying electrode 102. , 106 in the recording image point forming area 103, they are aggregated as indicated by reference numeral 110. That is, the charged coloring material component 110 in the ink 107 is aggregated by staying in the recording image point forming area 103.
On the other hand, the ink solvent 111 whose colorant concentration has decreased due to the aggregation of the colorant components 110 in this way flows in the direction of the dashed arrow 112 without being obstructed by the electric field.

FIG. 1B shows a step of causing the aggregated colorant component 110 to fly by the force of the electric field. In order to form a strong vertical electric field for flight, both the aggregating electrodes 105 and 106 are set to the ground potential, and the aggregating electrodes 105 and 106 are also set.
In accordance with an image signal from the signal voltage source 113, for example, a plus 2 is applied to the flying electrode 102 provided with the insulating layer 104 interposed therebetween.
A pulse signal voltage of 00V is applied. By applying the pulse signal voltage, the recording image area 103 between the aggregating electrodes 105 and 106 is perpendicular to the head substrate 101,
That is, a high electric field (-10 ⁵⁾ toward the recording medium 116.
(V / cm) is formed, and the colorant component 110 that is positively charged and aggregated becomes flying particles 114 and flies toward the recording medium 116 as indicated by an arrow 115.

The recording medium 116 is, for example, plain paper, and is arranged at a distance of about 100 μm from the flying electrode 102 and the aggregating electrodes 105 and 106 on the head substrate 101, and a counter electrode which also serves as a platen on the back surface thereof. 11
7 are arranged. The counter electrode 117 is grounded, which makes it possible to further stabilize the flight of the coloring material component, which is the flying particles 114. During the flight of the color material component, the flight electrode 102 injects a positive charge into the ink 107 in the recording image area 103, so that the aggregated color material component 110 can fly efficiently. In this way, the image is recorded on the recording medium 116.

As described above, according to this embodiment, the aggregation electrodes 105 and 1 are used to prevent the aggregation of the color component and the flight of the aggregated color component.
06 and the flight electrode 102 are performed separately, the voltage applied by the aggregating voltage source 109 and the signal voltage source 113
Thus, it is possible to optimize the flight signal pulse voltage applied together.

Therefore, even if the flying voltage is set to a low voltage to prevent the electric field interference between the adjacent flying electrodes, the coloring component can be aggregated with a sufficiently high aggregation voltage, which will be described later. When a large number of ink ejection openings are arranged to form a multi-nozzle head as in the first embodiment, good recording without mutual interference between recording image points becomes possible.

(Second Embodiment) FIG. 2 is an exploded perspective view showing an embodiment in which the present invention is applied to a multi-nozzle head in which a plurality of flying electrodes are arranged in an ink transport path.

In this embodiment, an insulating head substrate 101 made of a glass substrate coated with a ceramic substrate or a glass plate having a thickness of about 1 mm is provided, and a width of 100 μm corresponding to a recording dot is provided on the head substrate 101. The flying electrodes 102 are formed along the direction perpendicular to the plane of the drawing. 50 μ is on the flying electrode 102.
An insulating layer 104 made of, for example, glass is formed in a thickness of several μm to several tens of μm except for the recording image point forming region 103 having a size of about m.

On the insulating layer 104, a pair of aggregating electrodes 105, which is a common electrode having a gap of about 100 μm for aggregating the charged coloring material component in the ink, in a direction orthogonal to the flying electrode 102, 106 is formed.
If necessary, an insulating film (not shown) such as a SiO ₂ film having a thickness of several μm or less is coated on the aggregating electrodes 105 and 106 so that the ink solvent from the aggregating electrodes 105 and 106 can be transferred. The charge injection is prevented, and at the same time, the discharge between the aggregating electrodes 105 and 106 and the flying electrode 102 is prevented. Flying electrode 102 and aggregating electrode 1
The thickness of 05 and 106 is about several thousand angstroms.

The recording head is covered with a cover 201 of an ink transport system provided with a gap of about 50 μm. The cover 201 is made of a resin having a dielectric constant similar to that of the ink solvent so as not to disturb the electric field formed by the flying electrode 102 and the aggregating electrodes 105 and 106. The cover 201 is connected to the ink introduction tube 202, and is also provided with an ink supply flow path 205 and an ink recovery flow path 206 formed by a flow path forming projection plate 203 and a projection portion 204 provided on the bottom surface of the cover 201. Have.

An ink recirculation mechanism including a pump (not shown) is connected to the ink introduction tube 202, and a positive pressure is applied by the pump from the ink recirculation mechanism,
Ink is introduced. This ink is supplied to the ink supply channel 20.
5, the recording image point forming area 103 of the flying electrode 102
The ink is supplied to the above, and further, is recovered by the ink recirculation mechanism via the ink recovery channel 206 to which a negative pressure is applied by the pump of the ink recirculation mechanism. In the cover 201, the ink ejection holes 20 are provided at positions corresponding to the recording image point formation area 103.
7 is open.

The end portion of the flying electrode 102 is drawn out of the cover 201 and connected to the signal voltage source 113. On the other hand, the aggregating electrodes 105 and 106 are drawn out from both ends of the head substrate 101 in the longitudinal direction (not shown) and are connected to an aggregating voltage source (not shown).

Next, the operation of this embodiment will be described. The aggregation of the colorant components of the ink and the flight operation of the aggregated colorant components in this example are basically the same as those in the first example. First, the ink in which the colorant component is positively charged is introduced into the ink introduction tube 202. This ink is supplied onto the recording image point forming area 103 of the flying electrode 102 by the ink supply channel 205. This recording image point forming area 10
The ink of No. 3 is aggregated by the high electric field due to the voltage applied between the aggregation electrodes 105 and 106.

In this state, a pulse signal voltage corresponding to an image signal is applied from the signal voltage source 113 to the flying electrode 102, so that a high electric field in the direction perpendicular to the head substrate 101 ( -10 ⁵ V / cm) is formed, and the colorant component that has been positively charged and agglomerated becomes a flying particle, is ejected from the ink ejection port 207, and is arranged at a position above the cover 201 at a distance of about several hundred μm. Flying toward the recorded recording medium. A counter electrode (not shown) serving as a platen is arranged on the back surface of the recording medium. This counter electrode is grounded, which makes it possible to stabilize the flight of the colorant component, which is the flying particle. In this way, the image corresponding to the image signal is recorded on the recording medium.

When the colorant component flies to the recording medium, as in the first embodiment, the flying electrode 102 injects a positive charge into the ink 107 in the recording image area 103.
The flying of the aggregated coloring material component 110 is efficiently performed. In this case, the amount of charge injected into the ink 107 depends on the signal voltage source 11
3 is determined by the magnitude and pulse width of the pulse signal voltage applied to the flying electrode 102. Therefore, the magnitude and / or the pulse width of these pulse signal voltages are changed for each recording dot according to the image signal, and the dot size is changed. Modulation is made possible for gradation recording.

On the other hand, the ink that has passed through the ink supply channel 205 is recovered through the ink recovery channel 206. The ink is regulated by the cover 201, so that the ink supply channel 205 and the ink recovery channel 206 are provided.
Flowing in a layer having a constant thickness of about 50 μm, which enables stable aggregation and flight of the colorant components.

Also in this embodiment, as in the first embodiment, the aggregation of the colorant component and the flight of the aggregated colorant component are individually performed using the aggregation electrodes 105 and 106 and the flight electrode 102. It is possible to optimize both the voltage applied by the aggregating voltage source 109 and the flight signal pulse voltage applied by the signal voltage source 113. Therefore, even if the flying voltage is set to a low voltage to prevent the electric field interference between the adjacent flying electrodes, the colorant component can be aggregated with a sufficiently high aggregation voltage. When a large number of ink ejection ports are arranged in a multi-nozzle head, it is possible to perform good recording without mutual interference between recording image points.

(Third Embodiment) FIG. 3 is a diagram showing a series of recording steps in a third embodiment of the present invention, and the structure of the recording head is the same as that in FIG. In addition, FIG.
The step of aggregating the colorant component and the step of flying the agglomerated colorant component shown in (b) are the same as those in FIGS. 1 (a) and 1 (b). In this embodiment, after the flying process of the aggregated colorant component shown in FIG. 3B, the residual colorant after the flight is removed by an electric field having a polarity opposite to that at the time of aggregation as shown in FIG. 3C. The ink is conveyed together with the ink.

That is, as shown in FIG.
Contrary to the colorant component aggregating step of (a), the aggregating electrode 106 on the downstream side of the ink 107 in the transport direction is set to the ground potential, and the aggregating electrode 10 on the upstream side of the ink 107 in the transport direction.
By applying a peeling voltage of, for example, plus 50 V, which is the same polarity as the charging polarity of the colorant, from the aggregating voltage source 118, a high electric field having a polarity opposite to the aggregating electric field is formed.
Due to this electric field, the residual color material 119 that has not been ejected receives the force in the direction of the arrow 120 and is pushed out together with the ink flow. In this way, the recording image point formation region 103 of the flying electrode 102 is cleaned after each flight of the colorant component, and new ink is always conveyed to the initial state, so that the stable flight of the colorant component is achieved. It can be performed.

FIG. 4 is a diagram showing the timing relationship of the voltage applied to each electrode in this embodiment. (A) is the voltage applied to the aggregating electrode 105, (b) is the aggregating electrode 106.
, (C) shows the signal pulse voltage applied to the flying electrode 102, respectively.

First, at the timing t1, the aggregating electrode 106 is placed.
A voltage of plus 50 V is applied to the electrode 1 and the aggregation electrode 1
05 is set to the ground potential. As a result, an electric field that causes the positively charged coloring material component to exert a force in the direction opposite to the flow of the ink 107 of FIG. 3 on the coloring material component causes the flying electrodes 105 and 106.
A recording image point forming area 1 of the flying electrode 102 formed between
In 03, the colorant component 110 aggregates. The ink solvent after the colorant components have aggregated flows by the above-described ink recirculation mechanism.

Next, at the timing t2, the aggregating electrode 10 is used.
Both 5 and 106 are set to the ground potential, and a signal voltage of 200 V is applied to the flying electrode 102. In this way, the aggregating electrode 10 intersects with the flying electrode 102.
A high electric field in the vertical direction acts on the agglomerated colorant components in the ink between 5, 106, and the agglomerated colorant components fly toward the recording medium. At this time, the charge is directly injected from the flying electrode 102 into the aggregated colorant component, which facilitates the flight. A thin SiO ₂ film is coated on the aggregating electrode 102 to prevent injection of charges of opposite polarity from the flying electrode 102.

Further, at the next timing t3, a voltage of plus 50 V is applied to the aggregating electrode 105 and the aggregating electrode 106 is set to the ground potential, whereby the flying electrode 1
The electric field force in the same direction as the ink flow is applied to the positively charged and agglomerated coloring material component remaining in the recording image point forming area 103 of No. 02 to remove the remaining coloring material component together with the ink flow, and is returned to the initial state at the timing of t4. To do. In this way, it is possible to stably fly the aggregated colorant component and perform recording.

(Fourth Embodiment) FIG. 5 is a sectional view showing the structure of a recording head portion of an ink jet recording apparatus using a magnetic ink as a fourth embodiment of the present invention.

That is, in this recording head, an insulating head substrate 301 made of a ceramic substrate or a glass plate having a glass layer applied to the ink transport path 300 and having a thickness of about 1 mm is provided, and the lower portion of the head substrate 301 is provided. An electromagnet 309 that generates a magnetic field for agglomeration is disposed in the. On the other hand, on the head substrate 301, flying electrodes 302 having a width of about 100 μm corresponding to recording dots are formed along a direction perpendicular to the plane of the drawing. On the flying electrode 302, an insulating layer 304 made of, for example, glass is formed with a thickness of several μm to several tens of μm except for the recording image point forming region 303 having a size of about 50 μm.

On the insulating layer 304, a pair of induction electrodes 305 and 306 having a gap of about 100 μm for aggregating the charged coloring material component in the ink are formed along the direction orthogonal to the flying electrode 302. To be done. The induction electrodes 305 and 306 are covered with an insulating film (not shown) such as a SiO ₂ film having a thickness of several μm or less as necessary, so that the charge from the induction electrodes 305 and 306 to the ink solvent is reduced. At the same time as preventing the injection, the induction electrodes 305, 3
The discharge between 06 and the flying electrode 302 is prevented.
The thickness of the flight electrode 302 and the induction electrodes 305 and 306 is
Thousands of Angstroms.

Next, the operation of aggregating and flying the coloring material components in the ink conveyed to the ink conveying path 300 will be described with reference to FIGS. 5 (a) and 5 (b). FIG. 5A shows a step of aggregating the colorant component in the ink. Ink 307
As the magnetic ink, a magnetic ink in which a magnetic and insulating coloring agent is dispersed and suspended in an ink solvent is used.
By 0, it is carried on the head substrate 301 along the direction of a solid arrow 308 by a constant amount. This magnetic ink 307
The coloring material component inside is regulated so as to resist the flow of the ink 307 by the magnetic field generated by passing a current through the electromagnet 309, and the induction electrodes 305, 3 of the flying electrode 302.
In the recording image point forming area 303 between 06, the images are aggregated as indicated by reference numeral 310. That is, the coloring agent component having magnetism in the magnetic ink 307 is aggregated by staying in the recording image point forming area 303. On the other hand, as described above, the colorant component 310
The ink solvent 311 whose colorant concentration has decreased due to the agglomeration of particles flows in the direction of the broken line arrow 312 without being obstructed by the magnetic field.

FIG. 5B shows a step of causing the aggregated colorant component 310 to fly by the force of the electric field. In order to form a strong vertical electric field for flight, a signal voltage source 313 supplies a voltage of, for example, +200 V to the flight electrode 302 provided with the induction electrodes 305 and 306 and the insulating layer 304 interposed therebetween.
The pulse signal voltage of is applied. By applying the pulse signal voltage, the recording image area 3 between the induction electrodes 305 and 306 is formed.
03, a high electric field in the direction perpendicular to the head substrate 301, that is, in the direction toward the recording medium 316 (-10 ⁵ V / c
m) is formed, and the aggregated colorant component 310 becomes the flying particles 3
It becomes 14 and flies toward the recording medium 316 as shown by an arrow 315.

The recording medium 316 is, for example, plain paper, and the flying electrode 302 and the induction electrode 3 on the head substrate 301.
The counter electrode 317 arranged at a position of about 100 μm from 05, 306 and serving as a platen on the back surface thereof.
Are arranged. During the flight of this colorant component, the magnetic ink 30 is applied to the recording image area 303 by the flying electrode 302.
A high electric field formed in a direction toward the recording medium 316 between the induction electrodes 305 and 306, which are set to the ground potential, in which electric charges are injected into the condensed colorant component 310.
Are repelled, and particles 314 are formed in the direction of the recording medium 316 to efficiently fly. The colorant component remaining on the recording image point formation area 303 after the colorant component has flown is conveyed and removed together with the ink by cutting off the current flowing through the electromagnet 309 and turning off the magnetic field.

In the first to fourth embodiments, the flying electrode and the pair of aggregating electrodes or the inductive electrode have a three-dimensional structure with a thin insulating layer sandwiched between them. The flying electrode and the aggregating electrode or the inducing electrode may be provided on the same head substrate so as to sandwich the electrode or the inducing electrode. Further, the flying electrode may be provided as a common electrode and the aggregating electrode or the induction electrode may be provided as an individual electrode. Further, the ink ejection holes of the cover may not be individually provided for each recording dot but may have a continuous slit shape.

(Fifth Embodiment) FIG. 6 is a sectional view showing the schematic arrangement of an ink jet recording apparatus according to the fifth embodiment of the present invention, and FIG. 7 is a view as seen from the direction of arrow A in FIG. Is. In this example, an ink in which a coloring agent charged to a predetermined polarity was dispersed in a solvent was used, and the flow of the coloring agent component in this ink was regulated by the force of the electric field between the pair of aggregating electrodes to cause aggregation. The aggregating colorant component is caused to fly toward the recording medium by the force of the electric field generated by the flying electrodes intersecting the aggregating electrode with the insulating layer sandwiched therebetween.

In this embodiment, the main ink chamber 401, the low-concentration ink chamber 402, and the high-concentration ink chamber 403 are arranged on the same plane, and the main ink chamber 401 and the low-concentration ink chamber 402 are recovered. The low-concentration ink chamber 402 and the high-concentration ink chamber 403 are connected by the passages 404 and 405, and the transfer passage 406. Further, the main ink chamber 401 and the high-concentration ink chamber 403 are connected by an ink recirculation mechanism having ink supply channels 407 and 408 and pumps 409 and 410.

The main ink chamber 401 is for aggregating and flying the colorant component in the supplied ink, and the aggregating electrode 411 is provided on the inner wall surface of the low concentration ink chamber 402 side. Ink discharge port 4 opened on the opposite side
A flight electrode 415 is provided so as to face 14.

The flying electrode 415 is formed on the insulating substrate 421 provided on the inner wall surface of the main ink chamber 401. As shown in FIG. 7, the insulating substrate 421 has an ink recovery port 4 which is an inlet of recovery channels 404 and 405 connecting the main ink chamber 401 and the low-concentration ink chamber 402.
12, 413 are formed, and the flight electrode 415 is formed on the insulating substrate 421 except for these ink recovery ports 412 and 413.

Next, the operation of this embodiment will be described. The ink used here is a colloidal coloring agent in which a pigment and a control agent for positive charging are mixed with a binder in an ink solvent made of insulating kerosene or isoparaffin of 10 ⁸ Ωcm or more, which is a kind of petroleum. Disperse and float,
The colorant is charged in a positive polarity. The colorant may be charged in a negative polarity, in which case the voltages applied to the aggregating electrode 411 and the flying electrode 415 may be of opposite polarity.

The ink having the coloring agent charged to the positive polarity is supplied from the high density ink chamber 403 to the pumps 409 and 41.
It is supplied to the main ink chamber 401 by the ink supply flow paths 407 and 408 with a positive pressure of zero. In this state, when a positive voltage having the same polarity as the charging polarity of the coloring agent, for example, a voltage of about 1.0 kV DC is applied to the aggregating electrode 411 from the aggregating voltage source 419, the positively charged coloring agent component aggregates. The force of the electric field applied from the working electrode 411, that is, the electrostatic repulsion force, causes the particles to separate from the aggregating electrode 411, thereby causing the particles to aggregate. That is, in the ink in the main ink chamber 401, the concentration of the coloring material is high at a position far from the aggregating electrode 411, and the aggregating coloring material component gathers in the vicinity of the flying electrode 415.

Next, the signal voltage source 42 is applied to the flying electrode 415.
When a pulse signal voltage corresponding to an image signal from 0, that is, a voltage of about 500 V is applied at the timing of forming an image point, the aggregated colorant component existing in the vicinity of the flight electrode 415 is moved by the flight electrode 415. Due to the force of the electric field formed, flying particles 416 become flying particles 416 from the ink ejection port 414 and fly toward the recording medium 417. Recording medium 417
Is made of plain paper, for example, and a counter electrode 418 which also functions as a platen is arranged on the back surface of the plain paper. The counter electrode 418 is grounded, which allows the flying particles 416 to be exposed.
It is possible to stabilize the flight of the colorant component. In this way, the image is recorded on the recording medium 417.

On the other hand, in this way, the coloring material component is contained in the flying electrode 41.
The ink near the aggregating electrode 411 in the main ink chamber 401, whose colorant concentration has become thin by moving to near 5, is
It is discharged from the ink collecting ports 412 and 413 formed so as to be exposed from the aggregating electrode 411 to the low-concentration ink chamber 402 through the collecting channels 404 and 405, and is temporarily stored. The ink having a very low concentration of the colorant component in the low-concentration ink chamber 402 and containing almost only the ink solvent is transported to the high-concentration ink chamber 403 containing a large amount of the colorant through the transport channel 406, and the By being dissolved in the ink in the concentration ink chamber 403, it is concentrated to the same level as the colorant concentration of the ink in the main ink chamber 401. The ink in the high-concentration ink chamber 403 passes through the supply flow paths 407 and 408 which are driven by the pumps 409 and 410, and the main ink chamber 401.
Is supplied to. The ink in the main ink chamber 401 is kept at a constant pressure by pumps 409 and 410.

Although the number of the ink recovery ports, the recovery channels, and the ink supply channels is two in the above embodiment, the number of these is arbitrary and may be one or three or more. (Sixth Embodiment) FIG. 8 is a view showing an aggregating electrode according to a sixth embodiment of the present invention, and is a view seen from the direction of arrow A in FIG. 6 as in FIG. As shown in the figure, in the present embodiment, the aggregation electrodes 422 and 423 are connected to the ink recovery port 41.
It is formed in a concentric shape so as to surround the periphery of 2,413. In other words, in the fifth embodiment, the aggregation electrode 411 is a planar electrode formed in the portion excluding the ink recovery ports 412 and 413, whereas in the present embodiment, a plurality of linear electrodes having different diameters are used. It consists of The other structure is similar to that of the fifth embodiment.

Although the number of the aggregating electrodes is two in this embodiment, it may be one or three or more. Further, although the concentric agglomeration electrodes have three layers, they may have two layers or four layers or more, and may have a single ring shape instead of the concentric circle shape.

Also in this embodiment, the aggregation electrodes 422,
By applying a voltage having the same polarity as the charging polarity of the coloring material to 423,
By causing the colorant components around the aggregating electrodes 422 and 423 in the main ink chamber 401 to move away from the aggregating electrodes 422 and 423 by electrostatic repulsion, a high-concentration colorant component is aggregated near the flying electrodes. The flying electrodes can fly toward the recording medium.

Further, in this embodiment, the ink recovery port 412,
Aggregating electrodes 422, 42 provided only around 413
3, the colorant component in the ink around the ink recovery ports 412 and 413 is efficiently electrostatically repelled by the aggregating electrode 42.
Since the ink recovery ports 412 and 413 can be kept away from the ink collecting ports 412 and 423, it can be expected that the coloring agent components can be prevented from being retained and blocked in the vicinity thereof.

(Seventh Embodiment) FIG. 9 is a diagram showing the structure of the aggregating electrode in the seventh embodiment of the present invention.
(A) is a side sectional view of the ink chamber 401, and (b) and (c) are plan views of the bottom of the ink chamber 401. Note that (b) is a single nozzle head having one ink ejection port, and (c) is a plurality of ink ejection ports arranged in a direction perpendicular to the paper surface of the drawing of (a), that is, in the vertical direction of (c). This is an example in the case of a provided multi-nozzle head.

In this embodiment, as shown in FIG. 9, on the insulating substrate 501 provided at the bottom of the ink chamber 401,
The plurality of aggregating electrodes 511 to 515 are connected to the ink recovery port 41.
It is arranged in the direction from 2, 413 toward the flight electrode 415. Regarding the shapes of the aggregating electrodes 511 to 515, in the case of the single nozzle head of FIG. 9B, it is preferable that the aggregating electrodes 511 to 515 have a semi-arcuate shape with an appropriate curvature centered on the flying electrode 415. In the case of a multi-nozzle head, parallel straight lines are preferable. Other configurations are the fifth
It is similar to the embodiment of.

FIGS. 10 (a), (b) and (c) are various examples of voltage waveforms applied to the aggregating electrodes 511 to 515,
A, B, C, D and E are aggregation electrodes 511 and 51, respectively.
It is a voltage waveform applied to 2,513,514,515.

In FIG. 10A, a pulse voltage having the same pulse width is sequentially applied to the flying electrode 415 from the furthest position aggregating electrode 511 to the aggregating electrode closer to the flying electrode 415 with the same pulse width. In the example (b), the rising timing is sequentially shifted from the aggregation electrode 511 farthest from the flying electrode 415 to the aggregation electrode closer to the flying electrode 415, and the same pulse voltage is applied to the falling timing. , (C) is a flight electrode 415.
From the aggregation electrode 511 farthest to the flying electrode 41
5 is an example in which a voltage whose voltage value gradually decreases is applied toward the aggregation electrode closer to 5. 10 (a) (b) (c)
In any of the above cases, the polarity of the applied voltage is the same as the charging polarity of the colorant component.

As described above, when the voltages whose timings or voltage values are out of phase are sequentially applied to the aggregating electrodes 511 to 515, the colorant components in the ink in the main ink chamber 401 are sequentially received from the aggregating electrodes 511 to 515. Due to the electrostatic repulsive force, the colorant components are aggregated while being transported toward the flight electrode 415, and the aggregated colorant components are collected in the vicinity of the flight electrode 515.

Next, when a pulse signal voltage of, for example, about 500 V is applied to the flying electrode 415 at the timing at which an image point corresponding to the image signal is to be formed, the aggregated colorant components existing in the vicinity of the flying electrode 415 are removed. By the force of the electric field formed by the flying electrode 415, the flying particles become flying particles from the ink ejection port 414 and fly toward the recording medium. In this way, the image is recorded on the recording medium. Other operations are
The description is omitted because it is similar to the fifth embodiment.

According to this embodiment, a plurality of aggregation electrodes 51 are used.
1 to 515 cause the colorant component to be aggregated while being sequentially transferred toward the flying electrode 515, so that the colorant component can be aggregated more effectively than in the fifth and sixth embodiments.

[0082]

As described above, according to the present invention, it is possible to separate and optimally control the aggregation of the colorant component and the flight to the recording medium. In addition, the aggregated colorant component can be efficiently ejected toward the recording medium.

Further, particularly when a multi-nozzle head having a plurality of ink ejection ports is constructed, the flying voltage is lowered by reducing the distance between the recording head and the recording medium in order to prevent electric field interference between adjacent electrodes. However, because the aggregation voltage required for aggregation of the colorant components can be set separately from this,
The colorant component can be effectively aggregated.

[Brief description of drawings]

FIG. 1 is a cross-sectional view for explaining a configuration of a recording head and an aggregation / flying operation of a colorant component in an inkjet recording apparatus according to a first embodiment of the present invention.

FIG. 2 is an exploded perspective view showing a configuration of a recording head in an inkjet recording apparatus according to a second embodiment of the present invention.

FIG. 3 is a cross-sectional view for explaining a configuration of a recording head in an inkjet recording apparatus according to a third exemplary embodiment of the present invention, an operation of aggregating / flying a colorant component, and a residual colorant component removing operation.

FIG. 4 is a diagram showing a timing relationship of applied voltages to each electrode for explaining the operation of the embodiment.

FIG. 5 is a cross-sectional view for explaining a configuration of a recording head and an aggregation / flying operation of a colorant component in an inkjet recording apparatus according to a fourth embodiment of the present invention.

FIG. 6 is a sectional view showing a schematic configuration of an inkjet recording apparatus according to a fifth embodiment of the present invention.

FIG. 7 is a diagram showing a configuration of an aggregating electrode in the same example.

FIG. 8 is a diagram showing the structure of an aggregating electrode according to a sixth embodiment of the present invention.

FIG. 9 is a cross-sectional view and a plan view showing the configuration of the main part of an inkjet recording apparatus according to a seventh embodiment of the present invention.

FIG. 10 is a diagram showing a timing relationship of applied voltages to the aggregating electrode in the example.

[Explanation of symbols]

100 ... Ink transport path 101 ... Head substrate 102 ... Flying electrode 103 ... Recording image point forming area 104 ... Insulating layer 105, 106 ... Electrodes for aggregation 107 ... Ink 109 ... Voltage source for aggregation 110 ... Aggregated color component 111 ... Ink solvent 113 ... Signal voltage source 114 ... Flying particles 116 ... Recording medium 117 ... Counter electrode 118 ... Voltage source for removing residual colorant 119 ... Residual colorant 201 ... Cover 202 ... Ink supply pipe 205 ... Ink supply channel 206 ... Ink recovery channel 207 ... Ink ejection port 300 ... Ink transport path 301 ... Head substrate 302 ... Flying electrode 303 ... Recording image point forming area 304 ... Insulating layer 305, 306 ... Aggregation electrode 307 ... Ink 309 ... Electromagnet 310 ... Aggregated color component 311 ... Ink solvent 313 ... Signal voltage source 314 ... Flying particles 316 ... Recording medium 317 ... Counter electrode 401 ... Main ink chamber 402 ... Low density ink chamber 403 ... High-density ink chamber 404, 405 ... Recovery flow path 406 ... Transport channel 407, 408 ... Ink supply channel 409, 410 ... Pump 411 ... Electrode for aggregation 412, 413 ... Ink recovery port 414 ... Ink ejection port 415 ... Flying electrode 416 ... Flying particles 417 ... Recording medium 418 ... Counter electrode 419 ... Voltage source for aggregation 420 ... Signal voltage source 421 ... Insulating substrate 422, 423 ... Aggregating electrode 501 ... Insulating substrate 502 ... Ink supply port 511-515 ... Electrodes for aggregation

Front page continuation (72) Inventor Yasuo Hosaka 1 Komukai Toshiba-cho, Saiwai-ku, Kawasaki-shi, Kanagawa Toshiba Research & Development Center Co., Ltd. (72) Inventor Shuzo 1 Komukai-shiba-cho, Kawasaki-shi, Kanagawa Prefecture 1-shares Company Toshiba Research & Development Center (72) Inventor Kazushi Nagato 1 Komukai Toshiba Town, Saiwai-ku, Kawasaki City, Kanagawa Prefecture Toshiba Research & Development Center Co., Ltd. (72) Koichi Ishii 1 Komukai Toshiba Town, Kawasaki City, Kanagawa Prefecture Address In Toshiba Research and Development Center (72) Inventor Hideyuki Nakao 1 Komukai Toshiba-cho, Sachi-ku, Kawasaki-shi, Kanagawa Inside Toshiba Research and Development Center (72) Inventor Teruo Murakami Toshiba Komukai-Toshi, Kawasaki-shi, Kanagawa No. 1 in the town, Toshiba Research & Development Center Co., Ltd. (56) References JP-A-2-235755 (JP, A) JP-A-54-85031 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) B41J 2/06

Claims (7)

(57) [Claims] 1. An ink jet recording apparatus for performing recording by aggregating a colorant component in an ink in which a colorant charged to a predetermined polarity is dispersed in a solvent and flying the aggregated colorant component toward a recording medium. And having an aggregating electrode provided in the ink transport path,
Between the aggregating electrode and the ground potential point, the same polarity as that of the colorant is used.
By applying a unipolar DC voltage, the flow of the colorant component in the ink is regulated by the force of the electric field to agglomerate the colorant component, and the aggregating electrode is provided separately for the flight electrode. With electrodes
The image signal between the flying electrode and the ground potential point.
An ink jet recording apparatus comprising: a flying unit that causes a colorant component aggregated by the aggregating unit to fly toward a recording medium by the force of an electric field when a voltage is applied . 2. An inkjet recording apparatus for recording by aggregating a colorant component in an ink in which a colorant charged to a predetermined polarity is dispersed in a solvent and flying the aggregated colorant component toward a recording medium. And having at least first and second aggregating electrodes provided at predetermined intervals along the ink transport direction in the ink transport path, and grounding the first aggregating electrode upstream of the ink transport direction.
By applying a DC voltage having the same polarity as the charging polarity of the coloring material to the second aggregation electrode on the downstream side in the ink transport direction as a potential point , the flow of the coloring material component in the ink is regulated by the force of the electric field. An aggregating means for aggregating the colorant component, and a flying electrode arranged in the vicinity of the aggregating electrode,
And a flying unit for flying the colorant component aggregated by the aggregating unit toward the recording medium by the force of the electric field by applying a voltage according to an image signal between the flying electrode and the ground potential point. An inkjet recording device characterized by the above. 3. The second aggregating electrode is used as a ground potential point, and a direct current voltage having the same polarity as the charging polarity of the colorant is applied to the first aggregating electrode to obtain the first aggregating electrode . 1st and 2nd
3. The inkjet recording apparatus according to claim 2 , further comprising a removing unit that conveys and removes the coloring material component remaining between the aggregating electrodes to the downstream side in the ink conveying direction. 4. An ink jet recording apparatus for recording by aggregating a colorant component in an ink in which a colorant charged to a predetermined polarity is dispersed in a solvent and flying the aggregated colorant component toward a recording medium. There is an ink chamber to which the ink is supplied, and at least one aggregating electrode provided in the ink chamber, and the same polarity as the charging polarity of the coloring agent is provided between the aggregating electrode and a ground potential point. An aggregating means for aggregating the colorant component by applying a DC voltage to move the colorant component in the ink away from the aggregating electrode by the force of the electric field, and a flying electrode provided separately from the aggregating electrode. Have
The image signal between the flying electrode and the ground potential point.
An ink jet recording apparatus comprising: a flying unit that applies a voltage to fly the colorant component aggregated by the aggregating unit toward a recording medium by the force of an electric field. By 5. Before SL agglomeration means and characterized in that the ink after aggregating the color material component further comprising collecting means for collecting through the recovery port provided in the vicinity of said aggregate electrodes
The inkjet recording device according to claim 4 . 6. An inkjet recording apparatus for recording by aggregating a colorant component in an ink in which a colorant charged to a predetermined polarity is dispersed in a solvent and flying the aggregated colorant component toward a recording medium. There is an ink chamber to which the ink is supplied , and a plurality of aggregating electrodes arranged in the ink chamber,
By applying a voltage having the same polarity as the colorant charging polarity and different at least one of the application timing and the voltage value to these aggregating electrodes, the colorant component in the ink is applied by the force of the electric field to the aggregating electrode. And a flying electrode provided separately from the aggregating electrode.
The image signal between the flying electrode and the ground potential point.
An ink jet recording apparatus comprising: a flying unit that applies a voltage to fly the colorant component aggregated by the aggregating unit toward a recording medium by the force of an electric field. 7. The flying means applies a voltage to a flying electrode for flying the colorant component aggregated by the aggregating means toward a recording medium by the force of an electric field, and at the same time, the flying electrode is aggregated. was by contacting the coloring material component, the ink jet recording apparatus according to any one of claims 1 to 6, characterized in that the charge injection into aggregated coloring material component.