JPH06278280A - Ink jet recording apparatus - Google Patents

Abstract

PURPOSE:To prevent the lowering of the life of the head of an ink jet recording apparatus by controlling a pulse driver so as to necessarily set all of electrodes to a GND level before emitting ink. CONSTITUTION:A driver control device 6 is equipped with a discharge signal generator 19 generating a discharge signal DISC becoming a high level from a low level in synchronous relation to the falling of the signal Hz from a pulse generator 12 and becoming a low level from a high level in synchronous relation to the rising of a signal INJ. The driver control device 6 necessarily sets all of electrodes 1a, 1b, 1c to a GND level before the emission of ink and discharges the charge accumulated in the electrodes to prevent the flow of a discharge current to a nozzle of a non-emission mode. By this constitution, the lowering of the life of a head can be prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording apparatus used for output printing of an office computer, a personal computer or the like, and in particular, a conductive ink is supplied with an alternating current to boil the conductive ink, and a bubble pressure generated at that time is generated. The present invention relates to an ink jet recording apparatus of an electric ink jet type in which ink is ejected from a nozzle.

[0002]

2. Description of the Related Art In recent years, ink jet recording apparatuses have come to be widely used as output printers for office computers and the like because of quietness in printing.

A conventional ink jet recording apparatus will be described below.

FIG. 4 shows a conventional controller for an ink jet recording apparatus, and 7 is an ink jet head. 1
Reference numerals a, 1b and 1c are electrodes, 2a and 2b are nozzles corresponding to a pair of electrodes with a pair of adjacent electrodes, and 8 is a conductive ink filled between the nozzles. Reference numeral 3 denotes a driver device that outputs an output of either a power supply voltage-GND pulse voltage or high impedance to each electrode,
4a, 4b and 4c are pulse drivers corresponding to the respective electrodes,
Reference numeral 5 is a power source for applying a voltage to the electrodes. Reference numeral 6 is a high impedance signal HZa, HZb, HZ for determining a high impedance output to each pulse driver 4a, 4b, 4c.
c, as well as pulse signals PLSa, PLSb, PLSc that determine the number of pulses and the pulse frequency.

5 and 6 show the structure of the ink jet head 7, 9 is a nozzle plate, and 10 is a head base material.

FIG. 7 shows the configuration of the driver control device 6.
Reference numeral 11 is a CPU. 12 is a signal IN from the CPU 11
In synchronization with the falling edge of J, a pulse signal PPLS having a duty of 50% and an MPLS signal having a phase difference of 180 ° with the pulse signal PPLS are output for a certain period, and the high impedance signal HZ is output for a certain period in synchronization with the rising edge of the signal INJ. It is a pulse generator that outputs. 13, 14, 15,
Reference numerals 16, 17, and 18 are AND gates.

FIG. 8 shows a control timing chart when ink is simultaneously ejected from the nozzles 2a and 2b and when ink is ejected only from the nozzle 2a.

FIG. 9 shows a voltage waveform of each pulse driver output in FIG. 8 and a current waveform flowing between each electrode. Here, V _OUT a is the voltage level of the output OUTa of the pulse driver 4a, and V _OUT b is the output OUT of the pulse driver 4b.
The voltage level of b, V _OUT c is the voltage level of the output OUTc of the pulse driver 4c, Iab is the current flowing from the electrodes 1a to 1b, and Ibc is the current flowing from the electrodes 1b to 1c.

The operation of the ink jet recording apparatus having the above structure will be described below.

The CPU 11 outputs a print start signal INJ and print data signals Da, Db, Dc. The pulse generator 12 outputs a pulse signal PPLS with a duty of 50% and a signal MPLS having a phase difference of 180 ° with the signal PPLS for a certain period in synchronization with the fall of the signal INJ.
Further, the pulse generator 12 sets the high impedance signal HZ to high in synchronization with the rising edge of the signal INJ, and outputs the signal H in synchronization with the falling edge of the last pulse of the signal MPLS.
Set Z low.

When ink is ejected simultaneously from the nozzles 2a and 2b, Da, Db and Dc are all high. Therefore, the signals HZa, HZb, and HZc become high at the rising edge of the signal INJ, and the pulse drivers 4a, 4b, and 4c.
Outputs OUTa, OUTb, OUTc and each electrode 1
a, 1b, and 1c are power supply voltage levels. Then signal IN
When the signals PLSa and PLSc become high in synchronization with the fall of J, the output OUT of the pulse drivers 4a and 4c
a, OUTc and the electrodes 1a and 1c are at the GND level, and the electrode 1b is still at the power supply voltage level.
a potential difference is generated between the electrodes 1b and 1a and between the electrodes 1b and 1c,
Conductive ink 8 from electrode 1b to electrodes 1a, 1c
Currents Iab and Ibc flow through. Then the signal PLS
When a and PLSc change from high to low and the signal PLSb changes to high, the output OUT of the pulse drivers 4a and 4c is output.
a, OUTc and the electrodes 1a, 1c become the power supply voltage level, and the output OUTb of the pulse driver 4b and the electrode 1b.
Becomes a GND level, currents Iab and Ibc flow through the conductive ink 8 from the electrodes 1a and 1c to the electrode 1b, and then currents alternately flow.

As described above, the electrodes 1a, 1b, 1c alternately repeat the power supply voltage level and the GND level, and the current flows from the power supply voltage level toward the GND level through the conductive ink 8 for a certain period. Then, the flowing current causes the conductive ink 8 between the nozzles 2a and 2b to be heated and boiled to generate bubbles. The conductive ink 8 is ejected from the nozzles 2a and 2b by this bubble.

When the signal HZ goes low in synchronization with the trailing edge of the last pulse of the signal MPLS, the signals HZa and HZ
b and HZc change from high to low, and the outputs OUTa, OUTb, OUTc of the pulse drivers and the electrodes 1a,
1b and 1c have high impedance.

Next, the operation when ink is ejected only from the nozzle 2a will be described.

The CPU 11 outputs a print start signal INJ and print data Da, Db, Dc. At this time Da, D
b is output high and Dc is output low. Since Da and Db are high and Dc is low, the high impedance signal HZ
a, HZb go high, HZc remains low,
The outputs OUTa and OUTb of the pulse drivers 4a and 4b are at the power supply voltage level, G while the signals HZa and HZb are high.
Outputs ND level, but pulse driver 4
The output OUTc of c is in a high impedance state because the signal HZc is low.

As described above, the electrodes 1a and 1b alternately repeat the power supply voltage level and the GND level for a certain period, and the conductive ink 8 is moved from the power supply voltage level to the GND level.
A current Iab flows through the conductive ink 8 to boil the conductive ink 8 and generate bubbles. This bubble causes the conductive ink 8 to be ejected from the nozzle 2a. On the other hand, since the electrode 1c has high impedance, no current flows in the conductive ink 8 between the electrodes 1b and 1c, and no ink is ejected from the nozzle 2b.

[0017]

However, in the above-mentioned conventional structure, when the nozzle 2b is in the non-ejection mode, the electrode 1c forming the nozzle 2b should have a high impedance. As shown, if the previous nozzle 1b was in the ejection mode, electric charges are accumulated in the output capacitance of the transistor that constitutes the pulse driver 4c, the floating capacitance of the electrodes and the wiring pattern, and the impedance becomes high impedance while holding the electric charge. ing. In this state, when the nozzle 2a is in the ejection mode and the nozzle 2b is in the non-ejection mode, the other electrode 1 constituting the nozzle 2b is
Since the power supply voltage level b and the GND level b are alternately repeated, the accumulated charge is discharged from the high impedance electrode 1c toward the electrode 1b during the period when the electrode 1b is at the GND level, and the conductive ink of the nozzle 2b is discharged. A direct current Ibc flows through 8. This DC current Ibc continues to flow until the accumulated charge is discharged.

Due to this DC current, electrode wear and electrolysis bubbles are generated, which causes a problem that the life of the head is shortened and ink ejection failure occurs.

In view of the above conventional problems, it is an object of the present invention to provide an ink jet recording apparatus which can prevent the life of the head from being shortened and can always eject ink stably.

[0020]

SUMMARY OF THE INVENTION An ink jet recording apparatus of the present invention comprises a plurality of electrodes, a plurality of nozzles corresponding to each pair of electrodes with adjacent electrodes as a pair of electrodes, and filling between the electrodes. And a pulse driver that is connected to the electrodes and applies an alternating pulse current to the conductive ink.The conductive ink is boiled by applying an alternating pulse current to the conductive ink. An ink jet recording apparatus in which a conductive ink is ejected from a nozzle by a generated bubble pressure is provided with a driver control device for controlling a pulse driver so that all electrodes are always set to a GND level before ink ejection. And

[0021]

According to the above configuration of the present invention, all the electrodes are always set to the GND level before the ink is ejected, so that the electric charge accumulated in the electrodes is discharged, and as a result, the discharge current flows to the nozzle in the non-ejection mode. In addition, it is possible to prevent deterioration of the head life due to electrode wear and generation of electrolysis bubbles, prevent ink ejection failure, and always realize stable ink ejection.

[0022]

EXAMPLES An example of an ink jet recording apparatus of the present invention will be described below with reference to FIGS.
The overall configuration of the control device and the configuration of the head are the same as those described in the conventional example with reference to FIGS. 4, 5 and 6, and thus the description thereof will be omitted here. To do.

FIG. 1 shows the configuration of the driver control device 6 in this embodiment. In FIG. 1, 11 is a CPU.
Reference numeral 12 outputs a pulse signal PPLS having a duty of 50%, an MPLS signal having a phase difference of 180 ° and a pulse signal PPLS having a phase difference of 180 ° for a certain period in synchronization with the fall of the signal INJ from the CPU 11, and goes high in synchronization with the rise of the signal INJ. It is a pulse generator that outputs the impedance signal HZ for a certain period. 13, 14, 15, 16, 17, 18 are A
It is an ND gate. Reference numeral 19 denotes a discharge signal generator that generates a discharge signal DISC that changes from low to high in synchronization with the falling edge of the signal HZ from the pulse generator 12 and changes from high to low in synchronization with the rising edge of the signal INJ. 22 is an OR gate.

FIG. 2 shows a control timing chart when ink is simultaneously ejected from the nozzles 2a and 2b and when ink is ejected only from the nozzle 2a.

FIG. 3 shows the voltage waveform of each pulse driver output in FIG. 2 and the current waveform flowing between each electrode. Here, V _OUT a is the voltage level of the output OUTa of the pulse driver 4a, and V _OUT b is the output OUT of the pulse driver 4b.
The voltage level of b, V _OUT c is the voltage level of the output OUTc of the pulse driver 4c, Iab is the current flowing from the electrodes 1a to 1b, and Ibc is the current flowing from the electrodes 1b to 1c.

The operation of the ink jet recording apparatus having the above structure will be described below.

First, the case where ink is ejected simultaneously from the nozzles 2a and 2b will be described. The CPU 11 outputs a print start signal INJ and print data signals Da, Db, Dc. At this time, Da, Db, Dc are all high,
Therefore, the signals HZa, HZb, and HZc become high at the rising edge of the signal INJ, and the output OUT of each pulse driver is output.
a, OUTb, OUTc and each electrode 1a, 1b, 1c
Becomes the power supply voltage level. Next, when the signals PLSa and PLSc become high in synchronization with the fall of the signal INJ,
The outputs OUTa and OUTc of the pulse drivers 4a and 4c and the electrodes 1a and 1c are at the GND level, and the electrode 1b remains at the power supply voltage level, so that a potential difference is generated between the electrodes 1b and 1a and between the electrodes 1b and 1c. 1b through the conductive ink 8 toward the electrodes 1a, 1c
ab flows. When the signals PLSa and PLSc change from high to low and the signal PLSb changes to high, the outputs OUTa and OUTc of the pulse drivers 4a and 4c and the electrodes 1a and 1c are set to the power supply voltage level, and the output OUTb of the pulse driver 4b and the electrode 1b are set to The level becomes GND, and the current Ibc flows from the electrodes 1a and 1c to the electrode 1b through the conductive ink 8.

As described above, the electrodes 1a, 1b, 1c alternately repeat the power supply voltage level and the GND level, and the current flows from the power supply voltage level toward the GND level through the conductive ink 8 for a certain period. Then, the flowing current causes the conductive ink 8 between the nozzles 2a and 2b to be heated and boiled to generate bubbles. The conductive ink 8 is ejected from the nozzles 2a and 2b by this bubble.

When the signal HZ goes low in synchronization with the trailing edge of the last pulse of the signal MPLS, the signals HZa, HZ
b and HZc change from high to low, the discharge signal DISC is output in synchronization with this, and the OR gate 20,
When the signals PLSa, PLSb, PLSc from 21, 22 become high, the outputs OUTa, OUTb, OUTc of the pulse drivers 4a, 4b, 4c and the electrodes 1a, 1 are output.
b and 1c are at the GND level until the next signal INJ is input.

Next, the operation when ink is ejected from only the nozzle 2a will be described.

The CPU 11 outputs a print start signal INJ and print data Da, Db, Dc. At this time Da, D
b is output high and Dc is output low. Since Da and Db are high and Dc is low, the high impedance signal HZ
a, HZb go high, HZc remains low,
Outputs OUTa and OUTb of the pulse drivers 4a and 4b
Outputs the power supply voltage level and the GND level while the signals HZa and HZb are high, but the output OUTc of the pulse driver 4c is in a high impedance state because the signal HZc is low.

As described above, the electrodes 1a and 1b alternately repeat the power supply voltage level and the GND level for a certain period, and the conductive ink 8 is moved from the power supply voltage level toward the GND level.
A current Iab flows through the conductive ink 8 to boil the conductive ink 8 and generate bubbles. This bubble causes the conductive ink 8 to be ejected from the nozzle 2a.

On the other hand, the output OUTc of the pulse driver 4c
Since the electrode 1c and the electrode 1c have high impedance, no current flows through the conductive ink 8 between the electrode 1b and the electrode 1c even when the potential of the electrode 1b changes alternately with the power supply voltage and the GND level. As shown in (1), Ibc becomes 0, and ink is not ejected from the nozzle 2b. At this time, the electrode 1c is at the GND level until just before the print start signal INJ is input, and the charge accumulation is zero, so that no discharge current is generated from the electrode 1c.

[0034]

As described above, according to the present invention, all the electrodes are always set to the GND level before the ink is ejected, so that the output capacitances of the transistors forming the electrodes, the wiring pattern and the pulse driver are accumulated. Electric charges are discharged, and as a result, discharge current does not flow through the nozzles in non-ejection mode, occurrence of bubbles due to electrode wear and electrolysis is suppressed, reduction in head life can be prevented, and ink ejection failure can be prevented.
Stable ink ejection can always be realized.

[Brief description of drawings]

FIG. 1 is a block diagram of a driver control device in an embodiment of an inkjet recording apparatus of the present invention.

FIG. 2 is a control timing chart in the embodiment.

FIG. 3 is an output voltage waveform diagram of each pulse driver and a current waveform diagram flowing between each electrode in the embodiment.

FIG. 4 is a block diagram of an overall configuration of a control device of the inkjet recording device.

FIG. 5 is a perspective view of an inkjet head.

6 is a sectional view taken along the line AA of FIG.

FIG. 7 is a block diagram of a driver control device of a conventional inkjet recording apparatus.

FIG. 8 is a control timing chart of a conventional example.

FIG. 9 is an output voltage waveform diagram of each pulse driver and a current waveform diagram flowing between each electrode in a conventional example.

[Explanation of symbols]

 1a electrode 1b electrode 1c electrode 2a nozzle 2b nozzle 6 driver control circuit 8 conductive ink 11 CPU 12 pulse generation circuit 19 discharge signal generation circuit

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hajime Shiraishi 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (1)

[Claims] 1. A plurality of electrodes, a plurality of nozzles provided corresponding to each pair of electrodes with adjacent electrodes as a pair of electrodes, conductive ink filled between the electrodes, and a conductive member connected to the electrodes. It is composed of a pulse driver that supplies an alternating pulse current to the conductive ink, and the conductive ink is boiled by applying an alternating pulse current to the conductive ink.
An ink jet recording apparatus in which a conductive ink is ejected from a nozzle by a bubble pressure generated at that time is provided with a driver control device for controlling a pulse driver so that all electrodes are always set to a GND level before ink ejection. Characteristic inkjet recording device.