JP3551822B2 - Driving method of ink ejecting apparatus and apparatus therefor - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method and a device for driving an ink ejecting apparatus.
[0002]
[Prior art]
The non-impact printer that replaces the current impact printers and is expanding its market dramatically is the simplest in principle and easy to multi-tone and color. As an example, there is an ink jet printing apparatus. Above all, the drop-on-demand type, which ejects only ink droplets used for printing, is rapidly spreading due to its good ejection efficiency and low running cost.
[0003]
Representative examples of the drop-on-demand type are a Kaiser type disclosed in Japanese Patent Publication No. 53-12138 and a thermal jet type disclosed in Japanese Patent Publication No. 61-59914. Among them, the former is difficult to miniaturize, and the latter requires a heat resistance of the ink in order to apply high heat to the ink, and each has a very difficult problem.
[0004]
As a new method for solving the above defects simultaneously, a shear mode type using piezoelectric ceramics disclosed in Japanese Patent Application Laid-Open No. 63-247051 is proposed. As shown in FIG. 7, the shear mode ink ejecting apparatus 600 includes a bottom wall 601, a top wall 602, and a shear mode actuator wall 603 therebetween. The actuator wall 603 includes a lower wall 607 bonded to the bottom wall 601 and polarized in the direction of arrow 611, and an upper wall 605 bonded to the top wall 602 and polarized in the direction of arrow 609. Two adjacent actuator walls 603 form a pair, form an ink flow path 613 therebetween, and form a space 615 between the next pair of actuator walls 603.
[0005]
A nozzle plate 617 having a nozzle 618 is fixed to one end of each ink channel 613, and electrodes 619 and 621 are provided on both sides of each actuator wall 603 as a metallized layer. Specifically, an electrode 619 is provided on the actuator wall 603 on the ink flow path 613 side, and an electrode 621 is provided on the actuator wall 603 on the space 615 side. The electrode 621 facing the space 615 is connected to the ground 623, and the electrode 619 provided in the ink flow path 613 is connected to a control circuit 625 for providing an actuator drive signal.
[0006]
Then, when the control circuit 625 applies a voltage to the electrode 619 of each ink flow channel 613, each actuator wall 603 undergoes piezoelectric thickness shear deformation in a direction to increase the volume of the ink flow channel 613. For example, as shown in FIG. 8, when a voltage E (V) is applied to the electrode 619c of the ink flow path 613c, electric fields are generated in the actuator walls 603e and 603f in the directions of arrows 631 and 632 perpendicular to the polarization direction, respectively. The walls 603e and 603f undergo a piezoelectric thickness shear deformation in a direction to increase the volume of the ink flow path 613c. At this time, the pressure in the ink flow path 613c including the vicinity of the nozzle 618c 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.
[0007]
The one-way propagation time T is a time required for the pressure wave in the ink flow path 613 to propagate in the longitudinal direction of the ink flow path 613, and the length L of the ink flow path 613 and the ink flow path 613 T = L / a is determined by the sound speed a in the ink inside.
[0008]
According to the pressure wave propagation theory, the pressure in the ink flow path 613 reverses and turns to a positive pressure just after T time has elapsed from the application of the voltage, but the electrode 621c of the ink flow path 613c is synchronized with this timing. Is returned to 0 (V).
[0009]
Then, the actuator walls 603e and 603f return to the state before deformation (FIG. 6), and pressure is applied to the ink. At this time, the pressure that has turned positive and the pressure generated when the actuator walls 603e and 603f return to the state before deformation are added, and a relatively high pressure is generated in a portion of the ink flow path 613c near the nozzle 618c. Thus, ink droplets are ejected from the nozzle 618c.
[0010]
More specifically, when 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 decreases because the ink droplets are ejected, and the one-way propagation time T Since the injection is not performed at all when it becomes almost an even number times, the time from the application of the voltage to the return of the voltage to 0 (V) is usually set to be equal to the one-way propagation time T or at least almost an odd number times. It is desirable that
[0011]
[Problems to be solved by the invention]
Conventionally, in this type of ink ejecting apparatus 600, the volume of the ejected ink droplets is determined by the shape of the ink flow path 613, the driving voltage, and the like. If necessary, there is a disadvantage that the shape of the ink flow path needs to be changed. In addition, even if a required amount of ink is obtained, the stability at the time of ejection is reduced, so that the driving frequency has to be reduced.
[0012]
In Japanese Patent Publication No. 30506/1991, it is proposed to control the volume of the ink droplet by applying an additional pulse for determining the tip position of the meniscus in the nozzle before the main pulse is applied. ing. According to this, when the main pulse is applied in a state where the meniscus in the nozzle is slightly protruded by the additional pulse, the volume of the ink droplet is slightly larger than that of the case of only the main pulse, but the volume is not increased much. I can't hope.
[0013]
Japanese Patent Publication No. 6-55513 proposes controlling the volume of ink droplets by combining a plurality of ink droplets continuously ejected using the resonance frequency in the air. According to this, a sufficient volume of the ink droplet is obtained, but as apparent from the description of the experiment described later, since the ink droplets coalesce during the flight, the flying direction is bent, Stable injection cannot be obtained. Further, there is a problem that the driving frequency cannot be increased. The present invention has been made in order to solve the above-described problems, and does not require a change in the shape of the ink flow path, can obtain an ink amount necessary for good printing, and stably even at a high driving frequency. It is an object of the present invention to provide a low-cost method for driving an ink ejecting apparatus capable of obtaining good print quality and capable of printing, and an apparatus therefor.
[0014]
[Means for Solving the Problems]
In order to achieve this object, according to the present invention, an ink flow path filled with ink, an actuator for increasing or decreasing the volume of the ink flow path to generate a pressure wave in the ink flow path, and an ink flow path for the ink flow path A nozzle for ejecting the ink in the ink flow path as ink droplets from one end, and continuously applying a plurality of ejection pulse signals having the same peak value to a print command per dot; Assuming that the time during which the pressure wave propagates one way in the road is T, the wave width of the first injection pulse signal applied first is 0.35T to 0.65T, and the wave width of the injection pulse signal applied second and subsequent times is Almost T , The time interval between the first ejection pulse signal and the subsequent ejection pulse signal is T And before the ink droplet ejected from the nozzle by the first ejection pulse signal leaves the nozzle, the first ejection pulse at the timing when the ink droplet is ejected from the nozzle by the second ejection pulse signal. After the signal, the second ejection pulse signal is applied to the actuator. According to this, a plurality of ink droplets are ejected by a plurality of ejection pulse signals in response to a print command per dot. At this time, the first ejection pulse signal having the wave width of 0.35T to 0.65T is less efficient than when the wave width is T, but before the ink droplet is ejected and the droplet leaves the nozzle, When the second ejection pulse signal is applied, new ink droplets are efficiently ejected, and after the preceding ink droplets have merged with the ink droplets in a state where they have not separated from the nozzles, the ink droplets are then ejected from the nozzles. You will fly away. Therefore, bending in the flight direction does not easily occur, and the ejection stability at a high frequency can be improved, and the required amount of ink per dot can be obtained.
[0015]
In addition, the present invention preferably converts a non-ejection pulse signal having the same peak value as the ejection pulse signal and a wave width of 0.3T to 0.7T between a rising timing and a falling timing of the non-ejection pulse signal. The control device applies the actuator to the actuator from the driving power source such that the time difference between the intermediate timing and the falling timing of the last injection pulse signal of the plurality of injection pulse signals is approximately 2.5T. This effectively reduces the residual pressure wave vibration in the ink flow path after ejection, and is stable at high speed even when the viscosity of the ink decreases due to ejection of relatively low-viscosity ink or temperature rise. Injection is possible.
[0016]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0017]
The ink ejecting apparatus 600 includes a bottom wall 601, a top wall 602, and a shear mode actuator wall 603 therebetween, similarly to the conventional inkjet head 600 shown in FIG. The actuator wall 603 includes a lower wall 607 bonded to the bottom wall 601 and polarized in the direction of arrow 611, and an upper wall 605 bonded to the top wall 602 and polarized in the direction of arrow 609. Two adjacent actuator walls 603 form a pair, form an ink flow path 613 therebetween, and form a space 615 between the next pair of actuator walls 603.
[0018]
A nozzle plate 617 having a nozzle 618 is fixed to one end of each ink channel 613, and electrodes 619 and 621 are provided on both sides of each actuator wall 603 as a metallized layer. The electrode 619 is covered with an insulating layer 630 for insulating the ink. The electrode 621 facing the space 615 is connected to the ground 623, and the electrode 619 provided in the ink flow path 613 is connected to a control circuit 625 which is an actuator driving circuit.
[0019]
An example of specific dimensions of the ink ejecting apparatus 600 will be described. The length L of the ink flow path 613 is 8.0 mm. The dimensions of the nozzle 618 are such that the diameter on the ink ejection side is 30 μm, the diameter on the ink flow path 613 side is 50 μm, and the length is 50 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) between the sound velocity a and the above L in the ink in the ink flow path 613 was 8 μsec.
[0020]
Next, a driving waveform 10 applied to the electrode 619 in the ink flow path 613 is shown in FIG. The driving waveform 10 includes ejection pulse signals A and B for ejecting ink droplets and a non-ejection pulse signal C for reducing residual pressure wave vibration in the ink flow path 613. The peak value (voltage value) of both B and the non-ejection pulse signal C is E (V) (for example, 20 (V)). In the most preferred embodiment, the width Wa of the ejection pulse signal A is equal to 0.5 times the one-way propagation time T of the pressure wave in the ink flow path 613, that is, 4 μsec, and the width Wb of the ejection pulse signal B is Is equal to the one-way propagation time T of the pressure wave in the ink flow path 613, that is, 8 μsec. The time Dw1 from the falling timing Wae of the ejection pulse signal A to the rising timing Wbs of the ejection pulse signal B also coincides with the one-way propagation time T of the pressure wave in the ink flow path 613, that is, 8 μsec. The width Wc of the non-ejection pulse signal C is 0.5 times the one-way propagation time T (L / a) of the pressure wave in the ink flow path 613, that is, 4 μsec. The time Dw2 from the falling timing Wbe of the ejection pulse signal B to the intermediate timing Wcm between the rising timing Wcs and the falling timing Wce of the non-ejection pulse signal C is the one-way propagation time T of the pressure wave in the ink flow path 613. 2.5 times, that is, 20 μsec.
[0021]
The non-ejection pulse signal C suppresses a rise in pressure by raising the non-ejection pulse signal to expand the volume of the ink flow path at the timing when the residual pressure wave vibration in the ink flow path due to the ejection pulse signal increases the pressure. At the timing when the residual pressure wave vibration lowers the pressure, the non-ejection pulse signal falls to return the volume of the ink flow path and suppress the pressure drop, thereby reducing the residual pressure wave vibration.
[0022]
Next, a control circuit 625 for realizing the drive waveform 10 will be described with reference to FIGS.
[0023]
The control circuit 625 shown in FIG. 2 includes a charging circuit 182, a discharging circuit 184, and a pulse control circuit 186.
[0024]
The input terminals 181 and 182 are input terminals for inputting pulse signals for setting voltages applied to the electrodes 619 in the ink flow path 613 to E (V) and 0 (V), respectively. The charging circuit 182 includes resistors R101, R102, R103, R104, and R105, and transistors TR101 and TR102.
[0025]
When an ON signal (+5 V) is input to the input terminal 181, the transistor TR101 conducts via the resistor R101, and a current flows from the positive power supply 187 to the emitter of the transistor TR101 from the collector of the transistor TR101 via the resistor R103. Accordingly, the voltage division of the resistors R104 and R105 connected to the positive power supply 187 increases, the current flowing to the base of the transistor TR102 increases, and the transistor TR102 conducts between the emitter and the collector. A voltage of 20 (V) from the positive power supply 187 is applied to the electrode 619 in the ink flow path 613 via the collector and the emitter of the transistor TR102 and the resistor R120. This timing is the timing of T1, T3 and T5 in the timing chart shown in FIG. FIG. 3 is a timing chart showing the input signals to the input terminals 181 and 182 of the control circuit 125 and the output at the electrode 619.
[0026]
Next, the discharging circuit 184 will be described. The discharging circuit 184 includes resistors R106 and R107 and a transistor TR103. When an ON signal (+5 V) is input to the input terminal 182, the transistor TR103 conducts via the resistor R106, and the electrode 619 is grounded via the resistor R120. Therefore, the electric charge applied to the actuator wall 603 of the ink flow path 613 shown in FIGS. 6 and 7 is discharged. This timing is the timing of T2, T4 and T6 in the timing chart shown in FIG.
[0027]
The input signal 11 of the drive waveform 10 input to the input terminal 181 of the charging circuit 182 is normally in an off state as shown in the timing chart (A) of FIG. It is turned on and turned off at timing T2. It is turned on at the subsequent timing T3, turned off at the timing T4, turned on at the timing T5, and turned off at the timing T6. The input signal 12 input to the input terminal 182 of the discharge circuit 184 is turned off when the input signal 11 is on (T1, T3, T5) as shown in the timing chart (B) shown in FIG. When 11 is off (T2, T4, T6), it is turned on.
[0028]
The output waveform 13 at the electrode 619 at that time is normally maintained at 0 (V), but at timing T1, electric charges are charged to the actuator wall 603 made of a piezoelectric element, and the transistor TR102 and the resistor R120 After the charging time Ta determined by the capacitance of the actuator wall 603, the voltage becomes E (V) (for example, 20 (V)). At timing T4, the voltage becomes 0 (V) after the discharge time Tb.
[0029]
As described above, the actual drive waveform 13 has a delay of Ta and Tb at the rise and fall, respectively, so that the ejection pulse signal B of the drive waveform 10 at the voltage of 1 / 2E (V) (for example, 10 (V)). The timings T3, T4, T5, and T6 are set so that the time Dw2 between the falling timing Wbe and the rising timing Wcs of the non-ejection pulse signal C and the intermediate timing Wcm of the falling timing Wce becomes the value shown in FIG. I do.
[0030]
Next, the pulse control circuit 186 that generates pulse signals having the above-described timings T1, T2, T3, T4, T5, and T6 input to the input terminal 181 of the charging circuit 182 and the input terminal 182 of the discharging circuit 184 will be described. I do.
[0031]
The pulse control circuit 186 is provided with a CPU 110 for performing various arithmetic processing. The CPU 110 has a RAM 112 for storing print data and various data, a control program for the pulse control circuit 186, and the above-described T1, T2, T3, T4, A ROM 114 storing sequence data for generating ON / OFF signals at timings T5 and T6 is connected. Here, the ROM 114 is provided with an ink ejection device control program storage area 114A and a drive waveform data storage area 114B, as shown in FIG. Therefore, the sequence data of the drive waveform 10 is stored in the drive waveform data storage area 114B.
[0032]
Further, the CPU 110 is connected to an I / O bus 116 for exchanging various kinds of data. The I / O bus 116 is connected to a print data receiving circuit 118 and pulse generators 120 and 122. The output of the pulse generator 120 is connected to the input terminal 181 of the charging circuit 182, and the output of the pulse generator 122 is connected to the input terminal 182 of the discharging circuit 184.
[0033]
CPU 110 controls pulse generators 120 and 122 according to the sequence data stored in drive waveform data storage area 114B of ROM 114. Therefore, by storing various patterns of the timings T1, T2, T3, T4, T5, and T6 in the drive waveform data storage area 114B in the ROM 114 in advance, the ejection pulse signal of the drive waveform 10 shown in FIG. Actuator wall 603 can be provided.
[0034]
The number of pulse generators 120 and 122, the number of charging circuits 182 and the number of discharging circuits 184 are equal to the number of nozzles of the inkjet head. In the present embodiment, control of one nozzle has been described as a representative, but control of other nozzles is similar.
[0035]
The results of the ink ejection test when driven in the above-described embodiment will be described with reference to the table in FIG.
[0036]
In the driving method using the driving waveform 10 described above, when driven at 20 (V), the ejection speed of the ink droplets is 8.0 m / s, and the two ink liquids correspond to the ejection pulse signals A and B. A drop was fired and the sum of the two ink drop volumes was 60 pl (picoliter). The highest driving frequency at which stable injection could be performed without splashing or stopping injection was 21.5 kHz.
[0037]
As a comparative experiment, when the drive is performed by changing the width Wa of the ejection pulse signal A of the drive waveform 10 from 0.3 to 1.05 times the one-way propagation time T of the pressure wave in the ink flow path 613, and the non-ejection pulse FIG. 5 shows the evaluation results of the ink droplet volume when the signal C was not applied and the highest driving frequency that enables stable ejection.
[0038]
From this result, it can be seen that when the width Wa of the ejection pulse signal A of the drive waveform 10 is 0.3 T or less, the volume of the ink droplet is greatly reduced. In addition, when the width Wa of the ejection pulse signal A is 0.7 T or more, the volume of the ink droplet does not change much, but it can be seen that the maximum driving frequency for stably ejecting is reduced by 10% or more.
[0039]
Next, a similar experiment was performed for the case where the non-ejection pulse signal C of the driving waveform 10 was eliminated. As a result, the volume of ink droplets increased and the maximum driving frequency at which stable ejection was possible decreased. The trends of the volume of the ink droplets and the maximum driving frequency for stable ejection with respect to the change of the width Wa of the pulse signal A were exactly the same. Although no data is described, similar results were obtained by changing the width Wc of the non-ejection pulse signal C from 0.3T to 0.7T by experiments.
[0040]
The reason for obtaining the above results may be a difference in the ejection state of ink droplets as described below.
[0041]
FIG. 6A shows the case where the width Wa of the ejection pulse signal A is shorter than 0.35T, and FIG. 6B shows the case where the width Wa of the ejection pulse signal A is in the range of 0.35T to 0.65T. FIG. 6C is a schematic diagram illustrating the ejection state of the ink droplet corresponding to the timings Wae, Wbe, and Wce in FIG. 1 when the width Wa of the ejection pulse signal A is longer than 0.65T.
[0042]
When the width Wa of the ejection pulse signal A in FIG. 6A is shorter than 0.35T, the ink droplet is not actually ejected by the ejection pulse signal A, and the meniscus 501a slightly protrudes from the nozzle 618 at the timing Wae. At timing Wbe, the ink droplet 502a is ejected by the ejection pulse signal B, and at the timing Wce, the meniscus 501a slightly jumps out of the ink droplet 503a flying away from the nozzle 618. This is an integral part of the ink droplet 502a and the ink volume is larger than that of the ink droplet 502a alone, but the ink volume cannot be expected to increase much. This is substantially the same as that described in Japanese Patent Publication No. 30506/1991.
[0043]
On the other hand, when the width Wa of the ejection pulse signal A is in the range of 0.35T to 0.65T, as shown in FIG. 6B, the ink droplet 501b is ejected by the ejection pulse signal A at the timing Wae. Is done. This is less efficient than the case where the ejection pulse signal A is set to the wave width T, but it can fly from the nozzle without the subsequent ejection pulse signal B. Then, at the timing Wbe, before the ink droplet 501b is completely separated from the nozzle 618, the ink droplet 502b is ejected by the ejection pulse signal B. At this time, since the ejection pulse signal B has a wave width T, as described in the related art, the ink droplet 502b is ejected most efficiently and at high speed, and the latter ink droplet 502b catches up with the former ink droplet 501b and is integrally formed. After that, at timing Wce, the residual pressure wave vibration in the ink flow path is suppressed by the non-ejection pulse signal C, and the integrated ink droplet 503b is cut off from the nozzle 618 and flies. A stable jet can be obtained without bending in the flight direction. The ink droplet 503b is formed by integrating the ink droplet 501b and the ink droplet 502b, and a sufficient ink volume can be obtained.
[0044]
Further, when the wave width Wa of the ejection pulse signal A is longer than 0.65T, as shown in FIG. 6C, the ink droplet 501c is ejected by the ejection pulse signal A at the timing Wae, and at the timing Wbe, After the ink droplet 501c is completely separated from the nozzle 618, the ink droplet 502c is ejected by the ejection pulse signal B, and at the timing Wce, the ink droplet 502b catches up with the ink droplet 501c and becomes united. , And fly away from the nozzle 618. This is substantially the same as that described in the aforementioned Japanese Patent Publication No. 6-55513. The integrated ink droplet 503c is an integral one of the ink droplet 501c and the ink droplet 502c, and a sufficient ink volume can be obtained. However, the ink droplet 501c and the ink droplet Since the droplets 502c are integrated, the flying direction is bent when integrated, and it becomes difficult to obtain a stable jet. In addition, the drive frequency (the frequency at which the drive waveform 10 is repeatedly output when one set of the drive waveforms 10) is reduced by an increase in the wave width Wa of the ejection pulse signal A. That is, printing cannot be performed at high speed.
[0045]
Therefore, from the above experiment, when the width Wa of the ejection pulse signal A of the drive waveform 10 is changed from 0.35T to 0.65T, the ejection drive is stably performed up to a higher drive frequency while maintaining the required volume of the ink droplet. Further, the non-ejection pulse signal C having a wave width of 0.3 to 0.7 T can be obtained by converting the non-ejection pulse signal into an intermediate timing Tcm between the rising timing Wcs and the falling timing Wce of the non-ejection pulse signal and the second injection. When the time difference Dw2 from the fall timing of the pulse signal B is approximately 2.5T, it can be seen that the volume of the ink droplet slightly decreases, but the maximum drive frequency at which stable ejection can be performed is greatly increased.
[0046]
As described above, one embodiment has been described in detail, but the present invention is not limited to this embodiment. In the above-described embodiment, the plurality of ejection pulse signals are the ejection pulse signal A and the ejection pulse signal B. However, the same tendency is obtained even when the number of ejection pulse signals is three or more in accordance with the required volume of the ink droplet. I know that.
[0047]
Further, in the above embodiment, the positive power supply 187 is used, but a negative power supply may be used by reversing the polarization direction of 609 and 611 in FIG. Further, as shown in FIG. 9, the polarization direction is reversed, the electrodes 719 on the ink flow path 713 side are connected to the ground, and the electrodes facing the space 715 are divided into two, and the electrodes 721 are respectively separated. And 722, the electrodes 721 and 722 may be connected to the injection charging circuit, respectively.
[0048]
In this embodiment, the ink is ejected by deforming the volume of the ink flow path 613 by piezoelectric deformation of the lower wall 607 and the upper wall 605 of the actuator wall 603. The ink may be ejected by being formed of a material that does not deform and deforming along with the other piezoelectric deformation. In the present embodiment, the air chambers 615 are provided on both sides of the ink flow path 613. However, the ink flow paths may be adjacent to each other without providing the air chambers.
[0049]
In addition, a diaphragm is provided in a part of the ink flow path, and a piezoelectric element and other mechanical vibration generating elements are attached to the diaphragm. The present invention can be implemented in a modified or improved mode.
[0050]
【The invention's effect】
As described above, according to the present invention, the width of the first ejection pulse signal is set to 0.35T to 0.65T, and the ejection pulse signals after the second ejection pulse signal are set to substantially T. , The time interval between the first ejection pulse signal and the subsequent ejection pulse signal is T And before the ink droplet ejected from the nozzle by the first ejection pulse signal leaves the nozzle, at the timing when the ink droplet is ejected from the nozzle by the second ejection pulse signal, after the first ejection pulse signal. By applying the second ejection pulse signal to the actuator, the following ink droplet is united with the ink droplet in a state where the preceding ink droplet does not leave the nozzle, and then fly away from the nozzle. Become. Therefore, bending in the flight direction does not easily occur, and the ejection stability at a high frequency can be improved, and the required amount of ink per dot can be obtained. Further, by applying a non-ejection pulse signal at a predetermined timing and a wave width after a plurality of ejection pulse signals, it is possible to suppress the residual pressure wave vibration in the ink flow path after the ejection of the ink droplets. Stable injection can be performed even with frequency printing.
[Brief description of the drawings]
FIG. 1 is a diagram illustrating a driving waveform of an ink ejecting apparatus according to an embodiment of the present invention.
FIG. 2 is a diagram illustrating a driving circuit of the ink ejecting apparatus.
FIG. 3 is a diagram showing a timing chart for driving the ink ejecting apparatus.
FIG. 4 is a diagram showing a storage area of a ROM of a control circuit of the ink ejecting apparatus.
FIG. 5 is a diagram illustrating the results of an experiment performed to determine an appropriate range of the width of the ejection pulse signal of the drive waveform of the ink ejection device.
FIG. 6 is a schematic diagram illustrating a flying state of ink droplets in an experiment conducted to determine an appropriate range of the width of an ejection pulse signal of a drive waveform of the ink ejection device.
FIG. 7 is a diagram showing a conventional example and an ink ejecting apparatus according to the present invention.
FIG. 8 is a diagram illustrating an operation of a conventional example and an ink ejecting apparatus according to the present invention.
FIG. 9 is a diagram illustrating an ink ejecting apparatus according to another embodiment of the present invention.
[Explanation of symbols]
10 Drive waveform
187 Positive power supply
600 inkjet head
603 Actuator wall
613 Ink flow path
625 control circuit

Claims (4)

An ink flow path filled with ink, an actuator for increasing or decreasing the volume of the ink flow path to generate a pressure wave in the ink flow path, and transferring the ink in the ink flow path from one end of the ink flow path to the ink. A nozzle for ejecting as droplets,
While continuously applying a plurality of ejection pulse signals having the same peak value to the print command per dot to the actuator,
Assuming that the time during which the pressure wave propagates in the ink flow path in one way is T, the pulse width of the first ejection pulse signal applied first is 0.35T to 0.65T, and the ejection pulse signal applied second and subsequent times is , The time interval between the first ejection pulse signal and the subsequent ejection pulse signal is T ,
Before the ink droplet ejected from the nozzle by the first ejection pulse signal leaves the nozzle, at the timing when the ink droplet ejected by the second ejection pulse signal is ejected from the nozzle, the first ejection pulse signal A method for driving the ink ejecting apparatus, wherein the second ejection pulse signal is applied to the actuator later. A non-ejection pulse signal having the same peak value as the plurality of ejection pulse signals and having a wave width of 0.3T to 0.7T is provided at an intermediate timing between a rising timing and a falling timing of the non-ejection pulse signal; 2. The method according to claim 1, wherein the actuator is applied to the actuator such that a time difference from a falling timing of an ejection pulse signal applied last in the ejection pulse signal is approximately 2.5T. . An ink flow path filled with ink, an actuator for increasing or decreasing the volume of the ink flow path to generate a pressure wave in the ink flow path, and transferring the ink in the ink flow path from one end of the ink flow path to the ink. In an ink ejecting apparatus including a nozzle that ejects a droplet and a driving device that applies an ejection pulse signal to the actuator,
The driving device continuously applies a plurality of ejection pulse signals having the same peak value to a print command per dot,
Assuming that the time during which the pressure wave propagates in the ink flow path in one way is T, the pulse width of the first ejection pulse signal applied first is 0.35T to 0.65T, and the ejection pulse signal applied second and subsequent times is , The time interval between the first ejection pulse signal and the subsequent ejection pulse signal is T ,
Before the ink droplet ejected from the nozzle by the first ejection pulse signal leaves the nozzle, at the timing when the ink droplet ejected by the second ejection pulse signal is ejected from the nozzle, the first ejection pulse signal A driving device for applying the second ejection pulse signal to the actuator later. A non-ejection pulse signal having the same peak value as the plurality of ejection pulse signals and having a wave width of 0.3T to 0.7T is provided at an intermediate timing between a rising timing and a falling timing of the non-ejection pulse signal; 4. The driving device according to claim 3, wherein the actuator is applied to the actuator such that a time difference from a falling timing of an ejection pulse signal applied last in the ejection pulse signal is approximately 2.5T.

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