JPH10157126A - Electrostatic ink jet recorder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make uniform the shape of an image on a recording medium by providing an electrophoretic electrode, a plurality of electrodes for jetting coloring matter particles and counter electrodes facing each other through a recording medium, classifying the counter electrodes into a plurality of groups and setting a voltage applying time for each group. SOLUTION: In the case of a multielement head, jetting electrodes 101 are classified into groups of 100 electrodes and a jetting electrode group 1 is connected with one end of a jetting electrode driver 102 having the other end connected with a jetting electrode power supply 103. A counter electrode group 1 faces the jetting electrodes No.1 through No.100 connected with one end of a counter electrode driver 107 having the other end connected with a counter electrode power supply 106. Similarly, a counter electrode 105 is connected with the counter electrode driver 107 and a gate electrode control section 108 controls power supply from the counter electrode power supply 106 to the counter electrode 105 through a counter electrode voltage applying time control section 110 and interruption of power supply.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrostatic ink jet recording apparatus, and more particularly to an electrostatic ink jet recording apparatus in which coloring material particles in a pigment ink are controlled by an electrophoretic phenomenon.

[0002]

2. Description of the Related Art FIGS. 4, 5 and 6 show a conventional electrostatic ink jet recording apparatus. FIG. 4 is a schematic view of a peripheral portion of a head of a conventional electrostatic ink jet recording device, FIG. 5 is a plan view of a peripheral portion of a head of the electrostatic ink jet recording device, and FIG. FIG. 6 is a waveform diagram of an applied voltage.

[0003] An electrostatic ink jet recording apparatus having a plurality of ejection electrodes, as shown in FIG.
1, an electrophoretic electrode 403 for concentrating the coloring material particles 501 in the pigment ink 401 shown in FIG. 5 on the ink ejection port 404, and a color concentrated on the ink ejection port 404. A plurality of ejection electrodes 40 for ejecting the material particles 501 and causing them to fly on the recording medium 405
6 and a counter electrode 407 that is disposed on the back surface of the recording medium 405 so as to face the same. The ink ejection port 404 is formed of a convex pigment-based ink 401 at the tip of each ejection electrode 406 as shown in FIG.
In order to form the meniscus 502 shown in FIG.
Is partitioned for each discharge electrode. Ink chamber 402
Is connected to an ink tank (not shown) by an ink supply port 409 and an ink discharge port 410 by a tube, so that a back pressure is applied to the ink in the ink chamber 402 and the pigment ink 401 in the ink chamber 402 is forced. Has been circulated.

Next, these operations will be described. This method utilizes an electrophoresis phenomenon in which, when an electric field is applied to a pigment-based ink containing charged coloring material particles, the coloring material particles move in one direction under the electric field. That is, when a constant voltage V1 shown in FIG. 6 is applied between the counter electrode 407 and the electrophoretic electrode 403 and an electric field is applied, the pigment-based ink 40
The color material particles 501 in 1 move to the ink ejection port 404 at a certain electrophoretic speed. Color material particles 5
When 01 moves, a meniscus 502 is generated. When the driver 503 is turned on to discharge the color material particles 501 and the voltage V2 shown in FIG. 6 and the pulse-shaped discharge electrode application voltage Vej of time T2 are applied to the discharge electrode 406, the discharge electrode 406 is discharged.
The color material particles 501 move and concentrate on the tip of the discharge electrode 406 by an electrostatic field generated between the discharge electrode 406 and the counter electrode 407. The color material particles 501 overcome the surface tension and the viscous force of the pigment ink by the electrostatic force, and the pulse-shaped ejection voltage V
At the timing synchronized with ej, as shown in FIG. 5, the color material particles 504 are scattered from the tip of the discharge electrode 406 and adhere to the recording medium 405. After that, the coloring material particles 501 are supplied by the ink supplied from the ink supply port 409. The above-described operation is repeatedly performed on the recording medium 405.
An image is formed thereon.

[0005]

In the above-mentioned conventional electrostatic ink jet recording apparatus, a plurality of discharge electrodes are formed due to variations in the shape of the discharge electrodes due to variations in the head manufacturing process, or variations in the positions of the discharge electrodes with respect to the counter electrode. Even if the same voltage is applied to the plurality of ejection electrodes, the amount of color material particles (toner particle amount) to be ejected is different, and the pixel shape on the recording medium is different.

For example, in terms of the shape of the discharge electrode, the sharper the tip of the discharge electrode is, the more easily the electric field concentration occurs, the larger the amount of color material particles to be discharged, and the larger the pixel shape on the recording medium.

In terms of the position of the discharge electrode with respect to the counter electrode, if the distance between a certain discharge electrode and the counter electrode is shorter than the distance between another discharge electrode and the counter electrode, the pixel shape on the recording medium becomes large. Conversely, if the distance between one ejection electrode and the opposing electrode is longer than the distance between another ejection electrode and the opposing electrode, the pixel shape on the recording medium becomes smaller.

[0008] Such variation in pixel shape becomes more remarkable as the number of ejection electrodes increases. Further, among the plurality of discharge electrodes, there is also a problem that the electric field is more easily concentrated at the discharge electrodes at both ends than the other electrodes, and the amount of color material particles to be discharged is increased, so that the pixel shape on the recording medium is increased.

It is an object of the present invention to provide a method for producing color material particles having a substantially uniform amount from any of the discharge electrodes, even if there is a variation in the shape of the discharge electrode due to a variation in the head manufacturing process or a variation in the position of the discharge electrode relative to the counter electrode. An object of the present invention is to provide an electrostatic ink jet recording apparatus which discharges an amount of ink and makes an image on a recording medium uniform.

[0010]

In the electrostatic ink jet recording apparatus of the present invention, an electric field is applied to a pigment-based ink containing charged coloring material particles to discharge the coloring material particles by Coulomb force acting on the coloring material particles. In an electrostatic ink jet recording apparatus that performs printing on a recording medium, an electrophoretic electrode for concentrating color material particles in the pigment-based ink on an ink discharge port by an electrophoretic phenomenon, A plurality of discharge electrodes for discharging the color material particles, and a counter electrode disposed at a position facing the ink discharge port via the recording medium, wherein the counter electrodes are grouped into a plurality. The voltage application time can be set for each group.

The electrostatic ink jet recording apparatus of the present invention applies an electric field to a pigment-based ink containing charged coloring material particles, discharges the coloring material particles by Coulomb force acting on the coloring material particles, and prints on a recording medium. And an electrophoretic electrode for concentrating the coloring material particles in the pigment-based ink on the ink ejection port by an electrophoretic phenomenon, and discharging the coloring material particles concentrated on the ink ejection port. And a plurality of ejection electrodes for causing a plurality of ejection electrodes to face each other, and a counter electrode disposed at a position facing the ink ejection ports via the recording medium. The value may be settable.

In the electrostatic ink jet recording apparatus of the present invention, an electric field is applied to a pigment-based ink containing charged coloring material particles, and the coloring material particles are ejected by Coulomb force acting on the coloring material particles to print on a recording medium. And an electrophoretic electrode for concentrating the coloring material particles in the pigment-based ink on the ink ejection port by an electrophoretic phenomenon, and discharging the coloring material particles concentrated on the ink ejection port. A plurality of ejection electrodes, a counter electrode disposed at a position facing the ink ejection port via the recording medium, and ejection for controlling the application by individually applying a voltage by grouping the ejection electrodes into a plurality. An electrode control unit, a counter electrode control unit configured to group the counter electrodes into a plurality of groups and individually apply and control a voltage, and set a time for applying a voltage for each group of the counter electrodes. It may have a counter electrode applying time controller.

According to the electrostatic ink jet recording apparatus of the present invention, an electric field is applied to a pigment-based ink containing charged coloring material particles, and the coloring material particles are discharged by Coulomb force acting on the coloring material particles to print on a recording medium. And an electrophoretic electrode for concentrating the coloring material particles in the pigment-based ink on the ink ejection port by an electrophoretic phenomenon, and discharging the coloring material particles concentrated on the ink ejection port. A plurality of ejection electrodes, a counter electrode disposed at a position facing the ink ejection port via the recording medium, and ejection for controlling the application by individually applying a voltage by grouping the ejection electrodes into a plurality. An electrode control unit, a counter electrode control unit for grouping the counter electrodes into a plurality and applying and controlling voltages individually, and a voltage value applied to the counter electrode can be changed for each group It may have a voltage applied varying unit.

[0014]

Next, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a configuration diagram showing a first embodiment of the present invention. FIG. 1 illustrates a multi-element head having 800 ejection electrodes as an example. Further, the distance between the counter electrode and the discharge electrode differs depending on the location due to the variation in the manufacturing process. That is, an example is shown in which the counter electrode group 1 side is smaller and becomes larger as it goes to the counter electrode group 8. When normal printing is performed in this state, the pixels on the recording medium passing over the opposing electrode group 1 are the largest, and the pixels on the recording medium passing over the opposing electrode group 8 are the smallest.

The number of ejection electrodes 101 is 100 at intervals. 1, No. 101, No. 201 ... No. 70
No. 1 is the ejection electrode group 1, and No. 1 2, No. 10
2, No. 202... No. 702 is the ejection electrode group 2, 100, no. 200, N
o. 300 ... No. 800 ejection electrode groups 100
The discharge electrodes of each group are connected by the same cable. The ejection electrode group 1 is connected to an ejection electrode driver 102, and the other end of the ejection electrode driver 102 is connected to an ejection electrode power supply 103 that supplies a voltage to the ejection electrode 101.
These ejection electrode drivers are supplied with a voltage to the ejection electrodes 101 of each group by being turned on / off by the ejection electrode control unit 104.

The counter electrode group 1 includes ejection electrode Nos. 1
From No. 100, which are connected to a counter electrode driver 107. The other of the counter electrode drivers is connected to a counter electrode power supply 106. Similarly, for the discharge electrode 101, No. 101 to No. 101 The counter electrode 105 facing the counter electrode 200 is referred to as a counter electrode group 2 and is connected to the counter electrode driver 109. Similarly, the counter electrodes 105 grouped up to the counter electrode group 8 are connected to counter electrode drivers provided for each group. The counter electrode application time control unit 110 determines the length of application time for supplying a voltage from the counter electrode power supply 106 to each counter electrode group. The counter electrode control unit 108 controls to supply or cut off a voltage from the counter electrode power source 106 to the counter electrode 105 divided into eight groups via the counter electrode application time control unit 110.

FIG. 2 is a waveform diagram of voltages applied to a plurality of ejection electrodes and a counter electrode. With reference to FIG. 2, an operation for discharging a substantially uniform color material particle amount from each discharge electrode will be described. The counter electrode control unit 108 sequentially outputs the counter electrode control signals A to H obtained by time-dividing the recording cycle T into eight equal parts to eight counter electrode drivers. The time width of the counter electrode control signal applied to each counter electrode group by the counter electrode application time control unit 110 differs. (T1 <T2 <T3
<T4 <T5 <T6 <T7 <T8) During the period (T1) in which the common electrode control signal A output to the common electrode driver 107 is turned on (T1), the ejection electrode No. 1 to N
o. A voltage is applied from a counter electrode power supply to a counter electrode group 1 that faces 100. A voltage is sequentially supplied from the counter electrode power source to the counter electrode 108 of the counter electrode group 8 from the counter electrode group 2 to the counter electrode 108 of the counter electrode group 8 for a period of T2 to T8.

At the timing when the counter electrode control signal A is turned on, the discharge electrode control unit 104 sends the discharge electrode No. from the image control unit (not shown). When the ejection electrode control unit 104 receives a signal indicating that image information is present at the ejection electrode No. 1, the ejection electrode control unit 104 outputs a signal to turn on the ejection electrode driver 102 through the ejection electrode control signal D1 (part in the figure). No. 1 including No. 1 101, No. 201 ... No. The ejection electrode voltage is applied to the ejection electrode group 1 of 701. In this case, the counter electrode control signal A and the ejection electrode No. Since a voltage is applied to the electrode No. 1, a sufficient electrostatic field is generated to discharge the color material particles, and the color material particles are set in the discharge electrode No. 1. No. 1 is ejected for T1 time. Thereby, a pixel is formed by adhering to the recording medium. Here, the ejection electrode No. The ejection electrode No. 1 of the ejection electrode group 1 to which the ejection voltage is applied in the same manner as the ejection electrode No. 1 101, No. 201 ... No. In 701, no color material particles are ejected because the counter electrode voltage is not applied. FIG. 2 (portion (1) in the figure) and no discharge electrode No. It is shown that ejection from 100 ([1] part in the figure) is performed for T1 time.

Further, during the period T2 when the counter electrode control unit signal B is turned on, the discharge electrode No. 101 (middle part of the figure), ejection electrode No. T2 from 102 (part (2) in the figure)
Discharge for a time. Discharge electrode No. No ejection is performed from 200 ([2] part in the figure).

The period T during which the counter electrode control signal H is on
In No. 8, the ejection electrode No. 701 (the middle part of the figure), 8
This indicates that the discharge is performed for T8 time from 00 ([8] part in the figure). Discharge electrode No. No ejection is performed from 702 (part (8) in the figure).

As described above, the opposing electrode group 1 discharges for the shortest T1 time, and the discharge time increases as the group number increases, and the group 8 discharges for the longest time. As a result, the shorter the distance, the greater the electric field concentration becomes. Therefore, the ejection application time is shortened. The longer the distance, the less the electric field concentration becomes. A substantially uniform amount of color material particles is discharged from the electrode. Here, how the color material discharge amount changes depending on the discharge time and the distance between the counter electrode and the discharge electrode is obtained in advance, and the voltage application time to each counter electrode group is determined in accordance with the change.

FIG. 3 is a block diagram showing a second embodiment of the present invention. The example which changes the voltage value applied to each counter electrode group is shown. In FIG. 3, an applied voltage variable unit 301 is provided instead of the voltage application time control unit described in the first embodiment. This utilizes the fact that the higher the voltage, the stronger the electric field and the larger the amount of color material particles to be ejected. The highest voltage V1 is applied to the opposing electrode group 1 and the voltage is sequentially lowered as the group number increases, and the lowest voltage V8 is applied to the opposing electrode group 8.
(V1>V2>V3>V4>V5>V6>V7> V8) As a result, the potential difference between the discharge electrode and the counter electrode of the counter electrode group 1 is minimized, and the potential difference between the discharge electrode and the counter electrode of the counter electrode group 8 is reduced. Is maximized and the electric field distribution of each group is made uniform. Here, how the color material discharge amount changes depending on the potential difference between the discharge electrode and the counter electrode and the distance between the counter electrode and the discharge electrode is determined in advance, and the voltage value applied to each counter electrode group is determined according to this. .

In the first embodiment, an example in which the voltage application time to each counter electrode group is changed is described, and in the second embodiment, an example in which the voltage value applied to each counter electrode group is changed has been described. It is also possible to change both the voltage application time and the applied voltage value.

In the first and second embodiments, 8
In the multi-element head having 00 ejection electrodes, an example has been described in which the ejection electrodes are divided into 100 groups and the counter electrodes are divided into 8 groups. However, the number of groups is not limited to this. It is possible to select an optimal value from the relation of easiness and cost.

[0026]

As described above, according to the present invention, the amount of color material particles to be discharged for each discharge electrode can be varied by changing the voltage application time or the voltage value applied to each of the opposing electrodes by dividing them. It is possible to absorb manufacturing variations and the like as much as possible, and to discharge a substantially uniform amount of color material particles from any discharge electrode. This has the effect of making the image shape on the recording medium uniform.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing a first embodiment of the present invention.

FIG. 2 is a waveform diagram of a voltage applied to a plurality of ejection electrodes and a counter electrode according to the present invention.

FIG. 3 is a configuration diagram showing a second embodiment of the present invention.

FIG. 4 is a schematic view of a peripheral portion of a head of a conventional electrostatic ink jet recording apparatus.

FIG. 5 is a plan view of a peripheral portion of a head of a conventional electrostatic ink jet recording apparatus.

FIG. 6 is a waveform diagram of a voltage applied between a conventional counter electrode and an electrophoretic electrode and to a discharge electrode.

[Explanation of symbols]

 101 discharge electrode 102 discharge electrode driver 103 discharge electrode power supply 104 discharge electrode control unit 105 counter electrode 106 counter electrode power supply 107 counter electrode driver 108 counter electrode control unit 109 counter electrode driver 110 counter electrode application time control unit 301 applied voltage variable unit 401 pigment System ink 402 ink chamber 403 electrophoresis electrode 404 ink discharge port 405 recording medium 406 discharge electrode 407 counter electrode 408 flow path wall 409 ink supply port 410 ink discharge port 501 color material particles 502 meniscus 503 driver 504 color material particle group

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Hitoshi Minemoto 7546 Yasuda, Niigata Nippon Electric Co., Ltd. (72) Inventor Yoshihiro Hagiwara 7546 Yasuda, Kashiwazaki-shi, Niigata Prefecture Inside Niigata Nippon Electric Co., Ltd.

Claims (6)

[Claims] An electrostatic ink jet recording apparatus for applying an electric field to a pigment-based ink containing charged coloring material particles and discharging the coloring material particles by Coulomb force acting on the coloring material particles to perform printing on a recording medium. An electrophoretic electrode for concentrating the color material particles in the pigment-based ink on the ink discharge port by an electrophoretic phenomenon, and a plurality of discharge electrodes for discharging the color material particles concentrated on the ink discharge port, A counter electrode disposed at a position opposite to the ink ejection port via the recording medium, wherein the counter electrode is grouped into a plurality of groups and a time for applying a voltage for each group can be set. Characteristic electrostatic ink jet recording apparatus. 2. An electrostatic ink jet recording apparatus which applies an electric field to a pigment-based ink containing charged coloring material particles, discharges the coloring material particles by Coulomb force acting on the coloring material particles, and performs printing on a recording medium. An electrophoretic electrode for concentrating the color material particles in the pigment-based ink on the ink discharge port by an electrophoretic phenomenon, and a plurality of discharge electrodes for discharging the color material particles concentrated on the ink discharge port, A counter electrode disposed at a position facing the ink discharge port via the recording medium, wherein the counter electrode is grouped into a plurality of groups, and a voltage value to be applied to each group can be set. Electrostatic ink jet recording apparatus. 3. The electrostatic ink jet recording apparatus according to claim 2, wherein a time for applying a voltage can be set for each group of the plurality of opposed electrodes. 4. An electrostatic ink jet recording apparatus which applies an electric field to a pigment-based ink containing charged coloring material particles and discharges the coloring material particles by Coulomb force acting on the coloring material particles to perform printing on a recording medium. An electrophoretic electrode for concentrating the color material particles in the pigment-based ink on the ink discharge port by an electrophoretic phenomenon, and a plurality of discharge electrodes for discharging the color material particles concentrated on the ink discharge port, A counter electrode disposed at a position facing the ink discharge port via the recording medium; a discharge electrode control unit configured to group the discharge electrodes into a plurality and individually apply and control a voltage; and A counter electrode control unit that groups and groups the plurality of electrodes to individually apply and control a voltage, and a counter electrode application time control unit that can set a time for applying a voltage for each group of the counter electrodes. Characteristic electrostatic ink jet recording apparatus. 5. An electrostatic ink jet recording apparatus which applies an electric field to a pigment-based ink containing charged coloring material particles and discharges the coloring material particles by Coulomb force acting on the coloring material particles to perform printing on a recording medium. An electrophoretic electrode for concentrating the color material particles in the pigment-based ink on the ink discharge port by an electrophoretic phenomenon, and a plurality of discharge electrodes for discharging the color material particles concentrated on the ink discharge port, A counter electrode disposed at a position facing the ink discharge port via the recording medium; a discharge electrode control unit configured to group the discharge electrodes into a plurality and individually apply and control a voltage; and It is characterized by having a counter electrode control unit for grouping a plurality of electrodes to individually apply and control voltages, and an applied voltage variable unit capable of changing a voltage value applied to the counter electrode for each group. Electrostatic inkjet recording device. 6. The electrostatic ink jet recording according to claim 5, further comprising a counter electrode application time control unit that can set a time for applying a voltage to each of the plurality of groups of the counter electrodes. apparatus.