JPH10278275A - Electrostatic ink jet recorder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a pulse width given to each discharge electrode by a simple circuit configuration based on gradation data even if the number of the electrodes or the number of gradations is increased in an electrostatic ink jet recorder for injecting ink droplet by Coulomb force operating colorant particles to print on a recording medium by giving an electric field to pigment ink containing charged particles. SOLUTION: A head controller 1 receives image data of number of times equal to that of gradations of image data within one recording period, then receives once or more of information without image data to be output irrespective of the gradation, i.e., dummy data, and serially transfers it to a shift register 2. The register 2 converts the serial data into parallel data, and transmits it to a logic circuit 3. The circuit 3 takes a logic of a control signal from the controller 1 and image data from the register 2, and controls a head driver 4 so that the head 5 is set to a non-ground floating state while receiving the image data.

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 A conventional electrostatic ink jet recording apparatus will be described in detail with reference to FIGS.

FIG. 5 is a schematic view of a conventional ink jet recording apparatus utilizing an electrophoretic phenomenon, FIG. 6 is a plan view of a conventional ink jet recording apparatus utilizing an electrophoretic phenomenon, and FIG. It is an applied voltage waveform diagram.

An electrostatic ink jet recording apparatus having a plurality of discharge electrodes is, as shown in FIG.
1, an electrophoretic electrode 103 for concentrating the color material particles 201 in the pigment ink 101 shown in FIG. 6 on the ink ejection port 104, and a color concentrated on the ink ejection port 104. A plurality of discharge electrodes 10 for discharging the material particles 201 and causing them to fly on the recording medium 105
6 and an opposing electrode 107 disposed on the back surface of the recording medium 105 so as to oppose the ejection electrode 106. Ink ejection port 1
Reference numeral 04 denotes a pigment-based ink 1 having a convex shape at the tip of each ejection electrode 106.
Each of the discharge electrodes is partitioned by the flow path wall 108 so that the meniscus 206 shown in FIG. The ink chamber 102 has an ink supply port 109 and an ink discharge port 11.
0 is connected to an ink tank (not shown) by a tube, applies back pressure to the ink in the ink chamber 102, and forces the pigment-based ink 101 in the ink chamber 102 to circulate.

Next, the operation 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, the voltage of the constant voltage V1 shown in FIG. 7 is applied to the electrophoretic electrode 103, and the ink chamber 10 filled with the pigment-based ink 101 shown in FIG.
2 when the electric field is applied to the color material particles 2 in the pigment-based ink 101
01 moves to the ink ejection port 104 at a certain electrophoretic speed. When the color material particles 201 move to the ink ejection port 104, a meniscus 206 is generated. The voltage Vej shown in FIG. 7 and the time T100 shown in FIG.
% Of the pulse-shaped ejection voltage Vej, the driver 202 shown in FIG. 6 is turned on, and the ejection electrode 106 and the counter electrode 1 are turned on.
07, the coloring material particles 201 move to the tip of the ejection electrode 106 and concentrate. The particles overcome the surface tension, viscous force, etc. of the pigment ink by the electrostatic force, and become fine color material particles 201 as shown in FIG. It flies from the tip and adheres onto the recording medium 105. Thereafter, replenishment of the color material particles 201 is performed, and such an operation is repeated to form an image on the recording medium 105.

Here, when printing multi-gradation image data, the time pulse width of the pulse-like ejection voltage Vej applied to the ejection electrode 106 is modulated by the gradation data, and is applied to the ink ejection port 104 of the color material particles 201. Is limited, and the dot diameter at the time of adhering to the recording medium 105 is modulated to perform gradation expression. In the schematic circuit diagram shown in FIG. 6, an image data control unit 205 to which image data including gradation data is transmitted from a higher-level control unit (not shown) generates pulse width data corresponding to the gradation data. Part 204
And a driver 202 for driving each ejection electrode 106
Is transmitted to the driver control unit 203 for on / off control of the image data. The pulse width generation unit 204 that has received the pulse width data generates a pulse width corresponding to each gradation data for each ejection electrode 106,
The ejection voltage Vej is supplied to the driver 202. The driver control unit 203 turns on / off the driver 202 corresponding to each of the ejection electrodes 106 according to the image data, and applies the ejection voltage Vej to the ejection electrodes 106.

For example, as shown in FIG.
In the case where the image data is transmitted such that the gradation data of the 4th gradation is 2/4 gradation in the first cycle, the 4/4 gradation in the second cycle and the 1/4 gradation in the third cycle, the pulse width is From the generation unit 204, T50
%, T100%, and T25% are supplied to the driver 202 with a pulse width, and the driver control unit 203
As a result, the driver 202 is turned on, and the ejection electrode 106 is supplied with the ejection voltage Vej based on the gradation data. Thereby, the dot diameter of the flying color material particles 201 is modulated, and dots having different diameters are formed and adhere to the recording medium 105.

[0008]

In the above-mentioned conventional electrostatic ink jet recording apparatus, first, the pulse width generating section for modulating the pulse width given to each ejection electrode based on the gradation data includes a number of ejection electrodes. As the number of gradations increases, there is a problem that the scale becomes complicated and large.

In connection with the first problem, in order to reduce the number of signal lines of image data transmitted to a large number of ejection electrodes,
There is also a method of serially transferring a plurality of image data at once. In this case, since only binary on / off data such as presence or absence of image data can be sent, multi-tone data is serially transmitted. There is a problem that it is difficult to transfer and print.

[0010]

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 ink droplets are ejected 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, and the electrophoretic electrode concentrated on the ink discharge port. A plurality of discharge electrodes for discharging color material particles, a counter electrode disposed at a position facing the ink discharge port via the recording medium, and a plurality of image data in one recording cycle of the image data. A head driving unit that sets the ejection electrode to a non-ground floating state while receiving and receiving the image data, wherein the head driving unit includes:
After receiving the image data the number of times equal to the number of gradations of the image data, dummy data output irrespective of the gradation is received one or more times.

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 ink droplets are ejected by Coulomb force acting on the coloring material particles to print on a recording medium. In the electrostatic ink jet recording apparatus to be performed, an electrophoretic electrode for concentrating the color material particles in the pigment-based ink on the ink discharge port by an electrophoretic phenomenon, and discharging the color material particles concentrated on the ink discharge port A plurality of ejection electrodes, a counter electrode disposed at a position facing the ink ejection port via the recording medium, and receiving the image data a plurality of times within one recording cycle of the image data. Head driving means for bringing the ejection electrode into a ground state during the first reception of the image data and in a non-ground floating state during the reception of the image data for the second time and thereafter. Means, within one the recording period, after receiving the image data of the number of times equal to the number of gradations of the image data, the dummy data output regardless of the tone may be received more than once.

[0012] The electrostatic ink jet recording apparatus of the present invention may have a serial-parallel conversion circuit for serially receiving image data given to the plurality of ejection electrodes and converting the image data to parallel.

[0013]

Next, embodiments of the present invention will be described in detail with reference to the drawings. In the present embodiment,
A description will be given using a head having 40 ejection electrodes as an example.

FIG. 1 is a schematic circuit diagram of a recording head control method using discharge electrode control means and recording head driving means, and FIG. 2 is a truth diagram of the recording head driving means.

Referring to FIG. 1, when image data including gradation data is transmitted from a higher-level control unit (not shown), the head control unit 1 divides a recording cycle according to the number of gradations, and The image data obtained by converting the data into the number of pulses and the data reading clock are serially transferred to the shift register 2 at the same time. The shift register 2 converts the serially transmitted head data into parallel data, and transmits image data corresponding to each ejection electrode to the logic circuit 3 from each output port (Data 1 to 40). The logic circuit 3 transmits a drive signal to the head driver 4 based on the truth diagram shown in FIG. As can be seen from the truth diagram of FIG. 2, the logic circuit 3 includes two control signals (enable signal, head energizing pulse width) sent from the head control unit 1 and image data sent from the shift register 2. And the head driver 4 corresponding to each ejection electrode
Control to give a state of off / non-ground floating (high impedance).

FIG. 3 is an applied voltage waveform diagram showing the principle of the printhead control method, and FIG. 4 is an applied voltage waveform diagram of the printhead control method during multi-tone printing.

The principle of the recording head control method will be described with reference to FIG. The recording cycle T in FIG. 3 is the same as (1/5) T1 in FIG. 4, and the basic operation of the present invention for outputting the multi-tone data described in FIG. 4 will be described in detail with reference to FIG. Things. In FIG. 1, a head control unit 1 receives image data (two gradations) from a higher-level control unit (not shown).
Is received, the head data and clock for 40 nozzles are set and transmitted to the shift register 2 simultaneously with the start of the recording cycle T. Prior to this, the head control unit 1 sets the enable signal to “L” and the head energizing pulse width to “H” from the time of turning on the power, and sets the output of the head driver 4 from the time of power-on in order to prevent improper ejection from the nozzles. All "L"
(0 V).

The head control unit 1 which has transmitted all the head data transmits to the logic circuit 3 the head energizing pulse width signal Tw.
An "L" pulse having a certain time width is transmitted. The logic circuit 3 takes the logic of two control signals (enable signal, head energizing pulse width) transmitted from the head control unit 1 and parallel head data for 40 nozzles transmitted from the shift register 2. A control signal is transmitted to the head driver 4 so as to perform output based on the truth diagram of FIG. The head driver 4 supplies and shuts off the ejection voltage Vej to 40 ejection electrodes (not shown) provided on the head 5 based on the control signal. Before transmitting new head data in the next cycle, the head control unit 1 changes the enable signal from “L” to “H”, thereby setting all the head drivers 4 to the non-ground floating state. The data is held until the time Tz at which the head data of the next cycle ends (part Z in the drawing).

Next, when the data as shown in FIG. 3 is transmitted to the heads 1 and 2, how the respective heads output will be described. The head 1 with image data outputs a pulse width of a voltage Vej, Tw to the head 5 in synchronization with the head energizing pulse width of the head control unit 1 (part in the figure). At the same time as the start of data transfer in the next cycle (part in the figure), the enable signal is switched from “L” to “H”, thereby setting a non-ground floating state. However, even when the head 1 is in the non-ground floating state, the head 1 is charged by a capacitive component such as ink in the head 5 on the load side. It is kept (in the figure ~
, HiZ). The head 1 in which there is no image data in the next cycle is forced to o by the “L” pulse of the head energizing pulse width from the head control unit 1 (part in the figure).
ff.

Since the head 2 has no image data in the first recording cycle T, even if the head energizing pulse width of the head control unit 1 becomes "L" (part in the figure), the ejection voltage V
ej is not output. Therefore, even if the data transfer in the next cycle is started (the middle part of the figure) and the enable signal is switched from “L” to “H” to be set to the non-ground floating state, the charging is not performed in the previous cycle. The head 2 is maintained at a voltage of 0 V (periods in the drawing). The ejection voltage Vej is output from the head 2 having the image data in the next cycle by the “L” pulse of the head energization pulse width from the head control unit 1 (part in the drawing).

As can be seen from the operation of the head 1, as described above, in the recording head driving means of the present invention, when image data is present, the head energizing pulse width Tw and the enable period Tz are combined (one recording cycle). ), Ejection voltage Vej
Will be output. By performing the above operation and supplying the discharge voltage Vej to the discharge electrode in the head 5, the color material particles fly by performing the operation already described in the conventional example and adhere to the recording medium to perform printing. .

FIG. 4 shows an operation of performing multi-tone printing of a plurality of ejection electrodes with a simple circuit configuration, which is a feature of the present invention.
This will be described using the applied voltage waveform of FIG. Here, as an example, an operation in which 40 ejection electrodes output image data including four gradation data is shown.

Basically, the printing operation described with reference to FIG. 3 is based on the printing operation.
The image data of the gradation and one or more dummy data (here, one-time image-less data) are added to the head control unit 1.
Transfer to That is, here, the recording cycle T is divided into 5 times of 4 + 1, and the gradation data corresponding to each ejection electrode is transmitted. In the gradation data, since the first to fourth transfers of the five divided periods are image data, and the last data is dummy data, the last (1/5) T1 of the printing period T is used. During the period, the power supply to the head is always turned off. Therefore, the pulse width as the gradation data of 100% duty is (4/5) T1.

Therefore, if the head 1 has gradation data of 75% duty, it is necessary to supply a pulse having a width of (3/5) T1 to the discharge electrode as the discharge voltage Vej. For this reason,
In the data transfer of each period (1/5) T1 divided into five as the gradation data of the head 1, the head control unit 1 reads "data present (hereinafter referred to as on)", "on", "on", and "data not present (hereinafter referred to as" on "). off)), and then dummy data “off” is transmitted. In the data transfer period of each cycle, the enable signal is changed from “L” to “H” as in FIG.
By doing so, the head driver 4 is set to the non-ground floating state. Prior to this, the head control unit 1 sets the enable signal to “L” and the head energizing pulse width to “H” from the time of turning on the power, and sets the output of the head driver 4 from the time of power-on in order to prevent improper ejection from the nozzles. All "L"
(0 V). By the above operation, the head 1 in which the 75% duty gradation is set is supplied with the discharge voltage Vej with a pulse width having a time width of 3 × Tw + 3 × Tz, that is, (3/5) T1, as shown in FIG. Is done.

When the same operation as that of the head 1 is performed and the head 2 is printed at 50% duty gradation, "on" is set in the data transfer of each of the five divided periods (1/5) T1.
If "on", "off", and "off" are sequentially transmitted and dummy data "off" is transmitted, the head 2 has a time width of 2 × Tw + 2 × Tz, that is, (2/5) T1, as shown in FIG. The ejection voltage Vej is applied with the pulse width having the pulse width.

In the case of a 100% duty gradation, as described above, if "on" is transmitted to all data and finally dummy data "off" is transmitted to the data transfer of the head 3, the output of the head 3 Is 4 × Tw as shown in FIG.
The ejection voltage Vej is supplied with a pulse width having a time width of + 4 × Tz, that is, (4/5) T1.

The output of the head 40 is "on" and "of" in the data transfer of each period (1/5) T1 divided into five.
f ”,“ off ”,“ off ”and dummy data“ off ”are sequentially transmitted, and the discharge voltage Vej is supplied with a pulse width having a time width of 1 × Tw + 1 × Tz, that is, (1/5) T1,
A gradation with a duty of 25% is performed.

In this way, when printing multi-gradation image data, for example, if the image data has m gradations, the recording cycle is divided by (m + 1) and the image data is transferred at the first m times, Transferred once at the end of the recording cycle as data,
By controlling the ejection electrode to be in a non-ground floating state while receiving the image data, it is possible to modulate the time for supplying the ejection voltage to the ejection electrode and to modulate the diameter of the ink droplet.

In the present embodiment, an example has been described in which dummy data is transferred once at the end of a recording cycle. However, as described above, the number of times of dummy data transfer is not limited to one. That is, if image data has m gradations, n
By selecting a value n that satisfies ≧ 1, the recording cycle is divided into (m + n), and the image data can be transferred in the first m times, and the dummy data can be transferred in the remaining time.

By receiving extra imageless information as dummy data once, for example, when printing 100% duty of four gradations, the width of the head energizing pulse for energizing the ejection electrodes is connected in the next printing cycle. It has the effect of preventing that.

[0031]

As described above, the electrostatic ink jet recording apparatus of the present invention receives the image data a plurality of times within one recording cycle of the image data, and keeps the ejection electrode non-conductive during the reception of the image data. Head driving means for bringing into a ground floating state, wherein the head driving means, within one recording cycle,
After receiving the image data the number of times equal to the number of gradations of the image data, in order to receive the image data absence information that is output regardless of the gradation, that is, the dummy data once or more,
Even if the number of ejection electrodes or the number of gradations increases, there is an effect that the pulse width given to each ejection electrode can be realized with a simple circuit configuration based on the gradation data.

Further, since image data to be transmitted to a large number of ejection electrodes is serially transferred by dividing a recording cycle in accordance with the number of gradations, the number of signal lines is reduced and multi-gradation image data is printed. There is an effect that makes it possible.

[Brief description of the drawings]

FIG. 1 is a schematic circuit diagram of a print head control method using a discharge electrode control unit and a print head driving unit according to the present invention.

FIG. 2 is a truth diagram of the recording head driving means of the present invention.

FIG. 3 is an applied voltage waveform showing the principle of the printhead control method of the present invention.

FIG. 4 is an applied voltage waveform in a print head control method during multi-tone printing according to the present invention.

FIG. 5 is a schematic diagram of a conventional ink jet recording apparatus utilizing an electrophoretic phenomenon.

FIG. 6 is a plan view of a conventional ink jet recording apparatus utilizing an electrophoretic phenomenon.

FIG. 7 is a waveform diagram of a voltage applied to a conventional ejection electrode and an electrophoretic electrode.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Head control part 2 Shift register 3 Logic circuit 4 Head driver 5 Head 101 Pigment ink 102 Ink chamber 103 Electrophoretic electrode 104 Ink ejection port 105 Recording medium 106 Ejection electrode 107 Counter electrode 108 Flow path wall 109 Ink supply port 110 Ink discharge Exit 201 Color material particles 202 Driver 203 Driver control unit 204 Pulse width generation unit 205 Image data control unit 206 Meniscus

Continuing on the front page (72) Inventor Tomoya Saeki 7546 Yasuda, Kashiwazaki City, Niigata Prefecture Inside Niigata Nippon Electric Co., Ltd. (72) Inventor Hitoshi Minemoto 7546 Yasuda Oaza, Kashiwazaki City, Niigata Niigata Nippon Electric Co., Ltd. Inventor Kazuo Shima 7546 Yasuda, Oji, Kashiwazaki, Niigata Pref. Niigata Nippon Electric Co., Ltd. (72) Inventor Yoshihiro Hagiwara, 7546 Yasuda, Oji, Kashiwazaki, Niigata Pref. Niigata Nippon Electric Co., Ltd. 7546 Yasuda, Niigata Nippon Electric Co., Ltd.

Claims (3)

[Claims] 1. An electrostatic ink jet recording apparatus which applies an electric field to a pigment-based ink containing charged coloring material particles, ejects ink droplets 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 a recording medium, and the discharge electrode during receiving the image data a plurality of times within one recording cycle of the image data and receiving the image data. A head driving unit for bringing the image data into a non-ground floating state, wherein the head driving unit receives the image data the number of times equal to the number of gradations of the image data within one recording cycle, and Regardless of the dummy data that is output regardless
An electrostatic ink jet recording apparatus characterized by receiving data at least twice. 2. An electrostatic ink jet recording apparatus for applying an electric field to a pigment-based ink containing charged coloring material particles and ejecting ink droplets 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 ejection port via a recording medium; and a discharge electrode for receiving image data a plurality of times within one recording cycle of the image data and receiving the image data first. The electrode is grounded and the image data is
And a head driving unit that is in a non-ground floating state during reception after the first time, wherein the head driving unit has received the image data a number of times equal to the number of gradations of the image data within one recording cycle. Thereafter, the electrostatic ink jet recording apparatus receives the dummy data output irrespective of the gradation once or more. 3. The electrostatic ink jet recording apparatus according to claim 1, further comprising a serial-to-parallel conversion circuit that serially receives image data given to the plurality of ejection electrodes and converts the image data into parallel data.