JP2845853B2 - Electrostatic inkjet recording device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art A conventional electrostatic ink jet recording apparatus is shown in FIGS.

FIG. 4 is a schematic view of a peripheral portion of a conventional electrostatic ink jet recording device head, FIG. 5 is a plan view of a peripheral portion of the head of the electrostatic ink jet recording device, and FIG. 6 is a waveform diagram of a voltage applied to an ejection electrode. is there.

[0004] 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 to the electrophoretic electrode 403 and an electric field is applied, the color material particles 501 in the pigment-based ink 401 move at an electrophoretic speed to the ink ejection port 404. 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, a voltage is generated between the discharge electrode 406 and the counter electrode 407. The coloring material particles 501 move and concentrate at the tip of the discharge electrode 406 due to the electrostatic field generated. The particles overcome the surface tension, viscous force, etc. of the pigment ink by the electrostatic force, and become fine color material particle groups 504 as shown in FIG. Flying from the tip of
It adheres on the recording medium 405. Then, the ink supply port 4
The color material particles 501 are replenished by the ink supplied from the printer 09. The above operation is repeated to form an image on the recording medium 405.

[0006]

In the above-described 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 ejection electrode, the sharper the tip of the ejection electrode is, the more easily the electric field concentration occurs, the larger the amount of the coloring material particles to be ejected, 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.

[0009] Such a 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.

[0010] It is an object of the present invention to provide a method for forming a substantially uniform amount of color material particles 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 with respect 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.

[0011]

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 ejection electrodes for ejecting the color material particles, and a counter electrode disposed at a position facing the ink ejection port via the recording medium, and a voltage is applied to each of the plurality of ejection electrodes. Is 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. And a counter electrode disposed at a position facing the ink discharge port via the recording medium, and a voltage value applied to each of the plurality of discharge electrodes can be set. You may make it.

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. And a counter electrode disposed at a position facing the ink discharge port with the recording medium interposed therebetween. The discharge electrodes are grouped into a plurality, and a voltage is applied to each group. The time to perform 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 color material particles, and the color material particles are discharged by Coulomb force acting on the color 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. And a plurality of discharge electrodes for causing the discharge electrodes to face each other, and a counter electrode disposed at a position facing the ink discharge port via the recording medium. The value may be settable.

[0015]

Embodiments of the present invention will now 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, the case where the ejection electrode group 1 side is small and becomes larger as approaching the ejection electrode group 8 is shown.

When normal printing is performed in this state, the number of pixels on the recording medium passing over the ejection electrode group 1 is largest, and the number of pixels on the recording medium passing over the ejection electrode group 8 is smallest.

The number of the opposing electrodes 101 is 100 at intervals. 1, No. 101, No. 201,..., No.
701 is the first group of the counter electrode, 2, No. 10
2, No. 202,..., No. 702 is the counter electrode second
The group is referred to as No. 100, no. 20
0, No. 300,..., No. 800 counter electrodes first
It is divided into 100 groups up to 00 groups, and the counter electrodes of each group are connected by the same signal line. The first group of counter electrodes includes a counter electrode driver 10.
2 and the other end of the common electrode driver 102 is connected to a common electrode power supply 103.

The counter electrode driver 102 is turned on and off by a counter electrode control unit 104. This allows
A voltage is supplied from a counter electrode power supply 103 to the ejection electrodes 101 of each group. The discharge electrode group 1 includes a counter electrode N
o. No. 1 to No. It is connected to the ejection electrode driver 107 up to 100. The other end of the ejection electrode driver 107 is connected to the ejection electrode power supply 106. Similarly, the No. of the counter electrode 101 No. 101 to No. 101 The ejection electrode 105 facing the ejection electrode 200 is defined as an ejection electrode group 2, which is connected to the ejection electrode driver 109. Similarly, the ejection electrodes 1 grouped up to the ejection electrode group 8
Numeral 05 is connected to the discharge electrode driver provided for each group.

The discharge electrode application time control section 110 determines the length of the voltage application time supplied from the discharge electrode power supply 106 to each discharge electrode group.

The discharge electrode control unit 108 controls the supply and cutoff of the voltage from the discharge electrode power supply 106 to the discharge electrodes 105 divided into eight groups via the discharge electrode application time control unit 110.

Next, the operation of ejecting a substantially uniform amount of color material particles from each ejection electrode will be described with reference to the applied voltage waveform diagram of FIG. FIG. 2 is a waveform diagram of a voltage applied to a plurality of ejection electrodes and a counter electrode.

The ejection electrode control unit 108 sequentially outputs ejection electrode control signals A to H obtained by time-dividing the recording cycle T into eight equal parts to eight ejection electrode drivers. The time width of the ejection electrode control signal applied to each counter electrode group by the ejection electrode application time control unit 110 is different (T1 <T2).
<T3 <T4 <T5 <T6 <T7 <T8). During the period (T1) when the ejection electrode control signal A is turned on, the ejection electrode driver 1
07 is turned on, and a voltage is applied to the ejection electrode group 1 from the ejection electrode power supply. Next, during a period (T2) when the ejection electrode control signal B is turned on, the ejection electrode driver 109 is turned on, and a voltage is applied to the ejection electrode group 2 from the ejection electrode power supply. A voltage is sequentially supplied from the discharge electrode group 3 to the discharge electrodes 105 of the discharge electrode group 8 from the discharge electrode power supply 106 for a period of time T3 to T8.

Now, at the timing when the discharge electrode control signal A is turned on, the counter electrode control unit 104 sends a counter electrode No. from an image control unit (not shown). 1 receives a signal indicating that image information is present, the counter electrode control unit 104 outputs a signal for turning on the counter electrode driver 102 through the counter electrode control signal D1 (part in the figure), and outputs the counter electrode No. 1. No. 1 including No. 1 101, No. 201,..., No. The common electrode voltage is applied to the first group 701. In this case, the discharge electrode control signal A and the counter electrode No. Since a voltage is applied to the electrode group No. 1, a sufficient electrostatic field is generated for the color material particles to be discharged. Discharge toward 1. As a result, the color material particles adhere to the recording medium to form pixels. Here, the counter electrode No. 1 to the counter electrode No. 1 of the first group of the counter electrodes to which the voltage is applied. 101, N
o. No. 201,... In 701, since no discharge electrode voltage is applied, no color material particles are discharged. In FIG.
From the discharge electrode group 1 to the counter electrode No. 2 ((1) in the figure
No discharge of color material particles occurs toward the discharge electrode N
o. It is shown that ejection is performed for T1 toward 100 ([1] part in the figure). Further, in the period T2 during which the ejection electrode control unit signal B is turned on, the counter electrode No. 101 (middle part of the figure), counter electrode No. 1
No. 02 (portion (2) in the figure) for a period of T2. No ejection is performed toward 200 ([2] part in the figure). During the period T8 when the ejection electrode control signal H is on, the counter electrode No. 70
1 (middle of the figure), No. It is indicated that ejection is performed for T8 time toward 800 ([8] part in the figure). Discharge electrode No. No ejection is performed toward 702 (portion (8) in the figure).

As described above, the ejection is performed from the ejection electrode group 1 for the shortest T1 time, and the ejection time becomes longer as the group number increases, and the ejection is performed from the ejection electrode group 8 for the longest time. In such a place where the distance is short, the electric field concentration becomes large, so that the ejection application time is shortened. As a result, a substantially uniform amount of color material particles is discharged from each discharge 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,
The voltage application time is determined according to this.

FIG. 3 is a block diagram showing a second embodiment of the present invention. An example is shown in which the voltage value applied to each ejection electrode group is changed. In FIG. 3, an applied voltage varying unit 301 is provided instead of the voltage application time control unit 110 shown in FIG. This utilizes the fact that the higher the voltage, the stronger the electric field and the greater the amount of color material particles to be ejected.
In FIG. 3, the lowest voltage V1 is applied to the ejection electrode group 1, the voltage is sequentially increased as the group number increases, and the highest voltage V8 is applied to the ejection electrode group 8 (V1 <V2 <V3 <V4 <V5 < V6 <V7 <V
8). As a result, the potential difference between the discharge electrode and the counter electrode of the discharge electrode group 1 is minimized, and the counter electrode group 8
In this case, the potential difference between the discharge electrode and the counter electrode is maximized, and the electric field strength of each group is made substantially uniform. Here, it is previously determined 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, and the voltage application time to each discharge electrode group is determined accordingly. I have.

In the first embodiment, an example in which the voltage application time to each discharge electrode group is changed has been described, and in the second embodiment, an example in which the voltage value applied to each discharge electrode group has been 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 is described in which the opposing electrodes are divided into 100 groups and the ejection 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.

Further, a method of changing the voltage application time of each of the discharge electrodes without dividing the discharge electrodes into groups, a method of changing the voltage value applied to each of the discharge electrodes, or a method of changing the voltage application time for each of the discharge electrodes Also, a method of changing both the applied voltage value and the applied voltage value is possible, and the discharge amount of the color material particles can be made more uniform.

[0030]

As described above, in the electrostatic ink jet recording apparatus of the present invention, the amount of color material particles to be ejected for each ejection electrode can be reduced by changing the application time or voltage value of the voltage applied to the ejection electrode. By making it variable, there is an effect that it is possible to absorb manufacturing variations of the head portion and to discharge a substantially uniform amount of color material particles from any of the discharge electrodes.

[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.

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

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

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

FIG. 6 is a waveform diagram of a voltage applied to an ejection electrode.

[Explanation of symbols]

 Reference Signs List 101 counter electrode 102 counter electrode driver 103 counter electrode power supply 104 counter electrode control unit 105 discharge electrode 106 discharge electrode power supply 107, 109 discharge electrode driver 108 discharge electrode control unit 110 discharge electrode application time control unit 301 applied voltage variable unit 401 pigment ink 402 ink chamber 403 electrophoresis electrode 404 ink discharge port 405 recording medium 406 discharge electrode 407 counter electrode 408 channel 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 Tomoya Saeki 7546 Yasuda, Kashiwazaki-shi, Niigata Inside Niigata Nippon Electric Co., Ltd. In-house (72) Inventor Kazuo Shima 7546 Yasuda, Niigata Prefecture Kashiwazaki-shi Niigata Nippon Electric Co., Ltd. Person Tohru Yakushiji 7546 Yasuda, Kashiwazaki-shi, Niigata Niigata Nippon Electric Co., Ltd. (58) Field surveyed (Int.Cl. ⁶ , DB name) B41J 2/06

Claims (6)

(57) [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 facing the ink discharge port with the recording medium interposed therebetween, wherein a time for applying a voltage to each of the plurality of discharge electrodes can be set. Electric inkjet recording device. 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, and a voltage value to be applied to each of the plurality of discharge electrodes can be set. Type inkjet recording device. 3. The electrostatic ink jet recording apparatus according to claim 2, wherein a time for applying a voltage to each of the plurality of ejection electrodes can be set. 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, And a counter electrode disposed at a position facing the ink discharge port via the recording medium, wherein the discharge electrodes are 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. 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, wherein the discharge electrodes are grouped into a plurality of groups, and a voltage value to be applied to each group can be set. Electrostatic ink jet recording apparatus. 6. The electrostatic ink jet recording apparatus according to claim 5, wherein a time for applying a voltage can be set for each of the plurality of ejection electrode groups.