JPH06278281A - Ink jet device - Google Patents

Abstract

PURPOSE:To consume inductor energy due to the inductor accumulated in a pulse driver and to suppress the unnecessary emission of ink from a non- emission nozzle by always turning the FET constituting the pulse driver ON during a period unrelated to the emission of ink. CONSTITUTION:In a driver control unit 4a forming the signals Pa, HIa supplied to a pulse driver, an inverter 27 reversing the signal Pout generated in a conventional pulse driver is provided to form a signal Pout 1. The signal Pout 1 becomes an H-level during a period unrelated to the emission of ink and, by outputting the signal Pout 1 to the FET constituting the pulse driver, the inductor energy accumulated in the pulse driver is discharged by the turning-ON of the FET.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printing apparatus used for output printing of an office computer, a personal computer or the like, and in particular, a conductive ink is formed by applying an alternating current having an alternating frequency of 1 MHz or more to the conductive ink. The present invention relates to an ink-jet device of an energization ink-jet system, in which the ink is boiled and the ink is ejected from the nozzle by the bubble pressure generated at that time.

[0002]

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

First, a conventional ink jet device will be described below with reference to FIGS. FIG. 4 is a control block diagram of a conventional inkjet device. In FIG. 4, 6 is an inkjet head, and in the inkjet head 6, 1a, 1b, 1c are electrodes, 2a, 2
b is a nozzle corresponding to each pair of electrodes with the adjacent electrodes of the electrodes as a pair of electrodes, and 3a, 3b and 3c output either 50V, GND pulse voltage or high impedance according to the signal of the driver control device. Is a pulse driver that outputs to each electrode. 4a, 4b and 4c are high impedance signals HIa, HIb and HIc which determine a high impedance output to each pulse driver and pulse signals Pa, Pb and Pc which determine a pulse number and a pulse frequency.
The driver control device 5 for outputting the discharge data signals Da, Db, Dc and the selection signals SELa, SELb, SE for selecting the pulse phase of the pulse signal to each driver control device 4.
It is a CPU that outputs Lc.

FIG. 5 is an external view of the ink jet head 6,
FIG. 6 is a cross-sectional view taken along the line Z in FIG. 5, where 7 is the nozzle plate, 8 is the head bottom plate, and 9 is the conductive ink between the nozzles.

FIG. 7 is a circuit diagram of the pulse driver 3a. 10 is a 50V power source and 11 is an ON-OFF by a HIa signal.
FET (Field Effect Transistor), 12 is an FET that is turned on and off by a Pa signal, and 17 is an ON-OF of FET 11.
A transistor that outputs a high-impedance and power supply voltage 50V level to the collector by F, 13 is an ON- of FET12
50 depending on OFF and potential level of transistor 17
Transistors that output V, GND, and high impedance to OUTa, 15 and 16 are resistors, 18 is a diode, and 14 is F.
It is an inductor for high-speed switching of the ET12 and is indispensable for high-speed switching with a simple circuit configuration. .

FIG. 8 is a block diagram of the driver control device 4a. Reference numeral 19 is a 1 MHz pulse signal HP + and a pulse signal H of 50% duty in synchronization with the fall of the INJI signal.
A pulse generator that outputs an HP- signal having a phase difference of 180 degrees with P + for a certain period, 21 is a high impedance signal generator that generates a high impedance signal HI from the ejection data Da and the INJI signal, 20, 22, 23 are The pulse signals HP + and HP- are selected by the high impedance signal HI and the selection signal SELa, and the high impedance signal HI is selected.
Pulse signal HP + or HP- only during the period when is at H level
Is output to Pout and is output as a Pa signal output. Here, the H level period of the high impedance signal HI is set to a period during which 100 pulses of the pulse signal HP + or HP− enter.

9 and 10 are control timing charts of the ink jet device when the nozzles 2a and 2b eject ink simultaneously and when only the nozzle 2a ejects ink, showing pulse currents flowing in the conductive ink of the nozzle 2a. Ia
b, the pulse current flowing through the nozzle 2b is Ibc.

The operation of the ink jet device constructed as described above will be described below. First,
The operation when ink is ejected from the nozzles 2a and 2b will be described. The CPU 5 turns on the ejection data Da, Db, Dc to each driver control device in synchronism with the INJI signal to set it to the H level for a certain period, and sets the selection signals SELa and SELc of each driver control device to the H level and SELb.
To L level. As a result, as shown in the timing charts of FIGS. 9 and 10, in the driver control devices 4a and 4c, only the first 100 pulses of the HP + signal are selected and become the pulse signals Pa and Pc.

On the other hand, in the driver control device 4b, HP-
Only the first 100 pulses of the signal are selected and the pulse signal Pb
Becomes Further, the discharge data signals Da, Db, Dc are all H
From the level, the HI signal of FIG. 8 becomes H level, and all the high impedance signals HIa, HIb, HIc become H level.

Now, the operation of the pulse driver 3a will be described. First, the high impedance signal HIa is L
When the level is reached, the FET 11 is turned off during that period.
Therefore, the transistor 17 is also turned off and the transistor
The collector terminal of 13 becomes high impedance. In this state, when the pulse signal Pa becomes H level, the FET 12 turns on, the diode 18 turns on and the pulse driver output O
UTa becomes GND level. On the contrary, when the pulse signal Pa becomes L level, the FET 12 turns off and the diode 18
Is turned off, and the pulse driver output OUTa becomes high impedance like the collector terminal of the transistor 13.

On the other hand, the high impedance signal HIa is H
When the level is reached, the FET 11 is turned on during that period. Therefore, the transistor 17 is also turned on, and the collector output of the transistor 17 becomes the potential 50V of the power supply 10. In this state,
When the pulse signal Pa becomes H level, FET12 turns on.
Then, the diode 18 turns on and the pulse driver output OUT
a becomes the GND level. At this time, the current I _L flows from the power supply 10 to the inductor 14 via the resistor 15. At this time, the inductor energy E _{L of the} equation 1 is accumulated in the inductor 14.

[0012]

[Equation 1] E _L = (1/2) · L · I _L ^{2 On the} contrary, when the pulse signal Pa becomes L level, the FET 12 is turned off, so that the pulse signal Pa is stored in the inductor 14 during the H level period. The inductor energy E _L is discharged, the output capacitance C of the FET 12 is rapidly charged,
12 turns off momentarily. This allows the transistor 13
The base potential of is rapidly set to the potential of the power source 10, 50V. Therefore, the emitter potential of the transistor 13 is
Since it becomes equal to the base potential of the pulse driver output O
UTa has a potential of 50V.

As described above, the output OUTa of the pulse driver 3a is GND depending on the H or L level of the pulse signal Pa while the high impedance signal HIa is at the H level.
Alternatively, with the potential of 50 V, the high frequency pulse output of 1 MHz becomes possible due to the effect of the inductor 14. Furthermore, since the high impedance signal HIa is at the L level and the pulse signal Pa is at the L level, the output OUTa of the pulse driver 3a becomes high impedance, and the output OUTa of the pulse driver 3a becomes the GND level, 50V level,
It will be in a high-impedance three-state state.

By the pulse driver operation as described above,
When the ejection data Da, Db, Dc are ON, each pulse driver outputs a pulse waveform of GND, 50V while the high impedance signals HIa, HIb, HIc are at H level.

However, as shown in FIG. 10, only the output OUTb of the pulse driver 3b has a pulse waveform whose phase is 180 degrees out of phase with other pulse driver outputs, so that the output potential of the pulse drivers 3a and 3c is 50V. When, the output potential of the pulse driver 3b is GND, conversely
When the output potentials of a and 3c are GND, the pulse driver 3b
Output potential is 50V.

From the above, the electrodes 1a, 1b, 1c alternately repeat the 50V potential and the GND potential, and the GND is changed from the 50V potential to the GND potential.
A pulse current I is passed through the conductive ink 9 toward the potential.
Ab and Ibc will flow. Therefore, the flowing pulse currents Iab and Ibc cause the conductive ink 9 between the nozzles 2a and 2b to boil and generate bubbles, so that the conductive ink 9 is ejected from the nozzles 2a and 2b. After the ejection is completed, the high impedance signals HIa and HI
b and HIc are switched from H level to L level, and all pulse driver outputs are in a high impedance state.

Next, the operation when ink is ejected from only the nozzle 2a will be described. The CPU 5 synchronizes with the INJI signal and sends the ejection data Da, Db to each driver control device.
Is turned on to be at the H level for a certain period of time, and Dc is kept at the L level while it is kept off. Further, the selection signals SELa and SELc of each driver control device are set to H level, SE
Set Lb to L level. Accordingly, as shown in the timing charts of FIGS.
Only the first 100 pulses of the P + signal are selected to become the pulse signal Pa, and the driver controller 4b sets HP
Only the first 100 pulses of the signal are selected to be the pulse signal Pb. The output Pc of the driver control device 4c is fixed at the L level because the ejection data Dc is OFF.

Further, since the ejection data signals Da and Db are at the H level and Dc is at the L level, the high impedance signal HI is obtained.
a and HIb are at H level, and HIc is at L level. Therefore, as in the case of the operation of ejecting ink from the nozzles 2a and 2b, when the ejection data Da and Db are ON, the pulse driver outputs OUTa and OUTb are the pulse waveforms of GND and 50V during the high impedance signal H level period. The output OUTc of the pulse driver 3c is
Since the high impedance signal HIc is at the L level, the other high impedance signals HIa and HIb are at the H level period,
High impedance state.

From the above, the electrodes 1a and 1b have a potential of 50 V and G
The ND potential is alternately repeated, and the pulse current Iab flows through the conductive ink 9 from the 50 V potential toward the GND potential, and the conductive ink 9 boils. Accordingly, the conductive ink 9 boils to generate bubbles, and the conductive ink 9 is ejected from the nozzle 2a. On the other hand, electrode 1
Since c has a high impedance, no pulse current flows in the conductive ink 9 between the electrodes 1b and 1c, and no ink is ejected from the nozzle 2b.

[0020]

In the conventional ink jet device as described above, when the nozzle 2b is in the non-ejection mode, the electrode 1c forming the nozzle 2b should have high impedance. Timing Chart As shown in FIGS. 9 and 10, when the nozzle 2b is in the ejection mode at the previous INJI timing, the inductor energy E _L is accumulated in the inductor 14 forming the pulse driver 3c, and the energy is stored in the inductor 14. High impedance while holding.

In such a state, when the nozzle 2a is in the ejection mode and the nozzle 2b is in the non-ejection mode, the other electrode 1b constituting the nozzle 2b has a pulse potential which alternately repeats 50 V and GND potential. And the electrode 1b is GN
Electrode 1c that is high impedance during the period of D potential
The inductor energy E _L held at the previous INJI timing is discharged from the electrode 1b to the electrode 1b, and the pulse current Ibc flows in the conductive ink 9 between the nozzles 2b. This pulse current Ibc is the inductor energy E _L
Continues to flow until it is consumed, resulting in a unidirectional pulse current from the electrode 1c to the electrode 1b. Therefore, the pulse current Ibc causes the conductive ink 9 to generate heat, which causes a problem that unnecessary ink is ejected from the nozzle 2b. The present invention solves the above problems, and an object of the present invention is to provide an inkjet device having a simple control device and no discharge current.

[0022]

In order to achieve the above-mentioned object, the present invention always turns on the FET constituting the pulse driver for a period unrelated to ejection during the period of the INJI signal and the next INJI signal. It is configured to include a simple driver control device.

[0023]

According to the present invention, since the FET constituting the pulse driver is turned on during the period unrelated to the ejection during the period of the INJI signal and the next INJI signal, the present invention realizes high-speed switching of the pulse driver. Energy is not accumulated in the inductor, and ink is not ejected from the nozzle in the non-ejection mode.

[0024]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below with reference to the drawings. However, only the block of the driver control device (FIG. 8) is different from the conventional one, and other FIG. 6 and 7 are the same as those of the conventional example, the description thereof will be omitted. FIG. 1 is a block diagram of a driver control device for an ink jet device according to an embodiment of the present invention, in which 24 is a pulse signal HP + or HP- synchronized with the fall of the INJI signal.
EN that generates the ENB signal that enables output of only 0 pulses
B signal generator, 26 inverts the ENB signal and outputs IEN
Inverter to generate B signal, 27 is the same as the conventional 20, 2
An inverter for inverting the gate output composed of 2 and 23 to output Pout, and a select device 25 for selecting either Pout or IENB as the output of the driver control device Pa according to the ejection data. Further, since the other driver control devices 4b and 4c have the same configuration, the description thereof will be omitted.

FIGS. 2 and 3 are control timing charts of the ink jet device when only the nozzle 2a is in the discharge mode. The pulse current flowing through the conductive ink of the nozzle 2a is Iab and the pulse current flowing through the nozzle 2b is Ibc.

The case where the nozzle 2a is in the discharge mode and the nozzle 2b is in the non-discharge mode will be described below. Timing Chart As shown in FIG. 2, the CPU 5 first outputs the ejection data Da and Db to each driver control device in synchronization with the INJI signal.
N and Dc are turned off, selection signals SELa and SELc of each driver control device are set to H level, and SELb is set to L level.
To level. Further, the ENB signal switches from the L level to the H level in synchronization with the fall of the INJI signal.
As a result, the pulse signal HP + or HP- is enabled only while the ENB signal is at the H level, which is the same as in the conventional case.
A pulse signal is output as Pout from the gate composed of 20, 22, and 23.

The pulse signal Pout is inverted by the inverter 27 and becomes Pout1. As a result, the Pout1 of each driver control device is always at the H level during the L period of the ENB signal, and during the H period of the ENB signal, the Pout1 of the driver control devices 4a and 4c has the same phase waveform as HP + and the driver control as in the conventional case. Pout1 of the device 4b has the same phase waveform as HP-.

Next, since the ejection data Da is ON at the output Pa of the driver control device 4a, the SELECT device 25
Pout1 is selected in the same manner, and similarly, Pout1 is the output Pb of the driver control device 4b and the inverted IENB of the ENB signal is the output Pc of the driver control device 4c.
Selected from 5. Further, the high impedance signal has the same waveforms HIa, HIb, and HIc as in the conventional case.

Next, the operation of the pulse drivers 3a, 3b, 3c will be described. Output Pa of each driver control device,
Pb and Pc are always at H level for a period not related to ejection, that is, the ENB signal is L period. Therefore, in the pulse driver shown in FIG. 7, the FET 12 connected to the outputs Pa, Pb, Pc of each driver control device is always ON during that period. Therefore, the inductor energy E _L accumulated in the inductor 14 is completely discharged during the L period of the ENB signal via the FET 12.

On the other hand, when the ENB signal is in the H period, the ejection data D
Since the output Pc of the driver control device 4c in which c is OFF is fixed at the L level, the FET1 of the pulse driver 3c is
2 is turned off, and the output OUTc of the pulse driver 3c
Becomes high impedance as shown in the timing chart of FIG. The outputs Pa and Pb of the driver control devices 4a and 4b whose discharge data are ON have pulse waveforms having a phase difference of 180 degrees. Therefore, as shown in FIG. 3, when the output OUTa of the pulse driver 3a is 50V, the output OUTb of the pulse driver 3b is GND, and when the output OUTa of the pulse driver 3a is GND, the pulse driver 3
The output OUTb of b becomes 50V. Therefore, ENB signal is H
Conductive ink 9 between the electrodes 1a and 1b during the level period
A pulse current Iab flows through the conductive ink 9 to boil, a bubble is generated, and the ink is ejected from the nozzle 2a. Further, since the output OUTc of the pulse driver 3c has high impedance, the potential of the electrode 1b is 50%.
Even if it changes alternately with V and GND, no current flows in the conductive ink 9 between the electrodes 1b and 1c, the pulse current Ibc becomes 0 as shown in the timing chart FIG. 3, and ink is ejected from the nozzle 2b. Absent.

[0031]

As is apparent from the above embodiments, the ink jet device according to the present invention has the driver control device configured to turn on the FETs forming the pulse driver during a period not related to ink ejection. Energy is not accumulated in the inductor that configures the driver, the discharge current from the inductor in the non-ejection mode nozzle is eliminated, and unnecessary ink ejection from the non-ejection mode nozzle is suppressed. It has the effect of suppressing electrode wear and generation of bubbles due to electrolysis.

[Brief description of drawings]

FIG. 1 is a block diagram of a driver control device of an inkjet device according to an embodiment of the present invention.

FIG. 2 is a timing chart in an example of the present invention.

FIG. 3 is a timing chart in an example of the present invention.

FIG. 4 is a control block diagram of the inkjet device of the present invention and the related art.

FIG. 5 is an outline view of an inkjet head of the present invention and a conventional inkjet head.

FIG. 6 is a cross-sectional view of an inkjet head of the present invention and a conventional inkjet head (FIG. 5).

FIG. 7 is a circuit diagram of the present invention and a conventional pulse driver.

FIG. 8 is a block diagram of a driver control device of a conventional inkjet device.

FIG. 9 is a control timing chart of a conventional inkjet device.

FIG. 10 is a control timing chart of a conventional inkjet device.

[Explanation of symbols]

1 (1a, 1b, 1c) ... electrode, 2 (2a, 2b) ... nozzle,
3 (3a, 3b, 3c) ... Pulse driver, 4 (4a, 4
b, 4c) ... Driver control device, 5 ... CPU, 6 ... Inkjet head, 7 ... Nozzle plate, 8 ... Head bottom plate, 9 ... Conductive ink, 10 ... Power supply, 11, 12 ... FE
T (field effect transistor), 13, 17 ... Transistor,
14 ... Inductor, 15, 16 ... Resistance, 18 ... Diode, 19 ... Pulse generator, 20 ... OR, 21 ... High impedance signal generator, 22, 23 ... AND, 24 ... E
NB signal generator, 25 ... SELECT device, 26, 27
… Inverter.

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

Claims (1)

[Claims] 1. An electrode, a nozzle provided corresponding to each pair of electrodes with an electrode adjacent to the electrode as a pair of electrodes, a conductive ink filled between the electrodes, and connected to the electrodes. The conductive ink is boiled by flowing a pulsed alternating current through the conductive ink, and the conductive ink is boiled by the bubble pressure generated at that time. In an inkjet device in which a volatile ink is ejected, the level is a GND level during a period not related to ink ejection.
An ink jet device, comprising: a driver control device for controlling the pulse driver so as to select three levels of high impedance, power supply voltage, and GND according to ejection data during a period related to ink ejection.