How to maintain your head unit

Abstract

To suppress the scattering of liquid discharged from a nozzle as mist.SOLUTION: A head rest maintenance method includes a first nozzle row equipped with a first nozzle, and a second nozzle row equipped with a second nozzle. In a first period, with respect to a first driving element corresponding to the first nozzle belonging to the first nozzle row, a first driving signal having a first waveform is supplied to discharge liquid from the first nozzle, and with respect to a second driving element corresponding to the second nozzle belonging to the second nozzle row, a second driving signal having a second waveform is supplied to discharge liquid from the second nozzle. In a second period, a third driving signal having a third waveform is supplied to the first driving element to discharge the liquid from the first nozzle, and a fourth driving signal having a fourth waveform is supplied to the second driving element to discharge the liquid from the second nozzle.SELECTED DRAWING: Figure 13

Description

[Technical Field]

[0001] The present invention relates to a maintenance method for a head unit. [Background technology]

[0002] A liquid ejection device such as an inkjet printer ejects a liquid such as ink from a pressure chamber provided in the head unit of the liquid ejection device through a nozzle by driving a piezoelectric element provided in the head unit with a drive signal to displace the piezoelectric element, thereby forming an image on a medium such as recording paper. In such a liquid ejection device, the liquid filled in the pressure chamber needs to be discharged from the nozzle to prevent deterioration in the quality of the image formed by the liquid ejection device, for example, due to thickening of the liquid filled in the pressure chamber. For this reason, techniques related to a flushing process for discharging the liquid filled in the pressure chamber from the nozzle have been proposed, as described in Patent Document 1, for example. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-240564 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in conventional technology, the flushing process involves ejecting the maximum amount of liquid that each nozzle in the head unit can eject, which causes the liquid ejected from the nozzles to become mist and scatter, which can lead to a decrease in the quality of the image formed by the liquid ejection device and can cause malfunctions in the liquid ejection device. [Means for solving the problem]

[0005] In order to solve the above problems, a maintenance method for a head unit according to the present invention is a maintenance method for a head unit comprising: a first nozzle array having a plurality of first nozzles arranged in parallel along a first axis and ejecting liquid; a second nozzle array having a plurality of second nozzles arranged in parallel along a second axis parallel to the first axis and ejecting liquid; a plurality of first pressure chambers provided corresponding to the plurality of first nozzles and filled with liquid; a plurality of second pressure chambers provided corresponding to the plurality of second nozzles and filled with liquid; a plurality of first drive elements provided corresponding to the plurality of first pressure chambers and varying the pressure in the corresponding first pressure chambers; a plurality of second drive elements provided corresponding to the plurality of second pressure chambers and varying the pressure in the corresponding second pressure chambers; and a supply unit that supplies drive signals to the plurality of first drive elements and the plurality of second drive elements, wherein the head unit maintains the head unit by supplying a first drive signal having a first waveform to one first drive element of the plurality of first drive elements during a first period. a second drive signal having a second waveform different from the first waveform is supplied to one of the second drive elements, during a second period different from the first period, to cause the liquid in the one first pressure chamber corresponding to the one first drive element to be discharged from one of the plurality of first nozzles, the liquid in the one second pressure chamber corresponding to the one second drive element to be discharged from one of the plurality of second nozzles, the liquid in the one first pressure chamber corresponding to the one second drive element to be discharged from one of the plurality of second nozzles, the liquid in the one first pressure chamber corresponding to the one second drive element to be discharged from one of the plurality of second nozzles, the liquid in the one first pressure chamber corresponding to the one second drive element to be discharged from one of the plurality of second nozzles, the liquid in the one first pressure chamber corresponding to the one first nozzle to be discharged from one of the plurality of first nozzles, the liquid in the one first pressure chamber corresponding to the one first drive element to be discharged from one of the plurality of first nozzles, the liquid in the one second pressure chamber corresponding to the one second drive element to be discharged from one of the plurality of second nozzles, the liquid in the one first pressure chamber corresponding to the one first nozzle to be discharged from one of the plurality of second nozzles, the liquid in the one first pressure chamber corresponding to the one first nozzle to be discharged from one of the plurality of first nozzles, the liquid in the one second pressure chamber corresponding to the one second nozzle to be discharged from one of the plurality of second nozzles, the liquid in the one first pressure chamber corresponding to the one first nozzle to be discharged from one of the plurality of first ... second pressure chamber corresponding to the one second nozzle to be discharged from one of the plurality of second nozzles, the liquid in the one first pressure chamber corresponding to the one first nozzle to be discharged from one of

[0006] Furthermore, a maintenance method for a head unit according to the present invention is a maintenance method for a head unit including: a first nozzle row having a plurality of first nozzles arranged in parallel along a first axis and ejecting liquid; a plurality of first pressure chambers provided corresponding to the plurality of first nozzles and filled with liquid; a plurality of first drive elements provided corresponding to the plurality of first pressure chambers and fluctuating the pressure in the corresponding first pressure chambers; and a supply unit that supplies drive signals to the plurality of first drive elements, wherein during a first period, a first drive signal having a first waveform is supplied to one first drive element of the plurality of first drive elements that corresponds to one first nozzle included in the plurality of first nozzles, thereby discharging liquid from one first pressure chamber of the plurality of first pressure chambers that corresponds to the one first drive element, and discharging the liquid from the one first nozzle, a second drive signal having a second waveform different from the first waveform is supplied to another first drive element among the drive elements, the other first nozzle being included in the plurality of first nozzles and corresponding to the one first nozzle adjacent thereto, thereby discharging liquid from the other first pressure chamber among the plurality of first pressure chambers corresponding to the other first drive element, from the other first nozzle; a third drive signal having a third waveform different from the first waveform is supplied to the one first drive element during a second period different from the first period, thereby discharging liquid from the one first pressure chamber, from the one first nozzle; and a fourth drive signal having a fourth waveform different from the second waveform and the third waveform is supplied to the other first drive element, thereby discharging liquid from the other first pressure chamber, from the other first nozzle.

[0007] Furthermore, a maintenance method for a head unit according to the present invention is a maintenance method for a head unit including: a first nozzle row having a plurality of first nozzles arranged in parallel along a first axis and ejecting liquid; a plurality of first pressure chambers provided corresponding to the plurality of first nozzles and filled with liquid; a plurality of first drive elements provided corresponding to the plurality of first pressure chambers and fluctuating the pressure in the corresponding first pressure chambers; and a supply unit that supplies drive signals to the plurality of first drive elements, wherein during a first period, a first drive signal having a first waveform is supplied to odd-numbered first drive elements of the plurality of first drive elements that correspond to odd-numbered first nozzles among the plurality of first nozzles, thereby discharging liquid from odd-numbered first pressure chambers corresponding to the odd-numbered first drive elements among the plurality of first pressure chambers, and discharging the liquid from the odd-numbered first nozzles a second drive signal having a second waveform different from the first waveform is supplied to even-numbered first drive elements corresponding to even-numbered first nozzles among the plurality of first nozzles, thereby discharging liquid from the even-numbered first pressure chambers corresponding to the even-numbered first drive elements among the plurality of first nozzles; a third drive signal having a third waveform different from the first waveform is supplied to the odd-numbered first drive elements during a second period different from the first period, thereby discharging liquid from the odd-numbered first pressure chambers from the odd-numbered first nozzles; and a fourth drive signal having a fourth waveform different from the second waveform and the third waveform is supplied to the even-numbered first drive elements, thereby discharging liquid from the even-numbered first pressure chambers from the even-numbered first nozzles.

[0008] A head unit maintenance method according to the present invention includes a first nozzle row having a plurality of first nozzles arranged in parallel along a first axis and ejecting liquid, a second nozzle row having a plurality of second nozzles arranged in parallel along a second axis parallel to the first axis and ejecting liquid, a plurality of first pressure chambers provided corresponding to the plurality of first nozzles and filled with liquid, a plurality of second pressure chambers provided corresponding to the plurality of second nozzles and filled with liquid, a plurality of first drive elements provided corresponding to the plurality of first pressure chambers and changing pressure in the corresponding first pressure chambers, and a supply unit that supplies drive signals to the plurality of first drive elements and the plurality of second drive elements, the supply unit including: a plurality of second drive elements that are provided corresponding to a plurality of second pressure chambers and that vary the pressure in the corresponding second pressure chambers; and a supply unit that supplies drive signals to the plurality of first drive elements and the plurality of second drive elements, the method comprising the steps of: supplying a first drive signal having a first waveform to odd-numbered first drive elements of the plurality of first drive elements that correspond to odd-numbered first nozzles among the plurality of first nozzles; a second drive signal having a second waveform different from the first waveform to even-numbered first drive elements of the plurality of first nozzles that correspond to even-numbered first nozzles among the plurality of first drive elements, thereby discharging liquid in even-numbered first pressure chambers that correspond to the even-numbered first drive elements from the even-numbered first nozzles, and supplying a second drive signal having a second waveform different from the first waveform to odd-numbered first drive elements of the plurality of second drive elements that correspond to odd-numbered second nozzles among the plurality of second nozzles, By supplying the second drive signal, liquid in odd-numbered second pressure chambers corresponding to the odd-numbered second drive elements among the plurality of second pressure chambers is discharged from the odd-numbered second nozzles, and by supplying the first drive signal to even-numbered second drive elements among the plurality of second drive elements corresponding to even-numbered second nozzles among the plurality of second nozzles, liquid in even-numbered second pressure chambers corresponding to the even-numbered second drive elements among the plurality of second pressure chambers is discharged from the even-numbered second nozzles, and in a second period different from the first period,By supplying the second drive signal to the odd-numbered first drive elements, liquid in the odd-numbered first pressure chambers is ejected from the odd-numbered first nozzles, by supplying the first drive signal to the even-numbered first drive elements, liquid in the even-numbered first pressure chambers is ejected from the even-numbered first nozzles, by supplying the second drive signal to odd-numbered second drive elements among the plurality of second drive elements corresponding to odd-numbered second nozzles among the plurality of second nozzles, liquid in odd-numbered second pressure chambers corresponding to the odd-numbered second drive elements among the plurality of second nozzles is ejected from the odd-numbered second nozzles, and by supplying the first drive signal to even-numbered second drive elements among the plurality of second drive elements corresponding to even-numbered second nozzles among the plurality of second nozzles, liquid in even-numbered second pressure chambers corresponding to the even-numbered second drive element among the plurality of second pressure chambers is ejected from the even-numbered second nozzle. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a block diagram showing an example of the configuration of an inkjet printer 1 according to an embodiment of the invention. [Figure 2] FIG. 1 is a perspective view showing an example of a schematic internal structure of an inkjet printer 1. [Figure 3] FIG. 10 is a cross-sectional view illustrating an example of the structure of a discharge section D[m]. [Figure 4] 2 is a plan view showing an example of the arrangement of nozzles N in the head unit 3. FIG. [Figure 5] FIG. 2 is a block diagram showing an example of the configuration of a head unit 3. [Figure 6] 10 is a timing chart for explaining an example of a signal supplied to the head unit 3. [Figure 7] FIG. 10 is an explanatory diagram illustrating an example of an individual designation signal Sd[m]. [Figure 8] FIG. 10 is an explanatory diagram illustrating an example of a flushing process according to the embodiment. [Figure 9]It is an explanatory diagram for explaining the flushing process according to Reference Example 1. [Figure 10] It is an explanatory diagram for explaining an example of droplets flying in the flushing process according to Reference Example 1. [Figure 11] It is an explanatory diagram for explaining an example of droplets flying in the flushing process according to the embodiment. [Figure 12] It is an explanatory diagram for explaining the flushing process according to Reference Example 2. [Figure 13] It is an explanatory diagram for explaining the flushing process according to Modification Example 1. [Figure 14] It is an explanatory diagram for explaining the flushing process according to Reference Example 3. [Figure 15] It is an explanatory diagram for explaining the flushing process according to Modification Example 2. [Figure 16] It is an explanatory diagram for explaining an example of droplets flying in the flushing process according to Reference Example 1. [Figure 17] It is an explanatory diagram for explaining an example of droplets flying in the flushing process according to Modification Example 2. [Figure 18] It is an explanatory diagram for explaining the flushing process according to Modification Example 3. [Figure 19] It is an explanatory diagram for explaining an example of the individual designation signal Sd[m] according to Modification Example 4.

Embodiments of the Invention

[0010] Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, in each figure, the dimensions and scales of each part are appropriately different from the actual ones. In addition, the embodiments described below are preferred specific examples of the present invention, so various technically preferable limitations are imposed. However, the scope of the present invention is not limited to these embodiments unless there is a description to specifically limit the present invention in the following description.

[0011] <<A. Embodiment>> In this embodiment, the liquid ejection device will be described using as an example an inkjet printer that ejects ink to form an image on recording paper P. Note that in this embodiment, ink is an example of a "liquid," and recording paper PP is an example of a "medium."

[0012] <<1. Inkjet Printer Overview>> An example of the configuration of an inkjet printer 1 according to this embodiment will be described below with reference to FIGS.

[0013] FIG. 1 is a functional block diagram showing an example of the configuration of an inkjet printer 1.

[0014] 1, print data Img indicating an image to be formed by the inkjet printer 1 is supplied from a host computer such as a personal computer or digital camera to the inkjet printer 1. The inkjet printer 1 executes a printing process to form an image indicated by the print data Img supplied from the host computer on recording paper PP.

[0015] The inkjet printer 1 comprises a control unit 2 that controls each part of the inkjet printer 1, a head unit 3 provided with an ejection section D that ejects ink, a drive signal generation unit 4 that generates a drive signal Com for driving the ejection section D, a transport unit 7 that changes the relative position of the recording paper PP with respect to the head unit 3, and a maintenance unit 8 that performs the maintenance process described below.

[0016] Note that this embodiment assumes a case in which the inkjet printer 1 includes one or more head units 3 and one or more drive signal generation units 4 that correspond one-to-one to the one or more head units 3. Specifically, this embodiment assumes a case in which the inkjet printer 1 includes four head units 3 and four drive signal generation units 4 that correspond one-to-one to the four head units 3. However, for ease of explanation, the following description may focus on one of the four head units 3 and one of the four drive signal generation units 4 that is provided to correspond to one of the head units 3, as shown in FIG.

[0017] The control unit 2 is configured to include one or more CPUs. However, the control unit 2 may include a programmable logic device such as an FPGA instead of or in addition to a CPU. Here, CPU is an abbreviation for Central Processing Unit, and FPGA is an abbreviation for field-programmable gate array. The control unit 2 is configured to include one or both of a volatile memory such as RAM (Random Access Memory) and a non-volatile memory such as ROM (Read Only Memory), EEPROM (Electrically Erasable Programmable Read-Only Memory), or PROM (Programmable ROM).

[0018] Although details will be described later, the control unit 2 generates signals for controlling the operation of each part of the inkjet printer 1, such as a print signal SI and a waveform designation signal dCom. Here, the waveform designation signal dCom is a digital signal that defines the waveform of the drive signal Com. The drive signal Com is an analog signal for driving the discharge section D. In this embodiment, it is assumed that the drive signal Com includes a drive signal Com-A and a drive signal Com-B. The drive signal generation unit 4 includes a DA conversion circuit and generates a drive signal Com having a waveform defined by the waveform designation signal dCom. The print signal SI is a digital signal that specifies the type of operation of the discharge section D. Specifically, the print signal SI is a signal that specifies the type of operation of the discharge section D by specifying whether or not to supply the drive signal Com to the discharge section D.

[0019] As shown in FIG. 1, the head unit 3 includes a supply circuit 31 and a recording head 32.

[0020] The recording head 32 has 2M discharge sections D. Here, the value M is a natural number that satisfies "M≧1." Note that, hereinafter, the mth discharge section D of the 2M discharge sections D provided in the recording head 32 may be referred to as discharge section D[m]. Here, the variable m is a natural number that satisfies "1≦m≦2M." Also, hereinafter, when a component or signal of the inkjet printer 1 corresponds to a discharge section D[m] of the 2M discharge sections D, the subscript [m] may be added to the symbol representing the component or signal.

[0021] The supply circuit 31 switches whether to supply the drive signal Com to the discharge section D[m] based on the print signal SI. Note that, hereinafter, the drive signal Com supplied to the discharge section D[m] may be referred to as the supply drive signal Vin[m].

[0022] As described above, in this embodiment, the inkjet printer 1 executes a printing process. When the printing process is executed, the control unit 2 generates signals, such as print signals SI, for controlling the head unit 3 based on the print data Img. When the printing process is executed, the control unit 2 also generates signals, such as waveform designation signals dCom, for controlling the drive signal generation unit 4. When the printing process is executed, the control unit 2 also generates signals for controlling the transport unit 7. In this way, during the printing process, the control unit 2 controls the transport unit 7 to change the relative position of the recording paper PP with respect to the head unit 3, while adjusting the presence or absence of ink ejection from the ejection unit D[m], the amount of ink ejection, and the timing of ink ejection, and controls each part of the inkjet printer 1 so that an image corresponding to the print data Img is formed on the recording paper PP.

[0023] As described above, in this embodiment, the inkjet printer 1 executes a maintenance process. Here, the maintenance process refers to a process for maintaining the ejection sections D provided in the head unit 3, and in this embodiment, includes a flushing process for discharging ink from the ejection sections D, a wiping process for wiping off foreign matter such as ink adhering to the vicinity of the nozzles N of the ejection sections D with a wiper, and a pumping process for sucking ink from the ejection sections D with a tube pump or the like. The maintenance unit 8 includes a discharged ink receiving section 80 for receiving ink discharged from the ejection sections D when the ink is discharged from the ejection sections D during the flushing process, a wiper for wiping off foreign matter such as ink adhering to the vicinity of the nozzles N of the ejection sections D, and a tube pump for sucking ink, air bubbles, and the like from the ejection sections D. The discharged ink receiving section 80 will be described later with reference to FIG. 2. The nozzles N will be described later with reference to FIG. 3. The wiper and tube pump are not shown.

[0024] When a flushing process is performed, the control unit 2 generates signals, such as a print signal SI, for controlling the head unit 3. When the inkjet printer 1 performs a flushing process, the print signal SI specifies the operation of the 2M ejection units D provided in the head unit 3 so that the 2M ejection units D operate in a predetermined manner. When a flushing process is performed, the control unit 2 generates signals, such as a waveform designation signal dCom, for controlling the drive signal generation unit 4, just as when a printing process is performed. When a flushing process is performed, the control unit 2 generates signals for controlling the transport unit 7 so that the head unit 3 moves to a position facing the discharged ink receiving unit 80. In this way, the control unit 2 controls each part of the inkjet printer 1 during the flushing process so that ink is discharged from the ejection units D provided in the head unit 3 to the discharged ink receiving unit 80.

[0025] FIG. 2 is a perspective view showing an example of the general internal structure of the inkjet printer 1. As shown in FIG.

[0026] In this embodiment, it is assumed that the inkjet printer 1 is a serial printer, as shown in Figure 2. Specifically, when executing a printing process, the inkjet printer 1 transports the recording paper PP in the sub-scanning direction, while reciprocating the head unit 3 in the main scanning direction that intersects the sub-scanning direction, and ejects ink from the ejection units D[m] to form dots Dt on the recording paper PP according to the print data Img. Hereinafter, the +X direction and its opposite direction, the -X direction, will be collectively referred to as the "X-axis direction," the +Y direction intersecting the X-axis direction and its opposite direction, the -Y direction, will be collectively referred to as the "Y-axis direction," and the +Z direction intersecting the X-axis and Y-axis directions and its opposite direction, the -Z direction, will be collectively referred to as the "Z-axis direction." In this embodiment, as illustrated in FIG. 2, the +X direction from the upstream -X side toward the downstream +X side is defined as the sub-scanning direction, and the +Y and -Y directions are defined as the main scanning directions. In this embodiment, as illustrated in FIG. 2, the +Z direction is defined as the ink ejection direction from the ejection section D[m].

[0027] As shown in FIG. 2, the inkjet printer 1 according to this embodiment includes a housing 100 and a carriage 110 that is capable of reciprocating within the housing 100 in the Y-axis direction and that carries four head units 3. In this embodiment, as shown in FIG. 2, it is assumed that the carriage 110 stores four ink cartridges 120, each corresponding to one of the four colors of ink: cyan, magenta, yellow, and black. As described above, it is also assumed in this embodiment that the inkjet printer 1 includes four head units 3, each corresponding to one of the four ink cartridges 120. Each ejection section D[m] receives a supply of ink from the ink cartridge 120 corresponding to the head unit 3 in which the ejection section D[m] is provided. This allows each ejection section D[m] to fill itself with the supplied ink and eject the filled ink from the nozzles N. Note that the ink cartridges 120 may also be provided outside the carriage 110.

[0028] As described above, the inkjet printer 1 according to this embodiment also includes a transport unit 7. As illustrated in FIG. 2 , the transport unit 7 includes a carriage transport mechanism 71 for reciprocating the carriage 110 in the Y-axis direction, a carriage guide shaft 76 that supports the carriage 110 so that it can reciprocate in the Y-axis direction, a medium transport mechanism 73 for transporting the recording paper PP, and a platen 75 provided on the +Z side of the carriage 110. Therefore, when a printing process is performed, the transport unit 7 uses the carriage transport mechanism 71 to reciprocate the head unit 3 together with the carriage 110 along the carriage guide shaft 76 in the Y-axis direction, and the medium transport mechanism 73 to transport the recording paper PP on the platen 75 in the +X direction, thereby changing the relative position of the recording paper PP with respect to the head unit 3 and enabling ink to land on the entire recording paper PP.

[0029] FIG. 3 is a schematic partial cross-sectional view of the recording head 32, in which the recording head 32 is cut so as to include the ejection portion D[m].

[0030] 3, the ejection section D[m] includes a piezoelectric element PZ[m], a cavity CV filled with ink, a nozzle N communicating with the cavity CV, and a vibration plate 321. The ejection section D[m] ejects ink from the cavity CV through the nozzle N when the piezoelectric element PZ[m] is driven by a supply drive signal Vin[m]. The cavity CV is a space defined by a cavity plate 324, a nozzle plate 323 in which the nozzle N is formed, and the vibration plate 321. The cavity CV communicates with a reservoir 325 via an ink supply port 326. The reservoir 325 communicates with the ink cartridge 120 corresponding to the ejection section D[m] via an ink intake port 327. The piezoelectric element PZ[m] has an upper electrode Zu[m], a lower electrode Zd[m], and a piezoelectric body Zm[m] disposed between the upper electrode Zu[m] and the lower electrode Zd[m]. The lower electrode Zd[m] is electrically connected to a power supply line Ld set to a potential VBS. When a supply drive signal Vin[m] is supplied to the upper electrode Zu[m] and a voltage is applied between the upper electrode Zu[m] and the lower electrode Zd[m], the piezoelectric element PZ[m] is displaced in the +Z direction or the -Z direction according to the applied voltage, causing the piezoelectric element PZ[m] to vibrate. The lower electrode Zd[m] is bonded to the diaphragm 321. Therefore, when the piezoelectric element PZ[m] is driven to vibrate by the supply drive signal Vin[m], the diaphragm 321 also vibrates. The vibration of the diaphragm 321 changes the volume of the cavity CV and the pressure inside the cavity CV, causing the ink filled in the cavity CV to be ejected from the nozzle N.

[0031] Figure 4 is an explanatory diagram showing an example of the arrangement of four head units 3 mounted on a carriage 110 and a total of 8M nozzles N provided in the four head units 3 when the inkjet printer 1 is viewed in a plane in the +Z direction.

[0032] 4, each head unit 3 mounted on the carriage 110 is provided with two nozzle rows NL. Here, a nozzle row NL is a plurality of nozzles N arranged to extend in a row in a predetermined direction. In this embodiment, it is assumed as an example that each nozzle row NL is composed of M nozzles N arranged to extend in the X-axis direction.

[0033] Furthermore, hereinafter, of the two nozzle rows NL provided in the head unit 3, one nozzle row NL may be referred to as nozzle row NL-1, and the other nozzle row NL may be referred to as nozzle row NL-2. More specifically, in this embodiment, nozzle row NL-1 is composed of M nozzles N arranged along an axis AX-1 parallel to the X-axis direction, and nozzle row NL-2 is composed of M nozzles N arranged along an axis AX-2 parallel to the X-axis direction and positioned in the +Y direction of the axis AX-1. That is, in this embodiment, the head unit 3 is equipped with a total of 2M nozzles N, including M nozzles N belonging to nozzle row NL-1 and M nozzles N belonging to nozzle row NL-2. Note that nozzle row NL-1 is an example of a "first nozzle row," nozzle row NL-2 is an example of a "second nozzle row," axis AX-1 is an example of a "first axis," and axis AX-2 is an example of a "second axis."

[0034] Furthermore, hereinafter, of the 2M nozzles N provided in the head unit 3, the nozzle N belonging to the nozzle row NL-1 may be referred to as nozzle N-1, and the nozzle N belonging to the nozzle row NL-2 may be referred to as nozzle N-2. Furthermore, hereinafter, of the M nozzles N-1 belonging to the nozzle row NL-1, the m1-th nozzle N-1 may be referred to as nozzle N-1[m1], and of the M nozzles N-2 belonging to the nozzle row NL-2, the m2-th nozzle N-2 may be referred to as nozzle N-2[m2]. Here, the variable m1 is a natural number that satisfies "1≦m1≦M", and the variable m2 is a natural number that satisfies "1≦m2≦M". Note that the nozzle N-1 is an example of a "first nozzle", and the nozzle N-2 is an example of a "second nozzle".

[0035] Furthermore, hereinafter, of the 2M discharge units D provided in the head unit 3, the discharge unit D including the nozzle N-1 belonging to the nozzle row NL-1 may be referred to as discharge unit D-1, and the discharge unit D including the nozzle N-2 belonging to the nozzle row NL-2 may be referred to as discharge unit D-2. That is, the 2M discharge units D[1] to D[2M] provided in the head unit 3 include M discharge units D-1[1] to D-1[M] corresponding to the nozzle row NL-1 and M discharge units D-2[1] to D-2[M] corresponding to the nozzle row NL-2. Furthermore, hereinafter, the discharge unit D-1 including the nozzle N-1[m1] may be referred to as discharge unit D-1[m1], and the discharge unit D-2 including the nozzle N-2[m2] may be referred to as discharge unit D-2[m2].

[0036] In the following, the piezoelectric element PZ provided in the discharge section D-1[m1] may be referred to as the piezoelectric element PZ-1[m1], and the piezoelectric element PZ provided in the discharge section D-2[m2] may be referred to as the piezoelectric element PZ-2[m2]. In the following, the supply drive signal Vin supplied to the discharge section D-1[m1] may be referred to as the supply drive signal Vin-1[m1], and the supply drive signal Vin supplied to the discharge section D-2[m2] may be referred to as the supply drive signal Vin-2[m2]. In the following, the cavity CV provided in the discharge section D-1[m1] may be referred to as the cavity CV-1[m1], and the cavity CV provided in the discharge section D-2[m2] may be referred to as the cavity CV-2[m2]. The piezoelectric element PZ-1 is an example of a “first driving element,” and the piezoelectric element PZ-2 is an example of a “second driving element.” The cavity CV-1 is an example of a “first pressure chamber,” and the cavity CV-2 is an example of a “second pressure chamber.”

[0037] <<2. Head Unit Overview>> The head unit 3 will be outlined below with reference to FIGS.

[0038] FIG. 5 is a block diagram showing an example of the configuration of the head unit 3.

[0039] 5, the head unit 3 includes a supply circuit 31 and a recording head 32. The head unit 3 also includes a wiring La to which the drive signal Com-A is supplied from the drive signal generating unit 4, and a wiring Lb to which the drive signal Com-B is supplied from the drive signal generating unit 4.

[0040] 5, the supply circuit 31 includes 2M switches Wa[1] to Wa[2M] that correspond one-to-one to the 2M discharge units D[1] to D[2M], 2M switches Wb[1] to Wb[2M] that correspond one-to-one to the 2M discharge units D[1] to D[2M], and a connection state designation circuit 310 that designates the connection state of each switch. Note that the supply circuit 31 is an example of a "supply unit." The connection state designation circuit 310 generates a connection state designation signal Qa[m] that designates the on / off state of the switch Wa[m] and a connection state designation signal Qb[m] that designates the on / off state of the switch Wb[m] based on at least some of the signals of the print signal SI, the latch signal LAT, and the change signal CH supplied from the control unit 2. The switch Wa[m] switches between conduction and non-conduction between the wiring La and the upper electrode Zu[m] of the piezoelectric element PZ[m] provided in the discharge section D[m] based on the connection state designation signal Qa[m]. In this embodiment, the switch Wa[m] is turned on when the connection state designation signal Qa[m] is at a high level and turned off when the connection state designation signal Qa[m] is at a low level. When the switch Wa[m] is turned on, the drive signal Com-A supplied to the wiring La is supplied to the upper electrode Zu[m] of the discharge section D[m] as the supply drive signal Vin[m]. The switch Wb[m] switches between conduction and non-conduction between the wiring Lb and the upper electrode Zu[m] of the piezoelectric element PZ[m] provided in the discharge section D[m] based on the connection state designation signal Qb[m]. In this embodiment, the switch Wb[m] is turned on when the connection state designation signal Qb[m] is at a high level and turned off when the connection state designation signal Qb[m] is at a low level. When the switch Wb[m] is turned on, the drive signal Com-B supplied to the wiring Lb is supplied to the upper electrode Zu[m] of the discharge section D[m] as the supply drive signal Vin[m].

[0041] Next, the operation of the head unit 3 will be described with reference to FIGS.

[0042] In this embodiment, when the inkjet printer 1 performs a printing process or a flushing process, one or more unit periods TP are set as the operating period of the inkjet printer 1. In each unit period TP, the inkjet printer 1 according to this embodiment can drive each ejection section D[m] for the printing process or the flushing process. Note that, below, the unit period TP during which the printing process is performed will sometimes be referred to as the printing unit period TPP, and the unit period TP during which the flushing process is performed will sometimes be referred to as the flushing unit period TPF.

[0043] FIG. 6 is a timing chart showing various signals such as the drive signal Com supplied to the head unit 3 during the unit period TP.

[0044] 6, the control unit 2 outputs a latch signal LAT having a pulse PLL, thereby defining a unit period TP as the period from the rising edge of the pulse PLL to the rising edge of the next pulse PLL. Furthermore, the control unit 2 outputs a change signal CH having a pulse PLC1 and a pulse PLC2 in a unit period TP. The control unit 2 divides the unit period TP into a control period TQ1 from the rising edge of the pulse PLL to the rising edge of the pulse PLC1, a control period TQ2 from the rising edge of the pulse PLC1 to the rising edge of the pulse PLC2, and a control period TQ3 from the rising edge of the pulse PLC2 to the rising edge of the pulse PLL.

[0045] The print signal SI according to this embodiment includes 2M individual designation signals Sd[1] to Sd[2M] that correspond one-to-one to the 2M discharge sections D[1] to D[2M]. The individual designation signal Sd[m] designates the drive mode of the discharge section D[m] in each unit period TP when the inkjet printer 1 executes a printing process or a flushing process. 6, prior to each unit period TP, the control unit 2 supplies a print signal SI including 2M individual designation signals Sd[1] to Sd[2M] in synchronization with a clock signal CL to the connection state designation circuit 310. Then, during the unit period TP, the connection state designation circuit 310 generates a connection state designation signal Qa[m] and a connection state designation signal Qb[m] based on the individual designation signal Sd[m].

[0046] In this embodiment, it is assumed that in a printing unit period TPP, which is the unit period TP during which the printing process is executed, the ejection section D[m] can form any of the following dots Dt: a large dot made of ink with an ink amount ξ1, a medium dot made of ink with an ink amount ξ2 that is less than the ink amount ξ1, and a small dot made of ink with an ink amount ξ3 that is less than the ink amount ξ2. In the following, when the unit period TP is the printing unit period TPP, the ejection section D may be referred to as a printing ejection section DP.

[0047] Furthermore, in this embodiment, it is assumed that in a flushing unit period TPF, which is the unit period TP during which the flushing process is performed, the ejection section D[m] is capable of performing a large amount of ink ejection, which ejects an ink amount ξ4, and a small amount of ink ejection, which ejects an ink amount ξ5 that is less than the ink amount ξ4. Note that, hereinafter, when the unit period TP is the flushing unit period TPF, the ejection section D may be referred to as the ejection section DF to be flushed.

[0048] FIG. 7 is an explanatory diagram for explaining the individual designation signal Sd[m].

[0049] As illustrated in FIG. 7 , in this embodiment, the individual designation signal Sd[m] can take one of four values ​​during a printing unit period TPP, which is the unit period TP during which the printing process is executed: a value of "1" that designates the discharge section D[m] as a large-dot-forming discharge section DP-1; a value of "2" that designates the discharge section D[m] as a medium-dot-forming discharge section DP-2; a value of "3" that designates the discharge section D[m] as a small-dot-forming discharge section DP-3; and a value of "4" that designates the discharge section D[m] as a non-dot-forming discharge section DP-N. Here, the large-dot-forming discharge section DP-1 is the print discharge section DP that forms large dots during the printing unit period TPP. The medium-dot-forming discharge section DP-2 is the print discharge section DP that forms medium dots during the printing unit period TPP. The small-dot-forming discharge section DP-3 is the print discharge section DP that forms small dots during the printing unit period TPP. Furthermore, the non-dot-forming discharge section DP-N is a print discharge section DP that does not form dots during the print unit period TPP.

[0050] 7, in this embodiment, the individual designation signal Sd[m] can take one of three values ​​during a flushing unit period TPF, which is the unit period TP during which the flushing process is performed: a value of "5" that designates the discharge section D[m] as a large-volume ink discharge section DF-1; a value of "6" that designates the discharge section D[m] as a small-volume ink discharge section DF-2; and a value of "7" that designates the discharge section D[m] as a discharge-limited ink discharge section DF-N. Here, the large-volume ink discharge section DF-1 is a flushing target discharge section DF that discharges a large volume of ink during the flushing unit period TPF. The small-volume ink discharge section DF-2 is a flushing target discharge section DF that discharges a small volume of ink during the flushing unit period TPF. The discharge-limited ink discharge section DF-N is a flushing target discharge section DF that does not discharge ink during the flushing unit period TPF.

[0051] Returning to the explanation in FIG. As illustrated in FIG. 6, in this embodiment, the drive signal Com-A has a waveform PA1 provided in the control period TQ1, a waveform PA2 provided in the control period TQ2, and a waveform PA3 provided in the control period TQ3.

[0052] Of these, the waveform PA1 is a waveform that goes from a reference potential V0 to a potential VLA1 that is lower than the reference potential V0, and a potential VHA1 that is higher than the reference potential V0, before returning to the reference potential V0. The waveform PA1 is determined so that when a supply drive signal Vin[m] having the waveform PA1 is supplied to the ejection section D[m], ink equivalent to the ink amount φ1 is ejected from the ejection section D[m]. The waveform PA2 is a waveform that goes from the reference potential V0 to a potential VLA2 that is lower than the reference potential V0, and a potential VHA2 that is higher than the reference potential V0, before returning to the reference potential V0. The waveform PA2 is determined so that when a supply drive signal Vin[m] having the waveform PA2 is supplied to the ejection section D[m], ink equivalent to the ink amount φ2 is ejected from the ejection section D[m]. The waveform PA3 is a waveform that goes from the reference potential V0 to a potential VLA3 that is lower than the reference potential V0, and a potential VHA3 that is higher than the reference potential V0, before returning to the reference potential V0. The waveform PA3 is determined so that when a supply drive signal Vin[m] having the waveform PA3 is supplied to the ejection section D[m], ink equivalent to an ink amount φ3 is ejected from the ejection section D[m]. In the following, the waveforms PA1, PA2, and PA3 may be collectively referred to as the waveform PAA.

[0053] In this embodiment, as an example, it is assumed that when the potential of the supply drive signal Vin[m] supplied to the ejection section D[m] is high, the volume of the cavity CV of the ejection section D[m] is smaller than when the potential is low. Therefore, when the ejection section D[m] is driven by the supply drive signal Vin[m] having a waveform PA1 or the like, the potential of the supply drive signal Vin[m] changes from low to high, causing the ink in the ejection section D[m] to be ejected from the nozzle N.

[0054] In addition, this embodiment assumes that waveforms PA1, PA2, and PA3 have approximately the same shape. That is, this embodiment assumes that ink amounts φ1, φ2, and φ3 are approximately the same. Below, ink amounts φ1, φ2, and φ3 may be collectively referred to as ink amount φL. Here, "substantially the same" not only refers to cases where they are completely identical, but also includes cases where they can be considered to be the same when errors are taken into consideration, such as cases where they are identical in terms of design but differ from each other due to manufacturing errors, and cases where they are identical in terms of specifications but differ from each other due to errors caused by disturbances, etc. In this specification, "substantially the same" is simply referred to as "the same." In other words, in this specification, "same" is a concept that includes "substantially the same."

[0055] As illustrated in FIG. 6, in this embodiment, the drive signal Com-B has a waveform PB1 provided in the control period TQ1, a waveform PB2 provided in the control period TQ2, and a waveform PB3 provided in the control period TQ3.

[0056] Of these, waveform PB1 is a waveform that starts at a reference potential V0, passes through a potential VLB1 that is lower than the reference potential V0 but higher than the potential VLA1, and a potential VHB1 that is higher than the reference potential V0 but lower than the potential VHA1, and then returns to the reference potential V0. The waveform PB1 is determined so that when a supply drive signal Vin[m] having waveform PB1 is supplied to ejection section D[m], ink equivalent to an ink amount φ4 is ejected from ejection section D[m]. Note that in this embodiment, it is assumed that the ink amount φ4 is smaller than the ink amount φ1. Furthermore, waveform PB2 is a waveform that transitions from reference potential V0 to potential VLB2, which is lower than reference potential V0 but higher than potential VLA2, and potential VHB2, which is higher than reference potential V0 but lower than potential VHA2, before returning to reference potential V0. When supply drive signal Vin[m] having waveform PB2 is supplied to ejection section D[m], waveform PB2 is determined so that ink equivalent to ink amount φ5 is ejected from ejection section D[m]. In this embodiment, it is assumed that ink amount φ5 is smaller than ink amount φ2. The waveform PB3 is a waveform that goes from the reference potential V0 to a potential VLB3 that is lower than the reference potential V0 but higher than the potential VLA3, and to a potential VHB3 that is higher than the reference potential V0 but lower than the potential VHA3, before returning to the reference potential V0. The waveform PB3 is determined so that when the supply drive signal Vin[m] having the waveform PB3 is supplied to the ejection section D[m], ink is not ejected from the ejection section D[m]. In the following description, the waveforms PB1 and PB2 may be collectively referred to as waveforms PBB. In this embodiment, it is assumed that the waveforms PB1 and PB2 have substantially the same shape.

[0057] In this embodiment, it is assumed that the ink amount ξ1 corresponds to the sum of the ink amount φ1, the ink amount φ2, and the ink amount φ3, the ink amount ξ2 corresponds to the sum of the ink amount φ1 and the ink amount φ2, the ink amount ξ3 corresponds to the sum of the ink amount φ4 and the ink amount φ5, the ink amount ξ4 corresponds to the sum of the ink amount φ1, the ink amount φ2, and the ink amount φ3, and the ink amount ξ5 is the same as the ink amount φ2.

[0058] 7, when the individual designation signal Sd[m] indicates a value of "1" that designates the discharge section D[m] as the large-dot-forming discharge section DP-1 during the print unit period TPP, the connection state designation circuit 310 sets the connection state designation signal Qa[m] to a high level during the control periods TQ1, TQ2, and TQ3. In this case, the switch Wa[m] is turned on throughout the print unit period TPP. Therefore, during the print unit period TPP, the discharge section D[m] is driven by the supply drive signal Vin[m] having waveforms PA1, PA2, and PA3, and discharges ink of an ink amount ξ1 corresponding to a large dot. Furthermore, if the individual designation signal Sd[m] indicates a value of "2" that designates the discharge section D[m] as the medium-dot-forming discharge section DP-2 during the print unit period TPP, the connection state designation circuit 310 sets the connection state designation signal Qa[m] to a high level during the control periods TQ1 and TQ2. In this case, the switch Wa[m] is turned on during the control periods TQ1 and TQ2. Therefore, during the print unit period TPP, the discharge section D[m] is driven by the supply drive signal Vin[m] having waveforms PA1 and PA2, and discharges ink at an ink volume ξ2 corresponding to a medium dot. Furthermore, if the individual designation signal Sd[m] indicates a value of "3," which designates the discharge unit D[m] as the small-dot-forming discharge unit DP-3 during the print unit period TPP, the connection state designation circuit 310 sets the connection state designation signal Qb[m] to a high level during the control periods TQ1 and TQ2. In this case, the switch Wb[m] is turned on during the control periods TQ1 and TQ2. Therefore, during the print unit period TPP, the discharge unit D[m] is driven by the supply drive signal Vin[m] having waveforms PB1 and PB2, and discharges ink at an ink volume ξ3 corresponding to a small dot. Furthermore, if the individual designation signal Sd[m] indicates a value of "4," which designates the discharge section D[m] as a non-dot-forming discharge section DP-N during the print unit period TPP, the connection state designation circuit 310 sets the connection state designation signal Qa[m] to a low level during control periods TQ1, TQ2, and TQ3, and sets the connection state designation signal Qb[m] to a low level during control periods TQ1 and TQ2, and to a high level during control period TQ3. In this case, the switch Wa[m] is turned off throughout the print unit period TPP, and the switch Wb[m] is turned off during control periods TQ1 and TQ2. Therefore, although the discharge section D[m] is driven by the supply drive signal Vin[m] having the waveform PB3 during the print unit period TPP, it does not discharge ink.

[0059] Furthermore, if the individual designation signal Sd[m] indicates a value of "5," which designates the discharger D[m] as the large-volume ink discharger DF-1 during the flushing unit period TPF, the connection state designation circuit 310 sets the connection state designation signal Qa[m] to a high level during the control periods TQ1, TQ2, and TQ3. In this case, the switch Wa[m] is turned on throughout the flushing unit period TPF. Therefore, during the flushing unit period TPF, the discharger D[m] is driven by the supply drive signal Vin[m] having waveforms PA1, PA2, and PA3, and discharges ink at an ink volume ξ4, which corresponds to a large ink discharge. Furthermore, if the individual designation signal Sd[m] indicates a value of "6" that designates the discharger D[m] as the small-amount ink discharger DF-2 during the flushing unit period TPF, the connection state designation circuit 310 sets the connection state designation signal Qa[m] to a high level during the control period TQ2. In this case, the switch Wa[m] is turned on during the control period TQ2. Therefore, during the flushing unit period TPF, the discharger D[m] is driven by the supply drive signal Vin[m] having the waveform PA2 and discharges an ink amount ξ5 corresponding to a small amount of ink discharge. Furthermore, when the individual designation signal Sd[m] indicates a value of "7" that designates the discharge unit D[m] as the discharge limiting discharge unit DF-N during the flushing unit period TPF, the connection state designation circuit 310 sets the connection state designation signal Qa[m] to low level during the control periods TQ1, TQ2, and TQ3, and sets the connection state designation signal Qb[m] to low level during the control periods TQ1 and TQ2, and to high level during the control period TQ3. As a result, although the discharge unit D[m] is driven by the supply drive signal Vin[m] having the waveform PB3 during the flushing unit period TPF, it does not discharge ink.

[0060] In the following, during the flushing unit period TPF, the waveform of the supply drive signal Vin[m] supplied to the discharge section D[m] designated as the large-volume ink discharge section DF-1 may be referred to as the large-volume ink discharge waveform PF1, the waveform of the supply drive signal Vin[m] supplied to the discharge section D[m] designated as the small-volume ink discharge section DF-2 may be referred to as the small-volume ink discharge waveform PF2, and the waveform of the supply drive signal Vin[m] supplied to the discharge section D[m] designated as the discharge-limiting discharge section DF-N may be referred to as the ink discharge-limiting waveform PFN. That is, in this embodiment, it is assumed that the large-volume ink discharge waveform PF1 is a waveform consisting of waveforms PA1, PA2, and PA3, the small-volume ink discharge waveform PF2 is the waveform PA2, and the ink discharge-limiting waveform PFN is the waveform PB3.

[0061] <<3. Flushing process>> The flushing process according to this embodiment will be described below with reference to FIGS.

[0062] FIG. 8 is an explanatory diagram for explaining an example of the flushing process according to this embodiment.

[0063] 8 illustrates the case where "M=6", that is, where each nozzle row NL provided in the head unit 3 is made up of six discharge sections D. That is, in the example illustrated in Fig. 8, it is assumed that the nozzle row NL-1 includes nozzles N-1[1] to N-1[6] corresponding to the discharge sections D-1[1] to D-1[6], and the nozzle row NL-2 includes nozzles N-2[1] to N-2[6] corresponding to the discharge sections D-2[1] to D-2[6]. In the example shown in FIG. 8, it is assumed that flushing processing is performed in six consecutive unit periods TP, ie, unit periods TP(1) to TP(6).

[0064] As illustrated in FIG. 8, the control unit 2 supplies a print signal SI to the head unit 3 during each of the unit periods TP(1) to TP(3) among the unit periods TP(1) to TP(6) during which the flushing process is performed, which designates each of the discharge sections D-1[1] to D-1[6] corresponding to the nozzle row NL-1 as a large-volume ink discharge section DF-1 and each of the discharge sections D-2[1] to D-2[6] corresponding to the nozzle row NL-2 as a small-volume ink discharge section DF-2, and during each of the unit periods TP(4) to TP(6), which designates each of the discharge sections D-1[1] to D-1[6] corresponding to the nozzle row NL-1 as a small-volume ink discharge section DF-2 and each of the discharge sections D-2[1] to D-2[6] corresponding to the nozzle row NL-2 as a large-volume ink discharge section DF-1.

[0065] That is, in this embodiment, the control unit 2 supplies a supply drive signal Vin-1[1] having a large-volume ink ejection waveform PF1 to the ejector D-1[1] during each of the unit periods TP(1) to TP(3), causing the ejector D-1[1] to operate as a large-volume ink ejector DF-1 and eject ink from the cavity CV-1[1] through the nozzle N-1[1] of the nozzle row NL-1. Also, the control unit 2 supplies a supply drive signal Vin-1[2] having a large-volume ink ejection waveform PF1 to the ejector D-1[2] during each of the unit periods TP(1) to TP(3), causing the ejector D-1[2] to operate as a large-volume ink ejector DF-1 and eject ink from the cavity CV-1[2] through the nozzle N-1[2] of the nozzle row NL-1. Furthermore, the control unit 2 supplies a supply drive signal Vin-2[1] having a small amount of ink discharge waveform PF2 to the discharge section D-2[1] during each of the unit periods TP(1) to TP(3), thereby operating the discharge section D-2[1] as a small amount of ink discharge section DF-2 and discharging ink from the cavity CV-2[1] through the nozzle N-2[1] belonging to the nozzle row NL-2. Furthermore, the control unit 2 supplies a supply drive signal Vin-2[2] having a small amount of ink discharge waveform PF2 to the discharge section D-2[2] during each of the unit periods TP(1) to TP(3), thereby operating the discharge section D-2[2] as a small amount of ink discharge section DF-2 and discharging ink from the cavity CV-2[2] through the nozzle N-2[2] belonging to the nozzle row NL-2. Furthermore, the control unit 2 supplies a supply drive signal Vin-1[1] having a small amount of ink discharge waveform PF2 to the discharge section D-1[1] during each of the unit periods TP(4) to TP(6), causing the discharge section D-1[1] to operate as a small amount of ink discharge section DF-2 and eject ink from the cavity CV-1[1] from the nozzle N-1[1] belonging to the nozzle row NL-1. Furthermore, the control unit 2 supplies a supply drive signal Vin-1[2] having a small amount of ink discharge waveform PF2 to the discharge section D-1[2] during each of the unit periods TP(4) to TP(6), causing the discharge section D-1[2] to operate as a small amount of ink discharge section DF-2 and eject ink from the cavity CV-1[2] from the nozzle N-1[2] belonging to the nozzle row NL-1. Furthermore, the control unit 2 supplies a supply drive signal Vin-2[1] having a large quantity ink ejection unit DF-1 to the ejection unit D-2[1] during each of the unit periods TP(4) to TP(6), thereby operating the ejection unit D-2[1] as the large quantity ink ejection unit DF-1 and causing the ink in the cavity CV-2[1] to be ejected from the nozzle N-2[1] belonging to the nozzle row NL-2. Furthermore, the control unit 2 supplies a supply drive signal Vin-2[2] having a large quantity ink ejection unit DF-1 to the ejection unit D-2[2] during each of the unit periods TP(4) to TP(6), thereby operating the ejection unit D-2[2] as the large quantity ink ejection unit DF-1 and causing the ink in the cavity CV-2[2] to be ejected from the nozzle N-2[2] belonging to the nozzle row NL-2.

[0066] FIG. 9 is an explanatory diagram for explaining the flushing process according to the first reference example.

[0067] 9, like Fig. 8, illustrates the case where "M=6", that is, the case where each nozzle row NL provided in the head unit 3 is made up of six discharge sections D. Also, like Fig. 8, Fig. 9 assumes the case where flushing processes are performed in unit periods TP(1) to TP(6).

[0068] As illustrated in Figure 9, the control unit 2 of reference example 1 supplies a print signal SI to the head unit 3 to designate each of the ejection sections D-1[1] to D-1[6] corresponding to nozzle row NL-1 as large-volume ink ejection section DF-1, and each of the ejection sections D-2[1] to D-2[6] corresponding to nozzle row NL-2 as large-volume ink ejection section DF-1, during each of the unit periods TP(1) to TP(6) in which the flushing process is performed.

[0069] 10 is a conceptual diagram showing how droplets ejected from nozzle N-1[m0] provided in head unit 3 fly as dots, and how droplets ejected from nozzle N-2[m0] provided in head unit 3 fly as dots when the flushing process according to Reference Example 1 is performed. Here, variable m0 is a natural number that satisfies "1≦m0≦M." That is, in FIG. 10, it is assumed that nozzle N-2[m0] is located in the +Y direction of nozzle N-1[m0], and that nozzle N-2[m0] is adjacent to nozzle N-1[m0] in the Y-axis direction.

[0070] 10, in the flushing process according to Reference Example 1, the discharger D-1[m0] is driven by a supply drive signal Vin-1[m0] having three waveforms PAA to operate as a large-volume ink discharger DF-1, and three dots Dt are successively discharged from the nozzle N-1[m0] provided in the discharger D-1[m0] in each unit period TP. Also, in the flushing process according to Reference Example 1, the discharger D-2[m0] is driven by a supply drive signal Vin-2[m0] having three waveforms PAA to operate as a large-volume ink discharger DF-1, and three dots Dt are successively discharged from the nozzle N-2[m0] provided in the discharger D-2[m0] in each unit period TP. Therefore, in the flushing process of reference example 1, the density of the flying dots Dt in the space between the head unit 3 and the recording paper PP is high, and the air flow flowing along the flying dots Dt causes the air pressure in the space located between nozzle N-1[m0] and nozzle N-2[m0] to be lower than the air pressure in other spaces around the head unit 3.

[0071] Hereinafter, the space located between the nozzle N-1[m0] of the ejection unit D-1[m0] operating as the large-volume ink ejection unit DF-1 and the nozzle N-2[m0] of the ejection unit D-2[m0] operating as the large-volume ink ejection unit DF-1 will be referred to as the inter-nozzle decompressed space SP. The density of the flying dots Dt in the space between the head unit 3 and the recording paper PP is high, and airflows toward the recording paper PP that occur around the flight paths of the dots Dt ejected from the nozzles N cause the inter-nozzle decompressed space SP to have a lower air pressure than the rest of the space around the head unit 3. This generates a strong airflow from the recording paper PP toward the inter-nozzle decompressed space SP. Hereinafter, the airflow that is generated by the ejection of dots Dt from the nozzles N and that flows toward the recording paper PP and then toward the inter-nozzle decompressed space SP will be referred to as the self-jet flow JF-A.

[0072] When a dot Dt is ejected from the nozzle N, the liquid protrudes from the nozzle N toward the recording paper PP while being elongated. The protruding portion then breaks off, and the broken portion flies and becomes a spherical dot Dt due to surface tension. In forming such dots Dt, a relatively large main droplet and relatively small satellite droplets and fine mist are generated. Because the satellite droplets and mist have a small mass and have little energy due to ejection, their flight speed is rapidly attenuated by air resistance during flight. Therefore, the satellite droplets and mist whose flight speed decreases and whose linear energy becomes zero before reaching the recording paper PP remain in space and are carried by the self-jet airflow, adhering to the head unit 3. In the flushing process of Reference Example 1, the mist is picked up by the self-jet JF-A heading toward the head unit 3 and adheres to the head unit 3. As a result, the areas around the openings of nozzle N-1[m0] and nozzle N-2[m0] could become contaminated with ink adhering as mist, which could result in ink not being able to be ejected normally from nozzle N-1[m0] and nozzle N-2[m0].

[0073] 10, in the flushing process according to Reference Example 1, as the dots Dt are ejected from the nozzle N-1[m0], reduced pressure occurs not only in the inter-nozzle reduced pressure space SP but also in the space on the -Y side of the nozzle N-1[m0]. Also, in the flushing process according to Reference Example 1, as the dots Dt are ejected from the nozzle N-2[m0], reduced pressure occurs not only in the inter-nozzle reduced pressure space SP but also in the space on the +Y side of the nozzle N-2[m0]. Hereinafter, the airflow into the space other than the inter-nozzle reduced pressure space SP that is generated as the dots Dt are ejected from the nozzle N will be referred to as airflow JF-B. As described above, the inter-nozzle decompression space SP is a space between the head unit 3 and the recording paper PP, sandwiched between the area where the dots Dt ejected from the ejection units D-1[1] to D-1[6] of the nozzle row NL-1 fly and the area where the dots Dt ejected from the ejection units D-2[1] to D-2[6] of the nozzle row NL-2 fly. Because the density of the flying dots Dt is high and an airflow from the nozzle N side toward the recording paper PP occurs, the air pressure there is likely to be lower than in spaces other than the inter-nozzle decompression space SP. On the other hand, in the space on the -Y side of nozzle N-1[m0] and the space on the +Y side of nozzle N-2[m0], even if an airflow toward the recording paper PP occurs around the flight path of the dots Dt on one side, there are no flying dots Dt on the other side and the density of the dots Dt is low, so air is easily replenished from the other side. This makes the air pressure less likely to be low. Therefore, the self-jet flow JF-A is a stronger airflow than the airflow JF-B.

[0074] Figure 11 is a conceptual diagram showing how droplets ejected from nozzle N-1[m0] provided in head unit 3 fly as dots when the flushing process of this embodiment is performed, and how droplets ejected from nozzle N-2[m0] provided in head unit 3 fly as dots.

[0075] 11, in the flushing process according to this embodiment, the ejector D-1[m0] is driven by a supply drive signal Vin-1[m0] having three waveforms PAA to operate as a large-volume ink ejector DF-1, and three dots Dt are successively ejected from the nozzle N-1[m0] provided in the ejector D-1[m0] during each unit period TP. On the other hand, in the flushing process according to this embodiment, the ejector D-2[m0] is driven by a supply drive signal Vin-2[m0] having one waveform PAA to operate as a small-volume ink ejector DF-2, and only one dot Dt is ejected from the nozzle N-2[m0] provided in the ejector D-2[m0] during each unit period TP. For this reason, in the flushing process according to this embodiment, the density of flying dots Dt in the space between the head unit 3 and the recording paper PP is lower than in the case of the above-mentioned Reference Example 1, and an inter-nozzle reduced pressure space SP is not generated between nozzle N-1[m0] and nozzle N-2[m0]. And, in the flushing process according to this embodiment, although an airflow JF-B is generated, a self-jet flow JF-A is not generated. For this reason, in the flushing process according to this embodiment, compared to Reference Example 1, the density of the dots Dt ejected from nozzle N-1[m0] and nozzle N-2[m0] in the space between the head unit 3 and the recording paper PP is lower, making it possible to reduce the amount of mist that gets stirred up around the nozzle N and reduce the amount of mist that adheres to the head unit 3. In other words, in the flushing process according to this embodiment, compared to Reference Example 1, it is possible to reduce the risk that ink will not be able to be ejected normally from nozzle N-1[m0] and nozzle N-2[m0].

[0076] FIG. 12 is an explanatory diagram for explaining the flushing process according to the second reference example.

[0077] 12, like Fig. 8, illustrates the case where "M=6", that is, the case where each nozzle row NL provided in the head unit 3 is made up of six discharge sections D. Also, like Fig. 8, Fig. 12 assumes the case where flushing processes are performed in unit periods TP(1) to TP(6).

[0078] As illustrated in FIG. 12, the control unit 2 of Reference Example 2 supplies a print signal SI to the head unit 3 during each of the unit periods TP(1) to TP(3) among the unit periods TP(1) to TP(6) during which the flushing process is performed, which designates each of the discharge sections D-1[1] to D-1[6] corresponding to the nozzle row NL-1 as a large-volume ink discharge section DF-1 and each of the discharge sections D-2[1] to D-2[6] corresponding to the nozzle row NL-2 as a discharge-limiting discharge section DF-N, and supplies a print signal SI to the head unit 3 during each of the unit periods TP(4) to TP(6) which designates each of the discharge sections D-1[1] to D-1[6] corresponding to the nozzle row NL-1 as a discharge-limiting discharge section DF-N and each of the discharge sections D-2[1] to D-2[6] corresponding to the nozzle row NL-2 as a large-volume ink discharge section DF-1.

[0079] As described above, in the flushing process according to Reference Example 2, when the discharge section D-1[m0] corresponding to the nozzle N-1[m0] operates as the large-volume ink discharge section DF-1, the discharge section D-2[m0] corresponding to the nozzle N-2[m0] operates as the discharge-limiting discharge section DF-N. Also, when the discharge section D-2[m0] corresponding to the nozzle N-2[m0] operates as the large-volume ink discharge section DF-1, the discharge section D-1[m0] corresponding to the nozzle N-1[m0] operates as the discharge-limiting discharge section DF-N. Therefore, in the flushing process according to Reference Example 2, no inter-nozzle decompression space SP is generated between the nozzle N-1[m0] and the nozzle N-2[m0]. Therefore, according to Reference Example 2, compared to Reference Example 1, it is possible to prevent the dots Dt discharged from the nozzle N from scattering as mist during the flushing process. That is, according to Reference Example 2, it is possible to reduce the amount of mist adhering to the head unit 3 during the flushing process, compared to Reference Example 1. In other words, in the flushing process of Reference Example 2, compared to Reference Example 1, it is possible to reduce the risk of ink not being ejected normally from nozzle N-1[m0] and nozzle N-2[m0].

[0080] However, in reference example 2, of the unit periods TP(1) to TP(6) during which the flushing process is performed, the control unit 2 stops the ejection of ink from the ejection sections D-2[1] to D-2[6] corresponding to the nozzle row NL-2 during the unit periods TP(1) to TP(3), and stops the ejection of ink from the ejection sections D-1[1] to D-1[6] corresponding to the nozzle row NL-1 during the unit periods TP(4) to TP(6). Therefore, in Reference Example 2, compared with Reference Example 1, in the flushing process, the time required to discharge a desired amount of ink from the head unit 3 becomes longer. More specifically, in Reference Example 2, the time required to discharge ink from the head unit 3 as the flushing process is about twice the time required to discharge ink from the head unit 3 as the flushing process in Reference Example 1. Thus, in Reference Example 2, the flushing process takes a long time, which is likely to impair the convenience of the user of the inkjet printer 1.

[0081] In contrast, the control unit 2 according to the present embodiment, among the unit periods TP(1) to TP(6) during which the flushing process is executed, instead of stopping the discharge of ink from the discharge parts D-2[1] to D-2[6] corresponding to the nozzle row NL-2 in the unit periods TP(1) to TP(3), causes each of the discharge parts D-2[1] to D-2[6] to execute a small amount of ink discharge, and instead of stopping the discharge of ink from the discharge parts D-1[1] to D-1[6] corresponding to the nozzle row NL-1 in the unit periods TP(4) to TP(6), causes each of the discharge parts D-1[1] to D-1[6] to execute a small amount of ink discharge. For this reason, according to the present embodiment, compared with Reference Example 2, in the flushing process, the time required to discharge a desired amount of ink from the head unit 3 can be shortened. That is, according to the present embodiment, it is possible to achieve both an improvement in print quality by suppressing the generation of mist and an improvement in user convenience by shortening the time required for the flushing process.

[0082] <<B. Modified Example>> Each of the above embodiments can be variously modified. Specific modification modes are exemplified below. Two or more modes arbitrarily selected from the following examples can be appropriately combined within a range where they do not conflict with each other. In the modified examples exemplified below, for elements whose actions and functions are equivalent to those of the embodiment, the reference numerals referred to in the above description are reused, and the detailed description of each is appropriately omitted.

[0083] <<Modified Example 1>> In the above-described embodiment, an example has been given in which each discharger D operates as a large-volume ink discharger DF-1 over a plurality of consecutive unit periods TP, but the present invention is not limited to this. For example, each discharger D may alternately operate as a large-volume ink discharger DF-1 and as a small-volume ink discharger DF-2 for each unit period TP during the flushing process. For example, if a discharger D operates as a large-volume ink discharger DF-1 in one unit period TP, it may then operate as a small-volume ink discharger DF-2 in another unit period TP following the one unit period TP.

[0084] FIG. 13 is an explanatory diagram for explaining the flushing process according to the first modification.

[0085] 13, like Fig. 8, illustrates the case where "M=6", that is, the case where each nozzle row NL provided in the head unit 3 is made up of six discharge sections D. Also, like Fig. 8, Fig. 13 assumes the case where flushing processes are performed in unit periods TP(1) to TP(6).

[0086] As illustrated in Figure 13, the control unit 2 of this modified example supplies a print signal SI to the head unit 3 to designate each of the ejection sections D-1[1] to D-1[6] corresponding to nozzle row NL-1 as large-volume ink ejection sections DF-1 and each of the ejection sections D-2[1] to D-2[6] corresponding to nozzle row NL-2 as small-volume ink ejection sections DF-2 in each of the odd-numbered unit periods TP(1), TP(3), and TP(5) among the unit periods TP(1) to TP(6) in which the flushing process is executed. Furthermore, the control unit 2 of this modified example supplies a print signal SI to the head unit 3 to designate each of the ejection sections D-1[1] to D-1[6] corresponding to the nozzle row NL-1 as a small amount of ink ejection section DF-2, and each of the ejection sections D-2[1] to D-2[6] corresponding to the nozzle row NL-2 as a large amount of ink ejection section DF-1, in each of the even-numbered unit periods TP(2), TP(4), and TP(6) among the unit periods TP(1) to TP(6) in which the flushing process is executed.

[0087] That is, the control unit 2 according to this modification supplies a supply drive signal Vin-1[1] having a large-volume ink ejection waveform PF1 to the ejector D-1[1] during each of the odd-numbered unit periods TP(1), TP(3), and TP(5), thereby operating the ejector D-1[1] as a large-volume ink ejector DF-1 and ejecting ink from the cavity CV-1[1] from the nozzle N-1[1] belonging to the nozzle row NL-1. Also, the control unit 2 according to this modification supplies a supply drive signal Vin-1[2] having a large-volume ink ejection waveform PF1 to the ejector D-1[2] during each of the odd-numbered unit periods TP(1), TP(3), and TP(5), thereby operating the ejector D-1[2] as a large-volume ink ejector DF-1 and ejecting ink from the cavity CV-1[2] from the nozzle N-1[2] belonging to the nozzle row NL-1. Furthermore, the control unit 2 according to this modification supplies a supply drive signal Vin-2[1] having a small amount of ink ejection waveform PF2 to the ejector D-2[1] during each of the odd-numbered unit periods TP(1), TP(3), and TP(5), thereby operating the ejector D-2[1] as a small amount of ink ejection unit DF-2 and ejecting ink from the cavity CV-2[1] from the nozzle N-2[1] belonging to the nozzle row NL-2. Furthermore, the control unit 2 according to this modification supplies a supply drive signal Vin-2[2] having a small amount of ink ejection waveform PF2 to the ejector D-2[2] during each of the odd-numbered unit periods TP(1), TP(3), and TP(5), thereby operating the ejector D-2[2] as a small amount of ink ejection unit DF-2 and ejecting ink from the cavity CV-2[2] from the nozzle N-2[2] belonging to the nozzle row NL-2. Furthermore, the control unit 2 according to this modification supplies a supply drive signal Vin-1[1] having a small amount of ink ejection waveform PF2 to the ejector D-1[1] during each of the even-numbered unit periods TP(2), TP(4), and TP(6), thereby operating the ejector D-1[1] as a small amount of ink ejection unit DF-2 and ejecting ink from the cavity CV-1[1] from the nozzle N-1[1] belonging to the nozzle row NL-1. Furthermore, the control unit 2 according to this modification supplies a supply drive signal Vin-1[2] having a small amount of ink ejection waveform PF2 to the ejector D-1[2] during each of the even-numbered unit periods TP(2), TP(4), and TP(6), thereby operating the ejector D-1[2] as a small amount of ink ejection unit DF-2 and ejecting ink from the cavity CV-1[2] from the nozzle N-1[2] belonging to the nozzle row NL-1. Furthermore, the control unit 2 according to this modification supplies a supply drive signal Vin-2[1] having a large-volume ink ejection waveform PF1 to the ejector D-2[1] during each of the even-numbered unit periods TP(2), TP(4), and TP(6), thereby operating the ejector D-2[1] as a large-volume ink ejector DF-1 and ejecting ink from the cavity CV-2[1] from the nozzle N-2[1] belonging to the nozzle row NL-2. Furthermore, the control unit 2 according to this modification supplies a supply drive signal Vin-2[2] having a large-volume ink ejection waveform PF1 to the ejector D-2[2] during each of the even-numbered unit periods TP(2), TP(4), and TP(6), thereby operating the ejector D-2[2] as a large-volume ink ejector DF-1 and ejecting ink from the cavity CV-2[2] from the nozzle N-2[2] belonging to the nozzle row NL-2.

[0088] FIG. 14 is an explanatory diagram for explaining the flushing process according to the third reference example.

[0089] 14, like Fig. 8, illustrates the case where "M=6", that is, the case where each nozzle row NL provided in the head unit 3 is made up of six discharge sections D. Also, like Fig. 8, Fig. 14 assumes the case where flushing processing is performed in unit periods TP(1) to TP(6).

[0090] As illustrated in Figure 14, the control unit 2 of reference example 3 supplies a print signal SI to the head unit 3 in each of the odd-numbered unit periods TP(1), TP(3), and TP(5) among the unit periods TP(1) to TP(6) in which the flushing process is executed, to designate each of the ejection sections D-1[1] to D-1[6] corresponding to nozzle row NL-1 as large-volume ink ejection sections DF-1, and to designate each of the ejection sections D-2[1] to D-2[6] corresponding to nozzle row NL-2 as discharge-limited ejection sections DF-N. Furthermore, the control unit 2 of reference example 3 supplies a print signal SI to the head unit 3 to designate each of the ejection sections D-1[1] to D-1[6] corresponding to the nozzle row NL-1 as a discharge limiting ejection section DF-N and each of the ejection sections D-2[1] to D-2[6] corresponding to the nozzle row NL-2 as a large quantity ink ejection section DF-1 in each of the even-numbered unit periods TP(2), TP(4), and TP(6) among the unit periods TP(1) to TP(6) in which the flushing process is executed.

[0091] That is, in reference example 3, the control unit 2 stops the ejection of ink from the ejection sections D-2[1] to D-2[6] corresponding to the nozzle row NL-2 during the odd-numbered unit periods TP(1), TP(3), and TP(5) of the unit periods TP(1) to TP(6) in which the flushing process is performed, and stops the ejection of ink from the ejection sections D-1[1] to D-1[6] corresponding to the nozzle row NL-1 during the even-numbered unit periods TP(2), TP(4), and TP(6). Therefore, in the third reference example, compared to the first reference example, the time required to discharge a desired amount of ink from the head unit 3 during the flushing process is longer.

[0092] In contrast, the control unit 2 of this modification, among the unit periods TP(1) to TP(6) in which the flushing process is performed, in the odd-numbered unit periods TP(1), TP(3), and TP(5), the control unit 2 stops ink ejection from the ejectors D-2[1] to D-2[6] corresponding to the nozzle row NL-2, but instead causes each of the ejectors D-2[1] to D-2[6] to eject a small amount of ink. In the even-numbered unit periods TP(2), TP(4), and TP(6), the control unit 2 stops ink ejection from the ejectors D-1[1] to D-1[6] corresponding to the nozzle row NL-1, but instead causes each of the ejectors D-1[1] to D-1[6] to eject a small amount of ink. Therefore, according to this embodiment, the time required to eject a desired amount of ink from the head unit 3 during the flushing process can be shortened compared to Reference Example 3. Furthermore, it is possible to suppress the generation of a strong air current toward the inter-nozzle decompression space SP without increasing the density of the dots Dt in the space between the head unit 3 and the recording paper PP. In other words, according to this embodiment, it is possible to achieve both improved print quality by suppressing adhesion of mist to the periphery of the nozzles N and improved user convenience by shortening the time required for the flushing process.

[0093] As described above, in this modified example, the control unit 2 supplies the supply drive signal Vin-1[1] having the large-volume ink ejection waveform PF1 to the piezoelectric element PZ-1[1] among the piezoelectric elements PZ-1[1] to PZ-1[6] during the unit period TP(1), thereby ejecting the liquid in the cavity CV-1[1] from the nozzle N-1[1], and supplies the supply drive signal Vin-2[1] having the small-volume ink ejection waveform PF2 different from the large-volume ink ejection waveform PF1 to the piezoelectric element PZ-2[1] among the piezoelectric elements PZ-2[1] to PZ-2[6], thereby ejecting the liquid in the cavity CV-1[1] from the nozzle N-1[1]. The liquid in V-2[1] is ejected from nozzle N-2[1], and in unit period TP(2), a supply drive signal Vin-1[1] having a small amount of ink ejection waveform PF2 different from the large amount of ink ejection waveform PF1 is supplied to piezoelectric element PZ-1[1], thereby ejecting the liquid in cavity CV-1[1] from nozzle N-1[1], and a supply drive signal Vin-2[1] having a large amount of ink ejection waveform PF1 different from the small amount of ink ejection waveform PF2 is supplied to piezoelectric element PZ-2[1], thereby ejecting the liquid in cavity CV-2[1] from nozzle N-2[1].

[0094] Therefore, according to this modified example, compared to the embodiment in which, during the unit period TP(1), a supply drive signal Vin-1[1] having a large amount of ink ejection waveform PF1 is supplied to the piezoelectric element PZ-1[1], and a supply drive signal Vin-2[1] having a large amount of ink ejection waveform PF1 is supplied to the piezoelectric element PZ-2[1], and during the unit period TP(2), a supply drive signal Vin-1[1] having a large amount of ink ejection waveform PF1 is supplied to the piezoelectric element PZ-1[1], and a supply drive signal Vin-2[1] having a large amount of ink ejection waveform PF1 is supplied to the piezoelectric element PZ-2[1], as in reference example 1, the density of the ink dots Dt ejected from nozzle N-1[1] and nozzle N-2[1] in the space between the head unit 3 and the recording paper PP is lowered, the amount of mist that rises around the nozzle N is reduced, and a deterioration in print quality due to the mist can be suppressed. Furthermore, according to this modified example, the time required for the flushing process can be shortened compared to the case in which, as in Reference Example 3, during the unit period TP(1), a supply drive signal Vin-1[1] having a large-volume ink discharge waveform PF1 is supplied to the piezoelectric element PZ-1[1], and a supply drive signal Vin-2[1] having an ink discharge limiting waveform PFN is supplied to the piezoelectric element PZ-2[1], and during the unit period TP(2), a supply drive signal Vin-1[1] having an ink discharge limiting waveform PFN is supplied to the piezoelectric element PZ-1[1], and a supply drive signal Vin-2[1] having a large-volume ink discharge waveform PF1 is supplied to the piezoelectric element PZ-2[1].

[0095] In this modified example, the unit period TP(1) is an example of a "first period", the unit period TP(2) is an example of a "second period", the piezoelectric element PZ-1[1] is an example of a "first drive element", the piezoelectric element PZ-2[1] is an example of a "second drive element", the supply drive signal Vin-1[1] supplied in the unit period TP(1) is an example of a "first drive signal", the supply drive signal Vin-2[1] supplied in the unit period TP(1) is an example of a "second drive signal", the supply drive signal Vin-1[1] supplied in the unit period TP(2) is an example of a "third drive signal", the supply drive signal Vin-2[1] supplied in the unit period TP(2) is an example of a "fourth drive signal", the large-volume ink discharge waveform PF1 is an example of a "first waveform" and a "fourth waveform", and the small-volume ink discharge waveform PF2 is an example of a "second waveform" and a "third waveform".

[0096] In addition, in this modified example, the supply drive signal Vin-1[1] supplied in the unit period TP(1) includes three waveforms PAA, the supply drive signal Vin-2[1] supplied in the unit period TP(1) includes one waveform PAA, the supply drive signal Vin-1[1] supplied in the unit period TP(2) includes one waveform PAA, and the supply drive signal Vin-2[1] supplied in the unit period TP(2) includes three waveforms PAA. Therefore, according to this modification, compared to Reference Example 1, it is possible to reduce the amount of mist generated from the ink ejected from nozzle N-1[1] and nozzle N-2[1], and further to suppress the mist generated from the dots Dt ejected from nozzle N-1[m0] and nozzle N-2[m0] from rolling up around nozzle N, thereby suppressing deterioration in print quality due to the mist. Furthermore, according to this modification, it is possible to reduce the time required for the flushing process compared to Reference Example 3.

[0097] <<Variation 2>> In the above-described embodiment and variant 1, an example has been given in which, in each unit period TP, supply drive signals Vin-1[1] to Vin-1[M] having the same waveform are supplied to the discharge units D-1[1] to D-1[M] corresponding to the nozzles N-1[1] to N-1[M] belonging to the nozzle row NL-1, and supply drive signals Vin-2[1] to Vin-2[M] having the same waveform are supplied to the discharge units D-2[1] to D-2[M] corresponding to the nozzles N-2[1] to N-2[M] belonging to the nozzle row NL-2, but the present invention is not limited to such an example. For example, in each unit period TP, among the supply drive signals Vin-1[1] to Vin-1[M] supplied to the discharge sections D-1[1] to D-1[M], one supply drive signal Vin-1 may have a different waveform from the other supply drive signals Vin-1, and among the supply drive signals Vin-2[1] to Vin-2[M] supplied to the discharge sections D-2[1] to D-2[M], one supply drive signal Vin-2 may have a different waveform from the other supply drive signals Vin-2. Furthermore, for example, among the discharge sections D-1[1] to D-1[M], the supply drive signal Vin-1 supplied to one discharge section D-1 may have a different waveform from the supply drive signal Vin-1 supplied to another discharge section D-1 adjacent to the one discharge section D-1, and among the discharge sections D-2[1] to D-2[M], the supply drive signal Vin-2 supplied to one discharge section D-2 may have a different waveform from the supply drive signal Vin-2 supplied to another discharge section D-2 adjacent to the one discharge section D-2.

[0098] FIG. 15 is an explanatory diagram for explaining the flushing process according to the second modification.

[0099] 15, like Fig. 8, illustrates the case where "M=6", that is, the case where each nozzle row NL provided in the head unit 3 is made up of six discharge sections D. Also, like Fig. 8, Fig. 15 assumes the case where flushing processes are performed in unit periods TP(1) to TP(6).

[0100] As illustrated in FIG. 15, the control unit 2 according to this modification designates the odd-numbered discharge units D-1[1], D-1[3], and D-1[5] of the discharge units D-1[1] to D-1[6] corresponding to the nozzle row NL-1 as large-volume ink discharge units DF-1 in each of the unit periods TP(1) to TP(3) among the unit periods TP(1) to TP(6) in which the flushing process is performed, and designates the even-numbered discharge units D-1[2], D-1[4], and , D-1[6] as small amount ink ejection units DF-2, and among the ejection units D-2[1] to D-2[6] corresponding to nozzle row NL-2, each of the odd-numbered ejection units D-2[1], D-2[3], and D-2[5] is designated as small amount ink ejection units DF-2, and each of the even-numbered ejection units D-2[2], D-2[4], and D-2[6] is designated as large amount ink ejection units DF-1, and a print signal SI is supplied to the head unit 3. Furthermore, the control unit 2 according to this modification designates each of the odd-numbered discharge units D-1[1], D-1[3], and D-1[5] of the discharge units D-1[1] to D-1[6] corresponding to the nozzle row NL-1 as small-volume ink discharge units DF-2 in each of the unit periods TP(4) to TP(6) among the unit periods TP(1) to TP(6) in which the flushing process is performed, and designates each of the even-numbered discharge units D-1[2], D-1[4], and D-1[5] as small-volume ink discharge units DF-3. A print signal SI is supplied to the head unit 3, which designates each of the odd-numbered discharge units D-2[1], D-2[3], and D-2[5] of the discharge units D-2[1] to D-2[6] corresponding to the nozzle row NL-2 as large-volume ink discharge units DF-1, and designates each of the even-numbered discharge units D-2[2], D-2[4], and D-2[6] as small-volume ink discharge units DF-2.

[0101] Figure 16 is a conceptual diagram showing how droplets ejected from nozzles N-1[1] to N-1[6] provided in head unit 3 fly as dots when the flushing process related to Reference Example 1 is performed.

[0102] 16, in the flushing process according to Reference Example 1, the discharge units D-1[1] to D-1[6] are driven by a supply drive signal Vin-1[m0] having three waveforms PAA, thereby operating as a large-volume ink discharge unit DF-1, and three dots Dt are continuously discharged from the nozzles N-1[1] to N-1[6] corresponding to the discharge units D-1[1] to D-1[6] in each unit period TP. Therefore, in the flushing process according to Reference Example 1, the density of the dots Dt in the space between the head unit 3 and the recording paper PP is increased, and inter-nozzle decompression spaces SP are generated between the nozzles N-1[1] and N-1[2], between the nozzles N-1[2] and N-1[3], between the nozzles N-1[3] and N-1[4], between the nozzles N-1[4] and N-1[5], and between the nozzles N-1[5] and N-1[6]. Therefore, in the flushing process according to Reference Example 1, a self-jet JF-A is generated between nozzle N-1[1] and nozzle N-1[2], between nozzle N-1[2] and nozzle N-1[3], between nozzle N-1[3] and nozzle N-1[4], between nozzle N-1[4] and nozzle N-1[5], and between nozzle N-1[5] and nozzle N-1[6]. Therefore, in the flushing process according to Reference Example 1, the head unit 3 may be contaminated by ink adhering as a mist, which may prevent the head unit 3 from ejecting ink normally.

[0103] FIG. 17 is a conceptual diagram showing how droplets ejected from nozzles N-1[1] to N-1[6] provided in the head unit 3 fly as dots when the flushing process according to this modified example is performed.

[0104] As illustrated in FIG. 17, in the flushing process according to this modified example, for example, in a unit period TP(1), among the ejection sections D-1[1] to D-1[6], the odd-numbered ejection sections D-1[1], D-1[3], and D-1[5] are each driven by a supply drive signal Vin-1[1], Vin-1[3], or Vin-1[5] having three waveforms PAA, and operate as large-volume ink ejection sections DF-1, while the even-numbered ejection sections D-1[2], D-1[4], and D-1[6] are each driven by a supply drive signal Vin-1[2], Vin-1[4], or Vin-1[6] having one waveform PAA, and operate as small-volume ink ejection sections DF-2. Therefore, in the flushing process of this modified example, the density of dots Dt in the space between the head unit 3 and the recording paper PP is lower than in the case of the above-mentioned reference example 1, and although air flow JF-B occurs, self-jet flow JF-A does not occur. For this reason, in the flushing process according to this modified example, compared to Reference Example 1, the density of the dots Dt ejected from the nozzles N-1[1] to N-1[6] in the space between the head unit 3 and the recording paper PP is lower, making it possible to reduce the amount of mist that rolls up around the nozzles N and reduce the amount of mist that adheres to the head unit 3. Similarly, in the flushing process according to this modified example, compared to Reference Example 1, the density of the dots Dt ejected from the nozzles N-2[1] to N-2[6] in the space between the head unit 3 and the recording paper PP is lower, making it possible to reduce the amount of mist that rolls up around the nozzles N and reduce the amount of mist that adheres to the head unit 3. In other words, in the flushing process according to this modified example, it is possible to reduce the risk of a state in which ink cannot be ejected normally from the nozzles N, compared to Reference Example 1.

[0105] <<Variation 3>> In the above-described modified example 2, the discharger D operates as the large-volume ink discharger DF-1 over a plurality of consecutive unit periods TP, but the present invention is not limited to this. For example, in the flushing process, the discharger D may alternately operate as the large-volume ink discharger DF-1 and the small-volume ink discharger DF-2 for each unit period TP.

[0106] FIG. 18 is an explanatory diagram for explaining the flushing process according to the third modification.

[0107] 18, like Fig. 8, illustrates the case where "M=6", that is, the case where each nozzle row NL provided in the head unit 3 is made up of six discharge sections D. Also, like Fig. 8, Fig. 18 assumes the case where flushing processing is performed in unit periods TP(1) to TP(6).

[0108] As illustrated in FIG. 18, the control unit 2 according to this modification designates each of the odd-numbered discharge units D-1[1], D-1[3], and D-1[5] of the discharge units D-1[1] to D-1[6] corresponding to the nozzle row NL-1 as large-volume ink discharge units DF-1 in each of the odd-numbered unit periods TP(1), TP(3), and TP(5) of the unit periods TP(1) to TP(6) in which the flushing process is performed. A print signal SI is supplied to the head unit 3, which designates each of the odd-numbered discharge units D-2[1], D-2[3], and D-2[5] of the discharge units D-2[1] to D-2[6] corresponding to the nozzle row NL-2 as small ink discharge units DF-2, and designates each of the even-numbered discharge units D-2[2], D-2[4], and D-2[6] as large ink discharge units DF-1. Furthermore, the control unit 2 according to this modification designates each of the odd-numbered discharge units D-1[1], D-1[3], and D-1[5] of the discharge units D-1[1] to D-1[6] corresponding to the nozzle row NL-1 as small-volume ink discharge units DF-2 in each of the even-numbered unit periods TP(2), TP(4), and TP(6) among the unit periods TP(1) to TP(6) in which the flushing process is performed, and designates each of the odd-numbered discharge units D-1[1], D-1[3], and D-1[5] of the discharge units D-1[1] to D-1[6] corresponding to the nozzle row NL-1 as small-volume ink discharge units DF-2, and designates the even-numbered discharge units D-1[2], D-1[4] , and D-1[6] as large-volume ink ejection units DF-1, and among the ejection units D-2[1] to D-2[6] corresponding to nozzle row NL-2, each of the odd-numbered ejection units D-2[1], D-2[3], and D-2[5] is designated as large-volume ink ejection units DF-1, and each of the even-numbered ejection units D-2[2], D-2[4], and D-2[6] is designated as small-volume ink ejection units DF-2. A print signal SI is supplied to the head unit 3.

[0109] That is, the control unit 2 according to this modification supplies a supply drive signal Vin-1[1] having a large-volume ink ejection waveform PF1 to the ejector D-1[1] during each of the odd-numbered unit periods TP(1), TP(3), and TP(5), thereby operating the ejector D-1[1] as a large-volume ink ejector DF-1 and ejecting ink from the cavity CV-1[1] from the nozzle N-1[1] belonging to the nozzle row NL-1. The control unit 2 according to this modification also supplies a supply drive signal Vin-1[2] having a small-volume ink ejection waveform PF2 to the ejector D-1[2] during each of the odd-numbered unit periods TP(1), TP(3), and TP(5), thereby operating the ejector D-1[2] as a small-volume ink ejector DF-2 and ejecting ink from the cavity CV-1[2] from the nozzle N-1[2] belonging to the nozzle row NL-1. Furthermore, the control unit 2 according to this modification supplies a supply drive signal Vin-2[1] having a small amount of ink ejection waveform PF2 to the ejector D-2[1] during each of the odd-numbered unit periods TP(1), TP(3), and TP(5), thereby operating the ejector D-2[1] as a small amount of ink ejection unit DF-2 and ejecting ink from the cavity CV-2[1] from the nozzle N-2[1] belonging to the nozzle row NL-2. Furthermore, the control unit 2 according to this modification supplies a supply drive signal Vin-2[2] having a large amount of ink ejection waveform PF1 to the ejector D-2[2] during each of the odd-numbered unit periods TP(1), TP(3), and TP(5), thereby operating the ejector D-2[2] as a large amount of ink ejection unit DF-1 and ejecting ink from the cavity CV-2[2] from the nozzle N-2[2] belonging to the nozzle row NL-2. Furthermore, the control unit 2 according to this modification supplies a supply drive signal Vin-1[1] having a small amount of ink ejection waveform PF2 to the ejector D-1[1] during each of the even-numbered unit periods TP(2), TP(4), and TP(6), thereby operating the ejector D-1[1] as a small amount of ink ejection unit DF-2 and ejecting ink from the cavity CV-1[1] from the nozzle N-1[1] belonging to the nozzle row NL-1. Furthermore, the control unit 2 according to this modification supplies a supply drive signal Vin-1[2] having a large amount of ink ejection waveform PF1 to the ejector D-1[2] during each of the even-numbered unit periods TP(2), TP(4), and TP(6), thereby operating the ejector D-1[2] as a large amount of ink ejection unit DF-1 and ejecting ink from the cavity CV-1[2] from the nozzle N-1[2] belonging to the nozzle row NL-1. Furthermore, the control unit 2 according to this modification supplies a supply drive signal Vin-2[1] having a large-volume ink ejection waveform PF1 to the ejector D-2[1] during each of the even-numbered unit periods TP(2), TP(4), and TP(6), thereby operating the ejector D-2[1] as a large-volume ink ejection unit DF-1 and ejecting ink from the cavity CV-2[1] from the nozzle N-2[1] belonging to the nozzle row NL-2. Furthermore, the control unit 2 according to this modification supplies a supply drive signal Vin-2[2] having a small-volume ink ejection waveform PF2 to the ejector D-2[2] during each of the even-numbered unit periods TP(2), TP(4), and TP(6), thereby operating the ejector D-2[2] as a small-volume ink ejection unit DF-2 and ejecting ink from the cavity CV-2[2] from the nozzle N-2[2] belonging to the nozzle row NL-2.

[0110] As described above, in this modified example, the control unit 2 supplies the supply drive signal Vin-1[1] having the large-volume ink ejection waveform PF1 to the piezoelectric element PZ-1[1] among the piezoelectric elements PZ-1[1] to PZ-1[6] corresponding to the nozzles N-1[1] to N-1[6] belonging to the nozzle row NL-1 during the unit period TP(1), thereby causing the liquid in the cavity CV-1[1] to be ejected from the nozzle N-1[1], and supplies the supply drive signal Vin-1[2] having the small-volume ink ejection waveform PF2, which is different from the large-volume ink ejection waveform PF1, to the piezoelectric element PZ-1[2]. By supplying a supply drive signal Vin-1[1] having a small amount of ink ejection waveform PF2 to the piezoelectric element PZ-1[1], the liquid in the cavity CV-1[2] is ejected from the nozzle N-1[2], and by supplying a supply drive signal Vin-1[2] having a large amount of ink ejection waveform PF1 different from the small amount of ink ejection waveform PF2 to the piezoelectric element PZ-1[2], the liquid in the cavity CV-1[2] is ejected from the nozzle N-1[2].

[0111] Therefore, according to this modified example, compared to the embodiment in which, during the unit period TP(1), a supply drive signal Vin-1[1] having a large-volume ink ejection waveform PF1 is supplied to the piezoelectric element PZ-1[1], and a supply drive signal Vin-1[2] having a large-volume ink ejection waveform PF1 is supplied to the piezoelectric element PZ-1[2], and during the unit period TP(2), a supply drive signal Vin-1[1] having a large-volume ink ejection waveform PF1 is supplied to the piezoelectric element PZ-1[1], and a supply drive signal Vin-1[2] having a large-volume ink ejection waveform PF1 is supplied to the piezoelectric element PZ-1[2], as in reference example 1, the density of the ink dots Dt ejected from nozzle N-1[1] and nozzle N-1[2] in the space between the head unit 3 and the recording paper PP is lower, reducing the amount of mist that swirls up around the nozzle N and making it possible to suppress deterioration in print quality due to the mist.

[0112] In this modified example, the piezoelectric element PZ-1[1] is an example of a "one first driving element," the piezoelectric element PZ-1[2] is an example of an "other first driving element," the supply driving signal Vin-1[1] supplied in the unit period TP(1) is an example of a "first driving signal," the supply driving signal Vin-1[2] supplied in the unit period TP(1) is an example of a "second driving signal," the supply driving signal Vin-1[1] supplied in the unit period TP(2) is an example of a "third driving signal," the supply driving signal Vin-1[2] supplied in the unit period TP(2) is an example of a "fourth driving signal," the large-volume ink ejection waveform PF1 is an example of a "first waveform" and a "fourth waveform," and the small-volume ink ejection waveform PF2 is an example of a "second waveform" and a "third waveform."

[0113] In addition, in this modified example, the supply drive signal Vin-1[1] supplied in the unit period TP(1) includes three waveforms PAA, the supply drive signal Vin-1[2] supplied in the unit period TP(1) includes one waveform PAA, the supply drive signal Vin-1[1] supplied in the unit period TP(2) includes one waveform PAA, and the supply drive signal Vin-1[2] supplied in the unit period TP(2) includes three waveforms PAA. Therefore, according to this modified example, compared to reference example 1, the density of ink dots Dt ejected from nozzle N-1[1] and nozzle N-1[2] in the space between the head unit 3 and the recording paper PP is lower, reducing the amount of mist that rises around nozzle N and making it possible to suppress a decrease in print quality caused by the mist.

[0114] In addition, in this modified example, the control unit 2 supplies, in the unit period TP(1), a supply drive signal Vin-1[1], Vin-1[3], or Vin-1[5] having a large-volume ink ejection waveform PF1 to odd-numbered piezoelectric elements PZ-1[1], PZ-1[3], and PZ-1[5] among the piezoelectric elements PZ-1[1] to PZ-1[6] corresponding to the nozzles N-1[1] to N-1[6] belonging to the nozzle row NL-1, thereby ejecting the liquid from the cavities CV-1[1], CV-1[3], and CV-1[5] to the nozzles N-1[1], N-1[3], or , N-1[5], and in the unit period TP(1), the liquid in the cavities CV-1[2], CV-1[4], and CV-1[6] is discharged from the nozzles N-1[2], N-1[5], and the liquid in the cavities CV-1[2], CV-1[4], and CV-1[6] is discharged from the nozzles N-1[2], N-1[5], and the liquid in the cavities CV-1[2], CV-1[4], and CV-1[6] is discharged from the nozzles N-1[2], N-1[5], and the liquid in the cavities CV-1[2], CV-1[4], and CV-1[6] is discharged from the nozzles N-1[2], N-1[5], and the liquid in the cavities CV-1[2], CV-1[4], and CV-1[6] is discharged from the nozzles N-1[5], N-1[5], and the liquid in the cavities CV-1[5], ... In the unit period TP(2), the liquid in the cavities CV-1[1], CV-1[3], and CV-1[5] is discharged from the nozzles N-1[1], N-1[3], or N-1[6], and by supplying a supply drive signal Vin-1[1], Vin-1[3], or Vin-1[5] having a small amount of ink discharge waveform PF2 to the odd-numbered piezoelectric elements PZ-1[1] to PZ-1[6] corresponding to the nozzles N-1[1] to N-1[6] belonging to the nozzle row NL-1, the liquid in the cavities CV-1[1], CV-1[3], and CV-1[5] is discharged from the nozzles N-1[1], N-1[3], or N-1[6]. In the unit period TP(2), the liquid in the cavities CV-1[2], CV-1[4], and CV-1[6] is discharged from the nozzles N-1[2], N-1[5], and the liquid in the cavities CV-1[2], CV-1[4], and CV-1[6] is discharged from the nozzles N-1[2], N-1[5], and the liquid in the cavities CV-1[2], CV-1[4], and CV-1[6] is discharged from the nozzles N-1[2], N-1[5], and the liquid in the cavities CV-1[2], CV-1[4], and CV-1[6] is discharged from the nozzles N-1[2], N-1[5], and the liquid in the cavities CV-1[2], CV-1[4], and CV-1[6] is discharged from the nozzles N-1[2], N-1[5], and the liquid in the cavities CV-1[2], CV-1[4], and CV-1[6] is discharged from the nozzles N-1[5 ...Discharge from N-1[4] or N-1[6].

[0115] Therefore, according to this modification, it is possible to suppress the deterioration of print quality caused by mist compared to Reference Example 1. Furthermore, according to this modification, it is possible to shorten the time required for the flushing process compared to Reference Example 3.

[0116] In this modified example, one nozzle N-1 among the odd-numbered nozzles N-1[1], N-1[3], and N-1[5] is an example of an "odd-numbered first nozzle," one nozzle N-1 among the even-numbered nozzles N-1[2], N-1[4], and N-1[6] is an example of an "even-numbered first nozzle," the piezoelectric element PZ-1 corresponding to the odd-numbered first nozzle is an example of an "odd-numbered first driving element," and the piezoelectric element PZ-1 corresponding to the even-numbered first nozzle is an example of an "even-numbered first driving element," The supply drive signal Vin-1 supplied to odd-numbered first drive elements in the unit period TP(1) is an example of a "first drive signal," the supply drive signal Vin-1 supplied to even-numbered first drive elements in the unit period TP(1) is an example of a "second drive signal," the supply drive signal Vin-1 supplied to odd-numbered first drive elements in the unit period TP(2) is an example of a "third drive signal," and the supply drive signal Vin-1 supplied to even-numbered first drive elements in the unit period TP(2) is an example of a "fourth drive signal."

[0117] In addition, in this modified example, the supply drive signal Vin-1 supplied to the odd-numbered first drive elements in the unit period TP(1) includes three waveforms PAA, the supply drive signal Vin-1 supplied to the even-numbered first drive elements in the unit period TP(1) includes one waveform PAA, the supply drive signal Vin-1 supplied to the odd-numbered first drive elements in the unit period TP(2) includes one waveform PAA, and the supply drive signal Vin-1 supplied to the even-numbered first drive elements in the unit period TP(2) includes three waveforms PAA. Therefore, according to this modified example, compared to Reference Example 1, the density of the ink dots Dt ejected from nozzle N-1[1] and nozzle N-2[1] in the space between the head unit 3 and the recording paper PP is lower, reducing the amount of mist that rises up around nozzle N and making it possible to suppress deterioration in print quality due to the mist. Also, according to this modified example, it is possible to shorten the time required for the flushing process compared to Reference Example 3.

[0118] In addition, in this modified example, the control unit 2 supplies, in the unit period TP(1), the supply drive signal Vin-1[1], Vin-1[3], or Vin-1[5] having the large-volume ink ejection waveform PF1 to the odd-numbered piezoelectric elements PZ-1[1], PZ-1[3], and PZ-1[5] among the piezoelectric elements PZ-1[1] to PZ-1[6] corresponding to the nozzles N-1[1] to N-1[6] belonging to the nozzle row NL-1, thereby ejecting the liquid from the cavities CV-1[1], CV-1[3], and CV-1[5] to the nozzles N-1[1], N-1[3], or In the unit period TP(1), the liquid in the cavities CV-1[2], CV-1[4], and CV-1[6] is discharged from the nozzles N-1[5], and by supplying the supply drive signal Vin-1[2], Vin-1[4], or Vin-1[6] having a small amount of ink discharge waveform PF2 different from the large amount of ink discharge waveform PF1 to the even-numbered piezoelectric elements PZ-1[2], PZ-1[4], and PZ-1[6] among the piezoelectric elements PZ-1[1] to PZ-1[6] corresponding to the nozzles N-1[1] to N-1[6] belonging to the nozzle row NL-1, the liquid in the cavities CV-1[2], CV-1[4], and CV-1[6] is discharged from the nozzles N-1[2], ], N-1[4], or N-1[6], and in the unit period TP(1), a supply drive signal Vin-2[1], Vin-2[3], or Vin-2[5] having a small amount of ink ejection waveform PF2 is supplied to odd-numbered piezoelectric elements PZ-2[1], PZ-2[3], and PZ-2[5] among piezoelectric elements PZ-2[1] to PZ-2[6] corresponding to nozzles N-2[1] to N-2[6] belonging to nozzle row NL-2, thereby ejecting the liquid from cavities CV-2[1], CV-2[3], and CV-2[5] to nozzles N-2[1], N-2[ 3] or N-2[5], and in the unit period TP(1), the liquid in the cavities CV-2[2], CV-2[4], and CV-2[6] is discharged from the nozzles N-2[2], N-2[4], or N-2[5] by supplying a supply drive signal Vin-2[2], Vin-2[4], or Vin-2[6] having a large amount of ink discharge waveform PF1 to the even-numbered piezoelectric elements PZ-2[2], PZ-2[4], and PZ-2[6] among the piezoelectric elements PZ-2[1] to PZ-2[6] corresponding to the nozzles N-2[1] to N-2[6] belonging to the nozzle row NL-2.N-2[6], and in the unit period TP(2), the liquid in the cavities CV-1[1], CV-1[3], and CV-1[5] is discharged from the nozzles N-1[1], N-1[3], or N-1[5] by supplying a supply drive signal Vin-1[1], Vin-1[3], or Vin-1[5] having a small amount of ink discharge waveform PF2 to the odd-numbered piezoelectric elements PZ-1[1] to PZ-1[6] corresponding to the nozzles N-1[1] to N-1[6] belonging to the nozzle row NL-1. In the unit period TP(2), the liquid in the cavities CV-1[2], CV-1[4], and CV-1[6] is discharged from the nozzles N-1[2], N-1[4], or Vin-1[6] by supplying a supply drive signal Vin-1[2], Vin-1[4], or Vin-1[6] having a large amount of ink discharge waveform PF1 different from the small amount of ink discharge waveform PF2 to the even-numbered piezoelectric elements PZ-1[2], PZ-1[4], and PZ-1[6] among the piezoelectric elements PZ-1[1] to PZ-1[6] corresponding to the nozzles N-1[1] to N-1[6] belonging to the nozzle row NL-1. In the unit period TP(2), the liquid in the cavities CV-2[1], CV-2[3], and CV-2[5] is discharged from the nozzles N-1[6], and ...2[1], N-2[3], or N-2[5] by supplying the supply drive signal Vin-2[1], Vin-2[3], or Vin-2[5] having the large-volume ink discharge waveform PF1 to the odd-numbered piezoelectric elements PZ-2[1], PZ-2[3], and PZ-2[5] among the piezoelectric elements PZ-2[1] to PZ-2[6] corresponding to the nozzles N-2[1] to N-2[6] belonging to the nozzle row NL-2. In the unit period TP(2), the liquid in the cavities CV-2[2], CV-2[4], and CV-2[6] is discharged from the nozzles N-2[2], N-2[4], or N-2[6] by supplying a supply drive signal Vin-2[2], Vin-2[4], or Vin-2[6] having a small amount of ink discharge waveform PF2 to the even-numbered piezoelectric elements PZ-2[2], PZ-2[4], and PZ-2[6] among the piezoelectric elements PZ-2[1] to PZ-2[6] corresponding to the nozzles N-2[1] to N-2[6] belonging to the nozzle row NL-2.

[0119] Therefore, according to this modification, it is possible to suppress the deterioration of print quality caused by mist compared to Reference Example 1. Furthermore, according to this modification, it is possible to shorten the time required for the flushing process compared to Reference Example 3.

[0120] In addition, in this modified example, the supply drive signal Vin-1 supplied to the odd-numbered first drive elements in the unit period TP(1) includes three waveforms PAA, the supply drive signal Vin-1 supplied to the even-numbered first drive elements in the unit period TP(1) includes one waveform PAA, the supply drive signal Vin-1 supplied to the odd-numbered first drive elements in the unit period TP(2) includes one waveform PAA, and the supply drive signal Vin-1 supplied to the even-numbered first drive elements in the unit period TP(2) includes three waveforms PAA. Therefore, according to this modified example, compared to Reference Example 1, the density of the ink dots Dt ejected from nozzle N-1[1] and nozzle N-2[1] in the space between the head unit 3 and the recording paper PP is lower, reducing the amount of mist that rises up around nozzle N and making it possible to suppress deterioration in print quality due to the mist. Also, according to this modified example, it is possible to shorten the time required for the flushing process compared to Reference Example 3.

[0121] <<Variation 4>> In the above-described embodiment and modifications 1 to 3, the large-volume ink discharge waveform PF1 includes three waveforms PAA, and the small-volume ink discharge waveform PF2 includes one waveform PAA. However, the present invention is not limited to this. For example, the waveform included in the large-volume ink discharge waveform PF1 and the waveform included in the small-volume ink discharge waveform PF2 may be different.

[0122] FIG. 19 is an explanatory diagram for explaining the individual designation signal Sd[m] according to the fourth modification.

[0123] 19, in this modified example, when the individual designation signal Sd[m] indicates a value of "5" that designates the discharger D[m] as the large-volume ink discharger DF-1 during the flushing unit period TPF, the connection state designation circuit 310 sets the connection state designation signal Qa[m] to a high level during the control periods TQ1, TQ2, and TQ3. In this case, the switch Wa[m] is turned on throughout the flushing unit period TPF. Therefore, during the flushing unit period TPF, the discharger D[m] is driven by the supply drive signal Vin[m] having waveforms PA1, PA2, and PA3, and discharges ink at an ink volume ξ4 corresponding to a large ink discharge. Furthermore, if the individual designation signal Sd[m] indicates a value of "6," which designates the discharger D[m] as the small-volume ink discharger DF-2 during the flushing unit period TPF, the connection state designation circuit 310 sets the connection state designation signal Qb[m] to a high level during the control periods TQ1 and TQ2. In this case, the switch Wb[m] is turned on during the control periods TQ1 and TQ2. Therefore, during the flushing unit period TPF, the discharger D[m] is driven by the supply drive signal Vin[m] having waveforms PB1 and PB2, and discharges an ink amount ξ6, which is smaller than the ink amount ξ4.

[0124] That is, in this modified example, it is assumed that the large amount of ink discharge waveform PF1 is a waveform made up of waveforms PA1, PA2, and PA3, and the small amount of ink discharge waveform PF2 is a waveform made up of waveforms PB2 and PB2.

[0125] As described above, in this modification, the first drive signal includes three waveforms PAA, the second drive signal includes two waveforms PBB, the third drive signal includes two waveforms PBB, and the fourth drive signal includes three waveforms PAA. That is, in this modification, the waveform included in the first drive signal is different from the waveform included in the second drive signal, which is different from the waveform included in the third drive signal, which is different from the waveform included in the second drive signal, which is different from the waveform included in the fourth drive signal, and which is different from the waveform included in the third drive signal. Therefore, according to this modified example, compared to the embodiment in which each of the first to fourth drive signals includes three waveforms PAA, as in Reference Example 1, the density of the ink dots Dt ejected from the nozzle N in the space between the head unit 3 and the recording paper PP is lower, reducing the amount of mist that rises around the nozzle N and making it possible to suppress a decrease in print quality due to the mist.

[0126] Furthermore, in this modified example, when the piezoelectric element PZ[m] is driven by the supply drive signal Vin[m] having the waveform PAA, the speed of the dot Dt ejected from the nozzle N[m] is faster than the speed of the dot Dt ejected from the nozzle N[m] when the piezoelectric element PZ[m] is driven by the supply drive signal Vin[m] having the waveform PBB. Therefore, according to this modified example, compared to the embodiment in which each of the first to fourth drive signals includes three waveforms PAA, as in Reference Example 1, the density of the ink dots Dt ejected from the nozzle N in the space between the head unit 3 and the recording paper PP is lower, reducing the amount of mist that rises around the nozzle N and making it possible to suppress a decrease in print quality due to the mist. In this modified example, the waveform PAA is an example of a "first drive pulse," and the waveform PBB is an example of a "second drive pulse."

[0127] Furthermore, in this modified example, when the piezoelectric element PZ[m] is driven by the supply drive signal Vin[m] having the waveform PAA, the amount of dots Dt ejected from the nozzle N[m] is greater than the amount of dots Dt ejected from the nozzle N[m] when the piezoelectric element PZ[m] is driven by the supply drive signal Vin[m] having the waveform PBB. Therefore, according to this modified example, compared to the embodiment in which each of the first to fourth drive signals includes three waveforms PAA, as in Reference Example 1, the density of the ink dots Dt ejected from the nozzle N in the space between the head unit 3 and the recording paper PP is lower, reducing the amount of mist that rises around the nozzle N and making it possible to suppress a decrease in print quality due to the mist.

[0128] <<Variation 5>> In the above-described embodiment and modifications 1 to 5, it is assumed that the waveforms PA1, PA2, and PA3 included in the drive signal Com-A have substantially the same shape, and the waveforms PB1 and PB2 included in the drive signal Com-B have substantially the same shape, but the present invention is not limited to such an embodiment. For example, the waveforms PA1 and PA2 may have waveforms with different shapes, the waveforms PA1 and PA3 may have waveforms with different shapes, or the waveforms PA2 and PA3 may have waveforms with different shapes. Furthermore, the waveforms PB1 and PB2 may have waveforms with different shapes.

[0129] <<Variation 6>> In the above-described embodiment and modified examples 1 to 5, the drive signal Com-A includes three ejection waveforms, waveforms PA1, PA2, and PA3, and the drive signal Com-B includes two ejection waveforms, waveforms PB1 and PB2, as the ejection waveforms that eject ink from the nozzle N. However, the present invention is not limited to such an embodiment. For example, the drive signal Com-A may include at least one ejection waveform, and the drive signal Com-B may include at least one ejection waveform.

[0130] <<Variation 7>> In the above-described embodiment and variants 1 to 6, the drive signal Com includes two signals, drive signal Com-A and drive signal Com-B, but the present invention is not limited to this form. For example, the drive signal Com may include only the drive signal Com-A and not the drive signal Com-B. In this case, the drive signal Com-A only needs to include at least two or more ejection waveforms. Furthermore, for example, the drive signal Com may include only the drive signal Com-B and not the drive signal Com-A. In this case, the drive signal Com-B only needs to include at least two or more ejection waveforms. Furthermore, for example, the drive signal Com may include, in addition to the drive signal Com-A and the drive signal Com-B, a drive signal having a waveform different from the drive signal Com-A and the drive signal Com-B.

[0131] <<Variation 8>> In the above-described embodiment and modified examples 1 to 7, the head unit 3 is illustrated as having two nozzle rows NL, nozzle row NL-1 and nozzle row NL-2, but the present invention is not limited to this. The head unit 3 may be equipped with only the above-described single nozzle row NL-1, or may be equipped with three or more nozzle rows NL. Note that, when the head unit 3 has three or more nozzle rows NL, the nozzle rows NL-1 and NL-2 are adjacent nozzle rows NL. In other words, when the head unit 3 has three or more nozzle rows NL, there is no other nozzle row NL between the nozzle rows NL-1 and NL-2. When the head unit 3 has three or more nozzle rows NL, the piezoelectric element PZ corresponding to the nozzle row NL arranged on the +Y-axis side of the nozzle row NL-2 may be driven in the same manner as the piezoelectric element PZ-1 corresponding to the nozzle row NL-1, or may be driven in a manner different from the piezoelectric element PZ-1 corresponding to the nozzle row NL-1 and the piezoelectric element PZ-2 corresponding to the nozzle row NL-2. In other words, even when the head unit 3 has three or more nozzle rows NL, by driving the piezoelectric elements PZ corresponding to the nozzle rows NL located on both sides of each inter-nozzle decompression space SP in the configurations of the above-described embodiment and modified example, it is possible to suppress self-jet flow and prevent mist from adhering to the head unit 3.

[0132] <<Variation 9>> In the above-described embodiments and variants 1 to 8, the nozzle rows NL1 and NL-2 included in the head unit 3 have been described. However, when multiple head units 3 are lined up in the Y-axis direction, there is also an inter-nozzle reduced pressure space SP between the head units 3, and in order to prevent mist from adhering to the head unit 3 due to self-jetting, the piezoelectric elements PZ corresponding to the nozzle rows NL located on both sides of the inter-nozzle reduced pressure space SP between the head units 3 are driven in the configurations of the above-described embodiments and variants, thereby suppressing self-jetting and preventing mist from adhering to the head unit 3.

[0133] <<Variation 10>> In the above-described embodiment and variations 1 to 9, it is assumed that the inkjet printer 1 is equipped with four head units 3, but the present invention is not limited to this. The inkjet printer 1 may be equipped with one to three head units 3, or the inkjet printer 1 may be equipped with five or more head units 3.

[0134] <<Modification 11>> In the above-described embodiment and variations 1 to 10, the inkjet printer 1 is a serial printer, but the present invention is not limited to this. The inkjet printer 1 may also be a so-called line printer, in which the head unit 3 has multiple nozzles N that extend wider than the width of the recording paper PP. [Explanation of symbols]

[0135] 1...inkjet printer, 2...control unit, 3...head unit, 4...drive signal generation unit, 7...transport unit, 8...maintenance unit, 31...supply circuit, 32...recording head, D...ejection section, N...nozzle

Claims

1. a first nozzle row including a plurality of first nozzles arranged in parallel along a first axis and configured to eject liquid; 、 a plurality of second nozzles arranged in parallel along a second axis parallel to the first axis and ejecting a liquid; a second nozzle row including: a plurality of first pressure chambers that are provided corresponding to the plurality of first nozzles and are filled with liquid; a plurality of second pressure chambers filled with liquid, the second pressure chambers being provided corresponding to the plurality of second nozzles; a pressure adjusting unit for adjusting the pressure in the corresponding first pressure chamber; a plurality of first drive elements; a pressure adjusting unit for adjusting the pressure in the second pressure chamber; a plurality of second drive elements; a supply unit that supplies drive signals to the plurality of first drive elements and the plurality of second drive elements; A maintenance method for a head unit comprising: In the first period, For one first driving element among the plurality of first driving elements, providing a first drive signal having a first waveform; Among the plurality of first pressure chambers, a liquid in one first pressure chamber corresponding to the one first driving element Body, Among the plurality of first nozzles, one first nozzle corresponding to the one first pressure chamber is discharged. Let, For one second driving element among the plurality of second driving elements, providing a second drive signal having a second waveform different from the first waveform; Among the plurality of second pressure chambers, a liquid in one second pressure chamber corresponding to the one second driving element is Body, Among the plurality of second nozzles, one second nozzle corresponding to the one second pressure chamber is discharged. Let, In a second period different from the first period, For the one first driving element, supplying a third drive signal having a third waveform different from the first waveform; Discharging the liquid in the one first pressure chamber from the one first nozzle; For the one second driving element, providing a fourth drive signal having a fourth waveform different from the second waveform and the third waveform; By doing so, Discharging the liquid in the one second pressure chamber from the one second nozzle; the first waveform and the fourth waveform have the same shape; The second waveform and the third waveform have the same shape. A maintenance method characterized by:

2. The first drive signal is a first driving element for driving the first driving element to eject liquid from the first nozzle; a first number of drive pulses; The second drive signal is a second driving element for driving the second driving element to eject liquid from the second nozzle; a second number of drive pulses different from the first number; The third drive signal is a third driving element for driving the first driving element to eject liquid from the first nozzle; a third number of drive pulses different from the first number; The fourth drive signal is a fourth driving element for driving the one second driving element to eject liquid from the one second nozzle; a fourth number of drive pulses different from the second number and the third number; 2. The maintenance method according to claim 1, wherein:

3. The first drive signal is a first driving element for driving the first driving element to eject liquid from the first nozzle; Including a drive pulse, The second drive signal is a second driving element for driving the second driving element to eject liquid from the second nozzle; Including a drive pulse, The third drive signal is a third driving element for driving the first driving element to eject liquid from the first nozzle; Including a drive pulse, The fourth drive signal is a fourth driving element for driving the one second driving element to eject liquid from the one second nozzle; Including a drive pulse, The waveform of the first drive pulse is different from the waveform of the second drive pulse, The waveform of the first drive pulse is different from the waveform of the third drive pulse, The waveform of the second drive pulse is different from the waveform of the fourth drive pulse, The waveform of the third drive pulse is different from the waveform of the fourth drive pulse.

2. The maintenance method according to claim 1, wherein:

4. When the first driving element is driven by the first driving pulse, the first nozzle The velocity of the liquid ejected from When the one second driving element is driven by the second driving pulse, the one second nozzle faster than the velocity of the liquid being discharged from The maintenance method according to claim 3, wherein:

5. When the first driving element is driven by the first driving pulse, the first nozzle The amount of liquid dispensed from When the one second driving element is driven by the second driving pulse, the one second nozzle The amount of liquid discharged from 5. The maintenance method according to claim 3 or 4.

6. a first nozzle row including a plurality of first nozzles arranged in parallel along a first axis and configured to eject liquid; 、 a plurality of first pressure chambers that are provided corresponding to the plurality of first nozzles and are filled with liquid; a pressure adjusting unit for adjusting the pressure in the corresponding first pressure chamber; a plurality of first drive elements; a supply unit that supplies drive signals to the plurality of first drive elements; A maintenance method for a head unit comprising: In the first period, Among the plurality of first driving elements, one first nozzle included in the plurality of first nozzles For a corresponding one of the first drive elements, providing a first drive signal having a first waveform; Among the plurality of first pressure chambers, a liquid in one first pressure chamber corresponding to the one first driving element Body, Discharge from the one first nozzle, Among the plurality of first driving elements, one of the plurality of first nozzles is included in the plurality of first nozzles, and For other corresponding first drive elements for other adjacent first nozzles, providing a second drive signal having a second waveform different from the first waveform; Among the plurality of first pressure chambers, the liquid in the other first pressure chambers corresponding to the other first driving element Body, Discharge from the other first nozzle, In a second period different from the first period, For the one first driving element, supplying a third drive signal having a third waveform different from the first waveform; Discharging the liquid in the one first pressure chamber from the one first nozzle; With respect to the other first driving element, providing a fourth drive signal having a fourth waveform different from the second waveform and the third waveform; By doing so, Discharging the liquid in the other first pressure chamber from the other first nozzle; the first waveform and the fourth waveform have the same shape; The second waveform and the third waveform have the same shape. A maintenance method characterized by:

7. The first drive signal is a first driving element for driving the first driving element to eject liquid from the first nozzle; a first number of drive pulses; The second drive signal is a second driving element for driving the other first driving element to eject liquid from the other first nozzle; a second number of drive pulses different from the first number; The third drive signal is a third driving element for driving the first driving element to eject liquid from the first nozzle; a third number of drive pulses different from the first number; The fourth drive signal is a fourth driving element for driving the other first driving element to eject liquid from the other first nozzle; a fourth number of drive pulses different from the second number and the third number; The maintenance method according to claim 6,

8. The first drive signal is a first driving element for driving the first driving element to eject liquid from the first nozzle; Including a drive pulse, The second drive signal is a second driving element for driving the other first driving element to eject liquid from the other first nozzle; Including a drive pulse, The third drive signal is a third driving element for driving the first driving element to eject liquid from the first nozzle; Including a drive pulse, The fourth drive signal is a fourth driving element for driving the other first driving element to eject liquid from the other second nozzle; Including a drive pulse, The waveform of the first drive pulse is different from the waveform of the second drive pulse, The waveform of the first drive pulse is different from the waveform of the third drive pulse, The waveform of the second drive pulse is different from the waveform of the fourth drive pulse, The waveform of the third drive pulse is different from the waveform of the fourth drive pulse. The maintenance method according to claim 6,

9. When the first driving element is driven by the first driving pulse, the first nozzle The velocity of the liquid ejected from When the other first driving element is driven by the second driving pulse, the other first nozzle faster than the velocity of the liquid being discharged from The maintenance method according to claim 8 .

10. When the first driving element is driven by the first driving pulse, the first nozzle The amount of liquid dispensed from When the other first driving element is driven by the second driving pulse, the other first nozzle The amount of liquid discharged from 10. The maintenance method according to claim 8 or 9.

11. a first nozzle row including a plurality of first nozzles arranged in parallel along a first axis and configured to eject liquid; 、 a plurality of first pressure chambers that are provided corresponding to the plurality of first nozzles and are filled with liquid; a pressure adjusting unit for adjusting the pressure in the corresponding first pressure chamber; a plurality of first drive elements; a supply unit that supplies drive signals to the plurality of first drive elements; A maintenance method for a head unit comprising: In the first period, Among the plurality of first driving elements, odd-numbered first nozzles among the plurality of first nozzles For the corresponding odd-numbered first drive elements, providing a first drive signal having a first waveform; Among the plurality of first pressure chambers, odd-numbered first pressure chambers corresponding to the odd-numbered first drive elements The liquid in the pressure chamber Discharge from the odd-numbered first nozzles, Among the plurality of first driving elements, even-numbered first nozzles among the plurality of first nozzles For the corresponding even-numbered first drive elements, providing a second drive signal having a second waveform different from the first waveform; Among the plurality of first pressure chambers, even-numbered first pressure chambers corresponding to the even-numbered first drive elements The liquid in the pressure chamber Discharge from the even-numbered first nozzles, In a second period different from the first period, For the odd-numbered first drive elements, supplying a third drive signal having a third waveform different from the first waveform; Discharging the liquid in the odd-numbered first pressure chambers from the odd-numbered first nozzles; For the even-numbered first drive elements, providing a fourth drive signal having a fourth waveform different from the second waveform and the third waveform; By doing so, discharging the liquid in the even-numbered first pressure chambers from the even-numbered first nozzles; A maintenance method characterized by:

12. The first drive signal is The odd-numbered first driving elements are driven to eject liquid from the odd-numbered first nozzles. a first number of first driving pulses for driving; The second drive signal is The even-numbered first driving elements are driven to eject liquid from the even-numbered first nozzles. a second number of second driving pulses for driving that are different from the first number; The third drive signal is The odd-numbered first driving elements are driven to eject liquid from the odd-numbered first nozzles. a third number of third driving pulses for driving that are different from the first number; The fourth drive signal is The even-numbered first driving elements are driven to eject liquid from the even-numbered first nozzles. The fourth driving pulses to be driven include a fourth number different from the second number and the third number. nothing, The maintenance method according to claim 11,

13. The first drive signal is The odd-numbered first driving elements are driven to eject liquid from the odd-numbered first nozzles. a first driving pulse for driving the The second drive signal is The even-numbered first driving elements are driven to eject liquid from the even-numbered first nozzles. a second driving pulse for driving the The third drive signal is The odd-numbered first driving elements are driven to eject liquid from the odd-numbered first nozzles. a third driving pulse for driving the The fourth drive signal is The even-numbered first driving elements are driven to eject liquid from the even-numbered first nozzles. a fourth driving pulse for driving the The waveform of the first drive pulse is different from the waveform of the second drive pulse, The waveform of the first drive pulse is different from the waveform of the third drive pulse, The waveform of the second drive pulse is different from the waveform of the fourth drive pulse, The waveform of the third drive pulse is different from the waveform of the fourth drive pulse. The maintenance method according to claim 11,

14. the first waveform and the fourth waveform have the same shape; The second waveform and the third waveform have the same shape. The maintenance method according to claim 11,

15. The waveform of the first drive pulse, the waveform of the second drive pulse, and the waveform of the third drive pulse the waveform of the fourth drive pulse is the same as the waveform of the fourth drive pulse, the first number and the fourth number are the same number, the second number and the third number are the same number; 13. The maintenance method according to claim 2, 7 or 12.

16. The waveform of the first drive pulse and the waveform of the fourth drive pulse have the same shape. the law of nature, The waveform of the second drive pulse and the waveform of the third drive pulse have the same shape. Ru, 14. The maintenance method according to claim 3, 8, or 13.

17. a first nozzle row including a plurality of first nozzles arranged in parallel along a first axis and configured to eject liquid; 、 a plurality of second nozzles arranged in parallel along a second axis parallel to the first axis and ejecting a liquid; a second nozzle row including: a plurality of first pressure chambers that are provided corresponding to the plurality of first nozzles and are filled with liquid; a plurality of second pressure chambers filled with liquid, the second pressure chambers being provided corresponding to the plurality of second nozzles; a pressure adjusting unit for adjusting the pressure in the corresponding first pressure chamber; a plurality of first drive elements; a pressure adjusting unit for adjusting the pressure in the second pressure chamber; a plurality of second drive elements; a supply unit that supplies drive signals to the plurality of first drive elements and the plurality of second drive elements; A maintenance method for a head unit comprising: In the first period, Among the plurality of first driving elements, odd-numbered first nozzles among the plurality of first nozzles supplying a first drive signal having a first waveform to the corresponding odd-numbered first drive elements; By this, among the plurality of first pressure chambers, odd-numbered first pressure chambers corresponding to the odd-numbered first drive elements are the liquid in the first pressure chamber is discharged from the odd-numbered first nozzle, Among the plurality of first driving elements, even-numbered first nozzles among the plurality of first nozzles For the corresponding even-numbered first drive elements, a second waveform different from the first waveform is provided. By supplying a second drive signal corresponding to the first pressure chamber, the even-numbered first drive signals are The liquid in the even-numbered first pressure chamber corresponding to the moving element is discharged from the even-numbered first nozzle. Let, Among the plurality of second driving elements, odd-numbered second nozzles among the plurality of second nozzles By supplying the second drive signal to the corresponding odd-numbered second drive elements, Among the odd numbered second pressure chambers, the odd numbered second pressure chambers correspond to the odd numbered second driving elements. the liquid is discharged from the odd-numbered second nozzles, Among the plurality of second driving elements, the even-numbered second nozzles among the plurality of second nozzles By supplying the first drive signal to the corresponding even-numbered second drive elements, Among the second pressure chambers, the even-numbered second pressure chambers corresponding to the even-numbered second driving elements the liquid is discharged from the even-numbered second nozzles, In a second period different from the first period, By supplying the second drive signal to the odd-numbered first drive elements, the liquid in the odd-numbered first pressure chamber is discharged from the odd-numbered first nozzle; By supplying the first drive signal to the even-numbered first drive elements, the liquid in the even-numbered first pressure chamber is discharged from the even-numbered first nozzle, Among the plurality of second driving elements, odd-numbered second nozzles among the plurality of second nozzles By supplying the first drive signal to the corresponding odd-numbered second drive elements, Among the odd numbered second pressure chambers, the odd numbered second pressure chambers correspond to the odd numbered second driving elements. the liquid is discharged from the odd-numbered second nozzles, Among the plurality of second driving elements, the even-numbered second nozzles among the plurality of second nozzles By supplying the second drive signal to the corresponding even-numbered second drive elements, Among the second pressure chambers, the even-numbered second pressure chambers corresponding to the even-numbered second driving elements The liquid is discharged from the even-numbered second nozzles. A maintenance method characterized by:

18. The first drive signal is Driving the first drive element to eject liquid from the first nozzle; a driving element capable of driving the second driving element so as to eject liquid from the second nozzle; a first number of The second drive signal is a second number of the drive pulses different from the first number; 18. The maintenance method according to claim 17,

19. The first drive signal is Driving the first drive element to eject liquid from the first nozzle; a first drive element capable of driving the second drive element so as to eject liquid from the second nozzle; including a dynamic pulse, The second drive signal is Driving the first drive element to eject liquid from the first nozzle; a second drive element capable of driving the second drive element so as to eject liquid from the second nozzle; including a dynamic pulse, The waveform of the first drive pulse is different from the waveform of the second drive pulse.

18. The maintenance method according to claim 17,

20. the first nozzle row and the second nozzle row are adjacent to each other; A maintenance method according to any one of claims 1 to 5 and claims 17 to 19. Law.

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