JP2001322264A - Ink droplet ejecting method and apparatus, and storage medium - Google Patents

Abstract

(57) Abstract: In a method and apparatus for ejecting ink droplets and a storage medium, when three or more ink droplets are ejected per dot, they are formed on a recording medium by continuous or discontinuous printing commands. It is possible to prevent the print quality from deteriorating due to the dot area increasing or decreasing. SOLUTION: In the case of jetting based on a continuous dot print command at a predetermined frequency, a jet pulse sequence is provided in which a plurality of ink droplets separately fly until a single dot print command reaches a recording medium. A first drive waveform;
When ejecting based on a print command of a dot to be printed at a frequency of about の or less of the predetermined frequency, a plurality of ink droplets separately fly for one dot until they reach a recording medium. A first drive waveform and a second drive waveform having a different ejection pulse train are prepared in advance, and if there is no print command immediately before one dot, the second drive waveform is used. Uses the first drive waveform.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a method and apparatus for ejecting ink droplets by an ink jet system and a storage medium.

[0002]

2. Description of the Related Art Conventionally, as an ink-jet type ink droplet ejecting apparatus, the volume of an ink flow path is changed by deformation of a piezoelectric material, and when the volume is reduced, ink in the ink flow path is ejected from a nozzle as droplets. In addition, there is known a device in which characters, figures, and the like are recorded on a recording medium.

As this type of ink-jet type ink droplet ejecting apparatus, there is a shear mode type head utilizing a piezoelectric material as disclosed in Japanese Patent Application Laid-Open No. 63-247051. FIG. 9 shows a cross-sectional view of one example. The head unit 600 includes an actuator substrate 601 in which a plurality of elongated groove-shaped ink flow paths 613 extending in the thickness direction of the drawing and a space 615 in which ink does not enter are arranged with a side wall 617 interposed therebetween, and a cover plate 602.
The side wall 617 is composed of a lower wall 611 and an upper wall 609 polarized in directions opposite to each other in the height direction of the side wall (arrows P1, P2). One end of each ink channel 613 has a nozzle 618, and the other end is connected to a manifold (not shown) for supplying ink. The end of the space 615 on the manifold side is closed so that ink does not enter. The electrodes 61 are provided on both side surfaces of each side wall 617.
9,621 are provided as metallization layers. Specifically, the side wall electrode 617 on the ink flow path 613 side has the electrode 61 inside the flow path.
9 are provided, and all the electrodes 619 in the flow path are grounded. An in-space electrode 621 is provided on the side wall 617 on the space 615 side. The electrodes 621 adjacent to each other in the same space 615 are insulated from each other and connected to a control device that supplies an actuator drive signal.

[0004] When the control device applies a voltage to a pair of space electrodes 621 adjacent to each other with the ink flow path 613 interposed therebetween, the side wall 617 undergoes a piezoelectric thickness shear deformation in a direction to increase the volume of the ink flow path 613. For example, when the ink flow path 613b is driven as shown in FIG. 10, the ink flow path 6
A voltage E is applied to the space electrodes 621c and 621d adjacent to each other across the electrode 13b.
When (V) is applied, an electric field is generated in the side wall 617c, d in the direction of arrow E orthogonal to the direction of polarization, and the upper and lower portions of the side wall 617c, d are each subjected to piezoelectric thickness sliding in the direction of increasing the volume of the ink flow path 613b. Deform. At this time, the pressure in the ink flow path 613b including the vicinity of the nozzle 618b decreases. This state is maintained for the one-way propagation time T of the pressure wave in the ink flow path 613. Then, ink is supplied from a manifold (not shown) during that time.

[0005] The one-way propagation time T corresponds to the ink flow path 6
13 is the time required for the pressure wave in the ink channel 613 to propagate in the longitudinal direction of the ink channel 613, and the length L of the ink channel 613
And T = L / a according to the sound velocity a in the ink inside the ink flow path 613. According to the pressure wave propagation theory, the pressure in the ink flow path 613 reverses and changes to a positive pressure just after T time has elapsed from the application of the voltage, but is applied to the space electrodes 621c and d in accordance with this timing. The returned voltage is returned to 0 (V).

Then, the side walls 617c and 617d return to the state before deformation (FIG. 9), and pressure is applied to the ink. At this time, the pressure that has turned positive and the pressure generated when the side walls 617 c and d return to the state before deformation are added, and a relatively high pressure is applied to the nozzle 61 of the ink flow path 613 b.
An ink drop is generated in a portion near 8b, and is ejected from the nozzle 618b.

More specifically, if the time from the application of the voltage to the return of the voltage to 0 (V) deviates from the one-way propagation time T, the energy efficiency drops because the ink drops are ejected, and the one-way propagation When the time T becomes almost an even multiple, the injection is not performed at all. Normally, when it is desired to increase the energy efficiency, for example, to drive at a voltage as low as possible, the voltage is reduced from 0 to
It is desirable that the time until returning to (V) is substantially equal to the one-way propagation time T, or at least approximately an odd multiple.

[0008]

It is known to increase the volume of a droplet by ejecting a plurality of ink droplets per dot in order to improve the print density and improve the print quality.
As one of the methods, there is a method in which a plurality of ink droplets are united during flight and land on a recording medium in a state where the droplet volume is increased. The area does not increase. On the other hand, the ink droplets fly separately until they land on the recording medium, and due to the relative movement between the head unit mounted on the carriage and the recording medium, the ink droplets land little by little to land. There is a method of expanding. According to the latter method, not only the print density can be improved, but also a gradation change is easily obtained by increasing or decreasing the number of ink droplets.

However, in recent years, the demand for high-speed printing and high-density printing has increased, and it has become necessary to eject three or more ink droplets per dot for high-density printing. After ejecting an ink droplet, the vibration of the meniscus of the ink stretched in the nozzle tends to affect the ejection of the next ink droplet. If the settings of the pulse width and the wave interval of the pulse train forming one dot are set so that a plurality of ink droplets fly separately until continuous printing, that is, when printing continuous dots at a high frequency, the ink droplets land on the recording medium. When dots are formed at a very low frequency (that is, dots are formed intermittently when a print clock is output at a high frequency), a plurality of ink droplets are united during flight due to the influence of residual vibration. Sometimes.
As a result, the area of the dots formed on the recording medium is reduced, and there is a difference between the area of the continuously printed area and the area of the dots, resulting in a problem that the printing quality is deteriorated.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems. In a case where one dot is formed by a plurality of ink droplets, a driving waveform for printing the dot is printed by using the immediately preceding printing waveform. By changing the drive waveform in accordance with the presence or absence of a dot, it is possible to always fly a plurality of ink droplets forming one dot separately, to increase the dot area formed on the recording medium, and to print with a high print density. It is an object of the present invention to provide a method and apparatus for ejecting ink droplets of good quality and a recording medium.

[0011]

According to a first aspect of the present invention, there is provided an ink jet printer comprising: an ejection pulse signal applied to an actuator for changing a volume of an ink flow path filled with ink; In an ink droplet ejecting method of generating a pressure wave in an ink flow path, applying pressure to ink, ejecting ink droplets from a nozzle, and ejecting a plurality of ink droplets in response to a print command of one dot, A first driving waveform having an ejection pulse train in which a plurality of ink droplets fly separately until a plurality of ink droplets reach a recording medium in response to a single dot printing command, when the ejection is performed based on a printing command of dots continuous in frequency; A plurality of ink droplets for one dot are ejected based on a print command of a dot to be printed at a frequency of about 1/2 or less of the predetermined frequency. Flies separate until it reaches, first
And a second drive waveform having an ejection pulse train different from that of the first drive waveform is prepared in advance, and if there is no print command immediately before one dot, the second drive waveform is used; otherwise, the second drive waveform is used. It is characterized in that the first drive waveform is used.

As described above, since the ejected ink droplets fly separately without being integrated and form a dot having a large area on the recording medium, the print density can be improved. Moreover, by selecting the first or second drive waveform having a different ejection pulse train according to the presence or absence of the immediately preceding printing,
A plurality of ink droplets forming one dot can always fly separately without being affected by the residual pressure wave vibration.

For example, the first drive waveform and the second drive waveform have a plurality of ejection pulses respectively corresponding to a plurality of ink droplets to be ejected, and at least one of the plurality of ejection pulses has a wave width or a pulse width. The above can be realized by making the wave interval different between the first drive waveform and the second drive waveform.

Preferably, the first drive waveform and the second drive waveform further include a non-ejection stabilizing pulse inserted between the plurality of ejection pulses to attenuate residual pressure wave vibration of ink. With such a configuration, a plurality of ink droplets forming one dot can be more stably and separately jetted until they reach the recording medium.

Further, the first drive waveform and the second drive waveform
The drive waveform further includes a non-ejection stabilizing pulse added after the plurality of ejection pulses to attenuate the residual pressure wave vibration of the ink, so that continuous dots are printed at a high frequency or intermittently. In either case of printing a dot, a plurality of ink droplets can be made to fly more stably and separately with the first or second drive waveform.

Further, the first drive waveform and the second drive waveform
In the drive waveform of, by properly setting the ejection pulse width, the non-ejection stabilization pulse width, and the width between pulses, even when ejecting four ink droplets per dot, the ink droplets always fly separately. It can be done.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. The configuration of the head unit used in the present embodiment is the same as that shown in FIG.

An example of specific dimensions of the head unit 600 will be described. The length L of the ink flow path 613 is 6.0 mm
It is. The size of the nozzle 618 is a taper type having a diameter of 26 μm on the ink droplet ejection side and a diameter of 40 μm on the ink flow path 613 side, and has a length of 75 μm. The viscosity at 25 ° C. of the ink used in the experiment was about 2 mPa · s, and the surface tension was 30 mN / m. The ratio L / a (= T) of the sound velocity a and the above L in the ink in the ink flow path 613 is 9.
It was 0 μsec.

FIG. 1 shows four dots for one dot printing command.
3 shows a driving waveform for ejecting one ink droplet. FIG.
(A) shows a driving waveform 1 used when printing each dot having four ink droplets continuously, that is, when printing at a high frequency. FIG. 1B shows that each dot having four ink droplets is intermittently printed at the frequency of FIG. 1A, that is, a substantially lower frequency (for example, half or less the frequency of FIG. 1A). 2 shows a drive waveform 2 used when printing is performed. The numbers attached to the figure correspond to the ink flow paths 61 described above.
3 is the ratio of the length of time to the one-way propagation time T of the pressure wave in FIG.

The drive waveform 1 shown in FIG. 1A shows ejection pulses F1, F2, F3, and F4 for ejecting ink droplets and non-ejection stability for reducing residual pressure wave vibration in the ink flow path 613. Pulses S1 and S2. The stabilization pulses S1 and S2 are, for example, when the residual pressure increases after the ink droplet has been ejected by the immediately preceding ejection pulse,
At the rising edge of the stabilizing pulse, the ink flow path is enlarged to reduce the pressure, and when the pressure falls, the ink flow path is restored at the falling edge of the stabilizing pulse, thereby substantially canceling out and attenuating the residual pressure wave vibration. Things. Peak value (voltage value) of all pulses of injection pulse and stabilization pulse
Is E (V) (for example, 16 (V) at 25 ° C.). The width Wa of the ejection pulse F1 is equal to 1.0 times the one-way propagation time T of the pressure wave in the ink flow path 613, that is, 9.0 μm.
sec. The width Wb of the ejection pulse F2 is equal to 0.7 times the time T, that is, 6.3 μsec. The interval Da between the ejection pulse F1 and the ejection pulse F2 is equal to 1.3 times the time T, that is, 11.7 μsec.
c. The width Sa of the stabilizing pulse S1 is equal to the time T
(L / a) is 0.5 times, that is, 4.5 μsec, and the interval Db from the ejection pulse F2 is equal to the time T.
2.15 times (L / a), that is, 19.35 μsec
It is. Interval Dc between stabilization pulse S1 and injection pulse F3
Is equal to 1.0 times the time T, that is, 9.0 μ
sec.

The width Wc of the ejection pulse F3 is equal to the time T, that is, 9.0 μsec.
4 has a width Wd equal to 0.6 times the time T, that is, 5.4 μsec. The interval Dd between the ejection pulse F3 and the ejection pulse F4 is equal to 1.5 times the time T, that is, 13.5 μsec. Stabilization pulse S
2 is 0.5 times the time T (L / a), that is, 4.5 μsec, and the interval De with the ejection pulse F4 is 2.15 times the time T (L / a). That is, 19.35 μsec.

The volume and stability of the ink droplet can be controlled by these wave widths and wave intervals.
In the case of the drive waveform 1 of (a), two ink droplets are continuously ejected, and the ink path 6
13 to suppress the residual pressure wave vibration, continuously eject two ink droplets again, and suppress the vibration by the subsequent stabilizing pulse S2. By ejecting ink droplets, 300 × 30
A drop volume of about 60 pl (picoliter) required for a resolution of about 0 dpi (dots / inch) has been achieved. These four separately ejected ink drops are 5
When dots (including four ink droplets) are continuously printed at a frequency of up to 8.5 kHz, the dots fly separately until they reach the recording medium, and are printed on the recording medium one at a time.
When one dot is formed, the dot becomes one elliptical dot extending in the scanning direction of the head unit 600.

FIG. 4 shows the comparison, as compared with the case where the recording medium is integrated after flying in the air and then reaches the recording medium.
Even in the case of the same ink droplet volume, the formed dot areas differ greatly.

The drive waveform 2 shown in FIG. 1B shows ejection pulses F5, F6, F7, F8 for ejecting ink droplets and non-ejection stability for reducing residual pressure wave vibration in the ink flow path 613. The peak values (voltage values) of all the pulses are E (V) (for example, 16 at 25 ° C.).
(V)). The width Wa of the ejection pulse F5 is equal to 1.0 times the time T, that is, 9.0 μsec. The width Wb of the ejection pulse F6 is equal to 0.65 times the time T, that is, 5.85 μsec. The interval Da between the ejection pulse F5 and the ejection pulse F6 is equal to 1.35 times the time T, that is, 12.15 μsec.
It is. The width Sa of the stabilizing pulse S5 is equal to the time T (L
/ A) is 0.5 times, that is, 4.5 μsec, and the interval Db from the ejection pulse F6 is equal to the time T (L / L).
2.15 times that of a), that is, 19.35 μsec. The interval Dc between the stabilizing pulse S3 and the ejection pulse F7 is
This corresponds to 1.3 times the time T, that is, 11.7 μs
ec.

The width Wc of the injection pulse F7 is equal to 0.7 times the time T, that is, 6.3 μsec, and the width Wd of the injection pulse F8 is equal to 0.6 times the time T, ie, 5.4 μsec. The interval Dd between the ejection pulse F7 and the ejection pulse F8 is equal to 1.D of the time T.
This corresponds to a factor of 5, that is, 13.5 μsec. The width Sb of the stabilizing pulse S4 is equal to 0. .0 of the time T (L / a).
5 times, that is, 4.5 μsec, and the interval De with the ejection pulse F8 is 2.15 of the time T (L / a).
Twice, that is, 19.35 μsec.

According to these wave widths and wave intervals, 2.5 to
4. printing of each dot at a frequency of 4.25 kHz (corresponding to intermittent printing when the printing clock signal of the recording device has the frequency of using the drive waveform of (a) above 1), which corresponds to intermittent printing And the stability can be controlled, and the driving waveform 2 in FIG.
Similar to the driving waveform 1 in (a), about 60 pl per dot required for a resolution of about 300 × 300 dpi
Droplet volume is achieved. In addition, as in the case described above, the dot becomes one elliptical dot extending in the scanning direction of the head unit 600.

In each of the above cases (a) and (b), the wave width and wave interval are set at the above-mentioned time T from 5 ° C. to 45 ° C.
It was obtained as a result of an experiment so as to perform stable injection without performing droplet-like injection if the accuracy falls within a range of ± 0.05 times (L / a).

FIG. 2 shows an example of which one of the drive waveforms 1 and 2 should be selected according to the presence or absence of the ejection command immediately before and after the ejection of an ink droplet. In FIG. 2A, the “conventional example” always uses the driving waveform 1 for ejecting four ink droplets per dot. In this driving method, FIG.
As shown in the print result of the conventional example of FIG. 7A, in a portion where dots are continuously printed, a large dot is stably formed on the recording medium. It has been experimentally confirmed that, in the case where the time when there is no print command alternates, the ink droplets are integrated during the flight and the dot diameter becomes small. Even when the driving waveform 2 was used for a portion where printing was continuously performed, a phenomenon in which ink droplets were integrated during flight was confirmed.

In the embodiment shown in FIG. 2B, the driving waveform 1 is used when there is a printing command immediately before, and the driving waveform 2 is used when there is no printing command immediately before. As described above, the low frequency used for the drive waveform 2 corresponds to the case where the print command is missing for the print clock signal when the print clock signal of the recording apparatus is the high frequency using the drive waveform 1, and When there is no print command, the driving waveform 2 is used.

Thus, even when the print commands are continuous,
Even when there is no print command, the ink droplets always fly separately, so that printing with a large dot diameter corresponding to the number of ink droplets can always be obtained as shown in the print result of FIG. In other words, by selecting a drive waveform prepared in advance in accordance with the presence or absence of the immediately preceding ink ejection command, ink droplets can always be separately ejected without being integrated, and the area of the dots formed on the recording medium can be reduced. It is possible to increase the print density, improve the print density, and obtain high print quality.

Next, details of a control device for realizing the drive waveform of the above embodiment will be described with reference to FIGS. 5, 6 and 7. FIG.

FIG. 5 is a block diagram showing the electrical configuration of the recording apparatus. The control system of the printer includes a microcomputer 41 having one chip, a ROM 42, and a RAM 43. The microcomputer 41 includes an operation panel 14 for a user to give a printing instruction, a motor driving circuit 35 for driving a recording medium transport motor 37, and a motor for driving a carriage scanning motor 38 equipped with a head unit. The drive circuit 16 and the like are connected.

The head unit 600 is driven by a drive circuit 21, which is controlled by a control circuit 22. That is, as shown in FIG. 9, each electrode 619 provided in each ink channel 613 of the head unit 600 is connected to the drive circuit 21. Drive circuit 21
Generates various pulse signals based on the control of the control circuit 22 and applies them to the electrodes 619.

Microcomputer 41 and ROM 42,
The RAM 43 and the control circuit 22 are connected via an address bus 23 and a data bus 24. The microcomputer 41 generates a print timing signal TS and a control signal RS according to a program stored in the ROM 42 in advance, and transfers them to the control circuit 22.

The control circuit 22 is constituted by a gate array, and based on the image data stored in the image memory 25, prints the image data on a recording medium in accordance with the print timing signal TS and the control signal RS. Data DATA, a transfer clock TCK synchronized with the print data DATA, a strobe signal STB,
A print clock CLK is generated and transferred to the drive circuit 21. Further, the control circuit 22 includes the personal computer 2
The image data transferred from an external device such as the external device 6 via the Centronics interface 27 is stored in the image memory 25. Then, the control circuit 22 generates a Centronics data reception interrupt signal WS based on the Centronics data transferred from the external device via the Centronics interface 27,
Transfer to the microcomputer 41. Note that each signal D
ATA, TCK, STB, and CLK are transferred via a harness cable 28 that connects the drive circuit 21 and the control circuit 22.

FIG. 6 shows the internal configuration of the drive circuit 21.
The drive circuit 21 includes a serial-parallel converter 31, a data latch 32, an AND gate 33, and an output circuit 34. The serial-parallel converter 31 is composed of a shift register having the same number of bit lengths as the ink flow path 613. The serial-parallel converter 31 receives print data DATA serially transferred from the control circuit 22 in synchronization with the transfer clock TCK. To PDn. The data latch 32 latches each of the parallel data PD0 to PDn according to the rise of the strobe signal STB transferred from the control circuit 22. AND gate 3
Reference numeral 3 denotes a logical product of each of the parallel data PD0 to PDn output from the data latch 32 and the print clock CLK transferred from the control circuit 22, and outputs drive data A0.
~ An is generated. The output circuit 34 generates a pulse signal based on the signal, and outputs the pulse signal to the electrode 6 of each ink flow path 613.
Output to # 19.

The output circuit 34 comprises a charging circuit 182 and a discharging circuit 184 as shown in FIG. Side wall 6
The seventeen piezoelectric materials and electrodes 619, 621 are equivalently represented by a capacitor 191 and electrodes 619, 621. The charging circuit 182 includes resistors R101, R102, R1
03, R104, R105, transistor TR101,
It is composed of TR102. When an ON signal (+5 V) is input as the drive data An, the transistor TR101 conducts via the resistor R101, and the positive power supply 18
9 from the transistor TR1 via the resistor R103.
01 flows from the collector to the emitter. Therefore, the voltage division of the voltage applied to resistors R104 and R105 connected to positive power supply 189 increases, the current flowing to the base of transistor TR102 increases, and the transistor TR102 conducts between the emitter and collector. The voltage of 20 (V) from the positive power supply 189 is applied to the transistor TR.
The voltage is applied to the space electrode 621 in the space 615 via the collector and emitter of 102 and the resistor R120.

The discharging circuit 184 includes resistors R106 and R10.
7. The driving data An is input through the inverter 181. When an ON signal (+5 V) as the inverted signal is input, the resistor R1
06, the transistor TR103 conducts, and the resistance R
The electrode 621 is grounded via 120. Therefore,
The charge applied to the side wall 617 is discharged.

In the ROM 42, as shown in FIG.
An ink ejection device control program storage area 42A, a drive waveform data storage area 42B storing sequence data for generating the drive waveforms 1 and 2, and a data presence / absence detection program storage area 42C described in detail later are provided. ing. The control circuit 22 generates the print clock signal CLK having a constant frequency as described above, and the image memory 25 generates the print clock signal CLK at each timing of the print clock signal CLK.
Print data stored in the head unit. At that time, the drive waveform data storage area 42B of the ROM
Are selectively read out from the drive waveforms 1 and 2 stored in the memory cell and supplied to the side wall 617. Further, a data presence / absence detection program having the determination data of FIG. 2 as a table is stored in the area 42C of the ROM. The control circuit 21 determines whether or not there is a print command, that is, print data immediately before the one dot, according to the data presence / absence detection program, and selects a drive waveform to be read as described above according to the determination result.

The presence or absence of print data is determined by driver software in an external device such as a personal computer, and drive waveforms 1 and 2 are generated based on the determination result and output to the control circuit 22. The actuator may be driven.
In this case, a storage medium storing the driving waveform data and a program for determining and outputting the driving waveform is provided as driver software.

Although the embodiment has been described above, the present invention is not limited to this. For example, the pulse width, number, combination, and the like of the ejection pulse and the stabilization pulse constituting the drive waveform can be freely modified.

In this embodiment, the actuator is of a shear mode type.
A configuration in which a pressure wave is generated by the deformation in the laminating direction may be used. Any material that generates a pressure wave in the ink flow path, not limited to the piezoelectric material, can be used.

[0043]

As described above, according to the present invention, in the case where one dot is formed by a plurality of ink droplets, when one dot is driven at a high printing frequency in accordance with the presence or absence of ejection immediately before the dot, By selectively using the driving waveform of a pulse train that causes ink droplets to fly separately and the driving waveform of a pulse train that causes each ink droplet to fly separately when driven at a low frequency, the ink droplets always reach the recording medium. ,
Flying can be stably performed separately, and as a result, the area of the dots formed on the recording medium increases, the print density improves, and high print quality can be obtained.

[Brief description of the drawings]

FIG. 1 is a diagram showing driving waveforms according to an embodiment of the present invention.

FIG. 2 is a diagram showing a comparison of a condition for selecting a drive waveform according to the embodiment of the present invention with a conventional example.

FIG. 3 is a schematic diagram showing a comparison of a result of printing with a drive waveform according to the embodiment of the present invention with a conventional example.

FIG. 4 is a schematic diagram illustrating a difference in dot diameter due to a difference in flying state.

FIG. 5 is a block diagram showing an electrical configuration according to the embodiment of the present invention.

FIG. 6 is a block diagram showing details of a drive circuit of FIG. 5;

FIG. 7 is a circuit diagram showing details of the output circuit of FIG. 6;

FIG. 8 is a block diagram showing a configuration of a ROM of FIG. 5;

FIG. 9 is a sectional view of a head unit according to a conventional example and an embodiment of the present invention.

FIG. 10 is a diagram illustrating the operation of the head unit in FIG. 9;

[Explanation of symbols]

 1 Drive Waveform 2 Drive Waveform 600 Head Unit 613 Ink Channel

Claims (7)

[Claims] 1. A pressure wave is generated in an ink flow path by applying an ejection pulse signal to an actuator for changing the volume of an ink flow path filled with ink, and a pressure is applied to the ink. In an ink droplet ejecting method of ejecting a plurality of ink droplets in response to a single dot printing command by ejecting from a nozzle, when ejecting based on a continuous dot printing command at a predetermined frequency, one dot is printed. A first driving waveform having an ejection pulse train that flies separately until a plurality of ink droplets reach a recording medium in response to a printing command; and a dot printing command for printing at a frequency of about の or less of the predetermined frequency. In the case where the ejection is performed based on the first drive waveform, a plurality of ink droplets fly separately until one dot reaches the recording medium, and are different from the first drive waveform. A second drive waveform having a column is prepared in advance, and when there is no print command immediately before one dot, the second drive waveform is used. In other cases, the first drive waveform is used. An ink droplet ejection method characterized by using: 2. The method according to claim 1, wherein the first drive waveform and the second drive waveform have a plurality of ejection pulses respectively corresponding to a plurality of ink droplets to be ejected. An ink droplet ejection method, wherein at least one wave width or wave interval is different between the first drive waveform and the second drive waveform. 3. The non-ejection stabilization method according to claim 2, wherein the first drive waveform and the second drive waveform are inserted between the plurality of ejection pulses to attenuate residual pressure wave vibration of ink. An ink droplet ejecting method, further comprising an activation pulse. 4. The non-ejection stabilizing device according to claim 3, wherein the first driving waveform and the second driving waveform are added after the plurality of ejection pulses to attenuate residual pressure wave vibration of ink. An ink droplet ejection method, further comprising a pulse. 5. The first driving waveform and the second driving waveform according to claim 4, wherein the first driving waveform has four ejection pulses and one non-injection stabilizing pulse is inserted between the two ejection pulses. And each injection pulse width time is defined as Wa, Wb, Wc, Wd, and the non-injection stabilized pulse width time is defined as
When Sa, Sb, and the width time between pulses are Da, Db, Dc, Dd, and De, the value of the ratio to the time T during which the pressure wave of the ink propagates one way in the ink flow path is shown in Table 1 below. ± 0.
05. A method for ejecting an ink droplet, which falls within the range of 05. [Table 1] 6. A head unit having an ink flow path having a nozzle filled with ink and ejecting an ink droplet, and an actuator for changing the volume of the ink flow path to apply pressure to the ink; Control means for applying an ejection pulse train for ejecting a plurality of ink droplets to the actuator in response to the command, wherein the control means: Data of a first driving waveform having an ejection pulse train for causing a plurality of ink droplets to fly separately until reaching a recording medium in response to a print command of one dot;
And when jetting based on a dot printing command for printing at a frequency of about 1/2 or less of the predetermined frequency,
Storage means for storing data of a second drive waveform having an ejection pulse train different from the first drive waveform for causing a plurality of ink droplets to fly separately for one dot until they reach a recording medium; Determining means for determining whether or not there is a print command immediately before, and based on the determination by the determination means, if there is no print command immediately before one dot, the second drive waveform is
An output unit for selectively outputting the first drive waveform to the actuator in other cases. 7. A pressure wave is generated in an ink flow path by applying an ejection pulse signal to an actuator for changing the volume of an ink flow path filled with ink, and a pressure is applied to the ink. A storage medium storing control means incorporated in a system for ejecting from a nozzle, wherein when ejecting based on a continuous dot printing command at a predetermined frequency, a plurality of inks are printed in response to one dot printing command. Data of a first drive waveform having ejection pulse trains for causing droplets to fly separately until they reach a recording medium;
And when jetting based on a dot printing command for printing at a frequency of about 1/2 or less of the predetermined frequency,
Storage means for storing data of a second drive waveform having an ejection pulse train different from the first drive waveform for causing a plurality of ink droplets to fly separately for one dot until they reach a recording medium; Determining means for determining whether or not there is a print command immediately before, and based on the determination by the determination means, if there is no print command immediately before one dot, the second drive waveform is
Output means for selectively outputting the first drive waveform in other cases.