JP2001334669A - Electrostatic ink jet recorder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrostatic ink jet recorder capable of preventing coloring agent particles during the ejection from scattering and of raising stability of the ejection of ink. SOLUTION: This ink jet recorder comprises a slit section for holding the ink including the charged coloring agent particles, a plurality of migration electrodes 3 (E1, E2) for integrally collecting the coloring agent particles, a plurality of recording electrodes 1 (S1-S3) for determining ink ejection positions, a plurality of aggregating electrodes 2 (C1-C3) for aggregating the coloring agent particles to the recording electrodes, counter electrode 4 that is opposed to the recording electrodes and applies a trigger for ink ejection, an aggregating electrode control driver 12 for aggregating the coloring agent particles to the ejection position, a counter electrode control driver for ejecting the ink from the recording electrode, a recording electrode control driver that controls the recording electrodes by applying a voltage by each group to the recording electrodes which are divided into a plurality of groups, and a migration electrode control driver that controls the migration electrodes by sequentially applying a voltage by each group to the migration electrodes which are divided into a plurality of groups.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrostatic ink jet recording apparatus for discharging ink from a discharge section (slit section) to a recording medium by electrostatic force.

[0002]

2. Description of the Related Art Ink jet technology is a printing technology capable of obtaining high image quality and high speed at low cost.
Widely used for facsimile, printer, word processor, etc.

[0003] Ink jet recording systems use a heating resistor such as an electrothermal transducer or a piezo element such as an electromechanical transducer as an energy generating means for flying color material particles. And an electrostatic type using electric energy as it is.

Among them, in the electrostatic ink jet technology, the production of the recording head is simpler than other methods, and the area gradation recording can be performed by controlling the electric signal applied to the recording electrode. Further, the amount of current consumed at the time of recording is remarkably small, and it can be said that this is a recording technology that is useful in the future as an energy-saving device. Furthermore, by using oil-based pigment ink,
It can perform printing with excellent water resistance, and is particularly useful for office automation applications.

Here, the principle of the electrostatic ink jet will be briefly described. As reported in JP-A-56-4467, when a recording voltage of several kV is applied between a recording electrode filled with ink and a counter electrode holding a recording medium, the recording voltage reaches a certain threshold. When crossed,
The electrostatic force acting on the ink overcomes the surface tension of the ink, and the ink droplet is ejected from the recording electrode to the counter electrode and flies.

[0006] Regarding the configuration of the head based on this principle,
For example, U.S. Pat.
No. -4467. In the configuration of this example, a nozzle hole is not necessarily required for each recording electrode, and the ink discharge port can be a so-called slit type common to a plurality of recording electrodes. A feature of such a configuration is that clogging due to drying of ink is reduced by not providing a nozzle. Therefore, this configuration is not only a so-called serial type head which has several hundred recording electrodes and scans in the width direction of the recording medium, but also a so-called line type head having recording electrodes for the width of the recording medium. It is also very effective.

In this electrostatic ink jet recording apparatus, in the case of a configuration having a plurality of recording electrodes, it is necessary to prevent the leakage of electric charge due to the formation of a closed loop with adjacent electrodes in order to operate each recording electrode independently. is there. For this purpose, an oily solvent having a high electric resistance is usually used as a solvent for the ink. In the example disclosed in Japanese Patent Application Laid-Open No. 58-215353, the specific resistance is about 10 6 Ωm and the surface tension is 18
× 10 -3 N / m, viscosity 2-30 × 10 -3 Pa · S, specific gravity 1.0 × 10 3 kg / m
³ (m ³ represents the cube of m) oil-based ink is used. As a coloring material, an oil-based pigment or an oil-based dye can be used. However, an oil-based pigment is mainly used because of its variety.

However, in a usual electrostatic ink jet recording apparatus, since both the color material particles and the solvent receive an electrostatic force, a relatively large amount of solvent is discharged together with the color material particles, and the print density is reduced. There was a problem.

Therefore, Japanese Patent Application Laid-Open No. 8-295502,
As disclosed in Japanese Patent Application Laid-Open No. 9-193389, an electrostatic ink jet recording apparatus has been proposed which solves these problems by mainly discharging only colorant particles from ink. In these examples, the principle of ejection is not always clearly explained,
By providing a plurality of electrodes (electrophoretic electrodes), the coloring material particles are concentrated on the recording electrode and the coloring material particles fly mainly, so that the solvent is not contained in a very small amount in the ejected ink. It will be solved.

In this method, it is assumed that the color material particles are positively charged. In this method, a negative DC voltage is applied to a counter electrode (platen) disposed on the back of the recording medium, and the recording electrode is applied to the migration electrode. By applying a higher positive potential, the coloring material particles are concentrated, and then a pulse voltage equal to or higher than that of the migration electrode is applied to the recording electrode to separate and eject ink. Was.

In the above-mentioned method, concentration of the coloring material particles occurs during a period in which the potential of the electrophoresis electrode is higher than that of the recording electrode, but while the recording voltage (recording electrode control signal) is applied to the recording electrode, On the contrary, a phenomenon was found in which the coloring material particles caused diffusion due to the magnitude relationship of the potential.

Further, Japanese Patent Application Laid-Open No. 10-151751 discloses that in the above-mentioned method, by performing divided driving,
It is disclosed that the number of drivers is reduced and cost is prevented.

FIG. 6 is a configuration diagram showing an electrostatic ink jet recording apparatus disclosed in Japanese Patent Application Laid-Open No. 10-151751, and FIG. 7 is a connection diagram showing a connection between a control driver and each electrode.

In FIG. 6 and FIG. 7, reference numeral 1 denotes a recording electrode composed of a plurality of recording electrodes S1 to S16 for providing an ejection position at which ink is ejected, and 3 is formed between a head block upper part 6 and a head block lower part 7. An electrophoretic electrode 4 composed of a plurality of electrophoretic electrodes E1 to E4 for concentrating color material particles over the width direction of the slit portion (ejection portion) as a whole is arranged opposite to the recording electrode 1 and the electrophoretic electrode 3, and is electrostatically arranged. A counter electrode for triggering ink ejection by a suction force, 5 is a recording medium (for example, recording paper), 8 is an ink flow path to which ink is supplied, 9 is an electrode substrate on which the recording electrode 1 is arranged, and 10 is a plurality of controls. A control driver composed of a driver, 10a applies a recording electrode control signal (recording voltage) to the recording electrode 1 and a recording electrode control driver 10b applies a migration electrode control signal (migration voltage) to the migration electrode 3. Dynamic electrode control driver, G1 to G4 are several groups of the recording electrode and the electrophoretic electrode, 11 is a protective resistor to prevent the current due to the discharge to counter electrode 4 flows, 13 is a DC power source.

A description will be given of a head configuration and a control method in the electrostatic ink jet recording apparatus thus configured.

As shown in FIG. 6, the head mainly comprises a recording electrode 1, a migration electrode 3, and a counter electrode 4. The migrating electrode 3 is disposed near the ink ejection port, and includes a plurality of groups G1.
To G4 (FIG. 7). Similarly, the recording electrodes 1 are grouped into the same number as the number of the migration electrodes 3, and the recording electrodes S1 to S4 in one group are individually connected to the driver 10a. The total number of drivers connected to the recording electrode 1 is the number of recording electrodes included in one group (here, four), and the recording electrodes of each group are provided to the driver so that they do not overlap within the group. Connected. Therefore, one driver is connected in parallel to the number of groups.

Next, the printing timing will be described with reference to FIGS. FIG. 8 shows a recording electrode applied voltage (recording electrode control signal) and a counter electrode applied voltage (counter electrode control signal).
FIG. 9A is a timing chart showing a recording cycle, FIG. 9B is a timing chart showing a first migration electrode control signal, and FIG. 9B is a timing chart showing a first migration electrode control signal. 9C is a timing chart showing a second migration electrode control signal, FIG. 9D is a timing chart showing a third migration electrode control signal, and FIG. 9E is a timing chart showing a fourth migration electrode control signal. 9 (f) is a timing chart showing a first recording electrode control signal, FIG. 9 (g) is a timing chart showing a second recording electrode control signal, and FIG. 9 (h) is a third recording. FIG. 9 (i) is a timing chart showing the electrode control signal.
9J is a timing chart showing the recording electrode control signal, and FIG. 9J is a timing chart showing the counter electrode control signal.

As shown in FIGS. 8 and 9, the printing cycle T is time-divided into the number of groups.
As shown in (b) to (e), they are sequentially driven within the printing cycle T. Also, a DC voltage is constantly applied to the counter electrode as a bias. When the recording voltage is applied, the same voltage is applied to all the recording electrodes connected in parallel, and among them, only the group belonging to the group in which the migration electrode is driven performs ink ejection (FIG. 9).
(See (f) to (i)). It is considered that this is because the coloring material particles are concentrated at the ink ejection port by the electric field of the migrating electrode, thereby creating a critical state of ink ejection. If no voltage is applied to the migrating electrode, the critical state is not attained. Therefore, even if a recording voltage is applied to the recording electrode in that state, ink ejection does not occur.

[0019]

However, in the above-described conventional electrostatic ink jet recording apparatus, the above-described divided driving method is used, and when the ink is ejected, the recording electrode 1 and the selected electrophoretic electrode 3 are discharged. When the potential difference between the recording electrode 1 and the recording electrode 1 becomes higher than that of the migrating electrode 3, the color material particles are diffused during ink ejection, and the color material particles become insufficient. Had. Also, even if the electrophoretic electrode 3 is at a higher potential than the recording electrode 1 before the ink is ejected and the color material particles are concentrated, if the potential difference is reduced or reversed at the time of ink ejection, the color concentrated on the recording electrode 1 will be reduced. The material particles are diffused in all directions with the ejection, and as a result, there is a problem that the responsiveness of the ink is deteriorated or the ink is not ejected. These problems become particularly serious when the number of recording electrodes is very large or when the recording frequency is very high. Therefore, according to the conventional electrostatic ink jet recording apparatus, although the number of drivers can be reduced, the color material particles are diffused at the time of ink ejection, so that a line head having hundreds to thousands of electrodes is used. If you use
This is a serious problem when a high response of several kHz is required.

In this electrostatic ink jet recording apparatus,
It is required to prevent the diffusion of the coloring material particles during the discharging period of the coloring material particles, and to enhance the ink ejection stability and the responsiveness.

In order to satisfy this requirement, the present invention can prevent the diffusion of the coloring material particles during the discharging period of the coloring material particles, and improve the ink ejection stability and the responsiveness. It is intended to provide a device.

[0022]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, an electrostatic ink jet recording apparatus according to the present invention comprises a slit section for holding an ink containing charged coloring material particles and forming a discharge section; A plurality of migrating electrodes for concentrating particles as a whole in the width direction of the slit portion, a plurality of recording electrodes for providing an ejection position for ejecting ink, and agglomeration of color material particles adjacent to the recording electrode and selectively at the recording electrode A plurality of agglomerated electrodes, a counter electrode arranged opposite to the recording electrode, the agglomerated electrode, and the migrating electrode to trigger the ink discharge by electrostatic attraction, and selectively applying a potential to the agglomerated electrode to a discharge position. An aggregation electrode control driver for selectively aggregating the color material particles, a counter electrode control driver for applying a counter electrode control signal to the counter electrode to selectively eject ink droplets from the recording electrode, and a plurality of recording electrodes A recording electrode control driver for grouping and applying a voltage individually in each group, and a migration electrode control driver for grouping the migration electrodes into a plurality and applying a voltage individually to each group and controlling them sequentially Is provided.

Thus, it is possible to prevent the diffusion of the coloring material particles during the discharging period of the coloring material particles, and to obtain an electrostatic ink jet recording apparatus capable of improving the ink discharging stability and the responsiveness.

[0024]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An electrostatic ink jet recording apparatus according to the first aspect of the present invention comprises a slit section for holding an ink containing charged coloring material particles and forming a discharge section, and a slit section for coloring the coloring material particles. A plurality of migrating electrodes for concentrating overall over the width direction of the portion, a plurality of recording electrodes for providing an ejection position for ejecting ink, and a plurality of adjoining recording electrodes for selectively aggregating coloring material particles on the recording electrodes. An aggregating electrode, an opposing electrode disposed opposite to the recording electrode, the aggregating electrode, and the migrating electrode to trigger ink ejection by electrostatic attraction, and selectively applying a potential to the aggregating electrode to selectively apply the potential to the ejection position. An aggregation electrode control driver for aggregating the color material particles, an opposite electrode control driver for applying an opposite electrode control signal to the opposite electrode to selectively eject ink droplets from the recording electrodes, and a plurality of recording electrodes grouped into a plurality. It has a recording electrode control driver that controls applied individually voltages within each group, and a migration electrode control driver that controls by applying sequentially voltages separately for each group by grouping migration electrode in a plurality.

According to this configuration, the ink can be aggregated by applying the aggregated electrode control signal to the aggregated electrode.
Diffusion of the coloring material particles during the discharging period of the coloring material particles can be prevented, ink ejection stability and responsiveness can be improved, and the number of necessary drivers can be reduced.

According to a second aspect of the present invention, there is provided the electrostatic ink jet recording apparatus according to the first aspect, wherein the electrophoresis electrode is disposed so as to be insulated and coated with an insulating material. .

According to this configuration, even if the arrangement density of the recording electrodes or the aggregated electrodes is increased, it is possible to prevent the discharge between the adjacent electrophoretic electrodes.

According to a third aspect of the present invention, in the electrostatic ink jet recording apparatus according to the first aspect, the electrophoretic electrode control driver does not select one of the grouped electrophoretic electrodes. At least during the printing period, a fixed potential equal to or lower than a ground potential or a potential applied to a selected migration electrode among the migration electrodes is applied to the migration electrode.

According to this structure, an unselected electrophoretic electrode has a floating potential, and has an effect of preventing ink from being erroneously ejected.

According to a fourth aspect of the present invention, in the electrostatic ink jet recording apparatus according to the first aspect, the aggregated electrode control driver is configured to control the aggregated electrode with respect to the aggregated electrode at least during a printing period. This is to apply a fixed potential voltage higher than the potential applied to the recording electrode.

According to this configuration, since the aggregation electrode has a floating potential, the concentration of the coloring material particles is deteriorated, and an effect of preventing problems such as non-ejection is generated.

Hereinafter, an embodiment of the present invention will be described with reference to FIG.
This will be described with reference to FIG.

(Embodiment 1) FIG. 1 is a configuration diagram showing an electrostatic ink jet recording apparatus according to Embodiment 1 of the present invention, and FIG. 2 is a diagram showing a control driver and respective components in the electrostatic ink jet recording apparatus of FIG. It is a connection diagram showing connection with an electrode.

1 and 2, reference numeral 1 denotes a recording electrode composed of a plurality of recording electrodes S1 to S16 for providing a discharge position for discharging ink, and 2 denotes a color material particle adjacent to the recording electrode 1 and selectively applied to the recording electrode 1. Aggregating electrodes C1 to C3 for aggregating
A plurality of electrophoresis electrodes E1 to E8 for concentrating color material particles over the width direction of a slit portion (ejection portion) formed between the head block upper portion 6 and the head block lower portion 7; Electrophoretic electrodes 4 are arranged opposite to the recording electrode 1 and the electrophoretic electrode 3, and are counter electrodes for triggering ink ejection by electrostatic attraction. 5 is a recording medium (for example, recording paper). Ink flow paths 9, an electrode substrate on which the recording electrodes 1 are arranged, 10 a control driver composed of a plurality of control drivers, DS 1 to DS 2
Denotes a recording electrode control driver for applying a recording electrode control signal (recording voltage) to the recording electrode 1, and DE1 to DE8 denote migration electrodes 3.
Electrode control driver (G1 to G8) for applying a migration electrode control signal (migration voltage) to a plurality of groups including a recording electrode and a migration electrode, and 11 is protection for preventing a current caused by discharge from flowing into the counter electrode 4. Resistor, DP is counter electrode 4
, A counter electrode control driver that supplies a counter electrode control signal to the recording electrode 1 to selectively discharge ink droplets, and 12 selectively applies a potential to the aggregation electrode 2 to selectively aggregate the color material particles at the discharge position. It is an aggregation electrode control driver. In FIG. 2, the recording electrode control drivers DS1 to DS4 group the plurality of recording electrodes 1 into a plurality (here, four), and control by applying a voltage individually in each group. The drivers DE1 to DE4 control the electrophoresis electrodes 3 by grouping the electrophoresis electrodes 3 into a plurality (here, 4) and applying a voltage to each group sequentially.

The configuration, arrangement, and the like of the electrostatic ink jet recording apparatus thus configured will be described.

First, in FIG. 1, the periphery of the recording head comprises a counter electrode 4, a recording medium 5 disposed on the front surface thereof, and a control driver 10. The recording head includes a head block and electrodes. The head block includes a head block upper part 6 and a head block lower part 7, and an ink flow path 8 sandwiched between them is filled with ink in which color material particles are dispersed. The electrodes are arranged in the ink flow path 8 and the electrode substrate 9
A plurality of recording electrodes 1 and a plurality of aggregated electrodes 2 are formed thereon. S1, S2,... Indicate the recording electrodes, and black indicates that the color material particles are concentrated. In this example, all the recording electrodes S1, S2, and S3 shown in the figure are selected, and the color material particles are concentrated. Also, C1, C2,... Indicate aggregated electrodes. The plurality of electrodes are arranged so as to protrude from a common opening or slit between the head block upper part 6 and the head block lower part 7. The head block upper part 6 is provided with the migration electrodes 3 indicated by E1, E2,. The migrating electrode 3 is arranged so as to divide the recording electrode 1 and the aggregation electrode 2 into groups. In the example shown in FIG. 1, two recording electrodes are arranged so as to form one group. The boundary between groups is the aggregation electrode (Fig. 1
C3), and the adjacent electrophoresis electrode (E in FIG. 1).
1 and E2) are insulated and arranged adjacently on the aggregated electrode at the boundary. At any electrode density, it is preferable that adjacent electrophoretic electrodes be insulated by an insulating film such as polyimide. The insulating material may be any material having a withstand voltage determined according to the electrode density and the voltage used. The electrophoresis electrode 3 is located on the upper part 6
However, the head block lower portion 7 may be arranged on the surface in contact with the ink.

Next, FIG. 2 shows a driver connection form. Assuming that the total number of recording electrodes is M × N and the total number of migrating electrodes, that is, the total number of groups is M, one group has N
Book recording electrodes are filled. In this case, the total number of aggregated electrodes is M × N + 1. Therefore, when drivers are connected to individual electrodes without performing divided driving, a total of M × N + 1 drivers of M × N recording electrode control drivers and one counter electrode control driver are required. When the division driving is performed, the total number of N recording electrode control drivers, M migration electrode control drivers, and one counter electrode control driver is reduced to M + N + 1. FIG.
In the example, the total number of recording electrodes is 16 and the number of groups is 8, so that the total number of migrating electrodes is 8, the number of recording electrodes in each group is 2, and the number of aggregated electrodes is 17. (Agglomeration electrodes are not shown in FIG. 2 for simplicity.) The required number of drivers is two recording electrode control drivers + electrophoresis electrode control driver 8
The number of the control electrodes and the counter electrode control driver is 11 in total.
This is a greatly reduced number of 16 recording electrode control drivers and one counter electrode control driver when the division drive is not performed, compared to a total of 17 recording electrode control drivers.

In FIG. 2, the recording electrode control driver is DS
1, DS2, the migration electrode control driver is DE1, DE2,
DE3, DE4,..., DE8, and the counter electrode control driver are denoted by DP. There are two recording electrode control drivers,
Each driver is connected in parallel in each group without duplication. In the example of FIG. 2, the recording electrode control driver DS1 includes groups G1 to S1, groups G2 to S3, groups G3 to S5, and groups G4 to S.
7,..., Groups G8 to S15 are connected in parallel,
The same signal voltage is applied at each signal timing.
Further, the electrophoresis electrodes 3 arranged corresponding to the group G1
Is connected to a migration electrode control driver DE1. Similarly, the recording electrode control driver DS2 includes groups G1 to S2, groups G2 to S4, groups G3 to S6,
Group G4 to S8, ..., Group G8 to S1
6 are connected in parallel. A migration electrode control driver DE2 is connected to the migration electrodes 3 corresponding to the group G2. Similar electrical connections are made in the other groups G3, G4,..., G8. The counter electrode control driver DP is provided on the counter electrode 4 with a protective resistor 11 for preventing discharge.
Connected via

Next, a control method in the electrostatic ink jet recording apparatus shown in FIGS. 1 and 2 will be described with reference to FIGS. FIG. 3A is a timing chart showing the voltage applied to the aggregation electrode (aggregation electrode control signal), FIG. 3B is a timing chart showing the voltage applied to the migration electrode (migration electrode control signal), and FIG. FIG. 3D is a timing chart showing a recording electrode applied voltage (recording electrode control signal) during ejection, FIG. 3D is a timing chart showing a recording electrode applied voltage (recording electrode control signal) during non-ejection, and FIG. FIG. 4 is a timing chart showing an electrode applied voltage (a counter electrode control signal). Similarly, FIG.
FIG. 4A is a timing chart showing the voltage applied to the aggregation electrode (coagulation electrode control signal), FIG. 4B is a timing chart showing the voltage applied to the migration electrode (migration electrode control signal), and FIG.
4 is a timing chart showing a recording electrode applied voltage (recording electrode control signal) at the time of ejection, FIG. 4D is a timing chart showing a recording electrode applied voltage (recording electrode control signal) at the time of non-ejection, FIG.
(E) is a timing chart showing a counter electrode applied voltage (counter electrode control signal).

First, focusing on only one recording electrode, a pair of aggregated electrodes adjacent thereto, and one electrophoretic electrode corresponding to these electrodes, an explanation of the electrical control method and the physical phenomenon will be given. Do. For example, in FIG.
1. Consider C1 and C2 as the aggregation electrode. further,
It is assumed that the color material particles are charged to a positive polarity. In the case of negatively charged coloring material particles, the same description can be made by reversing the relationship of the potential difference. Aggregated electrodes C1 and C
2 is applied with the applied voltage of the aggregation electrode shown in FIG. That is, in this example, a DC voltage of V1 is applied. A voltage applied to the migration electrode 3 is applied to the migration electrode 3 as shown in FIG. That is, in this example, V
2 DC voltages are applied. A pulse signal from the float ground voltage V3 is applied to the recording electrode 1. When ink is to be ejected, the voltage applied to the recording electrode is a pulse from the float ground voltage V3 to 0 V, and when ink is not ejected, the float ground voltage V3 is maintained. When the recording electrode applied voltage becomes 0 V, a potential difference occurs between the adjacent aggregated electrodes C1 and C2 and the migration electrode E1, and the potential of the recording electrode S1 becomes relatively low. Therefore, the positively charged coloring material particles have a low potential. Focus on the recording electrode S1,
Create a critical state for ink ejection. A negative pulse signal from the negative float ground voltage V4 is applied to the counter electrode 4 every printing cycle. When the coloring material particles are concentrated on the recording electrode S1 and the ink ejection is in a critical state, when a negative pulse is applied to the counter electrode 4, the positively charged coloring material particles and the solvent receive electrostatic attraction. Then, ink is ejected. When the voltage V1 applied to the aggregation electrode and the voltage V2 applied to the migration electrode and the voltage V3 applied to the recording electrode are set to the same value, the potential difference does not occur if the voltage applied to the recording electrode is kept at V3. Does not occur, and a critical state of ink ejection cannot be achieved. Therefore, even if a negative pulse is applied to the counter electrode 4, ink is not ejected. By performing such control, it is possible to selectively concentrate the color material particles and selectively discharge the ink.

It is to be noted that the voltage V1 applied to the aggregation electrode and the voltage V2 applied to the electrophoresis electrode need not be a DC voltage, as shown in FIG. 4, as shown in FIG.
A pulse signal having a voltage only during the pulse period of the counter electrode applied voltage (FIG. 4E) or a period including a part of them may be used, or the aggregated electrode applied voltage V1 and the migration electrode applied voltage V2 are the same. The timings need not be the same pulse length. Furthermore, the magnitude relationship between the applied voltage V1 and applied voltage V2 of the aggregation electrode and the applied voltage V2 of the migration electrode and the float ground voltage V3 of the recording electrode S1 is such that V1 ≧ V3, V2 ≧
Any value may be used as long as it is a fixed value satisfying V3. For example, when the applied voltage V1 of the aggregation electrode and the applied voltage V2 of the migration electrode are DC voltages, if the relationship of V1, V2> V3 is satisfied, the aggregation electrode C1, C2 and the migration electrode E1 always move from the recording electrode S1 to the recording electrode S1. Since concentration of the color material particles occurs, the concentration of the color material particles can be improved.

This embodiment is characterized in that the relationship between the potential difference between the aggregated electrodes C1, C2 and the migrating electrode E1 is kept constant even during the period when a signal is applied to the recording electrode S1, so that the ink discharge period This is because the diffusion of the coloring material particles in the inside can be prevented, and the stability and responsiveness of ink ejection can be improved. In the conventional method, as shown in FIG. 8, the coloring material particles concentrate on the recording electrode until a signal is applied to the recording electrode, but the potential difference disappears during the period when the signal is applied. In contrast to the diffusion of the color material particles, in the present embodiment, the color material particles are concentrated on the recording electrodes without being diffused even during the ejection of the ink.

Next, a method of divided driving in the electrostatic ink jet recording apparatus shown in FIGS. 1 and 2 will be described with reference to FIG. FIG. 5A is a timing chart showing a recording cycle.
FIG. 5B is a timing chart showing the aggregation electrode control signal, FIG. 5C is a timing chart showing the first migration electrode control signal, and FIG. 5D is a timing chart showing the second migration electrode control signal. 5 (e) is a timing chart showing a third migration electrode control signal, FIG. 5 (f) is a timing chart showing a fourth migration electrode control signal, and FIG. 5 (g) is a first recording electrode control signal. 5H is a timing chart showing the second recording electrode control signal, FIG. 5I is a timing chart showing the third recording electrode control signal, and FIG. FIG. 5K is a timing chart showing a recording electrode control signal, and FIG. 5K is a timing chart showing a counter electrode control signal. FIG. 5 shows a control method in a case where all the recording electrodes are divided into four groups, and ink ejection is performed for all the recording electrodes. Description will be made in correspondence with the wiring diagram of FIG.

In the case of four divisions, the recording cycle T is divided into four parts,
During the recording period of each T / 4, the recording electrode control signals ds1 to ds4 are applied to the recording electrodes belonging to each group at the same timing (FIGS. 5 (g) to (j)), and each group G1, G2, G
3. Drive G4 sequentially. First, a positive DC voltage is always applied to the aggregated electrode (not shown) adjacent to the recording electrode. Next, during the first T / 4 period, the group G1 is selected, and the print signals ds1 to ds1 corresponding to the recording electrodes S1 to S4 are selected.
ds4 is given. Similar signals are given because they are also connected in parallel to the other groups of electrodes. Further, a positive pulse voltage is applied to the migration electrode E1, and the other migration electrodes E2, E3,. Then, by applying a negative pulse voltage to the counter electrode 4 (FIG. 5 (k)), ink is discharged from the recording electrodes S1, S2, S3, S4 according to the print signal. No ink ejection occurs from the other recording electrodes S5, S6,. Each recording electrode control signal ds1
Differences in pulse lengths from .about.ds4 indicate that they correspond to images and print signals. When the first T / 4 ends, in the next T / 4, print signals ds1 to ds4 corresponding to the recording electrodes S5 to S8 are given. A positive pulse is applied only to the migration electrode E2, and the other migration electrodes E1, E
3,. . . Becomes 0V. Therefore, by applying a negative pulse voltage to the counter electrode 4, the recording electrodes S5, S6, S
7 and S8, ink is ejected according to the print signals ds1 to ds4. Similarly, printing is sequentially performed for each group in the period of the next T / 4 and the next T / 4, and printing by all the recording electrodes is completed in the printing cycle T.

The aggregation electrode and the migration electrode need to have a fixed voltage. This is because if an electrode is left floating, it has a potential due to electrostatic induction by a voltage applied to another electrode. In particular, unselected electrophoresis electrodes must be kept at a fixed potential. Otherwise, the electrophoresis electrode adjacent to the selected electrophoresis electrode has a potential close to the potential of the electrophoresis electrode selected by electrostatic induction, so that erroneous ejection of ink occurs at the recording electrodes of the group not originally selected. Because.

As described above, according to the present embodiment, since the ink can be aggregated by applying the aggregated electrode control signal to the aggregated electrode 2, the diffusion of the colorant particles during the discharge period of the colorant particles can be prevented. Thus, the ink ejection stability and responsiveness can be improved. Further, since the grouped electrophoretic electrodes 3 are insulated and arranged with an insulating material, even if the arrangement density of the recording electrodes 1 or the aggregated electrodes 2 is increased, discharge between the adjacent electrophoretic electrodes is prevented. Can be prevented. Further, electrophoresis electrode control drivers DE1 to DE
4 is a ground potential or a potential equal to or lower than a potential applied to a selected migration electrode among the migration electrodes, at least during a printing period, with respect to a migration electrode that is not selected among the grouped migration electrodes. Since the fixed potential is applied, it is possible to prevent the ink that is not selected from being erroneously ejected due to the unselected electrophoretic electrode having the floating potential. Further, the aggregation electrode control driver 12
With respect to the aggregated electrode 2, at least during the printing period,
Since a voltage of a fixed potential equal to or higher than the potential applied to the recording electrode 1 is applied, the concentration of the coloring material particles is deteriorated due to the floating potential of the aggregated electrode 2, which causes problems such as non-ejection. Can be prevented.

[0047]

As described above, according to the electrostatic ink jet recording apparatus of the first aspect of the present invention, a slit section for holding an ink containing charged color material particles and forming a discharge section; A plurality of migrating electrodes for concentrating color material particles as a whole over the width direction of the slit portion; a plurality of recording electrodes for providing an ejection position for ejecting ink; and color material particles adjacent to the recording electrodes and selectively applied to the recording electrodes. A plurality of aggregating electrodes for aggregating the ink, a counter electrode arranged opposite to the recording electrode, the aggregating electrode, and the migrating electrode to trigger an ink discharge by an electrostatic attraction force, and selectively applying a potential to the aggregating electrode for ejection An aggregation electrode control driver for selectively aggregating color material particles at positions,
A counter electrode control driver that applies a counter electrode control signal to the counter electrode and selectively ejects ink droplets from the recording electrodes, and groups a plurality of recording electrodes into a plurality, and individually applies a voltage in each group. By having a recording electrode control driver for controlling and an electrophoresis electrode control driver for grouping the electrophoresis electrodes into a plurality and applying a voltage to each group sequentially and controlling them individually, an aggregation electrode control signal is applied to the aggregation electrodes. Since the ink can be aggregated, it is possible to prevent the diffusion of the color material particles during the discharge period of the color material particles, to improve the ink discharge stability and responsiveness, and to reduce the number of necessary drivers. The advantageous effect described above can be obtained.

According to the electrostatic ink jet recording apparatus of the second aspect, in the electrostatic ink jet recording apparatus of the first aspect, the electrophoretic electrodes are arranged so as to be insulated and coated with an insulating material. Even if the arrangement density of the electrodes or the aggregation electrodes is increased, the advantageous effect that the discharge between the adjacent electrophoretic electrodes can be prevented can be obtained.

According to the electrostatic ink jet recording apparatus of the third aspect, in the electrostatic ink jet recording apparatus of the first aspect, the migrating electrode control driver comprises: At least during the printing period, a non-selected electrophoretic electrode is given a floating potential by applying a ground potential or a fixed potential equal to or lower than the potential applied to the selected electrophoretic electrode among the electrophoretic electrodes. Has the advantageous effect of preventing erroneous ejection of ink.

According to the electrostatic ink jet recording apparatus of the fourth aspect, in the electrostatic ink jet recording apparatus of the first aspect, the aggregated electrode control driver controls the aggregated electrode at least during a printing period. By applying a voltage of a fixed potential equal to or higher than the potential applied to the recording electrode, it is possible to prevent the concentration of the coloring material particles from being deteriorated due to the floating potential of the aggregated electrode, and to prevent non-discharge. This has the advantageous effect of preventing the occurrence of the problem described above.

[Brief description of the drawings]

FIG. 1 is a configuration diagram illustrating an electrostatic inkjet recording apparatus according to a first embodiment of the present invention.

FIG. 2 is a connection diagram showing a connection between a control driver and each electrode in the electrostatic ink jet printing apparatus of FIG. 1;

FIG. 3 (a) Aggregation electrode applied voltage (aggregation electrode control signal)
(B) Timing diagram showing electrophoretic electrode applied voltage (electrophoretic electrode control signal) (c) Recording electrode applied voltage at ejection (recording electrode control signal)
(D) Timing diagram showing recording electrode applied voltage (recording electrode control signal) during non-ejection (e) Timing diagram showing counter electrode applied voltage (counter electrode control signal)

FIG. 4 (a) Aggregate electrode applied voltage (aggregate electrode control signal)
(B) Timing diagram showing electrophoretic electrode applied voltage (electrophoretic electrode control signal) (c) Recording electrode applied voltage at ejection (recording electrode control signal)
(D) Timing diagram showing recording electrode applied voltage (recording electrode control signal) during non-ejection (e) Timing diagram showing counter electrode applied voltage (counter electrode control signal)

5A is a timing chart showing a recording cycle. FIG. 5B is a timing chart showing an aggregation electrode control signal. FIG. 5C is a timing chart showing a first migration electrode control signal. Timing diagram (e) Timing diagram showing third migration electrode control signal (f) Timing diagram showing fourth migration electrode control signal (g) Timing diagram showing first recording electrode control signal (h) Second diagram Timing diagram showing recording electrode control signal (i) Timing diagram showing third recording electrode control signal (j) Timing diagram showing fourth recording electrode control signal (k) Timing diagram showing counter electrode control signal

FIG. 6 is a configuration diagram showing an electrostatic ink jet recording apparatus disclosed in Japanese Patent Application Laid-Open No. 10-151751.

FIG. 7 is a connection diagram showing a connection between a control driver and each electrode.

FIG. 8 is a timing chart showing a recording electrode applied voltage (recording electrode control signal), a counter electrode applied voltage (counter electrode control signal), and a migration electrode application voltage (migration electrode control signal).

9A is a timing chart showing a recording cycle. FIG. 9B is a timing chart showing a first migration electrode control signal. FIG. 9C is a timing chart showing a second migration electrode control signal. (E) Timing diagram showing fourth migration electrode control signal (f) Timing diagram showing first recording electrode control signal (g) Timing diagram showing second recording electrode control signal (h) (I) Timing diagram showing fourth recording electrode control signal (j) Timing diagram showing counter electrode control signal

[Explanation of symbols]

1, S1, S2, S3, S4, S5, S6, S7, S
8, S9, S10, S11, S12, S13, S14,
S15, S16 Recording electrode 2, C1, C2, C3 Aggregated electrode 3, E1, E2, E3, E4 Electrophoresis electrode 4 Counter electrode 5 Recording medium 6 Upper head block 7 Lower head block 8 Ink flow path 9 Electrode substrate 10 Control driver 11 Protection resistor 12 Aggregated electrode control driver 13 DC power supply DS1, DS2 Recording electrode control driver DE1, DE2, DE3, DE4, DE5, DE6, D
E7, DE8 Electrophoresis electrode control driver DP Counter electrode control driver

Claims (4)

[Claims] 1. A slit section for holding an ink containing charged color material particles and forming a discharge section, a plurality of electrophoretic electrodes for concentrating the color material particles entirely in a width direction of the slit section, A plurality of recording electrodes for providing an ejection position at which the ink is ejected; a plurality of aggregation electrodes adjacent to the recording electrode for selectively aggregating coloring material particles on the recording electrode; the recording electrode; the aggregation electrode; An opposing electrode arranged opposite to the electrode to trigger ink ejection by electrostatic attraction, and an aggregation electrode control driver for selectively applying a potential to the aggregation electrode to selectively aggregate color material particles at the ejection position A counter electrode control driver that applies a counter electrode control signal to the counter electrode to selectively eject ink droplets from the recording electrodes; and a plurality of recording electrodes that are grouped into a plurality of groups. A recording electrode control driver for individually applying and controlling a voltage within the group, and a migration electrode control driver for grouping the electrophoretic electrodes into a plurality and applying and applying a voltage to each group sequentially and sequentially. Electrostatic ink jet recording apparatus. 2. The electrostatic ink jet recording apparatus according to claim 1, wherein said electrophoretic electrode is disposed so as to be insulated and covered with an insulating material. 3. The electrophoresis electrode control driver according to claim 1, wherein said electrophoresis electrode control driver selects a ground potential or a selection of said electrophoresis electrodes at least during a printing period with respect to electrophoresis electrodes not selected among said grouped electrophoresis electrodes. 2. The electrostatic ink jet recording apparatus according to claim 1, wherein a fixed potential equal to or lower than a potential applied to the applied migration electrode is applied. 4. The aggregated electrode control driver applies a voltage of a fixed potential to the aggregated electrode at least during a printing period, which is higher than the potential applied to the recording electrode. 2. The electrostatic ink jet recording apparatus according to 1.