JP2012126046A - Inkjet recording apparatus and method for generating drive waveform signal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inkjet recording apparatus and a method for generating a drive waveform signal by which respective ink drops within one pixel period and ink drops in respective pixel periods can be ejected at the same ejection speed, when ejecting zero to two ink drops within one pixel period, and voltage width to be used is prevented from getting larger to the utmost.SOLUTION: In the inkjet recording apparatus, when resonance frequency of a piezoelectric element is defined as f, and prescribed time consisting of time length equal to or under 1/f is defined as t, a head control substrate generates a second drive waveform signal including an ejection pulse P12 whose pulse width is AL-t, and a cancel pulse C11 which is applied after t elapses from a finish time of the ejection pulse P12 and has the same polarity as the ejection pulse P12.

Description

  The present invention relates to an inkjet recording apparatus and a drive waveform signal generation method.

In recent years, in an ink jet recording apparatus having a recording head for ejecting ink droplets, a driving frequency of 100 kHz (pixel period is 10 us) and within one pixel period in order to realize a printing speed of 1 m / s and a printing resolution of 1200 dpi. The recording head is driven by a 100 kHz binary driving method in which 0 or 1 ink droplet is discharged.
In the 100 kHz binary drive method, an ejection pulse for ejecting one ink droplet and a cancel pulse for suppressing the influence of reverberation vibration on a pressure wave generated in the pressure chamber by the ejection pulse are within one pixel period. The recording head is driven in accordance with the drive waveform signal included in.

Here, FIG. 15 (i) shows a drive waveform signal according to the 100 kHz binary drive method when ink droplets are ejected by the pulling method, and a pressure chamber connected to a piezoelectric element that pressurizes ink according to the drive waveform signal. The pressure waveform is shown in FIG. 15 (ii). The voltage V0 indicates a standby voltage according to the pulling method. In FIG. 15 (ii), times T1 and T2 after the application of ejection pulses P1 and P2 for ejecting ink droplets represent the time when ink droplets are ejected (time when the positive pressure becomes maximum), and the solid line indicates When the cancel pulse C1 is applied, the broken lines represent the pressure waveforms when the cancel pulse C1 is not applied. That is, as shown in FIG. 15 (ii), by applying the cancel pulse C1, the influence of reverberation vibration due to the ejection pulse P1 is alleviated, and the positive pressure at time T2 is suppressed to the same level as time T1. Therefore, the ink droplet ejection speed based on the ejection pulse P2 can be made the same as the ink droplet ejection speed based on the ejection pulse P1.
By the way, as shown in FIG. 15 (i), the pixel period in this case is that the pulse widths of the ejection pulse P1 and the cancel pulse C1 are AL (AL: Acoustic Length, half period of the natural vibration period of the pressure chamber), and the ejection pulse. If the cancel pulse C1 is applied after AL from the end time of P1, and the interval from the application of the cancel pulse C1 to the application of the ejection pulse P2 of the next pixel period is AL, 4AL is required at the shortest. Therefore, in order to realize the 100 kHz binary drive method (drive frequency is 100 kHz), the natural vibration period of the pressure chamber must be 5 us or less (the natural vibration frequency is 200 kHz or more).

  Therefore, there is a method of driving the recording head by a 50 kHz 2dpd driving method in which the driving frequency is 50 kHz (pixel period is 20 us) and 0 to 2 ink droplets are ejected within one pixel period.

  For example, as an ink jet recording apparatus using the 2dpd driving method, an ink jet apparatus that can eject ink efficiently and stably at high speed is known by synchronizing the pulse width of each ejection pulse with the natural vibration period of the pressure chamber. (See Patent Document 1).

JP 61-22959 A

However, according to the ink jet recording apparatus described in Patent Document 1, since the ejection pulse is synchronized with the natural vibration period of the pressure chamber, if the ejection pulse is simply applied repeatedly, two ink droplets are produced within one pixel period. When droplets are ejected, an ink droplet based on a later ejection pulse within the same pixel cycle has a problem that the ejection speed increases due to the influence of the earlier ejection pulse.
Furthermore, according to the ink jet recording apparatus described in Patent Document 1, as shown by the broken line in FIG. 15 (ii), the reverberation vibration based on the ejection pulse within a certain pixel period affects the ejection speed of the ink droplet in the next pixel period. Bring. The influence of the reverberation vibration can be suppressed by the application of the cancel pulse. However, as shown in FIG. 15 (i), the conventional cancel pulse has a voltage equal to the discharge pulse with respect to the standby voltage V0. Since it is applied so as to have a reverse polarity, there is a problem that the voltage width used in the entire drive waveform signal becomes wide.

  Therefore, the problem of the present invention is that when 0 to 2 ink droplets are ejected in one pixel cycle, each ink droplet in one pixel cycle and ink droplets in each pixel cycle can be ejected at the same ejection speed, and An object of the present invention is to provide an ink jet recording apparatus and a drive waveform signal generation method that do not expand the voltage range to be used as much as possible.

  In order to solve the above problems, an invention according to claim 1 is an ink jet recording apparatus, comprising a nozzle, a pressure chamber communicating with the nozzle, a resonance frequency f, and pressure applied to the ink in the pressure chamber. And a recording head in which the piezoelectric element applies pressure to the ink and ejects ink droplets from the nozzles according to the applied drive waveform signal, and ejects one ink droplet The drive for causing the recording head to discharge 0 to 2 ink droplets to one pixel, including a discharge pulse for performing the operation and a cancel pulse for suppressing the influence of reverberation vibration caused by the discharge pulse. Drive waveform signal generating means for generating a waveform signal, wherein the drive waveform signal generating means has a pulse width of one pulse period within one pixel period, where t is a predetermined time having a time length of 1 / f or less. Drive including a discharge pulse shorter by t than AL that represents a half cycle of the natural vibration period of the pressure chamber, and a cancel pulse that is applied after t has elapsed from the end of the discharge pulse and has the same polarity as the discharge pulse. A waveform signal is generated.

According to a second aspect of the present invention, in the ink jet recording apparatus according to the first aspect,
The drive waveform signal generation unit generates the drive waveform signal when the recording head ejects two ink droplets per pixel.

  According to a third aspect of the present invention, there is provided an inkjet recording apparatus comprising a nozzle, a pressure chamber communicating with the nozzle, and a piezoelectric element having a resonance frequency f and applying pressure to the ink in the pressure chamber. And a recording head in which the piezoelectric element applies pressure to the ink in accordance with the applied drive waveform signal to eject ink droplets from the nozzle, and an ejection pulse for ejecting one ink droplet And a cancel pulse for suppressing the influence of reverberation vibration due to the ejection pulse, and generating the drive waveform signal for causing the recording head to eject 0 to 2 ink droplets per pixel. Waveform signal generating means, and when the drive waveform signal generating means causes the recording head to eject one drop of ink to one pixel, the pulse width is the pressure within one pixel period. A first ejection pulse having a voltage equal to V1 which is equal to AL representing a half period of the natural oscillation period of the first oscillation pulse, and having the same polarity as the first ejection pulse applied 2AL after the end time of the first ejection pulse; A first drive waveform signal including a first cancel pulse composed of V2 having a pulse width equal to AL and a voltage smaller than V1 is generated, and the recording head ejects two ink droplets to one pixel. In this case, when a predetermined time having a time length of 1 / f or less is t, a second ejection pulse having a pulse width equal to AL and a voltage V1 within one pixel period and the end of the second ejection pulse. A third ejection pulse which is applied after AL from the time point and whose pulse width is shorter than AL by a voltage V1, and the third ejection pulse which is applied after t has elapsed since the end time of the third ejection pulse. Wherein the voltage is the same polarity to generate the second drive waveform signal including a second cancel pulse consisting of V2, the.

  According to a fourth aspect of the present invention, there is provided an ink jet recording apparatus comprising a nozzle, a pressure chamber communicated with the nozzle, and a piezoelectric element having a resonance frequency f and applying pressure to the ink in the pressure chamber. And a recording head in which the piezoelectric element applies pressure to the ink in accordance with the applied drive waveform signal to eject ink droplets from the nozzle, and an ejection pulse for ejecting one ink droplet And a cancel pulse for suppressing the influence of reverberation vibration due to the ejection pulse, and generating the drive waveform signal for causing the recording head to eject 0 to 2 ink droplets per pixel. Waveform signal generating means, and when the drive waveform signal generating means causes the recording head to eject one drop of ink to one pixel, the pulse width is the pressure within one pixel period. A first ejection pulse having a voltage equal to V1 which is equal to AL representing a half period of the natural oscillation period of the first oscillation pulse, and having the same polarity as the first ejection pulse applied 2AL after the end time of the first ejection pulse; Generating a first drive waveform signal including a first cancel pulse having a pulse width V that does not match AL and a voltage V2 smaller than V1, and applies two ink droplets to one pixel on the recording head. In the case of discharging, if a predetermined time having a time length of 1 / f or less is t, a second discharge pulse having a pulse width equal to AL and a voltage V1 within one pixel period, and the second discharge pulse Is applied after AL from the end of the third discharge pulse, the pulse width is shorter than AL by t and the voltage is V1, and the third discharge pulse is applied after t has elapsed from the end of the third discharge pulse. Discharge pal Voltage is the same polarity and generating a second drive waveform signal including a second cancel pulse consisting of V2, the a.

  According to a fifth aspect of the present invention, there is provided an ink jet recording apparatus comprising a nozzle, a pressure chamber communicating with the nozzle, and a piezoelectric element having a resonance frequency f and applying pressure to the ink in the pressure chamber. And a recording head in which the piezoelectric element applies pressure to the ink in accordance with the applied drive waveform signal to eject ink droplets from the nozzle, and an ejection pulse for ejecting one ink droplet And a cancel pulse for suppressing the influence of reverberation vibration due to the ejection pulse, and generating the drive waveform signal for causing the recording head to eject 0 to 2 ink droplets per pixel. Waveform signal generating means, and when the drive waveform signal generating means causes the recording head to eject one drop of ink to one pixel, the pulse width is the pressure within one pixel period. A first ejection pulse equal to AL representing a half period of the natural oscillation period of the first ejection pulse, the same polarity as the first ejection pulse applied 2 AL after the end time of the first ejection pulse, and a pulse width of AL When generating a first drive waveform signal including the same first cancel pulse and causing the recording head to eject two ink droplets to one pixel, a predetermined time having a time length of 1 / f or less Is t, a second ejection pulse having a pulse width equal to AL within one pixel period, and a third ejection pulse which is applied after AL from the end of the second ejection pulse and whose pulse width is shorter than AL by t. Generating a second drive waveform signal including an ejection pulse and a second cancel pulse that is applied after t has elapsed from the end of the third ejection pulse and has the same polarity as the third ejection pulse. , Each discharge pulse And the voltage V3 of the voltage V2 of the voltage V1 the second cancel pulse first cancel pulse, characterized by satisfying the relation V1> V2> V3.

  According to a sixth aspect of the present invention, in the ink jet recording apparatus according to any one of the third to fifth aspects, the individual electrodes provided for each of the plurality of piezoelectric elements and the plurality of piezoelectric elements are shared. Each piezoelectric element is disposed between the individual electrode and the common electrode, and a voltage V1 of each ejection pulse is applied between the individual electrode and the common electrode. A pressure for ejecting ink droplets from the nozzle is applied to the ink, and the voltage VCOM of the common electrode satisfies a relationship of VCOM ≧ V1.

  According to a seventh aspect of the present invention, in the ink jet recording apparatus according to the third or fourth aspect, the first drive waveform signal and the second drive waveform signal are voltages of each ejection pulse according to time. V1 is a signal that generates a level of any one of the voltage V2 of each cancel pulse and the standby voltage V0 for forming a standby state of the piezoelectric element, and the voltage V1, the voltage V2, and the standby voltage According to the drive circuit for applying any voltage of V0 to the piezoelectric element, and the voltage level of the first drive waveform signal or the second drive waveform signal generated by the drive waveform signal generation means, An input unit that inputs a selection signal for applying a voltage corresponding to the level of the voltage to the piezoelectric element to the driving circuit, and the selection signal has a signal level that is a selection level, respectively. The input unit is composed of a pair of first selection signal and second selection signal composed of two types of non-selection levels. The signal level of the first selection signal is a selection level according to the level of the voltage V1. A selection signal is generated, a selection signal in which the signal level of the second selection signal is a selection level according to the level of the voltage V2, and a signal level of the first selection signal according to the level of the standby voltage V0 And a selection signal in which a signal level of the second selection signal is a non-selection level is generated.

  According to an eighth aspect of the present invention, in the ink jet recording apparatus according to the fifth aspect, the first drive waveform signal and the second drive waveform signal are a voltage V1 of each ejection pulse according to time. A signal for generating a level of any one of the voltage V2 of the second cancel pulse, the voltage V3 of the first cancel pulse, and the standby voltage V0 for forming a standby state of the piezoelectric element A drive circuit for applying any one of the voltage V1, voltage V2, voltage V3, and standby voltage V0 to the piezoelectric element, and a first drive waveform signal generated by the drive waveform signal generating means Or an input unit for inputting, to the drive circuit, a selection signal for the drive circuit to apply a voltage corresponding to the voltage level to the piezoelectric element according to the voltage level of the second drive waveform signal. Each of the selection signals includes a pair of a first selection signal, a second selection signal, and a third selection signal having two types of signal levels, a selection level and a non-selection level. A selection signal whose signal level of the first selection signal is a selection level is generated according to the level of V1, and a selection signal whose signal level of the second selection signal is a selection level is generated according to the level of the voltage V2. Generating a selection signal whose signal level is the selection level according to the level of the voltage V3, and selecting the first selection signal, the second selection signal according to the level of the standby voltage V0, And a selection signal in which a signal level of the third selection signal is a non-selection level is generated.

  The invention according to claim 9 includes a nozzle, a pressure chamber communicated with the nozzle, and a piezoelectric element having a resonance frequency f and applying pressure to the ink in the pressure chamber. A recording head in which the piezoelectric element applies pressure to the ink in accordance with a drive waveform signal to be ejected to eject an ink droplet from the nozzle, an ejection pulse for ejecting one ink droplet, and reverberation vibration due to the ejection pulse Drive waveform signal generating means for generating the drive waveform signal for causing the recording head to eject 0 to 2 ink droplets per pixel, and a cancel pulse for suppressing the influence of A drive waveform signal generation method using an inkjet recording apparatus provided, wherein t is a predetermined time having a time length of 1 / f or less, and a pulse width is a natural vibration period of the pressure chamber within one pixel period. A drive waveform signal including a discharge pulse shorter than AL representing a half cycle by t and a cancel waveform having a polarity that is the same as the discharge pulse applied after t has elapsed from the end of the discharge pulse. It makes it produce | generate to a production | generation means, It is characterized by the above-mentioned.

The invention according to claim 10 is the drive waveform signal generation method according to claim 9,
When the recording head ejects two ink droplets per pixel, the drive waveform signal is generated by the drive waveform signal generation unit.

  The invention according to claim 11 includes a nozzle, a pressure chamber communicated with the nozzle, and a piezoelectric element having a resonance frequency f and applying pressure to the ink in the pressure chamber. A recording head in which the piezoelectric element applies pressure to the ink in accordance with a drive waveform signal to be ejected to eject an ink droplet from the nozzle, an ejection pulse for ejecting one ink droplet, and reverberation vibration due to the ejection pulse Drive waveform signal generating means for generating the drive waveform signal for causing the recording head to eject 0 to 2 ink droplets per pixel, and a cancel pulse for suppressing the influence of A method for generating a drive waveform signal by an ink jet recording apparatus, wherein when the recording head ejects one ink droplet to one pixel, the pulse width is the pressure within one pixel period. A first ejection pulse having a voltage equal to V1 which is equal to AL representing a half period of the natural oscillation period of the first oscillation pulse, and having the same polarity as the first ejection pulse applied 2AL after the end time of the first ejection pulse; The drive waveform signal generating means generates a first drive waveform signal including a first cancel pulse composed of V2 having a pulse width equal to AL and a voltage smaller than V1, and the recording head generates 2 for one pixel. In the case of ejecting ink droplets, assuming that a predetermined time having a time length of 1 / f or less is t, a second ejection pulse having a pulse width equal to AL and a voltage V1 within one pixel period; A third discharge pulse that is applied after AL from the end time of the second discharge pulse and whose pulse width is shorter than AL by t and the voltage is V1, and after t has elapsed from the end time of the third discharge pulse. A second cancel pulse is being pressurized the third ejection pulse of the same polarity the voltage is composed of V2, characterized in that to generate the driving waveform signal generating means and the second drive waveform signal including the.

  The invention according to claim 12 includes a nozzle, a pressure chamber communicated with the nozzle, and a piezoelectric element having a resonance frequency f and applying pressure to the ink in the pressure chamber. A recording head in which the piezoelectric element applies pressure to the ink in accordance with a drive waveform signal to be ejected to eject an ink droplet from the nozzle, an ejection pulse for ejecting one ink droplet, and reverberation vibration due to the ejection pulse Drive waveform signal generating means for generating the drive waveform signal for causing the recording head to eject 0 to 2 ink droplets per pixel, and a cancel pulse for suppressing the influence of A method for generating a drive waveform signal by an ink jet recording apparatus, wherein when the recording head ejects one ink droplet to one pixel, the pulse width is the pressure within one pixel period. A first ejection pulse having a voltage equal to V1 which is equal to AL representing a half period of the natural oscillation period of the first oscillation pulse, and having the same polarity as the first ejection pulse applied 2AL after the end time of the first ejection pulse; The drive waveform signal generating means generates a first drive waveform signal including a first cancel pulse composed of V2 whose pulse width does not match AL and whose voltage is smaller than V1, and the recording head generates one pixel for one pixel. In the case of ejecting two ink droplets, if a predetermined time having a time length of 1 / f or less is t, a second ejection pulse having a pulse width equal to AL and a voltage V1 within one pixel period A third discharge pulse that is applied after AL from the end time of the second discharge pulse and whose pulse width is shorter than AL by a voltage V1 and t has elapsed from the end time of the third discharge pulse. rear A second cancel pulse applied the third is a discharge pulse having the same polarity as the voltage is composed of V2, characterized in that to generate the driving waveform signal generating means and the second drive waveform signal including the.

  The invention according to claim 13 includes a nozzle, a pressure chamber communicated with the nozzle, and a piezoelectric element having a resonance frequency f and applying pressure to the ink in the pressure chamber. A recording head in which the piezoelectric element applies pressure to the ink in accordance with a drive waveform signal to be ejected to eject an ink droplet from the nozzle, an ejection pulse for ejecting one ink droplet, and reverberation vibration due to the ejection pulse Drive waveform signal generating means for generating the drive waveform signal for causing the recording head to eject 0 to 2 ink droplets per pixel, and a cancel pulse for suppressing the influence of A method for generating a drive waveform signal by an ink jet recording apparatus, wherein when the recording head ejects one ink droplet to one pixel, the pulse width is the pressure within one pixel period. A first ejection pulse having a voltage equal to V1 which is equal to AL representing a half period of the natural oscillation period of the first oscillation pulse, and having the same polarity as the first ejection pulse applied 2AL after the end time of the first ejection pulse; The drive waveform signal generating means generates a first drive waveform signal including a first cancel pulse composed of V3 having a pulse width equal to AL and a voltage smaller than V1, and the recording head generates 2 for one pixel. In the case of ejecting ink droplets, assuming that a predetermined time having a time length of 1 / f or less is t, a second ejection pulse having a pulse width equal to AL and a voltage V1 within one pixel period; A third discharge pulse that is applied after AL from the end time of the second discharge pulse and whose pulse width is shorter than AL by t and the voltage is V1, and after t has elapsed from the end time of the third discharge pulse. And a second drive waveform signal including the second cancel pulse having the same polarity as the third ejection pulse and a voltage V2 having a voltage larger than V3 and smaller than V1. It is characterized by.

  Therefore, according to the present invention, when ejecting 0 to 2 ink droplets within one pixel cycle, each ink droplet within one pixel cycle and ink droplets during each pixel cycle can be ejected at the same ejection speed and used. It is possible to provide an inkjet recording apparatus and a drive waveform signal generation method that do not increase the voltage width as much as possible.

1 is a schematic diagram illustrating a configuration of an ink jet recording apparatus according to an embodiment. It is sectional drawing of the head with which the inkjet recording device of FIG. 1 is equipped. FIG. 2 is a block diagram illustrating a control configuration of the ink jet recording apparatus of FIG. 1. It is a figure which shows typically the structure of the drive circuit part of FIG. FIG. 5 is a diagram showing a correspondence relationship between levels of two selection signals shown in FIG. 4 and voltages applied to individual electrodes. It is a figure which illustrates the drive waveform signal concerning this embodiment, (i) expresses the 1st drive waveform signal, and (ii) expresses the 2nd drive waveform signal, respectively. It is a figure which illustrates the waveform of the pressure wave of a pressure chamber when a head drives based on the 1st drive waveform signal concerning this embodiment. It is a figure which illustrates the waveform of the pressure wave of a pressure chamber when a head drives based on the 2nd drive waveform signal concerning this embodiment. It is a figure which shows the conventional structure of the drive circuit for applying three different voltages to an individual electrode, and the correspondence of the level of the selection signal in the said drive circuit, and the voltage applied to an individual electrode. FIG. 7 is a diagram illustrating a first modification example of the drive waveform signal shown in FIG. 6, where (i) represents a first drive waveform signal and (ii) represents a second drive waveform signal. FIG. 7 is a diagram illustrating a modified example 2 of the drive waveform signal shown in FIG. 6, where (i) represents a first drive waveform signal and (ii) represents a second drive waveform signal. It is a figure which shows typically the structure of the drive circuit part which implement | achieves the drive waveform signal shown in FIG. FIG. 13 is a diagram illustrating a correspondence relationship between levels of three selection signals illustrated in FIG. 12 and voltages applied to individual electrodes. It is a figure which shows the conventional structure of the drive circuit for applying four different voltages to an individual electrode, and the correspondence of the level of the selection signal in the said drive circuit, and the voltage applied to an individual electrode. It is a figure which illustrates the pressure wave of the pressure chamber when a conventional drive waveform signal and a head drive based on the drive waveform signal, (i) shows a drive waveform signal, and (ii) shows the waveform of a pressure wave. Represent each.

  Hereinafter, an ink jet recording apparatus according to a first embodiment of the present invention will be described with reference to FIGS.

  The ink jet recording apparatus 1 is a so-called line head type ink jet recording apparatus. As shown in FIG. 1, the inkjet recording apparatus 1 winds a recording roll 10 that is unwound from an unwinding roll 10 </ b> A and an unwinding roll 10 </ b> A that unwinds a long recording medium 10 wound around a circumferential surface. A take-up roll 10B to be taken, a back roll 20 disposed between the take-up roll 10A and the take-up roll 10B, an ink jet head part 30 for ejecting ink toward the recording medium 10, and an ink jet head part An intermediate tank 40 for supplying ink to 30, a storage tank 50 for storing ink supplied to the intermediate tank 40 by the liquid feed pump 60, and fixing for fixing the ink discharged to the recording medium 10 to the recording medium 10. And a mechanism 70.

The unwinding roll 10 </ b> A, the winding roll 10 </ b> B, and the back roll 20 are members made of a cylindrical shape that can rotate around its axis.
The unwinding roll 10 </ b> A winds the recording medium 10 several times around the circumferential surface. The unwinding roll 10A is rotated by a driving means (not shown) such as a motor, so that the recording medium 10 is unwound in the direction of X shown in FIG. The take-up roll 10B takes up the recording medium 10 unwound from the unwind roll 10A around the circumferential surface.
The back roll 20 supports the recording medium 10 conveyed by the unwinding roll 10A by winding it around a part of the peripheral surface, and conveys the recording medium 10 toward the take-up roll 10B.

  The inkjet head unit 30 is disposed in the vicinity of the back roll 20 and ejects ink toward the recording medium 10 to form an image based on the image data. The inkjet head unit 30 has a recording head 31 that ejects ink droplets. Here, since the ejection width that can be ejected by one recording head 31 is narrower than the outer dimensions of the recording head 31, the inkjet head unit 30 has a plurality of recording heads 31 with respect to the upper surface of the recording medium 10 in order to eject without gaps. Arranged in a staggered manner.

  As shown in FIG. 2, each recording head 31 includes an ink chamber 32 that stores ink supplied from the intermediate tank 40, a hole portion 33 that conveys ink in the ink chamber 32 downward, and a hole portion 33. A pressure chamber 34 that is communicated with the ink and supplied with ink through the hole 33, a vibration plate 35 that covers the upper surface of the pressure chamber 34, a piezoelectric element 36 that is disposed on the vibration plate 35, and a piezoelectric element 36. And two nozzles 37 and 38 positioned on the upper and lower surfaces, and a nozzle 39 that communicates with the lower surface of the pressure chamber 34 and discharges ink in the pressure chamber 34 as ink droplets. Here, the hole 33 to the electrode 38 are respectively provided according to the plurality of nozzles 39.

The ink chamber 32 stores ink supplied from the intermediate tank 40 via an ink tube 43 described later. The hole 33 is a hole that connects the lower surface of the ink chamber 32 and the side surface of the pressure chamber 34, and conveys ink in the ink chamber 32 to the pressure chamber 34.
The pressure chamber 34 stores ink supplied through the hole 33 therein. The pressure chamber 34 has an upper surface covered with the diaphragm 35 and a lower surface connected to the nozzle 39. The pressure chamber 34 applies pressure to the ink stored therein according to the vibration of the vibration plate 35 and pushes the ink to the nozzle 39. The vibration plate 35 is disposed between the piezoelectric element 36 (electrode 38) and the pressure chamber 34, and is joined to the upper surface of the pressure chamber 34. The diaphragm 35 vibrates according to the deformation of the piezoelectric element 36 and propagates a pressure wave in the pressure chamber 34.
The piezoelectric element 36 is made of PZT (lead zirconate titanate). The piezoelectric element 36 is disposed at a position where the upper and lower sides are sandwiched between the electrodes 37 and 38, and is deformed according to a potential difference between the electrodes 37 and 38 to vibrate the diaphragm 32 (apply pressure to the pressure chamber 34). It is an actuator for. Here, of the electrodes 37, 38, the electrode 37 is an individual electrode provided in the drive circuit unit 200 provided for each recording head 31 described later (for each piezoelectric element 36 provided in each recording head 31). Is a common electrode used in common for each recording head 31.
The nozzle 39 discharges the ink pushed out by the pressure chamber 34 as an ink droplet.

The intermediate tank 40 temporarily stores the ink supplied from the storage tank 50. The intermediate tank 40 is connected to a plurality of ink tubes 43, adjusts the back pressure of the ink in the recording heads 31, and supplies ink to each recording head 31.
The storage tank 50 stores ink to be supplied to the intermediate tank 40 via the supply pipe 51. Then, the ink is pumped up by a liquid feed pump 60 disposed in the middle of the supply pipe 51.
The fixing mechanism 70 fixes the ink ejected by the inkjet head unit 30 to the recording medium 10. The fixing mechanism 70 includes a heater for heating and fixing the ejected ink to the recording medium 10, a UV lamp for curing the ink by irradiating the ejected ink with UV (ultraviolet light), and the like. .

  Next, the control configuration of the inkjet recording apparatus 1 will be described with reference to the block diagram shown in FIG.

  As shown in FIG. 3, the inkjet recording apparatus 1 includes a control unit 100, a fixing mechanism 70 connected to the control unit 100, a communication interface unit 80, a motor driver 90, a motor M, and a drive circuit unit. 200 and a recording head 31 connected to the drive circuit unit 200. Here, since the fixing mechanism 70 and the recording head 31 are as described above, description thereof will be omitted.

The communication interface unit 80 is an interface for the control unit 100 to communicate with a host computer via a LAN (Local Area Network) or the like.
For example, the communication interface unit 80 receives image data transmitted from a host computer and transmits the image data to the control unit 100.

  The motor driver 90 is a driver for driving and controlling the motor M. Here, the motor M is a motor for moving the recording head 31 along the main scanning direction, for example.

  The control unit 100 includes a system controller 110, a head control board 120 (drive waveform signal generating means), and an encoder 130.

  The system controller 110 includes a CPU, a RAM, a ROM, an image memory, and the like, and controls the overall operation of the inkjet recording apparatus 1 by executing a program in the ROM. Specifically, the system controller 110 performs communication control with the host computer, image memory read / write control, motor M drive control via the motor driver 90, operation control of the fixing operation for the fixing mechanism 70, and the like.

  The head control board 120 is a page memory for storing image data received from the host computer, a line memory for storing image data of each pixel recorded in a line in the sub-scanning direction when recording on the recording medium 10, A drive waveform signal generation circuit for generating a drive waveform signal for driving the recording head 31 is included. The head control board 120 functions as a drive waveform signal generation unit that generates a drive waveform signal of the recording head 31 using a drive waveform signal generation circuit under an instruction signal output from the system controller 110. Here, the drive waveform signal generated by the head control board 120 is a signal for driving a recording head 31 to be described later by a 2 dpd (drop per dot) drive method, and within one pixel period shown in FIG. A first driving waveform signal for causing the recording head 31 to eject one ink droplet, and a second for causing the recording head 31 to eject two ink droplets within one pixel period shown in FIG. 6 (ii). Drive waveform signals. The head control board 120 selectively outputs one of the first drive waveform signal and the second drive waveform signal to the drive circuit unit 200. A detailed description of the first drive waveform signal and the second drive waveform signal will be described later.

  The encoder 130 is a rotary encoder for driving control of the motor M, and outputs the counted number of pulses to the head control board 120.

  The drive circuit unit 200 is a circuit for driving each recording head 31 based on a drive waveform signal generated by the head control board 120. Specifically, as shown in FIG. 4, the drive circuit unit 200 includes a shift register 210, a latch circuit 220, a selector 230, a level shifter 240 (input unit), and a drive circuit 250. The

  The shift register 210 converts bit serial data input from the head control board 120 into parallel data and outputs the parallel data to the latch circuit 220. The latch circuit 220 latches the parallel data output from the shift register 210 according to the input of the latch signal. Either the first drive waveform signal or the second drive waveform signal is input from the head control board 120 to the selector 230 as a drive waveform signal to be selected. In the selector 230, the parallel data latched by the latch circuit 220 is input to the select terminal. Therefore, the selector 230 converts the level of the drive waveform signal instructed by the head control board 120 from the first drive waveform signal and the second drive waveform signal and outputs the signal. The level shifter 240 outputs two selection signals D1 and D2 (a set of first selection signal and second selection signal) to the drive circuit 250 in accordance with the signal level (voltage level) of the drive waveform signal output from the selector 230. To enter. The two selection signals D1 and D2 have either a low level or a high level, and are input to the gates of a first P-type FET 261 and a second P-type FET 262 of the drive circuit 250 described later. Are input to the input side of the AND circuit 271.

  The drive circuit 250 includes a first power supply 251, a second power supply 252, a common power supply 255, a first P-type FET 261, a second P-type FET 262, a first N-type FET 263, and a logical product. A circuit 271 and electrodes 37 and 38 are included. The drive circuit 250 drives the recording head 31 by deforming the piezoelectric element 36 by a potential difference generated between the electrodes 37 and 38 based on the selection signals D1 and D2 output from the level shifter 240 (pressure chamber). 34).

The first power supply 251, the second power supply 252, and the common power supply 255 are power supplies for generating voltages V1, V2, and V0, respectively. Here, the common power supply 255 is a power supply connected to the electrode 38 (common electrode) shared by the respective drive circuit units 200, and generates a voltage V0 at each electrode 38.
The first P-type FET 261 and the second P-type FET 262 are P-type field effect transistors connected to the first power source 251 and the second power source 252, respectively. The first P-type FET 261 and the second P-type FET 262 receive a current between the drain and source when low level (selection level) selection signals D1 and D2 are input to the gates from the level shifter 240, respectively. When a high level (non-selection level) selection signal D1, D2 is input to the gate, control is performed so that no current flows between the drain and the source.
The AND circuit 271 is a logic circuit that outputs an output value of a logical product (AND) with respect to two input values of the selection signals D1 and D2 output from the level shifter 240. The first N-type FET 263 is an N-type field effect transistor having one end grounded (voltage: GND). The gate of the first N-type FET 263 is connected to the output side of the AND circuit 271. When a high level (selection level) signal is input from the AND circuit 271, a current flows between the drain and the source. When low level (non-selection level) selection signals D1 and D2 are input, control is performed so that no current flows between the drain and the source.

Therefore, for example, when the selection signal D1 output from the level shifter 240 is at a low level and D2 is at a high level, a current flows through the first P-type FET 261, but no current flows through the second P-type FET 262. . Since a low level signal is input to the gate of the first N-type FET 263 by the logical product of two selection signals (low level and high level) input to the AND circuit 271, No current flows through the N-type FET 263. Then, the voltage V1 of the first power supply 251 is applied to the electrode 37.
Similarly, when the selection signal D1 is at a high level and D2 is at a low level, no current flows through the first P-type FET 261, current flows through the second P-type FET 262, and the first N-type FET 263 There is no current flowing through. As a result, the voltage V2 of the second power supply 252 is applied to the electrode 37.
Further, when the selection signal D1 is at a high level and D2 is at a high level, no current flows through the first P-type FET 261 and the second P-type FET 262, and current flows through the first N-type FET 263. A voltage GND is applied to the electrode 37.
As a result, the signal levels of the selection signals D1 and D2 and the output (voltage applied to the electrode 37) are associated as shown in FIG. In consideration of the load on each circuit element included in the piezoelectric element 36 and the drive circuit 250, the control for setting the selection signal D1 to the low level and D2 to the low level is not executed.
Therefore, the drive circuit 250 can give the piezoelectric element 36 three different potential differences consisting of V0−V1, V0−V2, and V0−GND. Here, the three different potential differences represent the potential of the electrode 38 when the electrode 37 is set as the reference potential. Further, the voltage V0, the voltage V1, and the voltage V2 satisfy a relationship of V0 ≧ V1> V2.

(About drive waveform signals)
Next, a drive waveform signal generated for the head control board 120 to drive the recording head 31 will be described. Here, the head control substrate 120 drives a drive waveform signal (the first waveform) for driving the recording head 31 by a 2 dpd (drop per dot) driving method in which 0 to 2 ink droplets are ejected to the recording head 31 within one pixel period. 1 drive waveform signal, second drive waveform signal). The first drive waveform signal is a drive waveform signal generated when one drop of ink is ejected to the recording head 31 within one pixel cycle, and the second drive waveform signal is within one pixel cycle. 2 is a drive waveform signal generated when two ink droplets are ejected to the recording head 31. FIG. 6 is a diagram for explaining the drive waveform signal generated by the head control board 120. FIG. 6 (i) shows the first drive waveform signal, and FIG. 6 (ii) shows the second drive waveform. Each signal is represented. Further, the first drive waveform signal and the second drive waveform signal shown in FIGS. 6 (i) and (ii) are beaten with reference to a standby voltage V 0 representing a voltage for forming a standby state of the piezoelectric element 36. It is a drive waveform signal for ejecting ink droplets by a method.

  As shown in FIG. 6 (i), the first drive waveform signal includes an ejection pulse P1 (first ejection pulse) composed of voltage V1 (potential V0-V1) and a voltage V1 within one pixel period. And a cancel pulse C1 (first cancel pulse) composed of a small voltage V2 (potential V0-V2). Here, one pixel cycle refers to a section from the start point of the discharge pulse P1 to the start point of the discharge pulse P2, and has a time length of 4AL + S1 (AL: half cycle of the natural vibration period of the pressure chamber 34).

  The ejection pulse P1 is a drive pulse for the recording head 31 that is set so that the pulse width is equal to AL based on the natural vibration period of the pressure chamber 34 in order to cause the recording head 31 to eject ink droplets with stable ejection characteristics. is there. As shown in FIGS. 6I and 7, when the ejection pulse P1 is applied to the recording head 31 (piezoelectric element 36), the piezoelectric element 36 is in the process of decreasing the potential from V0 to V0-V1. As a result, a negative pressure wave acts on the pressure chamber 34 and ink is drawn into the pressure chamber 34. Thereafter, when the potential rises from V 0 -V 1 to V 0, a positive pressure wave acts on the pressure chamber 34 and ink is pushed out from the pressure chamber 34. As a result, the ink in the pressure chamber 34 is ejected from the nozzle 39 connected to the lower surface of the pressure chamber 34 as one ink droplet at time T1 shown in FIG.

  The cancel pulse C1 is a pulse applied to the recording head 31 in order to suppress the influence of the reverberation vibration of the pressure wave generated in the pressure chamber 34 by the ejection pulse P1, and the pulse width is set to AL. The cancel pulse C1 is applied 2AL after the end point of the ejection pulse P1, as shown in FIG. 6 (i).

Here, when the recording head 31 is driven based on the first drive waveform signal, when the ejection pulse P1 is applied to the recording head 31, a negative pressure wave acts on the pressure chamber 34 as described above. A post-positive pressure wave acts and ink droplets are ejected at time T1. If the cancel pulse C1 is not applied, the ink droplet ejected by the ejection pulse P2 at the time T2 of the next pixel period due to the influence of reverberation vibration based on the application of the ejection pulse P1, as shown by the broken line in FIG. Is lower than the ejection speed of the ink droplets ejected at time T1.
Therefore, for example, as shown in FIG. 15, when the cancel pulse C1 is applied after AL from the end point of the ejection pulse P1, a negative pressure wave acts in the pressure chamber 34. In order to suppress it, the voltage V2 of the cancel pulse C1 needs to have a polarity opposite to that of the voltage V1 of the ejection pulse P1. In such a case, the voltage width in the entire first drive waveform signal is widened.
Therefore, as described above, by applying the cancel pulse C1 2AL after the end of the ejection pulse P1, the cancel pulse C1 is applied during the time when the positive pressure wave acts in the pressure chamber 34, and the voltage Since V2 can have the same polarity as the voltage V1 of the ejection pulse P1, the voltage width in the entire first drive waveform signal can be narrowed.
Then, as shown by the solid line in FIG. 7, when the cancel pulse C1 is applied to the recording head 31, the ink droplet ejection speed (pressure) at each pixel period at time T1 and T2 is influenced by reverberation vibration. Is suppressed and becomes substantially equal.

  As shown in FIG. 6 (ii), the second drive waveform signal includes ejection pulses P11 and P12 (second ejection pulse and third ejection pulse) composed of voltage V1 and voltage V2 within one pixel period. And a cancel pulse C11 (second cancel pulse). Here, one pixel cycle refers to a section from the start point of the discharge pulse P11 to the start point of the discharge pulse P21 (second discharge pulse), and the time length of 4AL + S2 (= S1), as in the first drive waveform signal. Consists of.

  Each of the ejection pulses P11 and P12 is a drive pulse for ejecting one ink droplet to the recording head 31, and the pulse width of the ejection pulse P11 is set to AL and the pulse width of the ejection pulse P12 is set to AL-t. The Here, t is a time of 1 / f (the resonance period of the piezoelectric element 36, about 500 ns to about 1000 ns) or less when the resonance frequency of the piezoelectric element 36 is set to f (about 1 M to 2 MHz). In the second drive waveform signal, the ejection pulse P12 is applied after AL from the end point of the ejection pulse P11 within one pixel period. The ink droplets ejected by the ejection pulse P11 and the ink droplets ejected by the ejection pulse P12 are integrated after being ejected from the recording head 31, and are formed on the recording medium 10 as one ink droplet for the same pixel. To land on.

  The cancel pulse C11 is a pulse applied to the recording head 31 in order to suppress the influence of the reverberation vibration of the pressure wave generated in the pressure chamber 34, and the pulse width is set to AL. Further, the voltage V2 of the cancel pulse C11 has the same polarity as the voltage V1. As shown in FIG. 6 (ii), the cancel pulse C11 is applied after t has elapsed since the end of the ejection pulse P12. Therefore, the timing at which the cancel pulse C11 is applied is equal to the timing at which the cancel pulse C1 is applied.

  Here, if the cancel pulse C11 is not applied after the ejection pulse P12 is applied to the recording head 31 at time T12, the influence of reverberation vibration based on the application of the ejection pulse P12 as shown by the broken line in FIG. Thus, the ejection speed of the ink droplets ejected by the ejection pulse P21 at the time T21 of the next pixel cycle is smaller than the ejection speed of the ink droplets ejected by the ejection pulse P12 at the time T12. However, as described above, in the second drive waveform signal, since the cancel pulse C11 is applied after the ejection pulse P12 ends, the influence of the reverberation vibration is suppressed. Therefore, as shown by the solid line in FIG. 8, the ejection speed of the ink droplet ejected by the ejection pulse P21 is kept equal to the ejection speed of the ink droplet ejected by the ejection pulse P12 at time T12. Furthermore, since the voltage V2 of the cancel pulse C11 has the same polarity as the voltage V1 of the ejection pulse P12, the width of the voltage used in the second drive waveform signal is narrowed.

  Further, when the cancel pulse C11 is not applied, the ejection speed of the ink droplet ejected by the ejection pulse P12 is caused by the influence of reverberation vibration based on the application of the ejection pulse P11 as shown by the broken line in FIG. It becomes larger than the ejection speed of the ink droplets ejected by P11.

Therefore, if it is assumed that the cancel pulse C11 is applied without interruption immediately after the end of the ejection pulse P12 (that is, the cancel pulse C11 is applied without an interval of time t in FIG. 6 (ii)), the piezoelectric element is applied. The voltage applied to the element 36 changes from V1 to V2. As can be seen from FIG. 8, the potential change amount (V1-V2) in this case is the potential V0 when the ink droplet is ejected by the ejection pulse P11 from the potential V0-V1 when the ejection pulse P11 is applied. It becomes smaller than the potential change amount (V1). As a result, as indicated by the solid line in FIG. 8, the pressure wave of the positive pressure that acts after the ejection pulse P <b> 12 is applied can be made smaller than the broken line, so that the pressure when ink is pushed out from the pressure chamber 34 is weakened. As a result, the influence of reverberation vibration based on the application of the ejection pulse P11 when the ink droplet is ejected by the ejection pulse P12 is suppressed, and the ejection speed of the ink droplet ejected by the ejection pulse P12 is ejected by the ejection pulse P11. Is substantially equal to the ejection speed of the ink droplets.
However, in this case, in the above-described drive circuit 250, a circuit configuration for switching the voltage applied to the electrode 37 from V1 directly to V2 (that is, causing a potential difference of V1-V2) is required. Specifically, as shown in FIG. 9, a combination of two P-type FETs and N-type FETs, each having the same selection signal (the same signal level) input to each gate, is connected. A drive circuit 250 using four FETs is required.

On the other hand, as described above, when the cancel pulse C11 is applied at a time t after the end of the ejection pulse P12, the drive circuit 250 including a total of three FETs applies the ejection pulse P11 as shown in FIG. The influence of reverberation vibration on the ejection pulse P12 based on this can be suppressed.
That is, when the cancel pulse C11 is applied at an interval from the end of the ejection pulse P12 (returning to the standby voltage V0), the drive circuit unit 200 changes the voltage applied to the electrode 37 from the voltage V1 of the ejection pulse P12 to the standby voltage. An operation of switching from V0 and standby voltage V0 to voltage V2 of cancel pulse C11 is performed. Therefore, in each FET, a response operation to a change in the signal level of the selection signal for sequentially switching the voltage of the electrode 37 to V1, V0, and V2 occurs.
Here, in general, the response time for the response operation of each FET becomes shorter as the voltage used becomes higher. Therefore, for example, when using each FET that can operate at a response time of about 2000 ns to 100 ns and the piezoelectric element 36 having f of 1 MHz (1 / f is 1000 ns), by appropriately adjusting the voltage to be used, The response time for the response operation of each FET can be 1 / f or less.
Therefore, as described above, the time interval between the ejection pulse P12 and the cancel pulse C11 is set to a time t that is 1 / f or less (shorter than the response time of the piezoelectric element 36), so that each time from the end of the ejection pulse P12. The cancel pulse C11 is applied within the time when the FET is not short-circuited. Therefore, the piezoelectric element 36 is switched to V2 before the response to the change to the standby voltage V0 is completed even though the actually applied voltage has changed to V1, V0, V2. The applied voltage appears to have changed from V1 directly to V2.
As a result, as shown in FIGS. 6 (ii) and 8, when the cancel pulse C11 is applied, the (apparent) potential change amount (V1−) from the time when the ejection pulse P12 is applied to the time T12. V2) is smaller than the potential change amount (V0-V1) from the time point when the ejection pulse P11 is applied to the time T11. As a result, as indicated by the solid line in FIG. 8, the pressure wave of positive pressure acting at time T12 is smaller than that of the broken line, so that the pressure when ink is pushed out from the pressure chamber 34 is weakened. Therefore, as shown in FIG. 9, the reverberation vibration based on the application of the ejection pulse P11 at time T12 does not have to be provided in the drive circuit 250 for switching the voltage applied to the piezoelectric element 36 from V1 directly to V2. The influence is suppressed, and the ejection speed of the ink droplet ejected by the ejection pulse P12 is substantially equal to the ejection speed of the ink droplet ejected by the ejection pulse P11. At this time, since the drive circuit 250 does not execute the control for setting the selection signals D1 and D2 to the low level as shown in FIG. 5, the first P-type FET 261 and the second P-type FET 262 simultaneously receive currents. Since it does not become a flowing state, it leads to suppression of an instantaneous current and a through current.
Furthermore, since the pulse width of the ejection pulse P12 in this case is shorter by the time t than the pulse width AL of the ejection pulse P11, it is based on the application of the ejection pulse P11 to the ink droplet ejected by the ejection pulse P12. An increase in kinetic energy can be suitably suppressed.

(Regarding the operation of the recording head during 2dpd driving)
Next, an operation in which the head control board 120 drives the recording head 31 by the 2dpd driving method will be described.

First, the head control board 120 generates the first drive waveform signal shown in FIG. 6 (i) to the drive circuit unit 200 when ejecting one drop of ink to the recording head 31 within each pixel period. input.
Then, the drive circuit 250 of the drive circuit unit 200 switches each FET based on the low level selection signal D1 and the high level selection signal D2 output from the level shifter 240, and applies the voltage V1 of the ejection pulse P1 to the electrode 37 (piezoelectric). Applied to element 36).
Next, when the AL time has elapsed from the application time point, the drive circuit 250 switches each FET based on the high-level selection signals D1 and D2, and applies the standby voltage V0 to the piezoelectric element 36. At this time, one ink droplet is ejected from the recording head 31 at the time when the positive pressure of the pressure wave becomes maximum as shown at time T1 in FIG.
Further, when 2AL has elapsed from the end of the ejection pulse P1, the drive circuit 250 switches the FETs based on the high level selection signal D1 and the low level selection signal D2, and the voltage V2 of the cancel pulse C1. Is applied to the piezoelectric element 36. By applying the cancel pulse C1, after the recording head 31 ejects ink droplets to a certain pixel based on the ejection pulse P1, the ejection speed when ejecting ink droplets to the next pixel based on the ejection pulse P2 is as follows. Kept constant.
The drive circuit 250 applies the standby voltage V0 to the piezoelectric element 36 when the AL time has elapsed from the application time point of the cancel pulse C1. The head control board 120 discharges one ink droplet at each pixel cycle at the same discharge speed by sequentially switching the voltage applied to the piezoelectric element 36 at each timing within the one pixel cycle. Can do.

Next, the head control board 120 generates a second drive waveform signal shown in FIG. 6 (ii) when ejecting two ink droplets to the recording head 31 within each pixel period.
Then, the drive circuit 250 of the drive circuit unit 200 applies the voltage V1 of the ejection pulse P11 to the piezoelectric element 36. The drive circuit 250 applies the standby voltage V0 to the piezoelectric element 36 when the AL time has elapsed from the application time. At this time, one ink droplet is ejected from the recording head 31 at the time when the positive pressure of the pressure wave becomes maximum as shown at time T11 in FIG.
Further, when the AL time has elapsed since the end of the ejection pulse P11, the drive circuit 250 applies the voltage V1 of the ejection pulse P12 to the piezoelectric element 36. Here, since the time for applying the voltage V1 (pulse width of the ejection pulse P12) is set to AL-t, the kinetic energy increases based on the application of the ejection pulse P11 to the ink droplet ejected by the ejection pulse P12. Is suppressed.
Next, the drive circuit 250 applies the standby voltage V0 to the piezoelectric element 36 for a time t that is a time length of 1 / f or less from the end point of the ejection pulse P12. When the time t elapses (within a time during which each FET is not short-circuited), the drive circuit 250 switches each FET based on the high-level selection signal D1 and the low-level selection signal D2, and the voltage of the cancel pulse C11 V2 is applied to the piezoelectric element 36. At this time, when an ink droplet is ejected based on the ejection pulse P12 at time T12 shown in FIG. 8, the ink droplet and the ink droplet ejected based on the ejection pulse P11 are integrally recorded as one ink droplet. Land on the medium 10. Then, by applying the cancel pulse C11 immediately after the time t has elapsed, the piezoelectric element 36 behaves as if the applied voltage has changed directly from V1 to V2, so that the ejection pulses P11, P12 within the same pixel period. The ejection speed when ejecting ink droplets based on the above and the ejection speed when ejecting ink droplets based on the ejection pulse P21 in the next pixel period are equal.
Then, when the AL time has elapsed from the application time point of the cancel pulse C11, the drive circuit 250 applies the standby voltage V0 to the piezoelectric element 36. The head control board 120 sequentially executes switching of the voltage applied to the piezoelectric element 36 at each timing within the one pixel period, thereby ejecting two ink drops at the same ejection speed within each pixel period. Can do.

  Here, assuming that the natural vibration frequency of the pressure chamber 34, which is uniquely calculated from a known formula based on the flow path shape, the type of ink, and the like in the recording head 31, is 125 (kHz), S1 (= S2) shown in FIG. Is set to AL (pixel cycle: 5AL), a printing speed of 1 m / s, a printing resolution of 1200 dpi, and a pixel frequency of 50 kHz can be realized. Note that S1 (= S2) is preferably AL or a multiple of AL (2AL, 3AL, etc.).

As described above, according to the inkjet recording apparatus 1 according to the present embodiment, the second drive waveform signal includes the ejection pulse P12 having a pulse width of AL-t and t has elapsed from the end point of the ejection pulse P12. After that, a cancel pulse C11 having the same polarity as the ejection pulse P12 is included.
That is, since the cancel pulse C11 is applied after the end of the ejection pulse P12, the influence of the reverberation vibration due to the ejection pulse P12 is suppressed, and the ejection speed of the ink droplet ejected by the ejection pulse P21 in the next pixel cycle is the time At T12, it becomes equal to the ejection speed of the ink droplet ejected by the ejection pulse P12. Further, since the voltage V2 of the cancel pulse C11 has the same polarity as the voltage V1 of the ejection pulse P12, the width of the voltage used in the second drive waveform signal can be reduced.
Furthermore, since the time interval between the ejection pulse P12 and the cancel pulse C11 is a time t that is 1 / f or less (shorter than the response time of the piezoelectric element 36), the piezoelectric element 36 is as if the applied voltage is equal to the ejection pulse P12. It behaves as if the voltage V1 is changed directly to the voltage V2 of the cancel pulse C11. As a result, the influence of reverberation vibration based on the application of another ejection pulse (ejection pulse P11) in the same cycle to the ink droplet ejected by the ejection pulse P12 is suppressed, and therefore the ejection speed of the ink droplet is different from the other It becomes equal to the ejection speed of the ink droplet ejected by the ejection pulse. In addition, the drive circuit 250 has a total of FETs used in total compared to the conventional circuit configuration shown in FIG. 9 (a circuit configuration in which the voltage applied to the piezoelectric element 36 can be switched directly from V1 to V2). The number is small. That is, if the entire recording head 31 having a plurality of drive circuits 250 corresponding to the number of piezoelectric elements 36 is used, the total number of FETs to be used can be sufficiently smaller than the conventional circuit configuration. Manufacturing costs can be reduced.
Further, since the pulse width of the ejection pulse P12 is shorter than the AL by the time t, the increase in kinetic energy of the ink droplet ejected by the ejection pulse P12 based on the application of another ejection pulse is suitably suppressed. It becomes possible.
Therefore, according to the present invention, when ejecting 0 to 2 ink droplets within one pixel cycle, each ink droplet within one pixel cycle and ink droplets during each pixel cycle can be ejected at the same ejection speed and used. This can be said to be an inkjet recording apparatus and a drive waveform signal generation method that do not widen the voltage range as much as possible.

  Further, according to the inkjet recording apparatus 1, the cancel pulse C1 is applied in the first drive waveform signal. For this reason, the ejection speed of the ink droplets in each pixel period becomes equal with the influence of reverberation vibration being suppressed. Furthermore, since the cancel pulse C1 is applied 2AL after the end point of the ejection pulse P1, the cancel pulse C1 acts to create a negative pressure when a positive pressure wave is applied due to reverberation vibration, so the voltage V2 of the cancel pulse C1. Can be made to have the same polarity as the voltage V1 of the ejection pulse P1 for applying a negative pressure wave. Therefore, it is possible to keep the ink droplets during each pixel cycle at the same ejection speed when ejecting one ink droplet within one pixel cycle, and to narrow the voltage width to be used.

  In the inkjet recording apparatus 1, the voltage V0 (VCOM) of the electrode 38 that is a common electrode can be set so as to satisfy V0 ≧ V1.

  Further, the level shifter 240 sets the signal level of the selection signal D1 to a low level according to the level of the voltage V1, sets the signal level of the selection signal D2 to a low level according to the level of the voltage V2, and changes according to the level of the standby voltage V0. A selection signal is generated in which the signal levels of the selection signals D1 and D2 are low. In other words, the voltage corresponding to three different voltage levels can be easily applied to the piezoelectric element 36 simply by switching the signal level input to the drive circuit 250 by the level shifter 240.

"Modification 1"
In the first embodiment, as shown in FIG. 6 (i), the pulse width of the cancel pulse C1 related to the first drive waveform signal is assumed to be equal to AL. However, the pulse width of the cancel pulse C1 does not necessarily have to be AL. For example, as shown in FIG. 10 (i), a pulse width T1 that does not coincide with AL may be used. That is, the voltage value of the voltage V2 can be set more flexibly by making the pulse width of the cancel pulse C1 not coincide with the natural vibration period of the pressure chamber 34. In this case, S1 and S2 shown in FIGS. 10 (i) and (ii) are set to appropriate times so that the pixel period of the first drive waveform signal and the pixel period of the second drive waveform signal coincide with each other. Set to

"Modification 2"
In the first embodiment, as shown in FIGS. 6 (i) and (ii), the voltage of the cancel pulse C1 related to the first drive waveform signal is equal to the voltage of the cancel pulse C11 related to the second drive waveform signal. (Voltage V2). However, for example, as shown in FIGS. 11 (i) and (ii), the voltage of the cancel pulse C1 related to the first drive waveform signal is different from V3, and the voltage of the cancel pulse C11 related to the second drive waveform signal is different from V3. The voltage V2 may be used. Here, it is assumed that the voltage V1, the voltages V2, and V3 satisfy the relationship of V1>V2> V3.

FIG. 12 shows a drive circuit unit 200a for realizing the drive of the recording head 31 based on the drive waveform signal according to the second modification. In FIG. 12, the same components as those of the drive circuit unit 200 shown in FIG.
As shown in FIG. 12, the drive circuit unit 200a includes a shift register 210, a latch circuit 220, a selector 230, a level shifter 240a, and a drive circuit 250a.

  The level shifter 240a has three selection signals D1, D2, and D3 (a set of first selection signal, second selection signal, and third level) according to the signal level (voltage level) of the drive waveform signal output from the selector 230. Selection signal) is input to the drive circuit 250. The three selection signals D1, D2, and D3 have either a low level or a high level. The first P-type FET 261, the second P-type FET 262, and a third P, which will be described later, of the drive circuit 250a. Input to the gate of the type FET 264a. The selection signals D1, D2, and D3 are input to the input side of the AND circuit 271.

  The drive circuit 250a includes a first power supply 251, a second power supply 252, a third power supply 254a, a common power supply 255, a first P-type FET 261, a second P-type FET 262, and a third power supply. A P-type FET 264a, a first N-type FET 263, an AND circuit 271 and electrodes 37 and 38 are included. The drive circuit 250 drives the recording head 31 by deforming the piezoelectric element 36 by a potential difference generated between the electrodes 37 and 38 based on the selection signals D1, D2, and D3 output from the level shifter 240 ( Pressure is applied to the pressure chamber 34).

The third power source 254a is a power source for generating the voltage V3.
The third P-type FET 264a is a P-type field effect transistor connected to the third power source 254a. Each of the third P-type FETs 264a causes a current to flow between the drain and the source when a selection signal D3 of a low level (selection level) is input from the level shifter 240 to the gate, and a high level (to the gate). When a selection signal D3 of (non-selection level) is input, control is performed so that no current flows between the drain and the source.

Therefore, for example, when the selection signal D1 output from the level shifter 240 is at a low level (selection level) and D2 and D3 are at a high level, a current flows through the first P-type FET 261, while the second P-type FET 262 In addition, no current flows through the third P-type FET 264a. Since a low level signal is input to the gate of the first N-type FET 263 by the logical product of the three selection signals input to the AND circuit 271, a current flows through the first N-type FET 263. Not flowing. As a result, the voltage V1 of the first power supply 251 is applied to the electrode 37.
Similarly, when the selection signal D1 is at a high level, D2 is at a low level (selection level), and D3 is at a high level, no current flows through the first P-type FET 261 and the third P-type FET 264a. Current flows through the first P-type FET 262, and no current flows through the first N-type FET 263. As a result, the voltage V2 of the second power supply 252 is applied to the electrode 37.
When the selection signals D1 and D2 are at a high level and D3 is at a low level (selection level), no current flows through the first P-type FET 261 and the second P-type FET 262, and the third P-type FET 264a Current flows, and no current flows through the first N-type FET 263, so that the voltage V <b> 3 is applied to the electrode 37.
Furthermore, when the selection signals D1, D2, and D3 are at a high level (selection level), no current flows through the first P-type FET 261 to the third P-type FET 264a, and no current flows through the first N-type FET 263. Since it flows, the voltage GND is applied to the electrode 37.
As a result, the signal levels of the selection signals D1, D2, and D3 and the output (voltage applied to the electrode 37) are associated as shown in FIG. In consideration of the load on each circuit element included in the piezoelectric element 36 and the drive circuit 250, the control for changing the selection signals D1, D2, and D3 to other than the combinations shown in FIG. 13 (other combinations) is not executed.
Therefore, the drive circuit 250a can give the piezoelectric element 36 four different potential differences including V0-V1, V0-V2, V0-V3, and V0-GND. Here, the four different potential differences represent the potential of the electrode 38 when the electrode 37 is set as the reference potential. Further, the voltage V0, the voltage V1, the voltage V2, and the voltage V3 satisfy the relationship of V0 ≧ V1>V2> V3.

  By the way, in order to give four different potential differences to the piezoelectric element 36 by the conventional circuit configuration as shown in FIG. 9, it is necessary to newly add two FETs as shown in FIG. That is, according to the conventional circuit configuration shown in FIG. 14, a P-type FET and an N-type FET having the same selection signal (the same signal level) input to each gate are used as a set, and the three sets are connected. It is necessary to use a total of six FETs. On the other hand, in the drive circuit 250a according to the second modification example, as described above, four different potential differences can be given to the piezoelectric element 36 by a total of four FETs.

(About drive waveform signals)
Next, drive waveform signals generated for the head control board 120 to drive the recording head 31 will be described with reference to FIGS.

  As shown in FIG. 11 (i), the first drive waveform signal includes a discharge pulse P1 composed of voltage V1 (potential V0-V1) and a cancel composed of voltage V3 (potential V0-V3) within one pixel period. Pulse C1. According to the first drive waveform signal, as described in the first embodiment, by applying the cancel pulse C1, the influence of the reverberation vibration on the next pixel period due to the ejection pulse P1 is suppressed, and each pixel period Ink droplet ejection speeds are substantially equal.

  As shown in FIG. 11 (ii), the second drive waveform signal includes ejection pulses P11 and P12 composed of a voltage V1 and a cancel pulse composed of a voltage V2 larger than the voltage V3 of the cancel pulse C1 within one pixel period. C11. As shown in FIG. 11 (ii), the cancel pulse C11 is applied after t has elapsed since the end of the ejection pulse P12.

  Here, as shown in FIGS. 7 and 8, the time interval from time T12 to time T21 related to the second drive waveform signal is longer than the time interval from time T1 to time T2 related to the first drive waveform signal. Is shorter. Therefore, the influence of the reverberation vibration based on the application of the ejection pulse P12 to the ink droplet ejected by the ejection pulse P21 described in the first embodiment is based on the application of the ejection pulse P1 to the ink droplet ejected by the ejection pulse P2. It becomes stronger than the influence of reverberation vibration. However, as described above, since the voltage V2 of the cancel pulse C11 is set larger than the voltage V3 of the cancel pulse C1, the influence of reverberation vibration on the ink droplets ejected by the ejection pulse P21 is sufficiently suppressed.

  As described above, according to the second modification, the same effect as that of the ink jet recording apparatus 1 according to the first embodiment can be obtained, and the voltage V2 of the cancel pulse C11 is made larger than the voltage V3 of the cancel pulse C1. The influence of reverberation vibration on the ink droplets ejected by the ejection pulse P21 can be suppressed with higher accuracy. Further, the drive circuit 250a requires a smaller number of FETs in total than the conventional circuit configuration shown in FIG. In other words, if the entire recording head 31 having a plurality of drive circuits 250a corresponding to the number of piezoelectric elements 36 is used, the total number of FETs to be used can be sufficiently smaller than the conventional circuit configuration. Manufacturing costs can be reduced.

Note that the description in the above embodiment is an example of a suitable inkjet recording apparatus and drive waveform generation method according to the present invention, and the present invention is not limited to this.
Further, the detailed configuration and detailed operation of each part constituting the ink jet recording apparatus in the above embodiment can be appropriately changed without departing from the spirit of the present invention.

  For example, in the above embodiment, the second drive waveform signal includes a discharge pulse P12 having a pulse width of AL-t and a cancel having the same polarity as the discharge pulse P12 after t has elapsed from the end point of the discharge pulse P12. The pulse C11 is exemplified, but the first drive waveform signal includes the ejection pulse P1 having a pulse width of AL-t, and the ejection pulse P1 after t has elapsed from the end time of the ejection pulse P1. Even if the cancel pulse C1 having the same polarity is included, the same effect as that of the above embodiment can be obtained.

DESCRIPTION OF SYMBOLS 1 Inkjet recording device 30 Inkjet head part 31 Recording head 34 Pressure chamber 36 Piezoelectric element 37 Electrode (individual electrode)
38 electrodes (common electrode)
39 Nozzle 100 Control unit 120 Head control board 200 Drive circuit unit 240 Level shifter (input unit)
250 drive circuit P1 discharge pulse (first discharge pulse)
P11 Discharge pulse (second discharge pulse)
P12 Discharge pulse (third discharge pulse)
C1 cancel pulse (first cancel pulse)
C11 Cancel pulse (second cancel pulse)
200a Drive circuit unit 240a Level shifter (input unit)
250a drive circuit

Claims (13)

A nozzle, a pressure chamber communicating with the nozzle, and a piezoelectric element having a resonance frequency of f for applying pressure to the ink in the pressure chamber, and the piezoelectric element according to a drive waveform signal applied thereto A recording head that applies pressure to the ink and ejects ink droplets from the nozzles;
An ejection pulse for ejecting one drop of ink, and a cancel pulse for suppressing the influence of reverberation vibration due to the ejection pulse, and 0 to 2 ink drops per pixel on the recording head Drive waveform signal generating means for generating the drive waveform signal for discharging
With
The drive waveform signal generating means has a pulse width of t that is less than AL representing a half period of the natural vibration period of the pressure chamber in one pixel period, where t is a predetermined time having a time length of 1 / f or less. An ink jet recording apparatus that generates a drive waveform signal including a short ejection pulse and a cancel pulse that is applied after t has elapsed from the end of the ejection pulse and has the same polarity as the ejection pulse. The inkjet recording apparatus according to claim 1, wherein
The ink jet recording apparatus, wherein the drive waveform signal generating unit generates the drive waveform signal when the recording head ejects two ink droplets to one pixel. A nozzle, a pressure chamber communicating with the nozzle, and a piezoelectric element having a resonance frequency of f for applying pressure to the ink in the pressure chamber, and the piezoelectric element according to a drive waveform signal applied thereto A recording head that applies pressure to the ink and ejects ink droplets from the nozzles;
An ejection pulse for ejecting one drop of ink, and a cancel pulse for suppressing the influence of reverberation vibration due to the ejection pulse, and 0 to 2 ink drops per pixel on the recording head Drive waveform signal generating means for generating the drive waveform signal for discharging
With
When the drive waveform signal generating unit causes the recording head to eject one drop of ink to one pixel, within one pixel period, the pulse width represents AL representing a half period of the natural vibration period of the pressure chamber. The first ejection pulse having the same voltage V1 and the same polarity as the first ejection pulse applied 2AL after the end of the first ejection pulse and the pulse width is equal to AL and the voltage is smaller than V1 When a first drive waveform signal including a first cancel pulse composed of V2 is generated and two drops of ink are ejected to one pixel by the recording head, the time length is 1 / f or less. If the predetermined time is t, the pulse width is applied within AL after the end of the second discharge pulse and the second discharge pulse whose pulse width is equal to AL and the voltage is V1 within one pixel period. Also t A second discharge pulse having a voltage V1 and a second discharge pulse having a voltage of V2 and the same polarity as that of the third discharge pulse applied after t elapses after the end of the third discharge pulse. An inkjet recording apparatus that generates a second drive waveform signal including a cancel pulse. A nozzle, a pressure chamber communicating with the nozzle, and a piezoelectric element having a resonance frequency of f for applying pressure to the ink in the pressure chamber, and the piezoelectric element according to a drive waveform signal applied thereto A recording head that applies pressure to the ink and ejects ink droplets from the nozzles;
An ejection pulse for ejecting one drop of ink, and a cancel pulse for suppressing the influence of reverberation vibration due to the ejection pulse, and 0 to 2 ink drops per pixel on the recording head Drive waveform signal generating means for generating the drive waveform signal for discharging
With
When the drive waveform signal generating unit causes the recording head to eject one drop of ink to one pixel, within one pixel period, the pulse width represents AL representing a half period of the natural vibration period of the pressure chamber. The first ejection pulse having the same voltage V1 and the same polarity as the first ejection pulse applied after 2AL from the end of the first ejection pulse, and the pulse width does not match AL and the voltage is V1. When generating a first drive waveform signal including a first cancel pulse having a smaller V2 and causing the recording head to eject two ink droplets per pixel, the time length is 1 / f or less. If the predetermined time consisting of t is t, within one pixel period, the second ejection pulse whose pulse width is equal to AL and the voltage is V1, and the pulse width applied after AL from the end time of the second ejection pulse are applied. Than AL A second ejection pulse having a voltage V1 and a third ejection pulse having a voltage V1 that is applied after t has elapsed from the end of the third ejection pulse and has the same polarity as the third ejection pulse. An inkjet recording apparatus that generates a second drive waveform signal including a cancel pulse. A nozzle, a pressure chamber communicating with the nozzle, and a piezoelectric element having a resonance frequency of f for applying pressure to the ink in the pressure chamber, and the piezoelectric element according to a drive waveform signal applied thereto A recording head that applies pressure to the ink and ejects ink droplets from the nozzles;
An ejection pulse for ejecting one drop of ink, and a cancel pulse for suppressing the influence of reverberation vibration due to the ejection pulse, and 0 to 2 ink drops per pixel on the recording head Drive waveform signal generating means for generating the drive waveform signal for discharging
With
When the drive waveform signal generating unit causes the recording head to eject one drop of ink to one pixel, within one pixel period, the pulse width represents AL representing a half period of the natural vibration period of the pressure chamber. A first discharge pulse equal to the first discharge pulse, which is applied 2AL after the end point of the first discharge pulse and has the same polarity as the first discharge pulse and a pulse width equal to AL. When a drive waveform signal of 1 is generated and two drops of ink are ejected to one pixel by the recording head, assuming that a predetermined time having a time length of 1 / f or less is t, within one pixel cycle, A second ejection pulse having a pulse width equal to AL, a third ejection pulse applied AL after the end of the second ejection pulse and having a pulse width shorter by t than AL, and the third ejection pulse T has passed since the end And a second cancel pulse is applied is the third ejection pulse of the same polarity as the after, to generate a second drive waveform signal including,
An ink jet recording apparatus, wherein a voltage V1 of each ejection pulse, a voltage V2 of the second cancel pulse, and a voltage V3 of the first cancel pulse satisfy a relationship of V1>V2> V3. In the inkjet recording device according to any one of claims 3 to 5,
An individual electrode provided for each of a plurality of piezoelectric elements;
A common electrode used in common for the plurality of piezoelectric elements;
With
Each piezoelectric element is disposed between the individual electrode and the common electrode, and a voltage V1 of each ejection pulse is applied between the individual electrode and the common electrode to eject ink droplets from the nozzle. Applying pressure to the ink,
The ink jet recording apparatus, wherein the voltage VCOM of the common electrode satisfies a relationship of VCOM ≧ V1. In the ink jet recording apparatus according to claim 3 or 4,
The first drive waveform signal and the second drive waveform signal are a voltage V1 of each ejection pulse, a voltage V2 of each cancel pulse, and a standby voltage for forming a standby state of the piezoelectric element according to time. V0 is a signal that generates a voltage level of any one of
A drive circuit for applying any one of the voltage V1, the voltage V2 and the standby voltage V0 to the piezoelectric element;
The drive circuit applies a voltage corresponding to the voltage level to the piezoelectric element according to the voltage level of the first drive waveform signal or the second drive waveform signal generated by the drive waveform signal generation means. An input unit for inputting the selection signal to the drive circuit;
With
Each of the selection signals includes a set of a first selection signal and a second selection signal each having two types of signal levels, a selection level and a non-selection level.
The input unit generates a selection signal in which the signal level of the first selection signal is a selection level according to the level of the voltage V1, and the signal level of the second selection signal is selected according to the level of the voltage V2 Generating a selection signal that is a level, and generating a selection signal in which the signal level of the first selection signal and the signal level of the second selection signal are non-selection levels according to the level of the standby voltage V0. Inkjet recording apparatus. The inkjet recording apparatus according to claim 5, wherein
The first drive waveform signal and the second drive waveform signal are, according to time, a voltage V1 of each ejection pulse, a voltage V2 of the second cancel pulse, and a voltage V3 of the first cancel pulse. , A signal for generating a voltage level of any one of the standby voltage V0 for forming the standby state of the piezoelectric element,
A drive circuit for applying any one of the voltage V1, the voltage V2, the voltage V3, and the standby voltage V0 to the piezoelectric element;
The drive circuit applies a voltage corresponding to the voltage level to the piezoelectric element according to the voltage level of the first drive waveform signal or the second drive waveform signal generated by the drive waveform signal generation means. An input unit for inputting the selection signal to the drive circuit;
With
Each of the selection signals includes a pair of a first selection signal, a second selection signal, and a third selection signal, each of which has two types of signal levels: a selection level and a non-selection level.
The input unit generates a selection signal in which the signal level of the first selection signal is a selection level according to the level of the voltage V1, and the signal level of the second selection signal is selected according to the level of the voltage V2 A selection signal whose level is the selection level is generated according to the level of the voltage V3, and the first selection signal is generated according to the level of the standby voltage V0. An ink jet recording apparatus that generates a selection signal in which a signal level of the second selection signal and the third selection signal is a non-selection level. A nozzle, a pressure chamber communicating with the nozzle, and a piezoelectric element having a resonance frequency of f for applying pressure to the ink in the pressure chamber, and the piezoelectric element according to a drive waveform signal applied thereto A recording head that applies pressure to the ink to eject ink droplets from the nozzles, an ejection pulse for ejecting one ink droplet, a cancel pulse for suppressing the influence of reverberation vibration due to the ejection pulse, Drive waveform signal generation method by an ink jet recording apparatus comprising: drive waveform signal generation means for generating the drive waveform signal for causing the recording head to discharge 0 to 2 ink droplets per pixel Because
Assuming that a predetermined time having a time length of 1 / f or less is t, an ejection pulse whose pulse width is shorter by t than AL representing a half period of the natural vibration period of the pressure chamber in one pixel period, and the ejection pulse A drive waveform signal generation method that causes the drive waveform signal generation means to generate a drive waveform signal that includes a cancel pulse that is applied after t elapses from the end point of and has the same polarity as the ejection pulse. The drive waveform signal generation method according to claim 9,
A drive waveform signal generation method, wherein the drive waveform signal generation unit generates the drive waveform signal when the recording head ejects two ink droplets per pixel. A nozzle, a pressure chamber communicating with the nozzle, and a piezoelectric element having a resonance frequency of f for applying pressure to the ink in the pressure chamber, and the piezoelectric element according to a drive waveform signal applied thereto A recording head that applies pressure to the ink to eject ink droplets from the nozzles, an ejection pulse for ejecting one ink droplet, a cancel pulse for suppressing the influence of reverberation vibration due to the ejection pulse, Drive waveform signal generation method by an ink jet recording apparatus comprising: drive waveform signal generation means for generating the drive waveform signal for causing the recording head to discharge 0 to 2 ink droplets per pixel Because
When causing the recording head to eject one drop of ink to one pixel, the pulse width is equal to AL representing a half period of the natural vibration period of the pressure chamber and the voltage is V1 within one pixel period. And a first cancel pulse that is applied 2AL after the end of the first discharge pulse, has the same polarity as the first discharge pulse, and has a pulse width equal to AL and a voltage V2 smaller than V1. When the drive waveform signal generating unit generates the first drive waveform signal including the above and causes the recording head to eject two ink droplets to one pixel, the predetermined length of time is 1 / f or less. When time is t, a second ejection pulse having a pulse width equal to AL and a voltage V1 within one pixel period, and a pulse width that is applied after AL from the end of the second ejection pulse is less than AL. t A second discharge pulse having a voltage V1 and a second discharge pulse having a voltage of V2 and the same polarity as that of the third discharge pulse applied after t elapses after the end of the third discharge pulse. A drive waveform signal generation method comprising causing the drive waveform signal generation means to generate a second drive waveform signal including a cancel pulse. A nozzle, a pressure chamber communicating with the nozzle, and a piezoelectric element having a resonance frequency of f for applying pressure to the ink in the pressure chamber, and the piezoelectric element according to a drive waveform signal applied thereto A recording head that applies pressure to the ink to eject ink droplets from the nozzles, an ejection pulse for ejecting one ink droplet, a cancel pulse for suppressing the influence of reverberation vibration due to the ejection pulse, Drive waveform signal generation method by an ink jet recording apparatus comprising: drive waveform signal generation means for generating the drive waveform signal for causing the recording head to discharge 0 to 2 ink droplets per pixel Because
When causing the recording head to eject one drop of ink to one pixel, the pulse width is equal to AL representing a half period of the natural vibration period of the pressure chamber and the voltage is V1 within one pixel period. The first discharge pulse is applied after 2AL from the end time of the first discharge pulse and has the same polarity as the first discharge pulse, and the pulse width does not coincide with AL and the voltage is V2 smaller than V1. When the first drive waveform signal including the cancel pulse is generated by the drive waveform signal generation means and the recording head ejects two ink droplets for one pixel, the time length is 1 / f or less. When the predetermined time is t, within one pixel period, a second ejection pulse having a pulse width equal to AL and a voltage V1 is applied after AL from the end of the second ejection pulse, and the pulse width is AL. than A second ejection pulse having a voltage V1 and a third ejection pulse having a voltage V1 that is applied after t has elapsed from the end of the third ejection pulse and has the same polarity as the third ejection pulse. A drive waveform signal generation method comprising causing the drive waveform signal generation means to generate a second drive waveform signal including a cancel pulse. A nozzle, a pressure chamber communicating with the nozzle, and a piezoelectric element having a resonance frequency of f for applying pressure to the ink in the pressure chamber, and the piezoelectric element according to a drive waveform signal applied thereto A recording head that applies pressure to the ink to eject ink droplets from the nozzles, an ejection pulse for ejecting one ink droplet, a cancel pulse for suppressing the influence of reverberation vibration due to the ejection pulse, Drive waveform signal generation method by an ink jet recording apparatus comprising: drive waveform signal generation means for generating the drive waveform signal for causing the recording head to discharge 0 to 2 ink droplets per pixel Because
When causing the recording head to eject one drop of ink to one pixel, the pulse width is equal to AL representing a half period of the natural vibration period of the pressure chamber and the voltage is V1 within one pixel period. And a first cancel pulse composed of V3 having the same polarity as the first discharge pulse, the pulse width being equal to AL, and the voltage being smaller than V1, being applied after 2AL from the end of the first discharge pulse. When the drive waveform signal generating unit generates the first drive waveform signal including the above and causes the recording head to eject two ink droplets to one pixel, the predetermined length of time is 1 / f or less. When time is t, a second ejection pulse having a pulse width equal to AL and a voltage V1 within one pixel period, and a pulse width that is applied after AL from the end of the second ejection pulse is less than AL. t The third ejection pulse having a short voltage V1 and the same polarity as the third ejection pulse applied after t elapses from the end of the third ejection pulse, and the voltage is larger than V3 and smaller than V1. A drive waveform signal generation method, characterized in that the drive waveform signal generation means generates a second drive waveform signal including a second cancel pulse composed of V2.

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