JP2003175605A - Inkjet recorder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent clogging of a nozzle opening in a non-printing condition. <P>SOLUTION: This inkjet recorder comprises an inkjet recording head for ejecting ink drops from a nozzle opening by expanding and contracting a pressure generating chamber by displacement of a piezoelectric vibrator, a driving signal generating circuit 84 for generating a first driving signal for vibrating a meniscus in the vicinity of the nozzle opening in one printing cycle and a second driving signal for ejecting an ink drop, and a control signal generating circuit 80 for selectively outputting the first or second driving signal to the piezoelectric vibrator 48 based on the printing state or non-printing state. <P>COPYRIGHT: (C)2003,JPO

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an on-demand type ink.
Jet recording device, more specifically
The present invention relates to a technology for preventing clogging of a pad. [0002] On-demand type ink jet recording heads
The nozzles have a plurality of nozzle openings and a pressure communicating with each nozzle opening.
A pressure generation chamber is provided to expand the pressure generation chamber in response to the print signal.
It is configured to generate ink droplets by expanding and contracting
I have. By the way, ink droplets adhering to a recording medium
Bleeds or rubs in contact with other parts
Solvent will evaporate and solidify as soon as possible.
It is prepared as follows. Therefore, the printing operation is interrupted.
Nozzle openings that do not eject ink droplets frequently.
Ink has the problem that the solvent evaporates and causes clogging.
is there. To solve such problems, the printing operation must be compared.
For relatively long pauses, cap the nozzle opening
To take measures to prevent evaporation of the ink solvent.
Is required. However, even during the printing operation,
If all of the nozzle openings generate ink droplets evenly
And the frequency of ink ejection depends on the position of the nozzle openings.
Some of them are extremely low. Such a problem
If the printing operation is continued for a certain period of time
Retracts the recording head to the non-printing area, where all
Ink droplets from the nozzle openings
Printing has been performed, but the printing operation needs to be interrupted.
There is a problem that the printing speed is reduced. Such a problem
No ink drops are generated during printing operation to eliminate
Piezoelectric vibration provided in the pressure generating chamber communicating with the nozzle opening
The print signal is applied to the
Eye that vibrates the meniscus near the aperture
The clogging prevention technology is also described in Patent Documents 1 to 3.
As suggested. This clogging prevention technology
Can be extended as much as possible.
However, ink drops are forcibly ejected when clogging occurs
Must be performed, which leads to waste of ink.
Have a problem. In addition, ink can be applied near the nozzle opening.
Adjusting the power supply voltage to generate a swing signal,
The circuit configuration becomes complicated due to the need to adjust the resistance value
I have a problem. [Patent Document 1] JP-A-55-123476 [Patent Document 2] JP-A-57-61576 [Patent Document 3] U.S. Pat. No. 4,350,899 [0003] The present invention addresses such questions.
The purpose was to make
Cause the structure of the means for supplying the driving signal to be complicated
No signal is supplied to the non-printing nozzle opening to prevent clogging.
To provide an ink jet recording apparatus that can be supplied
That is. [0004] To solve such a problem.
Therefore, in the present invention, the displacement is caused by the displacement of the piezoelectric vibrator.
Inflating and contracting the force generating chamber to eject ink droplets from the nozzle opening
Ink jet recording head to discharge and within one printing cycle
A first drive that swings the menikas near the nozzle opening
And a second drive signal for discharging ink droplets.
Generated drive signal generation means and printing status or non-printing status
One of the first and second drive signals depending on the state.
Control signal generating means for selectively outputting the control signal to the piezoelectric vibrator.
And a step. [0005] The piezoelectric vibration attached to the nozzle opening involved in printing
A second signal is supplied to the child to eject ink droplets, and
For piezoelectric vibrators attached to nozzle openings that are not involved in printing,
The first drive signal is applied to swing the meniscus, and the pressure is increased.
Ink present in the generation chamber and ink near the nozzle opening
To reduce the viscosity of the ink near the nozzle opening.
To prevent clogging of the nozzle opening. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing an embodiment of the present invention;
It will be described based on. FIG. 1 shows the application of the driving method of the present invention.
An example of an ink jet recording apparatus suitable for performing
In the figure, reference numeral 1 is an ink jet line
With the recording head, the printing position P1, the ejection recovery position P2, and the key
The drive mechanism 2 is provided so that it can be moved to the capping position P3.
Have been killed. 3 is arranged facing the line recording head 1.
With the ink image holding drum placed, a drive mechanism (not shown)
The surface of the drum 4 driven at a more constant rotation speed
No bleeding on recording paper
For materials that excel in transferring ink, such as silicone rubber
Is formed by covering the formed ink image holding layer 5.
I have. Note that a drum is used instead of a drum as an ink image holding means.
May be used. Facing the ink image holding drum 3
The recording paper sent from the cassette 6 is
A pressure roller 7 that is in pressure contact with the image holding drum 3 is disposed.
You. The pressure roller 7 is supported by an eccentric shaft 8,
Retract upward during image formation, and lower during transfer to transfer
The backup roller 10 which transmits the pressure of
ing. [0007] In addition, there is no residual around the ink image holding drum 3.
Drum cleaner 11 for removing retained ink, ink
Heater 12 to promote drying of image, from drum surface
A peeling mechanism 13 for separating the recording paper is provided.
ing. Reference numeral 15 denotes a cleaning member for the recording head 1.
Is moved to the position P2 to drive the nozzle opening
Cleaning is performed by the wiper 16 and an ejection recovery operation is performed.
Reference numeral 17 denotes a sealing mechanism, which is a recording head 1.
Is driven when retracted to the position P3 and is made of rubber or the like.
The sealing member 18 elastically contacts the front surface of the recording head 1 and
This seals the aperture. FIGS. 2 and 3 show one embodiment of the recording head 1 described above.
An example is shown, and reference numeral 30 in the figure denotes a nozzle plate.
Cover the maximum width of the recording paper.
About 2,000 nozzle openings 31, 31 ‥‥
Degree, linear, or staggered vertically
Is configured. Note that the pitch for multiple dots is
H, for example, a plurality of nozzles, for example, four at intervals of 5 dots.
Of the ink image holding drum, and the recording is performed every one rotation of the ink image holding drum.
Move one dot at a time by one dot,
Use a recording head that can form an image for one page.
Can also be. Reference numeral 33 denotes a spacer, which is an adjacent nozzle opening.
When set in the printer so that
Pressure generating chambers 34, 34, 34
Through holes 35, 35, 35
You. 37 is a diaphragm forming member which faces the pressure generating chamber 34
Is formed as a thin portion 38, and
A thin portion 38 is sandwiched between portions facing the ink passages 46 and 47.
And elongated rectangular through holes 39 and 40 are provided.
You. Reference numeral 42 denotes an ink supply channel forming member, which is a diaphragm forming section.
Facing the thin portions 38, 38, 38, 38 # of the material 37
In the area, the piezoelectric vibrators 48, 48 of the vibrator unit 50,
A vibration unit through hole 43 through which 48 ° penetrates
In the portion facing the ink supply paths 46 and 47, a long groove 44,
45 are formed. Reference numerals 48, 48, and 48 ° denote piezoelectric vibrators.
Generates vibration in longitudinal vibration mode at the lowest possible drive voltage
The electrode and the piezoelectric vibration material are formed in a sandwich
And the same number of nozzle openings 31, 31, 31 °
A number of components are fixed to the base 49 to form a vibrator unit.
Has been established. Tip of piezoelectric vibrator 48, 48, 48 °
Is in contact with the vibrator unit through hole 43 of the flow path component 42
The end of the diaphragm forming member 3
7 are fixed to the thin portions 38, 38, 38 #. What
Incidentally, reference numeral 51 in the figure denotes a positioning mark formed on the base 46.
Vibration unit through hole of ink flow path forming member 40 with projection
41, the diaphragm forming member 37, the spacer 3
3, and positioning formed on the nozzle plate 30
The holes 52, 53, and 54 secure the positioning accuracy of each member.
Things. A recording head using such a transfer system
Are included in the dots formed on the ink image holding drum 3.
To quickly evaporate the ink solvent and transfer it to recording paper.
In order to improve the ink composition, for example, an ink having a composition of 3% by weight of pigment, 12% by weight of resin, 5% by weight of triethanolamine, 5% by weight of polyethylene glycol, 4% by weight of isopropyl glycol, 2% by weight of surfactant, and 69% by weight of water is used. The ink is supplied from the ink supply means 20 to the tube.
Sent to the recording head 1 via the
The ink is supplied to the ink supply means 20 by the tube 73 and circulated.
While being supplied smoothly to the pressure generating chamber. FIG. 4 shows the above-described ink jet recording apparatus.
FIG. 1 shows an embodiment of a drive circuit used for FIG.
Reference numeral 80 denotes a control signal generation circuit, which is connected to a tie from an external device.
Terminal 81 for inputting the printing signal and command for printing or non-printing
And a terminal 82 for inputting an instruction signal to
Switching transistors 85, 85, 85
An output terminal 83 for supplying a drive signal is provided. 84
Is a drive signal generation circuit, which receives timing signals from external devices.
Drive that operates the piezoelectric vibrator 48 based on the signal
It is configured to generate a signal. 85 is a switch
In this embodiment, the gate voltage is zero.
In the case of the enhancement type MOS transistor
The gate is composed of a control signal generation circuit.
The drive signal generating circuit receives the instruction signal from
Is applied to the piezoelectric vibrator 48
The piezoelectric vibrators 48, 48, 4 displace the ink droplets so much as to generate ink drops.
8 mm, or use the drive signal when not printing.
To generate small vibrations that do not generate ink droplets
It is configured as follows. FIG. 5 shows one example of the control signal generating circuit 80 described above.
In this embodiment, reference numeral 90 indicates a terminal 81.
From a timing signal input from the
One-shot multivibrator, 91
From the multivibrator 90 and the terminal 82
An AND circuit for outputting a logical product of these instruction signals, 92 is a finger
Inverter for inverting the display signal, 93 is one shot
Signals from multivibrator 90 and inverter 92
AND circuit that outputs the logical product of 94 is one
With the multivibrator, the signal from the AND circuit 93 is output.
A signal having a constant pulse width is output by the signal. This
These AND circuit 91 and one-shot multi-vibration
The signal from the data 94 is supplied to the control signal via the OR circuit 95.
Is output from the terminal 83. Configured like this
The circuit controls the number of nozzle openings in the control signal generation circuit 80.
Only the matching number is prepared. FIG. 6 shows one example of the driving signal generating circuit 84 described above.
1 shows an embodiment, in which reference numeral 100 denotes an external device.
The timing signal from the oscilloscope into a pulse signal of constant width
One-shot multivibrator for timing signal
A positive signal and a negative signal are output from the output terminal in synchronization. on the other hand
Is connected to the base of NPN transistor 101
To which a PNP transistor 102 is connected.
And when the timing signal is input, the power supply voltage VH
From the base-emitter voltage VBE1 of the transistor 108
02 until it reaches the voltage (VH-VBE102) minus
The capacitor 103 is charged with a constant current Ir.
You. The other end of the one-shot multivibrator 100
The NPN transistor 108 is connected to the
When the timing signal switches, the transistor 1
02 turns off and transistor 108 turns on instead
And the charge charged in the capacitor 103 is triggered.
When the base-emitter voltage VBE108 of the transistor 108 reaches
It is discharged at a constant current If until it reaches. That is, the base of transistor 102
The voltage between the transmitters is VBE102, and the resistance of the resistor 106 is Rr.
Then, the charging current Ir becomes Ir = Vbe102 / Rr, and when the capacitance of the capacitor 103 is C0,
The rise time Tr of the charging voltage is Tr = C0 × (VH−VBE102) / Ir. On the other hand, the discharge current If of the drive signal is
VBE 108 and resistor 107
Assuming that the resistance value is Rf, If = Vbe108 / Rr, and the fall time is Tf = C0 × (VH−VBE108) / If. (Note that between the base and emitter of the transistor
The voltage is usually about 0.7 volts and the power supply voltage is 30 volts
Since it is so small that it can be ignored,
It is assumed that the voltage between the base and the emitter is 0 volt.
You. As a result, the terminal voltage of the capacitor 103 has a constant gradient.
A rising region, a saturated region that maintains a constant value, and a constant region
A trapezoidal waveform having a region descending with a gradient is obtained. this
The voltage is current amplified by transistors 109 and 110.
And the piezoelectric vibrators 48, 48, 48
Is output as a drive signal. Next, using the drive signal generation circuit described above,
The operation when the piezoelectric vibrator is driven will be described. System
When a timing signal is input from the control signal generation circuit,
The signal generation circuit turns on the transistors 102 and 107
Turn off to output a drive signal with a trapezoidal voltage waveform. one
Connected to the piezoelectric vibrator 48 to be printed
The switching transistor 85 is used to generate a control signal.
Because it is turned on by the path 80, it is charged by the drive signal.
Will be charged. The control signal generation circuit 80 is provided with a signal from an external device.
Piezoelectric vibrator connected to the nozzle to be printed upon receiving a character signal
Switching transistor connected to 48, 48, 48 °
A signal is output to the star 85 to turn it on. This result
As a result, the aforementioned trapezoidal drive generated by the drive signal generation circuit 84 is generated.
The motion signal flows into the piezoelectric vibrator 48, and the piezoelectric vibrator 48
Charge with constant current. This allows ink drops to be printed
The piezoelectric vibrators 48, 48, 48 ° which should emit
The pressure generating chamber expands. And a certain time passes
Then, as described above, the transistor 108 is turned on.
Since the capacitor 103 is discharged, the piezoelectric
The electric charges of the oscillators 48, 48, 48 are also discharged, and the piezoelectric vibration
The pressure generating chamber is compressed when the
It is. As a result, as shown in FIGS.
The ink in the pressure generating chamber is compressed and enters through the nozzle opening.
It will fly as droplet K. On the other hand, nozzles that do not need to form dots
Connected to the piezoelectric vibrators 48, 48, 48 #
Marked on switching transistors 85, 85, 85 °
No one-shot multi-bi
A pulse signal P having a predetermined time width
(FIG. 7) outputs. As a result, the switching transistor
Are coincident with the pulse signal P.
Piezoelectric vibrator 4 that is turned on for a certain period
8, 48, 48 ‥‥ will start charging
Become. One-shot multi-vibration after a predetermined time
When the pulse signal P from the data 94 falls, the drive signal
Switching transistor 8 in the middle of rising
5 is turned off, so the voltage Vd up to this point
Charging ends. By the way, when the switch is turned off,
Driving signal to switching transistors 85, 85, 85 °
Voltage is applied as it is,
The piezoelectric vibrators 48, 48, and 48 are at voltage (Vc-Vd).
The piezoelectric vibrators 85 and 8
5,85 ° between the charging voltage Vd and the maximum driving signal voltage Vc
Since only the difference Vc−Vd is applied,
Compared to the voltage (Vc) when the off state is maintained during non-printing.
Switching transistors 85, 85, 85 ‥‥
Use transistors with low withstand voltage ratings
It becomes possible. In the state charged with the voltage Vd as described above,
Transistor 10 as well as the piezoelectric vibrator to be formed.
8 (FIG. 6) is turned on, the electric charge of the piezoelectric vibrator becomes
When discharged, it extends by an amount proportional to the charging voltage Vc-Vd.
Will be. Of course, the degree of this extension is
Smaller than the degree of elongation of the selected piezoelectric vibrator
The vibration member constituting the pressure generating chamber vibrates slightly
Will be. As a result, the piezoelectric vibrator is smaller than in printing.
Nozzle based on the voltage VS
Can elongate enough to cause ink droplets to fly from
Do not apply slight vibration to the ink in the pressure generating chamber.
And This vibration propagates the ink in the pressure generating chamber and
Reach the chil opening. Formed near the nozzle opening
Meniscus M flies ink due to the transmitted pressure wave
Vibrates in parallel to the direction (FIGS. 9A to 9E).
In the non-printing state, a
In this case, the generation of ink film is inhibited. Hereinafter, a dot is formed in accordance with the timing signal.
The piezoelectric vibrator 85 belonging to the nozzle opening to be formed is
Charge and discharge at a voltage sufficient to generate droplets,
Piezoelectric vibration belonging to the nozzle opening that does not need to form dots
A voltage is applied to the moving element 85 so that the ink drop does not fly.
The ink at the nozzle opening is swung by charging and discharging at the pressure Vd.
Is performed in parallel. Also, when a non-printing operation is performed,
The generated power is caused by dielectric loss and ohmic resistance of the piezoelectric vibrator 48.
Part is consumed due to loss, etc., and the piezoelectric vibrator 48 generates heat.
Will be. As a result, the piezoelectric
Prevents the cooling of the vibrator 48 and prevents piezoelectric vibration due to temperature drop
This will contribute to preventing moisture absorption of the child. Such non-printing
The application of the minute drive signal at the time is particularly performed with the piezoelectric material and Ag.
Pd-based electrode material laminated in a sandwich
Phenomenon of silver precipitation in the presence of moisture, like a vibrator
A piezoelectric vibrator where migration is likely to occur
Must be used in humid environments due to solvent vapor.
Works extremely effectively on inkjet recording heads
You. Incidentally, the transfer used in this embodiment
In the ink jet recording apparatus, as described above,
Wipe the nozzle opening to eliminate clogging of the nozzle opening.
Cleaning means to wipe off with an
Forcibly eject ink droplets regardless of character data
Lashing means. Ink composition and surroundings
It depends on the temperature, humidity, etc. of the environment.
Non-printing state lasts for 1.2 seconds when using ink
Flushing operation due to the formation of an ink film at the nozzle opening
A film that will not be able to print next time if not done
Is formed, and the non-printing state continues for 30 seconds.
In other words, flushing operation alone eliminates clogging
Cleaning operation is required. As described above, during non-printing, the nozzle opening
Lower the voltage level of the drive signal just enough to swing the varnish.
Applied to the piezoelectric vibrator to keep the non-printing state
At this time, as shown in FIG.
Keeps print quality constant even when drop ejection is not performed
And driven for about 600 to 850 seconds
If you perform the flushing operation even if it is left in the state,
Normal printing was possible. Also, even if flushing
In the event of clogging that requires action,
As shown in FIG. 11, the clogging of the nozzle opening is completely
The number of ink ejection pulses to be applied to erase
Ink consumption is inversely proportional to the meniscus swing duration.
It has been reduced. Further cleaning operations may be required.
Second drive even in case of severe clogging
Apply a signal to the piezoelectric vibrator for a certain period of time to swing the meniscus
After that, when the cleaning operation is performed, as shown in FIG.
As compared to when only the cleaning operation is performed.
Clogging in a short time inversely proportional to the scass swing duration
Could be eliminated. From the above, when not printing
A drive signal with a low level enough to swing the meniscus
Applying voltage to the piezoelectric vibrator is an extremely useful means.
It turned out. Further, a diaphragm is provided by such a piezoelectric vibrator.
Print head that generates ink droplets by pressing
Extends the piezoelectric vibrator in the pressure generation chamber corresponding to the print area.
Local deflection due to high stress due to shrinkage
And the dot formation position may be out of order.
You. However, in the non-printing state as described above,
When a small drive signal is applied to the piezoelectric vibrator,
Since a certain amount of stress also occurs in the pressure generation chamber in the area,
Improves print quality by reducing distortion of the entire head
Has the effect of contributing to In the above embodiment, the nozzle opening
An example of a print head that supplies ink from both sides of the
However, as shown in FIG.
Nozzle plate 114 having a hole 3 and a spacer member
The pressure generating chamber 117 is formed by the diaphragm 115 and the diaphragm 116.
From one side of the pressure generating chamber 117.
18 to supply ink, and the piezoelectric vibrator 119
The diaphragm 116 is pressed to generate ink droplets.
The same applies when applied to the formed inkjet recording head.
It is clear that it does work. By the way, the meniscus is formed near the nozzle opening.
In the ink that is formed, the vapor pressure of the solvent is affected by changes in temperature.
And the temperature rises as shown in FIG.
The film is formed in a short time. FIG.
Embodiment of a driving circuit configured to cope with various problems
In the figure, reference numeral 120 denotes a pulse width control.
Circuit that detects the outside air temperature near the nozzle opening
The signal from the stage 121 changes
Film formation ability and the optimum for inhibiting film formation at this time
Data from the storage means 124 storing the relationship with the swing amplitude
Is read, and one-shot
The pulse width of the vibrator 94 is configured to be set.
Have been. Reference numeral 122 in the figure denotes an analog-to-digital converter.
2 shows a file conversion means. According to this embodiment, for example, as shown in FIG.
Corresponding to individual printhead structure and ink composition
The ability to form a film due to the environmental temperature and prevent it
Means for storing the relationship with the oscillation amplitude of the meniscus necessary for
124, the temperature is detected by the temperature detecting means 121.
Swings according to the temperature T1, T2, T3 of the external environment
Data V1, V2, V3 representing the signal level are read.
As a result, one-time operation corresponds to the voltage to be applied during the non-printing period.
When the pulse width of the shot multivibrator 94 is
Shorter at lower temperatures and longer at higher temperatures
Automatically adjusts the printout without marking
Swings to the extent that it inhibits meniscus film formation
Let it. FIG. 17 shows a recording head driving circuit according to the present invention.
It is a block diagram which shows another Example, The code | symbol 130 in a figure is shown.
Are control signal generation circuits to be described later, and terminals 131 and 132
Print signal and timing signal from external device
And input from terminals 133, 134 and 135
Output shift clock signal, print signal and latch signal respectively
It is configured to 138, 138, 138 ‥
‥ is a flip-flop circuit constituting a latch circuit.
139, 139, 139} are shift clocks
The flip-flop circuit that constitutes the circuit
The print signal output from the flip-flop circuit 139 is flip-flopped.
Latching in the switching circuit 138, the switching transistors
85, 85, 85 °.
You. FIG. 18 shows one example of the drive signal generating circuit 80 described above.
In the embodiment, reference numeral 140 denotes a terminal 132.
Oscillator 14 that operates based on an input timing signal
Activated by the clock signal from terminal 1 and from terminal 131
Stores the input print signal from the external device in the memory 142
It is to let. In the figure, reference numeral 143 denotes a one-shot multibar.
With the vibrator, the connected piezoelectric vibrators 48, 48,
The count of the address counter 140 is 48
The key output from the address counter 140
The latch signal of the set pulse width by the carry signal.
The signal is output to the terminal 135. This latch signal is
Output to the slave 133 and the flip-flop circuit 1
The frequency is divided by 44 and becomes a switching signal as shown in FIG.
V) The print stored in the memory 142 as shown in FIG.
Gated by the signal and the switching signal and connected to this
All of the existing piezoelectric vibrators 48, 48, 48 °
The signal is alternately output to the terminal 134 every one cycle of the latch signal.
Force. The print signal output to the terminal 134 is
The shift register shown in FIG.
Output to the flip-flop circuit 139 forming the
The rising edge of the latch signal causes this flip
Flip-flop connected to flip-flop circuit 139
Is latched by the latch circuit 138. The piezoelectric vibrator for forming dots is shown in FIG.
In (IV), the print data A is the flip-flop circuit 1
38 (hereinafter referred to as printing section A)
Is based on the signal from the flip-flop circuit 138.
Trapezoidal drive signal that reaches the saturation voltage in the same way
Is applied to expand and contract enough to create an ink drop
Will be. On the other hand, a piezoelectric vibrator to maintain the non-printing state
Indicates that the print data B is a flip-flop in FIG.
Section (hereinafter, referred to as a printing section B)
), The switching transformer is in the middle of the drive signal voltage rise.
Because the transistor 85 turns off from on,
The trapezoidal voltage having a small pressure is applied to the piezoelectric vibrators 48, 48, 48.
‥‥. This results in the formation of dots
Align the timing with the discharge of the piezoelectric vibrator to be
Piezoelectric vibrators 48, 48, 48}
Discharge at the voltage of Vc-Vd.
Small expansion and contraction that does not form
The meniscus in the vicinity of the aperture swings,
This will prevent film formation. FIG. 20 shows another embodiment of the drive signal generating circuit.
In the figure, reference numeral 150 denotes a one-shot
The timing signal input to terminal 81
A pulse signal with a preset pulse width is synchronized with the
The PNP transistor is connected to the inverting terminal.
The star 151 is connected. And transistor 15
1, the capacitor 152 connected in series
In this state, the battery is charged by the voltage -VH of the power supply terminal. this
Therefore, when the transistor 151 is turned on, the transistor
The constant current Ir flows into the capacitor 151 by the
Thus, the capacitor 151 is charged. And
Diode 1 connected in parallel with capacitor 152
53 causes the terminal voltage of the capacitor 151 to become 0 volt.
Charging is completed when the charging is completed. On the other hand, the one-shot multivibrator 1
When 50 reverses, transistor 156 turns on
The capacitor 152 has a terminal voltage equal to the power supply terminal voltage−
Discharge current by transistor 158 until VH is reached
Discharge while being limited to a constant. These charge current and discharge
The current flows between the NPN transistor 159 and the PNP transistor.
Amplified by the resistor 160 and connected to the piezoelectric vibrator from the terminal 86
85, 85, 85 °. FIG. 21 shows the configuration of the drive signal generation circuit described above.
This shows the waveform diagram when the recording head is driven.
The piezoelectric vibrators 48, 48, 48 # to be formed
In the period shown as printing section A in III,
The drive signal in which the polarity is inverted is the signal in the above-described embodiment.
Is applied. In the non-printing period,
To generate ink droplets during the period shown as character section B
Is applied to the piezoelectric vibrator.
Nozzle opening by micro-vibrating the meniscus near the nozzle opening
Prevents nearby ink from forming a film. And unmarked
The switching transistor 85 in the cross-shaped state,
85, 85 are marked on the piezoelectric vibrators 48, 48, 48 °.
A voltage Vc-Vd lower by the applied swing charging voltage Vd is generated.
To be used as a switching transistor.
It is possible to use one with a small rated withstand voltage. FIG. 22 shows the driving signal generation of FIG. 21 described above.
FIG. 14 shows a modification of the circuit, and in this embodiment,
Corresponds to the flip-flop circuit 150 in FIG.
Circuit 170 with three one-shot multivibrators.
171 172 173 and the AND circuit 174
It has been achieved. In this embodiment, the terminal 81
When a timing signal is input, one-shot multi-by
A pulse with the pulse width set in the
Is forced. This one-shot multivibrator 171
The rising edge of the inverted signal of the AND circuit 174
Of the output from the one-shot multivibrator 173
A logical product (II in FIG. 23) is output. The one-shot multivibrator 171
In these pulse portions, the PNP transistor 151 is turned on.
And the capacitor 1 that is initially charged with -VH
52 is a constant current Ir determined by the transistor 154.
Recharge. In this way, the capacitor 152
When the battery has been charged, the charging operation is performed by the diode 153.
Is stopped. Next one-shot multivibrator
When the inverted signal is output from the transistor 171, the transistor 15
1 turns off. Then one shot multi vibrator
When the inverted output becomes “0”, the transistor 1
56 turns on, the capacitor 152 discharges, and the
Transistor 158 until the slave voltage -VH is reached
Discharge at a constant current If while being subjected to current limitation. Also,
Of the signals of the one-shot multivibrator 171
Set by the one-shot multivibrator 173
In the part, the transistor 151 turns on again and
The denser 152 is charged with the constant current If as described above.
You. FIG. 24 shows another embodiment of the present invention.
In the figure, reference numerals 180, 180, and 180 ° denote OR circuits.
And a flip-flop circuit 1 constituting a shift register
81, 181, 181} and switching means 85, 8
5, 85 °, and one terminal is described later.
The control signal generation circuit 183 outputs these switching signals.
All ON signal to turn on transistor 85, 85, 85 °
And a flip-flop circuit 18 at the other terminal.
1, 181 and 181} are input. 1
82, 182, 182 # constitute a shift register.
Flip-flop circuit, and the control signal generation circuit 183
If the shift clock and print signal are
The print signal is moved to a predetermined stage in synchronization with the
The flip-flop circuits 181, 181, 18
It is something that makes you touch. FIG. 25 shows an embodiment of the control signal generating circuit described above.
By way of example, in this embodiment two memories 190,
191 to alternately store and read
Works, and one of them is storing the print signal from the host.
The other memory outputs a print signal when
I have. In the figure, reference numeral 192 denotes an address counter,
Oscillator 193 operated by a timing signal input to
Activated by the clock signal from and input from terminal 81
Memory 1 from which the print signal from the selected external device is selected
90 and 191. 195 is one
Connect the connected piezoelectric vibrator with the shot multivibrator.
Address output when counting has been completed for the number of moving elements
Set by the carry signal from the
And outputs a latch signal having the same pulse width to the terminal 136.
is there. This latch signal is supplied to the flip-flop circuit 1
The frequency is divided by 96 and becomes a switching signal,
0, 191 are alternately output to the terminal 13
5 is output. The print signal output to the terminal 135 is
24 is shifted by the shift clock signal of the terminal 133.
The flip-flop circuit 182 forming the register
input. Then, to a predetermined flip-flop circuit 182,
The shifted print signal is the rising edge of the latch signal.
Connected to the flip-flop circuit 182
Is held in the flip-flop circuit 181 that is operating. 197 is a one-shot multivibration
From the one-shot multivibrator 195
Starts at the rising edge of the switch signal and swings the meniscus
To charge the piezoelectric vibrator to a voltage sufficient to
Cause a problem. This signal from terminal 137
Output to the OR circuit 180 of the drive circuit shown in FIG.
The piezoelectric vibrators 48, 48, 48 # in the non-printing state
Switching transistors 85, 85, 8 connected to ‥
5 °. In the figure, reference numeral 199 denotes a memory 1
9 shows means for switching 90,191. According to this embodiment, the switching transistor
Star 85, 85, 85 °
Not only can be implemented, but also the implementation shown in FIGS.
For example, a flip-flop from control signal generation circuit 183
The transfer speed of the print signal to the circuit 181 can be increased.
it can. FIG. 27 shows another embodiment of the present invention.
In the figure, reference numeral 200 denotes a structure similar to that of FIG.
The drive signal generation circuit 201 adopting FIG.
A second drive signal generation circuit having a similar configuration includes a first drive signal generator.
Configuration to output signals with different phases of the driving circuit 200
Have been. 203, 203, 203
An isolator that can output analog signals such as plastic
Control signal generation circuit 183 and switching transistor 8
5, 85, 85 ° connected between the gate and the control
The second drive signal generation circuit is operated by the input of the signal generation circuit 183.
A signal corresponding to the waveform of the path 201 is switched to a switching transistor.
The output is to the output terminals 85, 85, 85. In this embodiment, the control signal generation circuit 18
The instruction signals from 3 are isolator 203, 203, 2
03 ‥‥, and the second drive signal input here
The potential is converted by a signal from the generation circuit 201, and the switch is performed.
Output to the gate of the ching transistor 85. Second drive
The signal from the dynamic signal generation circuit 201 is a switching transformer.
Since input is also made to the source terminal of the
Transistor 85, 85, 85 ‥‥ gate-source
In the meantime, the same signal as the print signal is applied. mark
In the V-shaped state, the piezoelectric vibrators 48, 48, 48
A voltage obtained by subtracting the first drive signal from the second drive signal is applied
In the non-printing state, the first drive signal is generated.
Sometimes switching transistors 85, 85, 85 ‥‥
Only the second drive signal is applied since it is turned off.
Will be. As a result, the piezoelectric
A minute voltage is applied to the vibrators 48, 48, 48 °.
To swing the meniscus near the nozzle opening.
You. In this embodiment, as in the previous embodiment, the switch is used.
The pressure resistance of the chining means can be reduced. In the above-described embodiment, the switch
N-channel enhancement M
An example using an OS transistor has been described.
However, the same applies when using other types of solid state switching elements.
It is clear that it works. According to the present invention as described above,
The piezoelectric vibrator attached to the nozzle opening that does not eject ink droplets
Applies the first drive signal to swing the meniscus and
Ink in the force generation chamber and ink near the nozzle opening
To lower the viscosity of the ink near the nozzle opening
To prevent clogging of the nozzle opening.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagram showing an embodiment of an ink jet recording apparatus to which the present invention is applied. FIG. 2 is a cross-sectional view showing one embodiment of an ink jet recording head. FIG. 3 is an exploded perspective view showing the structure of the recording head. FIG. 4 is a block diagram showing one embodiment of a driving circuit of an ink jet recording head used in the present invention. FIG. 5 is a circuit diagram showing one embodiment of a control signal generation circuit. FIG. 6 is a circuit diagram showing one embodiment of a drive signal generation circuit. FIG. 7 is a waveform chart showing an operation of the above driving circuit. FIGS. 8A to 8E are explanatory diagrams showing a state of a meniscus at the time of printing by the above driving circuit. FIGS. 9A to 9E are explanatory diagrams showing states of a meniscus during non-printing by the same drive circuit. FIG. 10 is a diagram showing the relationship between the magnitude of the swing signal and the time during which the swing signal can be left. FIG. 11 is a diagram illustrating a relationship between a swing signal application time and an ink consumption amount until ejection recovery by flushing. FIG. 12 is a diagram illustrating a relationship between a swing signal application time and a duration of a cleaning operation required until recovery. FIG. 13 is a cross-sectional view illustrating an example of another type of inkjet recording head to which the driving method of the present invention can be applied. FIG. 14 is a diagram showing a relationship between a voltage applied to the piezoelectric vibrator when the piezoelectric vibrator is in a non-printing state and a time until clogging of a nozzle opening occurs, using ambient temperature as a parameter. is there. FIG. 15 is a block diagram showing an embodiment in which a swing signal applied to prevent clogging is adjusted according to the temperature of the environment. FIG. 16 is a diagram showing an example of data to be stored in a storage unit of the above device. FIG. 17 is a block diagram showing another embodiment of the drive circuit of the present invention. FIG. 18 is a block diagram showing an embodiment of a control signal generation circuit in the driving circuit. FIG. 19 is a waveform chart showing an operation of the above driving circuit. FIG. 20 is a circuit diagram showing another embodiment of the drive signal generation circuit. FIG. 21 is a waveform chart showing an operation of the drive signal generation circuit. FIG. 22 is a circuit diagram showing another embodiment of the drive signal generation circuit. FIG. 23 is a waveform chart showing the operation of the above driving circuit. FIG. 24 is a block diagram showing another embodiment of the drive circuit of the present invention. FIG. 25 is a block diagram showing an embodiment of a control signal generation circuit in the driving circuit. FIG. 26 is a waveform chart showing the operation of the above driving circuit. FIG. 27 is a block diagram showing another embodiment of the drive circuit of the present invention. FIG. 28 is a waveform chart showing the operation of the above device. [Description of Signs] 1 inkjet recording head 3 ink image holding drum 20 ink supply means 31 nozzle opening 34
Pressure generation chamber 48 Piezoelectric vibrator 80 Control signal generation circuit 84 Drive signal generation circuit

   ────────────────────────────────────────────────── ─── Continuation of front page    (31) Priority claim number Japanese Patent Application No. 5-98072 (32) Priority date April 23, 1993 (April 23, 1993) (33) Countries claiming priority Japan (JP) (72) Inventor Hiroe Shinmura             3-5-5 Yamato, Suwa-shi, Nagano Seiko             ー Epson Corporation (72) Inventor Haruo Nakamura             3-5-5 Yamato, Suwa-shi, Nagano Seiko             ー Epson Corporation (72) Inventor Toshihisa Saruta             3-5-5 Yamato, Suwa-shi, Nagano Seiko             ー Epson Corporation F term (reference) 2C057 AF72 AM16 AM21 AM31 AR04                       BA03 BA14

Claims (1)

Claims: 1. An ink jet recording head that expands and contracts a pressure generating chamber by displacement of a piezoelectric vibrator to discharge ink droplets from a nozzle opening, and that a meniscus near the nozzle opening is printed within one printing cycle. A drive signal generating means for generating a first drive signal for swinging and a second drive signal for ejecting ink droplets;
Or, an ink jet recording apparatus comprising: a control signal generating means for selectively outputting one of the first and second drive signals to the piezoelectric vibrator according to a non-printing state.