JPH0911475A - Ink jet recorder - Google Patents

Abstract

PURPOSE: To provide an ink jet recorder capable of improving a recording speed and always obtaining stable excellent recording image. CONSTITUTION: Ink 10 is supplied from an ink supply pipe 5 to a cavity 4. The supplied ink 10 is discharged from an ink recovery groove 9 to the exterior through the cavity 4 by an ink recovery pipe 6. The toner particles 11 in the ink 10 supplied to the cavity 4 are concentrated to the recording electrode 3 side by the operation of a toner concentrating electrode 7. The concentrated particles 11 are conveyed to the end of the electrode 3, and the ink 10 lowered in the concentration of the particles 11 is conveyed to an ink recovery groove 9. In this case, when a recording voltage Vej is applied only to the electrode for recording, an electric field between the electrodes 3 and 12 is strengthened, the particles 11 at the end of the electrode 3 are discharged toward the electrode 12 to be transferred onto a recording sheet 13.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention uses an ink in which charged colorant particles (toner particles) are dispersed in an insulating liquid (liquid carrier) to generate ink droplets by applying electrostatic force. The present invention relates to an inkjet recording apparatus that records an image by flying the generated ink droplets on a recording medium by electrostatic force.

[0002]

2. Description of the Related Art Recently, in the field of personal printers,
2. Description of the Related Art Printers called inkjet recording apparatuses, which form a desired image on a recording medium by ejecting ink droplets onto the recording medium, are widely used.

In such an ink jet recording apparatus,
A piezoelectric element, a heating element, or the like is used as a drive source for generating ink droplets. However, in these ink jet recording apparatuses, since a dye is used as a colorant, there is a problem that image storability is not sufficient, such as poor light resistance of recorded images and poor water resistance of recorded images.

Further, it is difficult to widely change the size of the generated ink droplets according to the recording signal. Therefore, the gradation method for changing the density in units of image points cannot be adopted, and the dither method using the binary recording image points, etc. The gradation image recording is performed by the gradation method. For this reason, it is difficult to obtain a recorded image with high definition and smooth gradation characteristics.

Therefore, recently, in order to solve these problems, a slit jet type recording apparatus using an ink in which charged colorant particles are dispersed in an insulating liquid has been developed.

Here, the ink jet recording apparatus will be briefly described. This inkjet recording device
The conductive ink supply tube is inside the conductive base, and the ink in which the charged colorant particles are dispersed in the insulating liquid is supplied into the ink supply tube. The tip of the ink supply tube is about 30 in the direction of ink flow.
The discharge position at the tip of the ink supply tube has a small radius of curvature. A predetermined recording voltage is applied to the ink supply tube.

Further, facing the ink supply tube,
There is a counter electrode held at ground potential. In addition, the excess ink that was supplied to the ink supply tube and did not fly,
It is guided to the surplus ink recovery path by the ink flow guide material. The ink in the surplus ink collection path is collected in the ink tank by a pump or the like.

When ink containing colorant particles charged to the same polarity as the recording voltage applied to the ink supply tube is supplied into the ink supply tube by the ink supply device,
The ink moves toward the ejection position, which is the flying point, at the tip of the ink supply tube.

When a recording voltage is applied to the ink supply tube, strong electric field concentration occurs at the ejection position at the tip of the ink supply tube. The colorant particles in the ink near the ejection position move to the ejection position by the action of strong electric field concentration, and the concentration of the colorant particles in the ink near the ejection position increases. Ink containing colorant particles with a higher concentration than the bulk ink is drawn out in filament form from the ejection position. Since the drawn-out ink filament contains high-concentration particles of the same polarity, it splits due to the electrostatic repulsive force between the particles to form fine ink droplets, which fly toward the counter electrode.

This ink jet recording apparatus is characterized in that the coloring material particles in the ink are made to fly at a higher density than the original ink, and by utilizing the density of the coloring material particles, the density of the coloring material particles can be made smaller than in the conventional case. It improves the selectivity of ink droplet generation. Further, since the nozzles corresponding to the flying droplet size as in the conventional ink jet recording are not used, there is no fear of nozzle clogging and the pigment particles can be used. Therefore, problems such as image storability and light resistance, which are problems of the conventional inkjet recording, are solved.

[0011]

However, the above-mentioned ink jet recording apparatus has the following problems. That is, the characteristic of ink flying in the above-described conventional inkjet recording apparatus is that the concentration of the colorant particles of the ink near the ejection position is increased and the ink having a high concentration of the colorant particles is drawn out in a filament shape from the ejection position.
Since the drawn-out ink filament contains high-concentration colorant particles of the same polarity, it splits due to electrostatic repulsion between the colorant particles, forming fine ink droplets that fly toward the counter electrode. To do.

In such an ink jet recording apparatus,
The feature is that the colorant particles in the ink are made to have a higher concentration than the original ink and consumed, and by utilizing the density of the colorant particle concentration, the selectivity of ink droplet generation from the slits is improved compared to the past. ing. However, the conventional inkjet recording apparatus has the following problems when the colorant particles are concentrated and ejected.

First, since the flying ink and the surplus ink that has not flown come out from the ink supply tube, there is an ink flow from the ink supply tube to the recovery path through the ink flow guide material.

Since this flow is such that it flows back at the tip of the ink supply tube, the flow easily vibrates and the ink position at the tip of the ink supply tube also fluctuates. In this case, for example, at a position where the ink is retracted into the tip of the ink supply tube, there is no ink in the tip, and thus the flight becomes unstable. When the ink reaches the tip of the ink supply tube, the tip of the ink has exceeded the tip of the ink supply tube, so the electric field is weak and the flight becomes unstable.

Further, since the agglomeration of the colorant particles in the ink occurs only at the tip of the ink supply tube, it takes time to cause the agglomeration of the colorant particles sufficient for the ink to fly. Therefore, the recording speed does not increase. Also, in order to increase the recording speed, it is necessary to increase the ink flow rate,
Then, the flow of ink becomes faster, and the ink position tends to become unstable as described above.

Further, when there are a plurality of ejection openings, the recording voltage is selectively applied so that the colorant particles fly from the desired ejection openings. However, it is difficult to aggregate the colorant particles only at the desired ejection port, and
This makes it more difficult to stably fly colorant particles at a sufficient concentration. Therefore, it is an object of the present invention to provide an inkjet recording apparatus which can improve the recording speed and can always obtain a stable and good recorded image.

[0017]

An ink jet recording apparatus of the present invention contains an ink in which charged colorant particles are dispersed in an insulating liquid and causes the ink to fly to a recording medium. An ink containing portion having an ejecting portion, a transporting means for concentrating the colorant particles in the ink in the ink containing portion, and guiding the ink having the concentrated colorant particles to the ejecting portion, the ink Is provided upstream of the discharge unit along the direction in which
A collecting unit that collects the diluted ink due to the concentration of the colorant particles by the carrying unit, and a discharge unit provided in the ejecting unit in the ink containing unit, and a predetermined recording voltage is applied, so that the carrying unit conducts the ink. And a flying unit for flying the ink, in which the coloring agent particles are concentrated, toward the recording medium.

Further, the ink jet recording apparatus of the present invention stores an ink in which charged colorant particles are dispersed in an insulating liquid, and ejects the ink onto a recording medium. An ink containing portion having: a concentrating means for concentrating the colorant particles in the ink in the ink containing part; a conveying means for guiding the ink having the colorant particles concentrated by the concentrating means to the ejection part; A recovery unit that is provided upstream of the ejection unit along the direction in which the ink is guided, and that recovers the ink that has been diluted by the concentration of the colorant particles by the concentration unit in the ink storage unit; and the recovery unit in the ink storage unit. The ink, which is provided in the ejection unit and is applied with a predetermined recording voltage, causes the ink, in which the colorant particles guided by the conveying unit are concentrated, to fly toward the recording medium. It is and a flying means to.

Further, the ink jet recording apparatus of the present invention contains an ink in which charged colorant particles are dispersed in an insulating liquid, and ejects the ink to a recording medium. An ink containing portion having a recording electrode provided in the discharge portion in the ink containing portion, a concentration electrode provided in a position facing the recording electrode in the ink containing portion, the recording electrode, and The coloring agent particles in the ink are concentrated on the recording electrode side by giving a predetermined potential difference to the concentration electrode, and the ink in which the coloring agent particles are concentrated is recorded on the ejection portion. Conveying means for leading to the tip of the electrode, collecting means for collecting the ink that has become diluted by the concentration of the colorant particles by the concentrating means on the side of the concentrating electrode, and front end of the recording electrode. It led colorant particles and a recording voltage applying means for applying a predetermined recording voltage to fly toward the ink concentrated on the recording medium to the recording electrode by a conveying means.

Further, the ink jet recording apparatus of the present invention stores an ink in which charged colorant particles are dispersed in an insulating liquid, and ejects the ink onto a recording medium. An ink containing portion having a plurality of recording electrodes arranged in parallel with the discharge portion of the ink containing portion; a transport means for transporting the ink toward the discharge portion in the ink containing portion; A plurality of ink flow paths that guide the conveyed ink to their tip portions for each of the plurality of recording electrodes; and the ink that is respectively guided by the plurality of ink flow paths from the respective tip ends of the plurality of recording electrodes. Recording voltage applying means for selectively applying a predetermined recording voltage for flying toward the recording medium to the plurality of recording electrodes is provided.

Further, the ink jet recording apparatus of the present invention stores an ink in which charged colorant particles are dispersed in an insulating liquid and ejects the ink onto a recording medium. An ink containing portion having a plurality of recording electrodes arranged in parallel with the ejection portion of the ink containing portion; a conveying means for conveying the ink toward the ejecting portion in the ink containing portion; A plurality of ink flow paths that are provided only at the respective tip portions of the electrodes and guide the ink conveyed by the conveying means to the tip portions of the plurality of recording electrodes, and from the respective tip portions of the plurality of recording electrodes, A recording voltage applying means for selectively applying a predetermined recording voltage for causing the inks, which are respectively guided by the plurality of ink flow paths, to fly toward the recording medium. It is provided with a door.

Further, the ink jet recording apparatus of the present invention contains an ink in which charged colorant particles are dispersed in an insulating liquid, and ejects the ink to the recording medium. An ink containing portion having a plurality of recording electrodes arranged in parallel with the discharge portion of the ink containing portion; a transport means for transporting the ink toward the discharge portion in the ink containing portion; A plurality of ink flow paths for guiding the transported ink to the tips of the recording electrodes for each of the plurality of recording electrodes, and the colorant particles in the ink transported by the transport means, which are provided in the transport means. Concentration means and a plurality of predetermined recording voltages for causing the inks, which are respectively guided by the plurality of ink flow paths, to fly toward the recording medium from the tips of the plurality of recording electrodes. And a recording voltage applying means for selectively applying against recording electrode.

Further, the ink jet recording apparatus of the present invention contains an ink in which charged colorant particles are dispersed in an insulating liquid, and ejects the ink to a recording medium. An ink containing portion having a plurality of recording electrodes arranged in parallel with the discharge portion of the ink containing portion; a transport means for transporting the ink toward the discharge portion in the ink containing portion; A plurality of ink flow paths for guiding the transported ink to the tips of the recording electrodes for each of the plurality of recording electrodes, and the colorant particles in the ink transported by the transport means, which are provided in the transport means. Concentration means and a plurality of predetermined recording voltages for causing the inks, which are respectively guided by the plurality of ink flow paths, to fly toward the recording medium from the tips of the plurality of recording electrodes. A recording voltage applying unit that selectively applies to the recording electrode, and an ink that is provided upstream of the ejection unit along the direction in which the ink is guided and is diluted by the concentration of the colorant particles by the concentration unit are used. And a collecting means for collecting.

Further, the ink jet recording apparatus of the present invention contains an ink in which charged colorant particles are dispersed in an insulating liquid, and ejects the ink to the recording medium. An ink containing portion having a plurality of recording electrodes arranged in parallel with the ejection portion of the ink containing portion; a conveying means for conveying the ink toward the ejecting portion in the ink containing portion; A plurality of ink flow paths provided so as to individually surround each of the recording electrodes only at the tip of the electrode, and the inks guided from the respective tips of the plurality of recording electrodes in the plurality of ink flow paths, respectively. Recording voltage applying means for selectively applying a predetermined recording voltage for causing the recording medium to fly toward the recording medium to the plurality of recording electrodes.

Further, the ink jet recording apparatus of the present invention contains an ink containing an ink obtained by dispersing charged colorant particles in an insulating liquid and ejecting the ink onto a recording medium. An ink containing portion having a plurality of recording electrodes arranged in parallel with the discharge portion of the ink containing portion; a transport means for transporting the ink toward the discharge portion in the ink containing portion; A plurality of ink flow paths for guiding the transported ink to the tips of the plurality of recording electrodes, and colors in the ink transported by the transport means, which are provided on the inlet side of the plurality of ink flow channels. A first concentrating means for concentrating the agent particles; a second concentrating means provided along the carrying direction of the carrying means for concentrating the coloring agent particles in the ink carried by the carrying means; Record A recording voltage for selectively applying a predetermined recording voltage to the plurality of recording electrodes for causing the inks, which are respectively guided by the plurality of ink flow paths, to fly toward the recording medium from the respective tips of the poles. And an application unit.

[0026]

According to the present invention, the coloring material particles in the ink are concentrated in the ink containing portion, and only the ink in which the coloring material particles are concentrated is guided to the tip portion of the recording electrode, so that the flow rate at the tip portion of the recording electrode is reduced. A small amount, a stable meniscus, and always a good recorded image can be obtained. Moreover, since the colorant particles are already concentrated at the tip of the recording electrode, the concentration process is shortened and the recording speed is improved.

Since the recording voltage applied to the recording electrode and the charged colorant particles have the same polarity, when the recording voltage is applied to the recording electrode, an electric field is generated not only in the direction of the recording medium but also in the direction of the adjacent recording electrode. Occurs. However, by providing an ink flow path corresponding to each of the plurality of recording electrodes, ink does not move from the recording electrode to another recording electrode. Therefore, the concentration of colorant particles is always high on the recording electrode, the concentration process is shortened, and the recording speed is improved.

Further, since the ink flow path corresponding to each of the plurality of recording electrodes is provided only at the tip portion of the recording electrode, there is a low possibility that the colorant particles will be clogged in the ink flow path.
High reliability.

Further, by providing a concentrating means for concentrating the colorant particles on the inlet side of the ink flow path corresponding to each of the plurality of recording electrodes, the colorant particles are concentrated in front of the ink flow path. The ink in the channel has a high concentration of colorant particles. For this reason, ink having a low concentration of colorant particles does not flow to the tip of the recording electrode, so that the meniscus at the tip of the recording electrode is stable and a good recorded image can be always obtained.

[0030]

Embodiments of the present invention will be described below with reference to the drawings. First, a first embodiment will be described. 1 to 3 show a main part of an ink jet recording apparatus according to this embodiment. That is, the recording head 1
Has a shape elongated in the main scanning direction, and has a slit-shaped opening 2 as a discharge portion for ejecting ink to the outside in the longitudinal direction of its front surface, and a plurality of recordings are made from this opening 2. The tips of the electrodes 3 are projected. Further, inside the recording head 1, it is integrated with the opening 2,
An ink cavity 4 is provided as an ink containing portion that contains the ink 10.

That is, the recording head 1 is composed of an electrically insulating upper base material 1A and a lower base material 1B.
A plurality of recording electrodes 3 are arranged in parallel on the upper surface (lower surface in the drawing) of A, and a cavity 4 is formed in the lower base material 1B. A toner concentration electrode 7 is provided on the bottom surface in the cavity 4 so as to face the recording electrode 3 and is unnecessary in the vicinity of the opening 2 and upstream of the opening 2 along the moving direction of the ink. An ink recovery groove 9 for recovering excess ink is formed, and an ink supply hole 8 for supplying ink 10 upstream of the ink recovery groove 9 is formed along the ink moving direction. .

The plurality of recording electrodes 3 are provided by the number corresponding to the recording width and the recording resolution, and are arranged in parallel on the upper substrate 1A in an electrically independent state.
Each tip of these recording electrodes 3 is located in the opening 2. In this case, the respective tip portions of the recording electrodes 3 are arranged at equal intervals so as to be aligned in a line in the main scanning direction, and are in a state of slightly protruding from the opening 2 to the outside.

A plurality of ink supply holes 8 are provided to uniformly supply the ink 10 in the main scanning direction of the cavity 4 (arrangement direction of the recording electrodes 3), and an ink supply pipe 5 is connected to each of them. ing. Further, an ink recovery pipe 6 for discharging unnecessary excess ink to the outside is connected to the ink recovery groove 9.

Here, the ink 10 will be described. In this embodiment, the ink 10 in which the toner particles (coloring material particles) that have been charged to a positive potential in advance are dispersed in the liquid carrier (insulating liquid) is used, and ink droplets are generated by electrostatic force. More specifically, the ink 10 is prepared by, for example, using a liquid carrier (insulating liquid) such as a petroleum solvent,
A toner in which a colorant pigment such as carbon black, a dispersant, and a charge control agent is dispersed in or on the surface of a binder made of resin or wax is used.

A counter electrode 12 is disposed in front of the recording head 1 and at a predetermined distance from the recording head 1 so as to face the recording electrode 3 (opening 2). Is held at ground potential. The counter electrode 12 and the recording electrode 3 are in contact with the counter electrode 12.
A recording paper 13 as a recording medium is arranged between the front end portion and the front end portion of the.

FIG. 4 is a diagram for explaining the concentration of toner particles in the ink and the ejection behavior of the ink using the recording head 1 configured as described above. That is, the ink 10 is
The ink is supplied from an ink reservoir (not shown) into the cavity 4 through the ink supply pipe 5. At this time, the ink 10 is in a state in which the toner particles 11 are uniformly dispersed in the liquid carrier. The supplied ink 10 is stored in the cavity 4
After passing through the inside, it is discharged from the ink collecting groove 9 to the outside by the ink collecting pipe 6.

The toner particles 11 in the ink 10 supplied into the cavity 4 are concentrated on the recording electrode 3 side by the action of the toner concentration electrode 7, and the concentrated toner particles 11 are deposited on the tip of the recording electrode 3. The ink 10 that has been conveyed and has a reduced concentration of toner particles 11 is conveyed to the ink recovery groove 9.

Next, based on the potential relationship between the recording electrode 3 and the toner concentration electrode 7 in the recording operation shown in FIG.
Concentration of the toner particles in the ink and the ejection behavior of the ink described above will be described. A predetermined bias voltage Vb is applied to the recording electrode 3 regardless of the presence or absence of recording. In each recording cycle, a predetermined recording voltage Vej is applied only to the recording electrode 3 that performs recording (discharges ink) according to the image signal. Further, a predetermined toner concentration voltage Vep is always applied to the toner concentration electrode 7. The relationship between these three voltages is Vb <Vej <Vep.

Since the toner particles 11 in the ink 10 are charged to a positive electric potential, when passing between the recording electrode 3 in the cavity 4 and the toner concentrating electrode 7, the toner particles 11 reach the recording electrode 3 side having a low electric potential. The toner particles 11 move by electrophoresis and are divided into a high concentration portion and a low concentration portion of the toner particles 11. Further, the toner particles 11 collect at the tip of the recording electrode 3 due to the electric field formed by the recording electrode 3 and the toner concentration electrode 7.

Therefore, when the ink 10 is supplied from the ink supply pipe 5 at an appropriate pressure, a meniscus is formed in the opening 2 due to the surface tension of the ink 10, the ink 10 does not flow out, and the excess concentration of the toner particles 11 is low. The ink 10 is discharged to the outside through the ink collecting groove 9 and the ink collecting pipe 6.

Next, the recording voltage Vej is selectively applied to the recording electrodes 3 for ejecting ink according to the image signal. When recording is not performed, the potential difference between the recording electrode 3 and the counter electrode 12 is Vb, but when recording is performed, the potential difference becomes Vej, and a strong electric field is generated between the tip of the recording electrode 3 and the counter electrode 12. 11 is discharged toward the counter electrode 12 and transferred onto the recording paper 13.

FIG. 6 is a block diagram of the periphery of the recording head of this recording apparatus. That is, the ink reservoir 250 is connected to the ink supply pipe 5 of the recording head 1 by the ink supply tube 251. Ink supply tube 25
An ink supply pump 252 is provided at an intermediate portion of the first recording medium 1, and the ink 10 in the ink reservoir 250 is supplied to the recording head 1 (cavity 4) by the ink supply pump 252. Further, the ink reservoir 250 and the ink recovery pipe 6 of the recording head 1 are connected by an ink recovery tube 253, and unnecessary ink that has not been used is recovered by the ink reservoir 250 and reused. .

On the toner concentration electrode 7 of the recording head 1,
The first power supply unit 254 that outputs the toner concentrated voltage Vep is connected, and the recording electrode 3 is connected to the recording electrode driving unit 256 that outputs the bias voltage Vb and the recording voltage Vej. An image information generation unit 257 that generates image information to be recorded and a second power supply unit 258 that outputs a bias voltage Vb are connected to the recording electrode drive unit 256. As a result, as described above, the toner concentration electrode 7
Is always applied with a predetermined toner concentration voltage Vep, a bias voltage Vb is applied to the recording electrode 3 that does not perform recording, and a recording voltage Vej is applied to the recording electrode 3 that performs recording. The processing is performed by the unit 256 based on the image information from the image information generation unit 257.

As described above, according to the first embodiment, the toner particles 11 in the ink 10 are concentrated in the cavity 4 of the recording head 1, and only the concentrated ink particles 11 are guided to the tip of the recording electrode 3. Therefore, the flow rate at the tip of the recording electrode 3 is small, the meniscus is stable, and a good recorded image can always be obtained. Further, since the toner particles 11 are already concentrated at the tip of the recording electrode 3, the concentration process is shortened and the recording speed is improved.

Next, the second embodiment will be described. 7 to 9 show a main part of the ink jet recording apparatus according to this embodiment. That is, the recording head 10
Reference numeral 1 denotes a shape that is long in the main scanning direction, and has a plurality of rectangular opening portions 102 as ejection portions for ejecting ink to the outside in the longitudinal direction of the front surface thereof. The tip ends of the plurality of recording electrodes 103 project from the respective 102. Further, inside the recording head 101, an ink cavity 104 as an ink containing portion that contains the ink 10 and a plurality of ink flow paths 109 that respectively connect the cavity 104 and the plurality of openings 102 are provided.

That is, the recording head 101 is composed of an electrically insulating upper base material 101A and a lower base material 101B, and a plurality of recording electrodes 103 are arranged at equal intervals at the tip of the upper surface of the lower base material 101B. A cavity 104 is formed on the upper surface (lower surface in the drawing) of the upper base member 101A, and a plurality of openings 102 are formed so as to face the plurality of recording electrodes 103, respectively. A plurality of ink flow paths 109 connecting the openings 102 and the cavities 104 are formed. On the rear surface corresponding to the opening 102 in the cavity 104, a toner-conveying electrode 107 for conveying the toner particles 11 in the ink 10 is provided.

An ink supply pipe 105 for supplying the ink 10 into the cavity 104 is connected to the upper surface of the lower base material 101B, that is, the bottom surface of the cavity 104, in the vicinity of the toner transport electrode 107. With
An ink recovery pipe 106 for recovering ink is connected to the upper surface of the cavity 104 facing the ink supply pipe 105. Here, a plurality of ink supply pipes 105 and ink recovery pipes 106 are provided to uniformly supply the ink 10 in the main scanning direction of the cavity 104 (arrangement direction of the recording electrodes 103).

The plurality of recording electrodes 103 are provided by the number corresponding to the recording width and the recording resolution, and as shown in FIG. 10, they are electrically independent from each other and are parallel to the tip end portion on the lower substrate 101B. The tips of the recording electrodes 103 are arranged and located in the openings 102, respectively. In this case, the respective tip portions of the recording electrodes 103 are arranged at equal intervals so as to be aligned in a line in the main scanning direction, and are slightly projected from the respective opening portions 102 to the outside.

Further, in this case, as shown in FIG. 10, corresponding to each of the plurality of independent recording electrodes 103,
A plurality of openings 102 are formed in the upper base material 101A, and the openings 102 and the cavity 1 are formed.
A plurality of ink flow paths 109 are formed so as to connect the recording electrodes 103 to each other and independently surround the recording electrodes 103.
Note that FIG. 10 illustrates the case of three recording electrodes 103 for the sake of simplification of the drawing.

In front of the recording head 101, the recording head 1
A counter electrode 110 is provided at a position away from 01 by a predetermined distance so as to face the recording electrode 103 (opening 102), and the counter electrode 110 is held at the ground potential. A recording paper 111 as a recording medium is arranged between the counter electrode 110 and the tip of the recording electrode 103 while being in contact with the counter electrode 110.

FIG. 11 is a diagram for explaining the conveyance of toner particles in ink and the ejection behavior of ink using the recording head 101 having the above-described structure. That is, ink 1
0 is supplied into the cavity 104 from an ink reservoir (not shown) through the ink supply pipe 105. At this time, the ink 10 is in a state in which the toner particles 11 are uniformly dispersed in the liquid carrier. The toner particles 11 in the ink 10 supplied into the cavity 104 pass through the ink flow path 109 by the action of the toner carrying electrode 107,
It is conveyed to the tip of the recording electrode 103. On the other hand, the ink 10 in which the concentration of the toner particles 11 has decreased is discharged to the outside from the ink recovery pipe 106.

Next, based on the potential relationship between the recording electrode 103 and the toner-conveying electrode 107 in the recording operation shown in FIG. 12, the conveyance of the toner particles in the ink and the ejection behavior of the ink described in FIG. 11 will be described. A predetermined bias voltage Vb is applied to the recording electrode 103 regardless of the presence or absence of recording. In each recording cycle, a predetermined recording voltage Vej is applied only to the recording electrode 103 that performs recording (discharges ink) according to the image signal. Further, the toner carrying electrode 1
A predetermined toner carrying voltage Vep is always applied to 07. The relationship between these three voltages is Vb <Vej <Vep.

Since the toner particles 11 in the ink 10 are charged to a positive potential, while the ink 10 flows from the ink supply pipe 105 through the cavity 104 to the ink recovery pipe 106, the toner particles 11 become toner. The electric field is applied between the carrying electrode 107 and the recording electrode 103 to carry it to the tip of the recording electrode 103. Here, when the recording voltage Vej higher than the bias voltage Vb is applied only to the recording electrode 103 for recording, the recording electrode 103 and the counter electrode 1
The electric field between the recording particles 103 and 10 becomes stronger, and the toner particles 11 at the tip of the recording electrode 103 are ejected toward the counter electrode 110 and transferred onto the recording paper 111.

FIG. 13 is a schematic view of the vicinity of the tip of the recording electrode 103 as seen from above. In this state, for example, the recording voltage Vej is applied only to the central recording electrode 103b of the three recording electrodes 103a, 103b and 103c, and the bias voltage Vb is applied to the other two two electrodes 103a and 103c. . In this case, the recording electrode 103b has the highest potential, and an electric field as indicated by an arrow in the figure is generated. Since the toner particles 11 are charged to the positive potential, they move in the direction of the lower potential.

Therefore, the toner particles 11 at the tip of the recording electrode 103b are ejected by the electric field toward the counter electrode 110, but also try to move toward the recording electrodes 103a and 103c on both sides. However, since the ink flow path 109 is formed for each recording electrode 103, the toner particles 11
Cannot move to the adjacent recording electrode 103, and the density of the ink 10 on the recording electrode 103 is kept high.

The ink flow path 109 corresponding to each recording electrode 103 is provided only at the tip of the recording electrode 103. The shape of the ink flow path 109 is almost determined by the recording resolution. For example, if the resolution is 300 dpi,
The width is about 50 μm and the height is about 300 μm. As described above, the toner particles 11 adhere to the narrow flow path and are easily clogged. For this reason, the reliability of the recording head is higher if the individual ink flow paths are made as short as possible. The toner particles 11 move toward the adjacent recording electrode 103 when the recording voltage Vej is applied because it is the portion where the recording electrode 103 is in contact with the ink 10. Therefore, the ink flow path 109 is provided only in that portion. .

Further, the shape of the opening (orifice) is also determined by the recording resolution in the ink jet recording apparatus using a piezoelectric element and the thermal ink jet type ink jet recording apparatus which are currently in practical use. However, in these recording apparatuses, the opening has a circular shape, and the diameter of the dot is about twice that of the opening.
As a μm, the opening becomes a hole of 45 μm.

However, in the recording head 101 of this embodiment, it is not necessary to make the opening 102 smaller than that in order to reduce the dot diameter, and even if the ink flow path 109 is provided for each recording electrode 103, it is currently in practical use. The reliability is higher than that of a commercialized inkjet recording device.

FIG. 14 is a block diagram of the periphery of the recording head of this recording apparatus. That is, the ink reservoir 260 is connected to the ink supply pipe 105 of the recording head 101 by the ink supply tube 261. An ink supply pump 262 is provided in the middle of the ink supply tube 261, and the ink 10 in the ink reservoir 260 is supplied to the recording head 101 by the ink supply pump 262.
(Cavity 104). In addition, the ink reservoir 260 and the ink recovery pipe 1 of the recording head 101.
No. 06 is connected to the No. 06 by an ink recovery tube 263.
It is collected in 60 and can be reused.

Toner conveying electrode 10 of recording head 101
7, a first power supply unit 264 that outputs the toner transport voltage Vep is connected, and the recording electrode driving unit 2 that outputs the bias voltage Vb and the recording voltage Vej is connected to the recording electrode 103.
66 is connected. An image information generation unit 267 that generates image information to be recorded and a second power supply unit 268 that outputs the bias voltage Vb are connected to the recording electrode drive unit 266. As a result, as described above, the predetermined toner carrying voltage Vep is always applied to the toner carrying electrode 107.
Is applied to the recording electrode 103 that does not perform recording, and the recording voltage Vej is applied to the recording electrode 103 that performs recording. These are supplied from the image information generating unit 257 by the recording electrode driving unit 256. Is performed based on the image information of.

As described above, according to the second embodiment, since the recording voltage applied to the recording electrode 103 and the charging polarity of the toner particles 11 are the same, when the recording voltage is applied to the recording electrode 103, the opposite electrode 110 is charged. An electric field is generated not only in the direction but also in the direction of the adjacent recording electrode 103. However, by providing the ink flow path 109 corresponding to each of the plurality of recording electrodes 103, the ink 10 does not move to the adjacent recording electrode 103. Therefore, the concentration of the toner particles 11 on the recording electrode 103 is always high, the concentration process is shortened, and the recording speed is improved.

Further, since the ink flow path 109 corresponding to each of the plurality of recording electrodes 103 is provided only in the vicinity of the tip end portion of the recording electrode 103, the possibility that the toner particles 11 will be clogged in the ink flow path 109 is low. , Reliable.

Next, the third embodiment will be described. 15 to 17 show a main part of the ink jet recording apparatus according to this embodiment. That is, this embodiment is similar to the second embodiment described above, except that the lower base material 101B is used.
The toner concentration electrode 108 for concentrating the toner particles 11 is additionally arranged in front of the recording electrode 103 on the upper surface of the above, that is, the bottom surface of the cavity 104. Through FIG. 10), the same parts are designated by the same reference numerals and detailed description thereof will be omitted.

FIG. 18 is a diagram for explaining the transport and concentration of toner particles in ink and the ejection behavior of ink using the recording head 101 configured as described above. That is, the ink 10 is supplied from the ink reservoir (not shown) into the cavity 104 through the ink supply pipe 105. At this time, the ink 10 is in a state in which the toner particles 11 are uniformly dispersed in the liquid carrier. Cavity 104
The toner particles 11 in the ink 10 supplied therein are transported to the ink flow path 109 by the action of the toner transport electrode 107. However, before being transported to the ink flow path 109, the toner particles 11 of the toner concentration electrode 108 are transported. It is concentrated by the action, and is conveyed to the tip portion of the recording electrode 103 through the ink flow path 109. On the other hand, the ink 10 in which the density of the toner particles 11 has decreased
Is discharged to the outside from the ink recovery pipe 106.

Next, based on the potential relationship among the recording electrode 103, the toner-conveying electrode 107, and the toner-concentrating electrode 108 in the recording operation shown in FIG. 19, the toner particles in the ink described in FIG. 18 are conveyed. Concentration and ink ejection behavior will be described. A predetermined bias voltage Vb is applied to the recording electrode 103 regardless of the presence or absence of recording. In each recording cycle, a predetermined recording voltage Vej is applied only to the recording electrode 103 that performs recording (discharges ink) according to the image signal. Further, a predetermined toner carrying voltage Vep is always applied to the toner carrying electrode 107, and a predetermined toner concentrating voltage Vh is always applied to the toner concentrating electrode 108. The relationship between these four voltages is Vb <Vej << Vh <Vep.

Since the toner particles 11 in the ink 10 are charged to a positive potential, while the ink 10 flows from the ink supply pipe 105 through the cavity 104 to the ink recovery pipe 106, the toner particles 11 become toner. An electric field between the carrying electrode 107 and the toner concentrating electrode 108 carries the toner to the vicinity of the toner concentrating electrode 108, and the concentration of the toner particles 11 is high in this part.

Further, due to the electric field between the toner concentration electrode 108 and the recording electrode 103, the toner concentration electrode 108 is
Toner particles 11 in the vicinity are conveyed to the tip of the recording electrode 103 through the ink flow path 109. Toner concentrating electrode 1
No. 08 is disposed on the inlet side of the ink flow path 109, so that the toner particles 11 guided to the ink flow path 109 are concentrated here, and the ink 10 having a high concentration of the toner particles 11 is the tip portion of the recording electrode 103. Will be supplied to.

When the recording voltage Vej higher than the bias voltage Vb is applied only to the recording electrode 103 for recording, the electric field between the recording electrode 103 and the counter electrode 110 becomes strong, and the tip of the recording electrode 103 is exposed. Some toner particles 1
1 is ejected toward the counter electrode 110 and is transferred onto the recording paper 111.

As described above, by supplying the ink 10 having a high concentration of the toner particles 11 to the tip portion of the recording electrode 103, the ink 10 at the tip portion of the recording electrode 103 has a high charge amount per volume and a recording frequency. Since the height becomes higher, high-speed recording becomes possible, and the distance between the recording electrode 103 and the recording paper 111 is increased, the recording paper 111 does not come into contact with the recording electrode 103 and the recorded image is not disturbed.

FIG. 20 is a block diagram of the periphery of the recording head of this recording apparatus. 14 is different from FIG. 14 in that the third power supply unit 2 applies the toner concentration voltage Vh to the toner concentration electrode 108.
Since 65 is added and the other points are the same as those in FIG. 14, the same portions are denoted by the same reference numerals and detailed description thereof will be omitted.

As described above, according to the third embodiment, the toner concentration electrode 10 for concentrating the toner particles 11 on the inlet side of the ink flow path 109 corresponding to each of the plurality of recording electrodes 103.
By providing 8, the toner particles 11 are concentrated before the ink flow path 109, so that all the ink 10 in the ink flow path 109 has a high concentration of the toner particles 11. For this reason, the ink 10 having a low concentration of the toner particles 11 does not flow to the tip of the recording electrode 103, so that the meniscus at the tip of the recording electrode 103 is stabilized and a good recorded image is always obtained.

[0072]

As described above in detail, according to the present invention, it is possible to provide an ink jet recording apparatus which can improve the recording speed and can always obtain a stable and good recorded image.

[Brief description of the drawings]

FIG. 1 is a sectional view schematically showing a main part of an inkjet recording apparatus according to a first embodiment of the present invention.

FIG. 2 is a perspective view showing the outer appearance of the recording head of the first embodiment.

FIG. 3 is an exploded perspective view of the recording head of the first embodiment.

FIG. 4 is a diagram for explaining the concentration of toner particles in the ink and the ejection behavior of the ink in the first embodiment.

FIG. 5 is a diagram illustrating a potential relationship between a recording electrode and a toner concentration electrode in a recording operation according to the first embodiment.

FIG. 6 is a configuration diagram of the periphery of the recording head of the ink jet recording apparatus according to the first embodiment.

FIG. 7 is a sectional view schematically showing a main part of an ink jet recording apparatus according to a second embodiment of the present invention.

FIG. 8 is a perspective view showing the outer appearance of the recording head of the second embodiment.

FIG. 9 is an exploded perspective view of the recording head according to the second embodiment.

FIG. 10 is an enlarged perspective view of the vicinity of the tip portion of the recording electrode of the recording head of the second embodiment.

FIG. 11 is a diagram for explaining the conveyance of toner particles in the ink and the ejection behavior of the ink in the second embodiment.

FIG. 12 is a diagram for explaining the potential relationship between the recording electrode and the toner carrying electrode in the recording operation of the second embodiment.

FIG. 13 is a schematic view for explaining an electric field generated when a recording voltage is applied to one recording electrode and is a schematic view of the vicinity of the tip of the recording electrode as viewed from above.

FIG. 14 is a configuration diagram around a recording head of an ink jet recording apparatus according to the second embodiment.

FIG. 15 is a sectional view schematically showing a main part of an inkjet recording apparatus according to a third embodiment of the present invention.

FIG. 16 is an exploded perspective view of the recording head of the third embodiment.

FIG. 17 is an enlarged perspective view of the vicinity of the tip of the recording electrode of the recording head of the third embodiment.

FIG. 18 is a diagram for explaining conveyance and concentration of toner particles in ink and ink ejection behavior in the third embodiment.

FIG. 19 is a diagram illustrating a potential relationship between a recording electrode, a toner conveying electrode, and a toner concentrating electrode in a recording operation according to the third embodiment.

FIG. 20 is a configuration diagram around a recording head of an ink jet recording apparatus according to a third embodiment of the present invention.

[Explanation of symbols]

1, 101 ... recording head, 2, 102 ... opening (ejection section), 3, 103 ... recording electrode, 4, 104 ... cavity (ink storage section), 7, 108 ... toner concentration electrode, 107 ... Toner transporting electrode, 109 ... Ink flow path, 10 ... Ink, 11 ... Toner particles (coloring material particles), 12,110 ... Counter electrode, 13,111 ... Recording paper (recording medium) , 250, 260 ... Increzer, 254, 264 ... First power supply unit, 256, 266
...... Recording electrode drive unit, 257,267 ...... Image information generation unit, 258,268 ...... Second power supply unit, 265 ...... Third unit
Power supply section.

Claims (9)

[Claims] 1. An ink containing portion containing an ink in which charged colorant particles are dispersed in an insulating liquid, and having an ejection portion for ejecting the ink onto a recording medium. Conveying means for concentrating the colorant particles in the ink in the ink containing section and for guiding the ink in which the colorant particles are concentrated to the ejection section; and an upstream side of the ejection section along a direction in which the ink is guided. And a recovery means for recovering the diluted ink due to the concentration of the colorant particles by the transport means, and the discharge part provided in the ink storage part, and by applying a predetermined recording voltage, An ink jet recording apparatus comprising: a flying unit configured to fly the ink, in which the colorant particles, which are guided by the transport unit, are concentrated toward the recording medium. 2. An ink containing section containing an ink in which charged colorant particles are dispersed in an insulating liquid, and having an ejection section for ejecting the ink onto a recording medium. Concentrating means for concentrating the colorant particles in the ink in the ink containing part, conveying means for guiding the ink having the colorant particles concentrated by the concentrating means to the ejection part, and along a direction in which the ink is guided. A recovery unit that is provided upstream of the ejection unit and that collects the ink that has become diluted due to the concentration of the colorant particles by the concentration unit in the ink storage unit; And a flying unit configured to fly the ink, in which the colorant particles guided by the carrying unit are concentrated, toward the recording medium when a recording voltage is applied. An ink jet recording apparatus according to. 3. An ink containing section for containing an ink in which charged colorant particles are dispersed in an insulating liquid, and having an ejection section for ejecting the ink onto a recording medium, A recording electrode provided in the ejection section in the ink containing section, a concentrating electrode provided in a position facing the recording electrode in the ink containing section, and a predetermined distance between the recording electrode and the concentrating electrode. And a potential difference between the colorant particles in the ink to concentrate on the recording electrode side, and the ink concentrated in the colorant particles guides the ink to the tip of the recording electrode located at the ejection portion. Collecting means for collecting the ink that has become thin due to the concentration of the colorant particles by the concentrating means on the side of the concentration electrode, and the colorant particles guided by the conveying means from the tip of the recording electrode are concentrated. An ink jet recording apparatus characterized by comprising a recording voltage applying means for applying to said recording electrodes a predetermined recording voltage to fly toward the ink which is on the recording medium. 4. An ink containing section for containing an ink in which charged colorant particles are dispersed in an insulating liquid, and having an ejection section for ejecting the ink onto a recording medium, A plurality of recording electrodes arranged in parallel with the ejection portion of the ink containing portion, a transporting means for transporting the ink toward the discharging portion in the ink containing portion, and a plurality of the inks transported by the transporting means. A plurality of ink flow paths leading to their tip portions for each of the recording electrodes, and the inks respectively led in the plurality of ink flow paths from the respective tip ends of the plurality of recording electrodes to fly toward the recording medium. An inkjet recording apparatus comprising: a recording voltage applying unit that selectively applies a predetermined recording voltage to the plurality of recording electrodes. 5. An ink containing section for containing an ink in which charged colorant particles are dispersed in an insulating liquid, and having an ejection section for ejecting the ink onto a recording medium, A plurality of recording electrodes arranged in parallel to the ejection portion of the ink containing portion, a conveying means for conveying the ink toward the ejecting portion in the ink containing portion, and provided only at each tip of the plurality of recording electrodes A plurality of ink flow paths for guiding the ink conveyed by the transfer means to their tip portions for each of the plurality of recording electrodes, and from the respective tip ends of the plurality of recording electrodes, in the plurality of ink passages, respectively. A recording voltage applying unit that selectively applies a predetermined recording voltage for causing the guided ink to fly toward the recording medium to the plurality of recording electrodes. Jet recording apparatus. 6. An ink containing portion containing an ink in which charged colorant particles are dispersed in an insulating liquid, and having an ejection portion for ejecting the ink onto a recording medium, A plurality of recording electrodes arranged in parallel with the ejection portion of the ink containing portion, a transporting means for transporting the ink toward the discharging portion in the ink containing portion, and a plurality of the inks transported by the transporting means. A plurality of ink flow paths that lead to their tips for each recording electrode; a concentrating means that is provided in the transporting means and that concentrates colorant particles in the ink that is transported by the transporting means; Recording for selectively applying a predetermined recording voltage to the plurality of recording electrodes for causing the inks, which are respectively guided by the plurality of ink flow paths, to fly toward the recording medium from each tip of the electrode An ink jet recording apparatus characterized by comprising a pressure application means. 7. An ink containing section containing an ink in which charged colorant particles are dispersed in an insulating liquid, and having an ejection section for ejecting the ink onto a recording medium, A plurality of recording electrodes arranged in parallel with the ejection portion of the ink containing portion, a transporting means for transporting the ink toward the discharging portion in the ink containing portion, and a plurality of the inks transported by the transporting means. A plurality of ink flow paths that lead to their tips for each recording electrode; a concentrating means that is provided in the transporting means and that concentrates colorant particles in the ink that is transported by the transporting means; Recording for selectively applying a predetermined recording voltage to the plurality of recording electrodes for causing the inks, which are respectively guided by the plurality of ink flow paths, to fly toward the recording medium from each tip of the electrode A pressure applying unit and a collecting unit that is provided upstream of the ejection unit along the direction in which the ink is guided and that collects the ink that has been diluted by the concentration of the colorant particles by the concentration unit. Characteristic inkjet recording device. 8. An ink containing portion containing an ink in which charged colorant particles are dispersed in an insulating liquid, and having an ejection portion for ejecting the ink onto a recording medium, A plurality of recording electrodes arranged side by side in the ejection section of the ink containing section, a transporting means for transporting the ink toward the ejecting section in the ink containing section, and only the tip portions of the plurality of recording electrodes, respectively. A plurality of ink flow paths provided so as to individually surround the recording electrodes, and the inks respectively guided by the plurality of ink flow paths from the respective tips of the plurality of recording electrodes are ejected toward the recording medium. An inkjet recording apparatus, comprising: a recording voltage applying unit that selectively applies a predetermined recording voltage to the plurality of recording electrodes. 9. An ink containing section for containing an ink in which charged colorant particles are dispersed in an insulating liquid, and having an ejection section for ejecting the ink onto a recording medium, A plurality of recording electrodes arranged in parallel with the ejection portion of the ink containing portion, a transporting means for transporting the ink toward the discharging portion in the ink containing portion, and a plurality of the inks transported by the transporting means. A plurality of ink channels leading to their tip portions for each recording electrode, and a first ink channel provided on the inlet side of the plurality of ink channels for concentrating the colorant particles in the ink transported by the transporting means. Concentration means, second concentration means provided along the conveyance direction of the conveyance means for concentrating the colorant particles in the ink conveyed by the conveyance means, from each tip of the plurality of recording electrodes, Multiple ink channels Recording voltage applying means for selectively applying a predetermined recording voltage for ejecting the ink, which is respectively guided to the recording medium, to the plurality of recording electrodes. Inkjet recording device.