JPH11123831A - Electrostatic ink jet recorder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simplify the structure while reducing the scale by concentrating the particles of a coloring material at an ink jet port through an electrophoretic electrode before jetting them from a jetting electrode, disposing a counter electrode oppositely to the ink jet port and converting a jetting electrode driving pulse, being applied depending on the fluctuation of a plurality of jetting electrode characteristics, in parallel through a head driving means. SOLUTION: Upon receiving an image data containing a pulse width data from a host position, a head control section 51 transfers a head data 57, obtained by converting the pulse width data into the number of pulses, and a clock 56 for reading data in serial to a shift register 52 every divided recording period. Since the image data and pulse width data being transmitted to a large number of jetting electrodes are transferred in serial while dividing the recording period depending on the gray level, the number of signal lines can be decreased and an image data of multiple gray level can be printed.

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 with reference to FIGS. 6, 7, 8 and 9. FIG.

FIG. 6 is a schematic view of an ink jet recording apparatus utilizing an electrophoretic phenomenon, FIG. 7 is a plan view of an ink jet recording apparatus utilizing an electrophoretic phenomenon, and FIG. 8 is a waveform diagram of voltage applied to an electrophoretic electrode and a discharge electrode. FIG. 9 shows a voltage waveform applied to each ejection electrode for correcting the variation in the resistance value.

Referring to FIG. 6 and FIG. 7, an electrostatic ink jet recording apparatus having a plurality of ejection electrodes includes an ink chamber 102 filled with a pigment-based ink 101 and a color material in the pigment-based ink 101. Inject the particles 201 into the ink ejection port 1
And a plurality of ejection electrodes 106 for ejecting the coloring material particles 201 concentrated on the ink ejection ports 104 and causing them to fly onto the recording medium 105.
And a counter electrode 107 disposed on the back surface of the recording medium 105 so as to face the ejection electrode 106. Ink ejection port 10
Reference numeral 4 denotes a convex pigment-based ink 10 at the tip of each ejection electrode 106.
Each discharge electrode is partitioned by the flow path wall 108 so as to form the meniscus 206 shown in FIG. The ink chamber 102 has an ink supply port 109 and an ink discharge port 110.
A back pressure is applied to the ink in the ink chamber 102 and the pigment-based ink 101 in the ink chamber 102 is forcibly circulated.

Next, the operation will be described with reference to FIGS. This apparatus utilizes an electrophoretic 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, a voltage of a constant voltage V1 is applied to the electrophoresis electrode 103, and the ink chamber 1 filled with the pigment ink 101 is charged.
When an electric field is applied to 02, the color material particles 201 in the pigment-based ink 101 move at a certain electrophoretic speed to the ink ejection port 104. When the color material particles 201 move to the ink ejection port 104, a meniscus 206 is generated. The voltage Vej is applied to the discharge electrode 106 for discharging the color material particles 201 for a time period of T25 to T25.
When a pulse-like discharge voltage Vej of 0% is applied, the driver 202 is turned on, and the color material particles 201 are discharged from the discharge electrode 1 by an electrostatic field generated between the discharge electrode 106 and the counter electrode 107.
Move to the tip of 06 and concentrate. The coloring material particles 201 overcome the surface tension, viscous force and the like of the pigment-based ink 101 by electrostatic force, become minute coloring material particles 201 at a timing synchronized with the pulse-shaped ejection voltage Vej, and form the tip of the ejection electrode 106. And adhere to 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, in the head manufacturing process, when the resistance values of the plurality of discharge electrodes 106 vary, and the discharge characteristics vary, the color material particles 201 having a uniform particle diameter are obtained.
The following describes a conventional correction method for ejecting.

In order to generate an arbitrary dot diameter, the correlation between the head resistance and the pulse width to be applied as shown in FIG. 2 is calculated in advance by experiments and evaluations. Then, the head resistance value of each ejection electrode is measured, and the pulse width applied to each ejection electrode is stored in a storage unit (not shown) based on FIG. In the schematic circuit diagram shown in FIG. 7, an image data control unit 205 to which image data is transmitted from a higher-level control unit (not shown) reads pulse width data stored for each ejection electrode from each storage unit, and outputs the image data. The pulse width data corresponding to the pulse width generation unit 204 and the driver 202 for driving each ejection electrode 106 are turned on.
The image data for off control is transmitted to the driver control unit 2
03 respectively. The pulse width generation unit 204 that has received the pulse width data generates a pulse width corresponding to each resistance value for the plurality of ejection electrodes 106 and supplies the ejection voltage Vej to the driver 202. The driver control unit 203 turns on / off the driver 202 corresponding to each of the plurality of ejection electrodes 106 according to the image data, and applies the ejection voltage Vej to the ejection electrodes 106.

For example, when there is a variation in the resistance value of each discharge electrode, the discharge electrode 1 is 2 GΩ, the discharge electrode 2 is 1 GΩ, the discharge electrode 3 is 1.5 GΩ,..., The discharge electrode 40 is 2.5 GΩ. According to FIG. 2, the pulse width generation unit 204 applies 15 μs, 5 μs, 10 μs,...
The ejection voltage having a pulse width of μs is supplied to the driver 202, and the driver control unit 203
2 is turned on, and an ejection voltage Vej based on the pulse width data is applied to each ejection electrode (FIG. 9). Thereby, the dot diameter of the flying color material particles 201 is made uniform and adheres onto the recording medium 105.

[0009]

In the above-mentioned conventional electrostatic ink jet recording apparatus, the pulse width generating section for modulating the pulse width given to each ejection electrode based on the pulse width data has a drive pulse in parallel with each ejection electrode. Supply
As the number of discharge electrodes and the number of gradations increase, there is a problem that the size becomes complicated and large.

[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 to eject ink droplets by the 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 the color material particles at an ink ejection port by an electrophoretic phenomenon, and the color material particles concentrated at the ink ejection port. A plurality of discharge electrodes for discharging, a counter electrode disposed at a position facing the ink discharge port via the recording medium, and a pulse width applied to each of the plurality of discharge electrodes in accordance with a characteristic variation of the discharge electrodes And a head driving means for serially receiving the plurality of ejection electrode drive pulses controlled by a host device and converting the pulses into parallel.

In the electrostatic ink jet recording apparatus according to the present invention, on / off / non-ground floating (high impedance) based on the drive pulse converted into a parallel signal.
The head driving means for performing the above control.

[0012]

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 driving means according to an embodiment of the present invention, FIG. 2 is a correlation diagram between a pulse width applied to an ejection electrode and variation in resistance value of the ejection electrode, and FIG. FIG. 4 is an applied voltage waveform diagram showing the principle of the printhead control method, FIG. 5 is an applied waveform diagram of the printhead control method for correcting the resistance value variation, and FIG. 6 is an ink jet using the electrophoresis phenomenon. It is a schematic diagram of a recording device.

Referring to FIG. 6, an electrostatic ink jet recording apparatus according to an embodiment of the present invention applies an electric field to a pigment-based ink 101 containing charged coloring material particles, and uses a Coulomb force acting on the coloring material particles. By ejecting ink droplets, the recording medium 10
5 is an electrostatic ink jet recording apparatus that performs printing on the ink ejection port 104 by electrophoresis.
Electrophoretic electrode 103 for concentrating the ink on the ink ejection port 104, a plurality of ejection electrodes 106 for ejecting the color material particles concentrated on the ink ejection port 104, and a plurality of ejection electrodes 106 disposed at a position facing the ink ejection port 104 via the recording medium 105. Counter electrode 107
And a plurality of ejection electrodes 1 in which the pulse width applied to each of the plurality of ejection electrodes 106 is controlled in accordance with the characteristic variation of the plurality of ejection electrodes 106.
The recording head driving means shown in FIG. 1 for receiving serially the 06 drive pulse from the host device and converting it into parallel.

Referring to FIG. 1, the recording head driving means includes a head control unit 51 for receiving image data from a host device (not shown), and a serial image data transmitted from the head control unit 51 for converting the image data into parallel image data. A shift register 52 for converting the data into data, a logic circuit 53 for transmitting a drive signal based on the truth table shown in FIG. 3, and a head driver 54 for driving a head 55 based on the drive signal. Consists of

When image data including pulse width data is transmitted from a host device (not shown) in FIG. 1, the head control unit 51 converts the pulse width data into the number of pulses for each divided recording cycle. The data 57 and the data reading clock 56 are serially transferred to the shift register 52 simultaneously. The shift register 52 converts the serially transmitted head data 57 into parallel data, and transmits image data corresponding to each ejection electrode to the logic circuit 53 from each output port (Data 1 to 40). The logic circuit 53 transmits a drive signal to the head driver 4 based on the truth table shown in FIG. As can be seen from the truth table of FIG. 3, the logic circuit 53 includes two control signals (an enable signal 58 and a head energizing pulse width signal 59) sent from the head controller 51 and an image sent from the shift register 52. By taking the logic with the data, the head driver 54 corresponding to each ejection electrode is turned on / off / non-ground floating (high / low).
Impedance).

The recording cycle T in FIG. 4 is the same as (1/5) T1 in FIG. 5, and the basic operation of the embodiment of the present invention for outputting pulse width data in FIG. This will be described in detail.

In the schematic block diagram of FIG. 1, when the head control unit 51 receives image data (two gradations) from a higher-level device (not shown), the head control unit 51 starts recording cycle T and simultaneously outputs head data 57 for 40 nozzles. The clock 56 is set and transmitted to the shift register 52. Prior to this, the head control unit 51 sets the enable signal 58 to “L” from the time of power-on in order to prevent improper ejection from nozzles and the like.
The head energization pulse width signal 59 is set to “H”, and the outputs Out1 to Out40 of the head driver 54 are all set to “L” (0 V).
Set to.

The head controller 51, which has transmitted all the head data, sends the head energizing pulse width signal 5 to the logic circuit 53.
9 transmits an “L” pulse having a time width of Tw.
In the logic circuit 53, 2 transmitted from the head control unit 51
Control signal (enable signal 58, head energizing pulse width signal 59) and four control signals transmitted from the shift register 52.
Parallel nozzle data Data1 to 40 for 0 nozzles
Then, a control signal is transmitted to the head driver 54 in order to perform an output based on the truth table of FIG. The head driver 54 controls the head 55 based on the control signal.
Supply and cutoff of the ejection voltage Vej to the 40 ejection electrodes (not shown) provided in the first embodiment.

Before transmitting new head data in the next cycle, the head controller 51 sets the enable signal 58 to "L".
To "H", the head driver 54 is all set to the non-ground floating state, and this state is maintained until the time Tz at which transmission of the head data of the next cycle ends.

Next, when data as shown in FIG. 4 is transmitted to the ejection electrodes 1 and 2, what kind of output is performed to each ejection electrode will be described. The ejection electrode 1 having image data is synchronized with the head energizing pulse width signal 59 of the head control unit 51 (the middle part in FIG. 4), and the voltage Vej,
A pulse Out1 having a pulse width Tw is output to the head 55. At the same time as the start of the next cycle of data transfer (FIG. 4)
(Middle part), and the enable signal 58 is switched from “L” to “H”, so that a non-ground floating state (shaded portion in FIG. 4) is set. However, since the discharge electrode 1 is charged by a capacitive component such as ink in the head 55 on the load side even when the discharge electrode 1 is in the non-ground floating state, the voltage Vej is maintained during the data transfer period of the next cycle. (Period in FIG. 4). The ejection electrode 1 having no image data in the next cycle is forcibly turned off by the “L” pulse of the head energization pulse width signal 59 from the head control unit 51 (the middle part in FIG. 4).

Since the ejection electrode 2 has no image data in the first recording cycle T, even if the head energizing pulse width signal 59 of the head control unit 51 becomes "L" (the middle part of FIG. 4), the ejection voltage Vej is not changed. No output. Therefore, even if the data transfer in the next cycle is started (the middle part of FIG. 4) and the enable signal is switched from “L” to “H” to be set to the non-ground floating state, charging is not performed in the previous cycle. Therefore, the ejection electrode 2 is maintained at a voltage of 0 V (periods in FIG. 4). The ejection voltage Vej is output from the ejection electrode 2 having image data in the next cycle by the “L” pulse of the head energization pulse width signal 59 from the head control unit 51 (the middle part in FIG. 4).

As can be seen from the above-described operation of the ejection electrode 1, in the recording head driving means of the present invention, when image data is present, a period in which the head energizing pulse width signal Tw and the enable period Tz are combined (one recording cycle) ), Ejection voltage Ve
j will be output. By performing the above operation, the head 55
By applying a discharge voltage Vej to the discharge electrodes in the
The color material particles fly by performing the operation already described in the conventional example, and adhere to the recording medium to perform printing.

Next, the operation of correcting the variation in the resistance values of a plurality of ejection electrodes with a simple circuit configuration, which is a feature of the present invention, will be described with reference to the applied voltage waveform of FIG. here,
For example, the resistance value of 40 ejection electrodes is 1.0 to 2.5 G
There is a variation between Ω, and the operation of discharging a uniform dot diameter of 10 μm from this discharge electrode will be described.

Basically, the printing operation described with reference to FIG. 3 is used. To generate an arbitrary dot diameter (for example, 10 μm), a head resistance value as shown in FIG. 2 is applied in advance. It is necessary to calculate the correlation of the pulse width by experiment and evaluation. Next, the head resistance value of each ejection electrode is measured, the pulse width required to obtain a uniform dot diameter is calculated from FIG. 2 described above, and the result for each ejection electrode is stored in storage means (not shown). ) Is stored in advance. In the schematic block diagram of FIG. 1, the host device (not shown) sends four-stage pulse width data and one or more dummy data (here, one-time imageless data) to the head control unit 5.
Transfer to 1. That is, the recording cycle T is divided into five times of 4 + 1, and pulse width data corresponding to each ejection electrode is transmitted. The pulse width data is one of the five divided periods.
Since the first to fourth transfers are pulse width data, and the last one is dummy data, the print cycle T1
In the last (1/5) T1 period, the power supply to the head is always turned off.

Here, the minimum pulse width must be determined by the variation in the resistance value of the discharge electrode to be used. As shown in FIG.
In the range of 2.5 GΩ, the pulse width at the lowest resistance value of 1 GΩ is 5 μs from the correlation diagram. Thereby, the longest pulse width is 2 when the resistance value is 2.5 GΩ.
Since the recording period is 0 μs, the recording period T1 is set to 25 μs, and the recording period T1 is divided into five parts, so that the variation in the resistance value of the ejection electrode can be corrected in 5 μs steps. If the discharge electrode 1 measures 2 GΩ, the discharge electrode 2 has 1.5 GΩ, the discharge electrode 3 has 2.5 GΩ, and the discharge electrode 40 has 1 GΩ, the resistance value of the discharge electrode 40 is 1 GΩ. Is from the correlation diagram of FIG.
The ejection electrode 2 stores 10 μs, the ejection electrode 3 stores 20 μs,... The ejection electrode 40 stores 5 μs.

The head controller 51 in FIG. 1 sequentially reads out the stored pulse width data, and in the case of the ejection electrode 1, applies a pulse having a width of 15 μs [(3/5) T1] to the ejection electrode. In the transfer of pulse width data of each period (1/5) T1 divided into five,
"Data available (hereinafter referred to as on)""on""on"
After sequentially transmitting “no data (hereinafter referred to as“ off ”)”, dummy data “off” is transmitted. In the data transfer period of each cycle, the head driver 54 is set to the non-ground floating state (shaded portion in FIG. 5) by changing the enable signal from “L” to “H” as in FIG. Prior to this, the head control unit 51 sets the enable signal to “L” and the head energizing pulse width to “H” from the time of turning on the power, and outputs all the outputs of the head driver 54 in order to prevent improper ejection from the nozzles. Set to “L” (0 V). By the above operation, the discharge electrode 1 is set to 3 × Tw + 3 × Tz, that is, 15 μs [(3/5) T1] as shown in FIG.
The ejection voltage Vej is supplied with a pulse width having a certain time width.

The same operation as that of the discharge electrode 1 is performed, and the data is sequentially transmitted to the discharge electrode 2 as "on", "on", "off", and "off" in the data transfer of each divided period (1/5) T1. Then, if the dummy data “off” is transmitted, FIG.
2 × Tw + 2 × Tz, that is, 10 μs [(2 /
5) The discharge voltage Ve has a pulse width having a time width of T1].
j is energized.

Discharge electrode 3 for supplying a pulse width of 20 μs
Sends “on” to all data during data transfer,
Finally, if the dummy data “off” is transmitted, the output of the ejection electrode 3 becomes 4 × Tw + 4 × Tz, that is, 2 ×, as shown in FIG.
The ejection voltage Vej is supplied with a pulse width having a time width of 0 μs [(4/5) T1].

The output of the discharge electrode 40 is "on" and "of" in the data transfer in each period (1/5) T1 divided into five.
f ”,“ off ”,“ off ”and dummy data“ off ”are sequentially transmitted, and 1 × Tw + 1 × Tz, that is, 5 μs [(1 /
5) The discharge voltage Ve has a pulse width having a time width of T1].
j is energized.

As described above, when correcting the variation in the resistance value of the ejection electrode, the recording cycle is divided into m and the pulse width data is transferred, and is transmitted as dummy data at least once at the end of the printing cycle. By controlling the ejection electrode to the non-ground floating state while receiving data, the time for supplying the ejection voltage to the ejection electrode can be modulated, and the diameter of the ink droplet can be made uniform.

[0032]

As described above, in the electrostatic ink jet recording apparatus of the present invention, a plurality of ejection electrode drive pulses whose pulse widths are respectively controlled in accordance with the variation in the characteristics of the plurality of ejection electrodes are ranked higher. Since there is a head driving unit that receives serially from the apparatus and converts the data into parallel data, even if the number of ejection electrodes or the number of gradations increases, the drive pulse given to each ejection electrode according to a change in ejection characteristics due to resistance value variation or the like. There is an effect that it can be varied with a simple circuit configuration and a uniform dot diameter can be discharged.

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

[Brief description of the drawings]

FIG. 1 is a schematic circuit diagram of a recording head driving unit according to an embodiment of the present invention.

FIG. 2 is a correlation diagram between a pulse width applied to an ejection electrode and a variation in resistance value of the ejection electrode according to the embodiment.

FIG. 3 is a truth table of the recording head driving unit of the embodiment.

FIG. 4 is an applied voltage waveform diagram of the printhead control method according to the embodiment.

FIG. 5 is an applied voltage waveform chart for resistance value variation correction in the print head control method according to the embodiment.

FIG. 6 is a schematic diagram of an ink jet recording apparatus using an electrophoresis phenomenon.

FIG. 7 is a plan view of a conventional ink jet recording apparatus.

FIG. 8 is a waveform diagram of a voltage applied to a conventional discharge electrode and an electrophoretic electrode.

FIG. 9 is a waveform diagram of a voltage applied to each ejection electrode for correcting a variation in resistance value according to the related art.

[Explanation of symbols]

 REFERENCE SIGNS LIST 51 head control unit 52 shift register 53 logic circuit 54 head driver 55 head 56 clock 57 head data 58 enable signal 59 head energization pulse width signal 101 pigment-based ink 102 ink chamber 103 electrophoretic electrode 104 ink discharge port 105 recording medium 106 discharge electrode 107 Counter electrode 108 Flow path wall 109 Ink supply port 110 Ink discharge port

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

Claims (2)

[Claims] 1. An electrostatic ink jet recording apparatus which applies an electric field to a pigment-based ink containing charged coloring material particles and ejects 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 on the ink discharge port by an electrophoretic phenomenon, a plurality of discharge electrodes for discharging the color material particles concentrated on the ink discharge port, and the recording medium. And a counter electrode disposed at a position facing the ink discharge port, and the plurality of discharge electrode drive pulses, the pulse widths of which are controlled according to the characteristic variation of the plurality of discharge electrodes. An electrostatic ink jet recording apparatus comprising: a head driving unit that receives serial data and converts the data into parallel data. 2. The electrostatic device according to claim 1, further comprising the head driving unit that controls on / off / non-ground floating (high impedance) based on the driving pulse converted into a parallel signal. Type inkjet recording device.