JPH09118014A - Ink-jet recording apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a recording apparatus recording with positively utilizing the spontaneous discharge of particles of a coloring matter because of a voltage impressed to an electrophoretic electrode. SOLUTION: This apparatus is provided with a dielectric member 208 having an ink chamber 201, an electrophoretic electrode 203 set in the periphery of the dielectric member 208, and an electrophoretic voltage-controlling part 101 for applying a constant voltage to the electrophoretic electrode 203. The ink chamber 201 has an ink discharge port 202 at one end and stores a pigment ink including charged particles 206 of a coloring matter. The particles 206 gathering at the ink discharge port 202 are let to fly onto a recording body 204 by static electricity. The controlling part 101 has a spontaneous discharge voltage-setting control function to output a predetermined threshold voltage V3 enabling the repeated spontaneous discharge of the particles 206.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet recording apparatus, and more particularly, to an ink jet recording apparatus which has an electrophoretic electrode and which causes charged color material particles in a pigment ink to fly to a recording medium by the action of electrostatic force. Regarding the device.

[0002]

2. Description of the Related Art FIGS. 5 and 6 show a conventional example. First, FIG.
At the main body of the recording head 200, the dielectric member 208
It is formed with. The dielectric member 208 has an ink ejection port 202 at one end and an ink chamber 201 for accommodating a pigment-based ink containing charged color material particles 206 therein. An electrophoretic electrode 203 is provided around the dielectric member 203. Then, the color material particles concentrated in the ink discharge port 202 are configured to fly onto the recording body 204 by an electrostatic force. Here, reference numeral 205 indicates a discharge electrode provided in the ink chamber along the ink discharge direction, and reference numeral 214 indicates a grounded counter electrode facing the ink discharge port 202 via the recording body 204.

More specifically, the ink chamber 201 will be described.
Are formed by hollowing out the inside of the dielectric member 208, and are formed so that the spatial cross-sectional area gradually decreases toward the ink ejection port 202. This ink chamber 201
Is sealed at the rear by the electrophoretic electrode 203. The electrophoretic electrodes 203 are provided on the rear side and the side of the ink chamber 201, and are fixed to the outer edge of the dielectric member 208. The pigment-based ink stored in the ink chamber 201 is a petroleum-based organic solvent (isoparaffin) in which fine particles (toner), which are coloring material particles 206 of a thermoplastic resin colored with a charge control agent, are dispersed. Apparently charged to the positive polarity by the zeta potential. The recording body 204 is plain paper.

Then, as shown in FIG. 6A, a predetermined voltage V having the same polarity as the coloring material particles 206 is applied to the electrophoretic electrode 203.
When 1 is applied, an electric field is formed between the electrophoretic electrode 203 and the ink discharge side tip of the discharge electrode 205,
Due to the action of this electric field, the coloring material particles 206 in the pigment-based ink are
Electrophoresis is applied to the color material particles 206, and the color material particles 206 are collected in the vicinity of the ink ejection port 202. Subsequently, as shown in FIG. 6B, when the pulsed voltage V2 is applied to the discharge electrode 205, an electric field is formed between the discharge electrode 205 and the counter electrode 214, and the color near the ink discharge port is generated. The material particles 206 are gradually pulled out from the ink meniscus and are further concentrated in one place. When the electrostatic force acting on the group of color material particles 206 overcomes the surface tension of the ink meniscus or the like, the color material particle group 206A flies from the ink ejection port 202 toward the counter electrode 214 and onto the recording body 204. Color material particles 2
06 is attached. The desired printing is performed on the surface of the recording medium by repeating the above printing operation while the recording medium 204 is being conveyed.

On the other hand, the color material particles 2 decreased around the ink ejection port 202 due to the emission of the color material particle group 206A.
06 is always conveyed and supplied from the back side of the ink chamber to the ink ejection port 202 under the action of the electric field formed by the electrophoretic electrode 203. As a result, the color material particle group 206A can be continuously discharged.

Here, the coloring material particles 206 are discharged from the discharge electrode 205.
If the pulse voltage V2 is applied to the discharge electrode 205 when the concentration is not sufficiently concentrated on the leading end of the sheet, the coloring material particles 206 are not ejected, and the size and density of the print dots become unstable, which adversely affects the image. There is an inconvenience of giving. Therefore, it is necessary to set the voltage applied to the electrophoretic electrode 203 as high as possible to sufficiently concentrate the color material particles 206 on the tip of the discharge electrode 205.

[0007]

However, in the above-mentioned conventional example, if the voltage applied to the electrophoretic electrode is set too high, the pulse voltage is not applied to the discharge electrode. There is a problem that the coloring material particles are ejected only by the voltage applied to the electrophoretic electrode, that is, so-called spontaneous ejection occurs. In addition, since it is necessary to apply a voltage to both the electrophoretic electrode and the discharge electrode at a predetermined timing when ejecting the coloring material particles, not only the power consumption is large, but also the ejection control system is complicated and the cost is increased. There was also an inconvenience.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to improve the disadvantages of the above-mentioned conventional example, and in particular, an ink jet recording apparatus for positively utilizing the spontaneous ejection of coloring material particles caused by the voltage applied to the electrophoretic electrode for recording operation. The purpose is to provide.

[0009]

In order to achieve the above object,
According to the first aspect of the present invention, a dielectric member having an ink ejection port at one end and an ink chamber for accommodating a pigment-based ink containing electrically charged color material particles, and a dielectric member of the dielectric member are provided. Equipped with a peripheral electrophoretic electrode and an electrophoretic electrode applied voltage control unit that applies a constant voltage to the electrophoretic electrode, and the coloring material particles concentrated at the ink ejection port fly to the recording medium by electrostatic force. Is configured to let. Then, the migration electrode applied voltage control unit has a predetermined threshold voltage V3 that enables repeated spontaneous ejection of the coloring material particles.
It is configured to have a spontaneous ejection voltage setting control function for controlling the output.

Therefore, in the present invention, when the voltage V3 is applied to the electrophoretic electrode by the electrophoretic electrode applied voltage controller, the coloring material particles are generated during the time T1 from the start of the voltage application, as shown in FIG. The color material particle groups are collected by the ink ejection port, and when the time T1 has elapsed, the color material particle group is ejected by spontaneous ejection. After that, the color material particles are replenished and supplied to the ink ejection port during the time T2, and when the time T2 elapses, a certain amount of the color material particles are collected in the ink meniscus and discharged as a color material particle group.
As a result, while the voltage V3 is being applied, the coloring material particle group is repeatedly discharged at intervals of the basic period T2, and dots are formed by the coloring material particle group at regular intervals on the surface of the conveyed recording material. Being done. Here, the basic cycle T2 refers to a cycle of repeated spontaneous ejection that occurs when the threshold voltage V3 is continuously applied to the electrophoretic electrode.

According to the second aspect of the present invention, the electrophoretic electrode applied voltage control section applies the voltage to the electrophoretic electrode when the discharge period of the color material particles set during printing is longer than the spontaneous discharge period T2. The voltage is controlled to be lower than the threshold voltage V3, and the voltage applied to the electrophoretic electrode is set to the threshold voltage V3 before the color material particles are discharged.

Therefore, in the present invention, when the voltage V4 is applied to the electrophoretic electrode, the color material particles in the ink chamber are concentrated on the ink ejection port. However, since the voltage V4 is lower than the threshold voltage V3 of the spontaneous ejection, the color material particle group is not ejected by the spontaneous ejection. Subsequently, the electrophoretic electrode applied voltage control unit switches the applied voltage to the electrophoretic electrode to the voltage V3 at which spontaneous ejection occurs before discharging the color material particles. As a result, the color material particles are gradually pulled out from the tip of the ink meniscus, and the color material particle group is discharged after a lapse of time T3 from the application of the voltage V3. For this reason, the color material particle groups are discharged at a cycle T4 longer than that when the voltage V3 is applied, and the surface of the conveyed recording material is separated by the color material particle groups at a wider interval than when the voltage V3 is applied. Dots are formed.

According to the third aspect of the invention, the electrophoretic electrode applied voltage control section applies the voltage to the electrophoretic electrode when the discharge period of the color material particles set at the time of printing is shorter than the spontaneous discharge period T2. A configuration is adopted in which the voltage is set to the voltage V5 which is the cycle T6 of the spontaneous ejection of the color material particles.

Therefore, in the present invention, when the voltage V5 is applied to the electrophoretic electrode, as shown in FIG. 4, the coloring material particles are collected at the ink ejection port within a certain time T5 from the application of the voltage V5. , The color material particle group is discharged at the time T5. After that, the supply and discharge of the color material particles are repeatedly performed at a cycle T6 shorter than that when the voltage V3 is applied. For this reason, the dots of the color material particle group are formed on the surface of the conveyed recording material at a narrower interval than when the voltage V3 is applied.

[0015] With the above, the above-mentioned object is achieved.

Here, the threshold voltage V3 is a voltage of 0.
Is the voltage at which spontaneous discharge occurs with a certain degree of certainty when gradually increased.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below with reference to FIGS. Here, the same parts as those in the configuration of the conventional example are designated by the same reference numerals, and the duplicate description will be omitted.

First, referring to FIG. 1, the recording head 100 is shown.
Is the same as the recording head 200 shown in the conventional example except that the discharge electrode 205 is not provided.
The pigment-based ink including the counter electrode 214, the recording body 204, and the charged coloring material particles 206 is also the same as that of the conventional example.

In this embodiment, in addition to these, the electrophoretic electrode 203 is provided with an electrophoretic electrode applied voltage control unit 101 for applying a predetermined voltage to the electrophoretic electrode 203. The migration electrode applied voltage control unit 101 also receives an input interface 103 for receiving print data D (including a print control code) output from a higher-level device.
And a control unit 102 that interprets the print data D received by the input interface 103 and sets an ejection cycle based on the ejection timing of the color material particle group 206A.

More specifically, in the present embodiment, the control unit 102 includes a microcomputer, and is configured to perform various print controls by sequentially executing a control program prepared in advance. . For example, the control unit 102 interprets the print data D and recognizes the ejection timing of the color material particle group 206A. Further, the ejection cycle is set from the recognized ejection timing. Further, it is determined whether the set ejection period is longer or shorter than the preset basic period T2, and the instruction signal S corresponding to the result of this determination is input to the migration electrode applied voltage control unit 101.

On the other hand, the applied voltage control unit 101 for the migration electrode
Is a spontaneous ejection voltage setting control function for controlling the output of a predetermined threshold voltage V3 that enables repeated spontaneous ejection of the coloring material particle group 206A, and the coloring material particle group 2 set at the time of printing.
When the ejection period of 06A is a period T4 longer than the spontaneous ejection period T2, the applied voltage to the electrophoretic electrode 203 is set and controlled to a voltage V4 lower than the threshold voltage V3, and the coloring material particle group The function of setting the voltage applied to the electrophoretic electrode 203 to the threshold voltage V3 before discharging 206A and the discharge cycle of the color material particle group 206A set at the time of printing are shorter than the spontaneous discharge cycle T2. It has a function of setting the voltage applied to the electrophoretic electrode 203 to the voltage V5 which is the period T6 of the spontaneous ejection to be discharged by the color material particle group 206A.

The above-described functions of the migration electrode applied voltage controller 101 are selectively activated according to the content of the instruction signal S received from the controller 102. For example, the electrophoretic electrode applied voltage control unit 101 includes a plurality of voltage drive circuits that apply different voltages V3, V4, and V5 to the electrophoretic electrodes 203, and the control unit 102 selectively energizes each voltage drive circuit. It may be configured.

Next, the overall operation according to this embodiment will be described with reference to FIGS.

Input interface 103 from upper device
When the print data D is input to the control unit 102, the control unit 102 interprets the received print data D and sets the ejection timing of the color material particles 206 so that desired printing can be performed on the surface of the recording medium being conveyed. recognize. After that, the control unit 102
The ejection cycle is grasped from continuous ejection timings, and it is determined whether the ejection cycle is longer or shorter than the preset basic cycle T2. Then, the instruction signal S corresponding to the determination result is input to the migration electrode applied voltage control unit 101.

Upon receiving the instruction signal S, the electrophoretic electrode applied voltage control section 101 applies a predetermined voltage having the same polarity as that of the color material particles 206 to the electrophoretic electrode 203 in accordance with the content of the instruction signal S. As a result, an electric field is formed between the electrophoretic electrode 203 and the counter electrode 214, and the color material particles 206 are collected at the ink ejection port 202. The electrostatic force acting on the bundle of color material particles 206 collected in the ink meniscus in relation to the voltage applied to the electrophoretic electrode 203 overcomes the ink meniscus force, the surface tension and the viscous force of the pigment-based ink, and the like. At this time, the color material particle group 206A is discharged.

Specifically, the electrophoretic electrode applied voltage control unit 101 that has received the instruction signal S has a threshold voltage V3 applied to the electrophoretic electrode 203 if the ejection period determined by the control unit 102 is the basic period T2. Is applied. When the voltage V3 is applied to the electrophoretic electrode 203, as shown in FIG.
The color material particles 206 are collected in the ink ejection port 202 during the time T1 from the start of the voltage application, and when the time T1 elapses, the color material particle group 206A is discharged by spontaneous ejection. After that, during the time T2, the color material particles 206 are discharged from the ink discharge port 20.
2, and a certain amount of color material particles 206 are collected in the ink meniscus when the time T2 has elapsed, and the color material particle group 206A
And is discharged. As a result, while the voltage V3 is being applied, the color material particle groups 206A are arranged at intervals of the basic period T2.
Are repeatedly discharged, and dots are formed on the surface of the conveyed recording material 204 by the color material particle groups 206A at regular intervals.

On the other hand, when the ejection period determined by the control unit 102 is longer than the basic period T2, the electrophoretic electrode applied voltage control unit 101 causes the electrophoretic electrode 203 to move as shown in FIG.
First, the voltage V4 is applied. When the voltage V4 is applied to the electrophoretic electrode 203, the coloring material particles 20 in the ink chamber 201 are
6 concentrates on the ink ejection port 202. However, the voltage V4
Is lower than the threshold voltage V3 for spontaneous discharge, the color material particle group 206A is not discharged by spontaneous discharge. Subsequently, the electrophoretic electrode applied voltage control unit 101 switches the applied voltage to the electrophoretic electrode 203 to the voltage V3 that causes spontaneous ejection according to the instruction signal S. As a result, the color material particles 20
6 is gradually pulled out from the tip of the ink meniscus,
When the time T3 has elapsed from the application of the voltage V3, the color material particle group 2
The discharge of 06A is performed. When the particles are discharged in a discharge cycle longer than the basic cycle T2, the voltage V4 is applied again and the above operation is repeated. Therefore, the voltage V
When the color material particle group 20 has a cycle T4 longer than that in the case where 3 is applied,
6A is discharged, and dots are formed on the surface of the conveyed recording material 204 by the color material particle group 206A at a wider interval than when the voltage V3 is applied. Where time T3
Is determined by the control unit 102 according to the application time of the voltage V4.

On the other hand, when the ejection period determined by the control unit 102 is shorter than the basic period T2, the electrophoretic electrode applied voltage control unit 101 causes the electrophoretic electrode 203 to have a voltage higher than the threshold voltage V3, as shown in FIG. A large voltage V5 is applied. When the voltage V5 is applied to the electrophoretic electrode 203, as shown in FIG. 4, the color material particles 206 are collected in the ink ejection port 202 within a certain time T5 from the application of the voltage V5, and the time T5 is reached.
The color material particle group 206A is discharged at the time of the above. After that, the supply and discharge of the color material particles 206 are repeatedly performed at a cycle T6 shorter than that when the voltage V3 is applied. Therefore, dots are formed on the surface of the conveyed recording material 204 by the color material particle group 206A at a narrower interval than when the voltage V3 is applied. Here, the time T4 is the control unit 1
02, the voltage Vbe (= V3 or V4) applied before the voltage V5 is applied to the electrophoretic electrode is determined by the magnitude and application time.

As described above, according to the present invention, the electrophoretic electrode applied voltage control unit 101 can repeatedly and spontaneously eject the color material particles 206 according to the ejection cycle of the color material particles 206 set at the time of printing. Given threshold voltage V3
Output control, the desired printing operation can be performed by positively utilizing the spontaneous ejection phenomenon, which has been a disadvantage in the conventional printing. Further, when the particles are discharged by the spontaneous discharge, the color material particles 206 are always sufficiently concentrated in the ink discharge port 202. Instability of dot size and density can be prevented, and stable high-resolution images can be printed. Further, unlike the conventional example, it is not necessary to provide the discharge electrode, and therefore, desired printing can be performed by controlling only the voltage applied to the electrophoretic electrode which also functions as the discharge electrode, which reduces power consumption. In addition to being able to reduce the cost, the control system can be relatively simplified, and the cost can be reduced. In addition to this, as a matter of course, it is possible to prevent the inconvenience that the printed image is disturbed due to the unexpected spontaneous ejection as in the conventional example.

Further, the applied voltage control section 101 for the migration electrode
Has a function of applying a voltage V4 that is lower than a threshold voltage V3 that causes spontaneous ejection. Therefore, even if the ejection cycle is longer than the basic cycle T2, the color material particles 206 are ejected at arbitrary ejection timings. In addition to being able to flexibly perform normal printing operations, it is also possible to perform various printing processes such as ink-saving printing.

Further, the applied voltage control unit 101 for the migration electrode
Has a function of applying a voltage V5 that is higher than a threshold voltage V3 that causes spontaneous ejection, so that high-speed printing and high-density printing can be easily performed, and gradation printing of a black-and-white grayscale image and the like can be performed. It can be done easily.

Here, regardless of the present embodiment, the voltage V3,
V5 may be at least a voltage at which spontaneous ejection is surely energized, and voltage V4 may be at least a voltage at which spontaneous ejection does not occur. Further, the voltage for causing spontaneous ejection may be configured so that not only two kinds of voltages V3 and V5 but also voltages of several stages can be applied.

[0033]

Since the present invention is constructed and functions as described above, according to this, the applied voltage control unit for the migration electrode is
Depending on the discharge cycle of the color material particles set during printing,
Since a predetermined threshold voltage V3 that enables repeated spontaneous ejection of the color material particles is output controlled, a desired printing operation can be performed by positively utilizing the spontaneous ejection phenomenon, which has been a disadvantage in conventional printing. You can Further, when the particles are discharged by spontaneous ejection, the color material particles are always sufficiently concentrated in the ink ejection port, so that the ejection failure of the color material particles and the size of the printing dot seen in the conventional example are observed. Instability and density can be prevented, and stable high-resolution images can be printed. Further, unlike the conventional example, it is not necessary to provide the discharge electrode, and therefore, desired printing can be performed by controlling only the voltage applied to the electrophoretic electrode which also functions as the discharge electrode, which reduces power consumption. In addition to being able to reduce the cost, the control system can be relatively simplified, and the cost can be reduced. In addition to this
As a matter of course, it is possible to prevent the inconvenience that the printed image is disturbed due to the unexpected spontaneous ejection as in the conventional example.

According to the second aspect of the present invention, the migration electrode applied voltage control unit has a function of applying the voltage V4 lower than the threshold voltage V3 that causes spontaneous ejection, so the ejection cycle is the basic cycle T2. Even if it is longer, the color material particles can be discharged at any discharge timing, the normal printing operation can be performed flexibly, and various printing processes such as ink-saving printing can be performed.

According to the third aspect of the present invention, the migration electrode applied voltage control section has a function of applying the voltage V5 higher than the threshold voltage V3 that causes spontaneous ejection, so that high-speed printing or high-density printing is performed. It is possible to provide an ink jet recording apparatus which is not excellent in the related art in that it is possible to easily perform the gradation printing of a monochrome grayscale image and the like in addition to the above.

[Brief description of the drawings]

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

FIG. 2 is a diagram showing a voltage applied to an electrophoretic electrode when the color material particles are ejected at a basic cycle T2 in the embodiment shown in FIG.

FIG. 3 is a diagram showing a voltage applied to the electrophoretic electrode when the color material particles are ejected at a period T4 longer than the basic period T2 in the embodiment shown in FIG.

FIG. 4 is a diagram showing a voltage applied to the electrophoretic electrode when the color material particles are ejected at a cycle T6 shorter than the basic cycle T2 in the embodiment shown in FIG.

FIG. 5 is a schematic configuration diagram showing a conventional example.

6 is a diagram showing voltages applied to an electrophoretic electrode and an ejection electrode in the conventional example shown in FIG.
6A shows the voltage applied to the electrophoretic electrode, and FIG.
(B) shows the voltage applied to the discharge electrode.

[Explanation of symbols]

 101 Applied Voltage Control Unit for Electrophoretic Electrode 102 Control Unit 103 Input Interface 201 Ink Chamber 202 Ink Ejection Port 203 Electrophoretic Electrode 204 Recording Body 205 Discharge Electrode 206 Color Material Particles 206A Color Material Particle Group 207 Dielectric Member 214 Counter Electrode

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Ryosuke Uematsu 5-7-1, Shiba, Minato-ku, Tokyo Inside the NEC Corporation (72) Inventor Kazuo Shima 5-7-1, Shiba, Minato-ku, Tokyo Japan Electric stock company

Claims (3)

[Claims] 1. A dielectric member having an ink discharge port at one end and an ink chamber for accommodating a pigment-based ink containing electrically charged color material particles, and a dielectric member provided around the dielectric member. The electrophoretic electrode and an electrophoretic electrode applied voltage control unit for applying a constant voltage to the electrophoretic electrode, so that the coloring material particles concentrated in the ink ejection port are ejected onto the recording medium by electrostatic force. In the inkjet recording apparatus configured as described above, the electrophoretic electrode applied voltage control unit has a spontaneous ejection voltage setting control function for controlling output of a predetermined threshold voltage V3 that enables repeated spontaneous ejection of the color material particles. Inkjet recording apparatus characterized by the following. 2. The applied voltage control unit for the electrophoretic electrode sets the applied voltage to the electrophoretic electrode when the discharge cycle of the color material particles set at the time of printing is longer than the spontaneous discharge cycle T2. The inkjet according to claim 1, wherein the voltage is controlled to be lower than the threshold voltage V3, and the voltage applied to the electrophoretic electrode is set to the threshold voltage V3 before the color material particles are discharged. Recording device. 3. The applied voltage control unit for the electrophoretic electrode sets the applied voltage to the electrophoretic electrode when the discharge cycle of the color material particles set at the time of printing is shorter than the spontaneous discharge cycle T2. Spontaneous discharge cycle T6 in which color material particles should be discharged
The ink jet recording apparatus according to claim 1, wherein the voltage V5 is set as follows.