Method for driving liquid ejection head, and liquid ejection apparatus

Abstract

The present application provides a kind of liquid ejection head driving method of liquid droplet can be ejected even if the viscosity of liquid is high, and liquid ejection device.The liquid ejection head driving method of the present application has: first step, by supplying driving signal with first waveform to driving element, so that the liquid level in the ejection part is protruded to the ejection direction first liquid column formation;Second step, in the case where first liquid column is formed, by supplying driving signal with second waveform to driving element, so that after the liquid level in the ejection part is protruded to the ejection direction second liquid column formation, part or all of the liquid constituting second liquid column is ejected as liquid droplet, and in the case where driving signal with first waveform and without second waveform is supplied to driving element, no liquid droplet is ejected from the ejection part, in the case where driving signal with second waveform and without first waveform is supplied to driving element, no liquid droplet is ejected from the ejection part.

Description

TECHNICAL FIELD

[0001] The present application relates to a driving method of a liquid ejection head, and a liquid ejection apparatus. BACKGROUND

[0002] In Patent Literature 1, a liquid ejection head that ejects liquid droplets by being supplied with a driving signal is disclosed.

[0003] However, in the above-described prior art, when the viscosity of the liquid becomes high, it can not be possible to eject liquid droplets.

[0004] Patent Literature 1: Japanese Patent Application Publication No. 2011-37257 SUMMARY

[0005] To solve the above problems, a driving method of a liquid ejection head according to a preferred embodiment of the present application is a driving method of a liquid ejection head having an ejection section that includes a driving element that is displaced by being supplied with a driving signal, a pressure chamber that increases and decreases the pressure inside thereof in accordance with the displacement of the driving element, and a nozzle that communicates with the pressure chamber and that ejects liquid filled inside the pressure chamber as liquid droplets in an ejection direction in accordance with the increase and decrease of the pressure inside the pressure chamber, in which the driving method has: a first step of forming a first liquid column in which a liquid surface inside the ejection section protrudes in the ejection direction, by supplying the driving element with a driving signal having a first waveform that includes a first driving pulse having a first driving component that decreases the pressure inside the pressure chamber and a second driving component that increases the pressure inside the pressure chamber; and a second step of ejecting a part or all of the liquid that constitutes the second liquid column as liquid droplets after forming a second liquid column in which the liquid surface inside the ejection section protrudes in the ejection direction, by supplying the driving element with a driving signal having a second waveform that includes a second driving pulse having a third driving component that decreases the pressure inside the pressure chamber and a fourth driving component that increases the pressure inside the pressure chamber, in a case where the first liquid column is formed, in which liquid droplets are not ejected from the ejection section in a case where the driving element is supplied with a driving signal having the first waveform and not having the second waveform, and liquid droplets are not ejected from the ejection section in a case where the driving element is supplied with a driving signal having the second waveform and not having the first waveform.

[0006] Further, in order to solve the above problems, a liquid ejecting apparatus according to a preferred embodiment of the present application includes: a liquid ejecting head including an ejecting portion including a driving element that is displaced by being supplied with a driving signal, a pressure chamber that increases and decreases a pressure inside the pressure chamber in accordance with the displacement of the driving element, and a nozzle that communicates with the pressure chamber and ejects a liquid filled inside the pressure chamber as a liquid droplet in an ejecting direction in accordance with the increase and decrease of the pressure inside the pressure chamber; and a control portion that controls the liquid ejecting head, the control portion performing control to form a first liquid column in which a liquid surface inside the ejecting portion protrudes in the ejecting direction by supplying the driving element with a driving signal having a first waveform including a first driving pulse having a first driving component that decreases the pressure inside the pressure chamber and a second driving component that increases the pressure inside the pressure chamber, and after the first liquid column is formed, ejecting a part or all of the liquid constituting the first liquid column as a liquid droplet after a second liquid column in which the liquid surface inside the ejecting portion protrudes in the ejecting direction is formed by supplying the driving element with a driving signal having a second waveform including a second driving pulse having a third driving component that decreases the pressure inside the pressure chamber and a fourth driving component that increases the pressure inside the pressure chamber, and in a case where the driving signal having the first waveform and not having the second waveform is supplied to the driving element, a liquid droplet is not ejected from the ejecting portion, and in a case where the driving signal having the second waveform and not having the first waveform is supplied to the driving element, a liquid droplet is not ejected from the ejecting portion. BRIEF DESCRIPTION OF DRAWINGS

[0007] Figure 1 A functional block diagram showing one example of the structure of the inkjet printer 1 in the present embodiment.

[0008] Figure 2 A schematic diagram exemplifying the inkjet printer 1.

[0009] Figure 3 A schematic diagram exemplifying the inkjet printer 1.

[0010] Figure 4 A block diagram showing one example of the structure of the liquid ejecting head HU.

[0011] Figure 5 A timing chart showing an operation in the recording period Tu[i] of the inkjet printer 1.

[0012] Figure 6FIG. 4 is a diagram for explaining five drive modes available for the individually designated signal Sd[m].

[0013] Figure 7 FIG. 5 is a diagram for explaining the drive signal Vin based on the drive mode a2 for the individually designated signal Sd[m].

[0014] Figure 8 FIG. 6 is a diagram for explaining the meniscus MS at the time point tl.

[0015] Figure 9 FIG. 7 is a diagram for explaining the meniscus MS at the time point t2.

[0016] Figure 10 FIG. 8 is a diagram for explaining the meniscus MS at the time point t3.

[0017] Figure 11 FIG. 9 is a diagram for explaining the meniscus MS at the time point t4.

[0018] Figure 12 FIG. 10 is a diagram for explaining the meniscus MS at the time point t5.

[0019] Figure 13 FIG. 11 is a diagram for explaining the meniscus MS at the time point t6.

[0020] Figure 14 FIG. 12 is a diagram for explaining the meniscus MS at the time point t7.

[0021] Figure 15 FIG. 13 is a diagram for explaining the meniscus MS at the time point t8.

[0022] Figure 16 FIG. 14 is a diagram for explaining the meniscus MS at the time point t9.

[0023] Figure 17 FIG. 15 is a diagram for explaining the meniscus MS at the time point tlO.

[0024] Figure 18 FIG. 16 is a diagram for explaining the variation characteristics of the pressure generated by the drive signal Vin.

[0025] Figure 19 FIG. 17 is a diagram for explaining the variation characteristics of the volume velocity of the ink in the nozzle N.

[0026] Figure 20 FIG. 18 is a diagram for explaining the relationship between the period Pw and the ejection performance value.

[0027] Figure 21 FIG. 19 is a diagram showing a flowchart of a generation example of the individually designated signals Sd[l] to Sd[m].

[0028] Figure 22 FIG. 10 is a diagram for explaining a flow of a generation example of the individual designation signal Sd[l] ~ Sd[m].

[0029] Figure 23 FIG. 11 is a diagram for explaining a specific example of the recording method using the drive waveform signal Com.

[0030] Figure 24 FIG. 12 is a diagram for explaining five drive modes in the first modification.

[0031] Figure 25 FIG. 13 is a diagram for explaining a specific example of the recording method using the drive waveform signal Com in the first modification.

[0032] Figure 26 FIG. 14 is a diagram for explaining six drive modes in the second modification.

[0033] Figure 27 FIG. 15 is a diagram for explaining a specific example of the recording method using the drive waveform signal Com in the second modification.

[0034] Figure 28 FIG. 16 is a diagram for explaining the drive signal Vin in the case where the liquid droplet DR is ejected in the third modification.

[0035] Figure 29 FIG. 17 is a diagram for explaining the drive signal Vin in the case where the liquid droplet DR is ejected in the fourth modification.

[0036] Figure 30 FIG. 18 is a functional block diagram showing one example of the structure of the inkjet printer la in the fifth modification.

[0037] Figure 31 FIG. 19 is a diagram for explaining a determination example of the number of drive pulses PL included in the drive signal Vinl.

[0038] Figure 32 FIG. 20 is a diagram for explaining the drive waveform signal Comb in the seventh modification.

[0039] Figure 33 FIG. 21 is a diagram for explaining the drive waveform signal Coma in the eighth modification.

[0040] Figure 34 FIG. 22 is a diagram for explaining the drive waveform signal Comc in the ninth modification.

[0041] Figure 35 FIG. 23 is a diagram for explaining the drive waveform signal Comd in the tenth modification.

[0042] Figure 36Fig. 1 is a diagram for describing a drive waveform signal Come in a first modification example.

[0043] Figure 37 Fig. 2 is a diagram for describing a drive waveform signal Comef in a second modification example.

[0044] Figure 38 Fig. 3 is a diagram for representing one example of a discharge portion Dg in a

[0045] Figure 39 Fig. 4 is a diagram for representing one example of a discharge portion Dh in a DETAILED DESCRIPTION

[0046] Hereinafter, a mode for carrying out the present application will be described with reference to the accompanying drawings. However, in each drawing, the size and the scale of each portion are appropriately different from the actual situation. Further, although the mode described below is a preferred specific example of the present application, various limitations are added in terms of technology, but the scope of the present application is not limited to these modes as long as the description below does not particularly limit the gist of the present application.

[0047] 1. First Embodiment

[0048] In the present embodiment, an inkjet printer 1 that forms an image on a recording paper P in a manner of discharging ink is exemplified, and a liquid discharge device is described. The inkjet printer 1 is one example of a liquid discharge device. Ink is one example of a liquid. The recording paper P is one example of a medium.

[0049] It is assumed that the ink in the present embodiment is high viscosity compared to general ink. Specifically, in the present embodiment, the viscosity of the ink is 20 millipascal seconds or more, and preferably 40 millipascal seconds. Hereinafter, in the drawings, millipascal seconds are sometimes referred to as "mPa seconds".

[0050] 1.1. Outline of Inkjet Printer 1

[0051] While referring to Figure 1 and Figure 2 , the structure of the inkjet printer 1 in the present embodiment will be described. Here, Figure 1 is a functional block diagram representing one example of the structure of the inkjet printer 1 in the present embodiment. Further, Figure 2 is a schematic diagram exemplifying the inkjet printer 1.

[0052] In the inkjet printer 1, print data Img indicating an image that the inkjet printer 1 is to form, and information indicating the number of prints that the inkjet printer 1 is to form of the image are supplied from a host computer such as a personal computer or a digital still camera. The inkjet printer 1 performs a print process of forming the image indicated by the print data Img supplied from the host computer on the recording paper P.

[0053] As exemplified in Figure 1 , the inkjet printer 1 includes a liquid ejection head HU provided with an ejection portion D that ejects ink, a control portion 6 that controls the operation of each portion of the inkjet printer 1, a drive waveform signal generation circuit 2 that generates a drive waveform signal Com for driving the ejection portion D, a storage portion 5 that stores a control program and other information of the inkjet printer 1, a conveyance mechanism 7 that conveys the recording paper P, and a movement mechanism 8 that moves the liquid ejection head HU.

[0054] In the present embodiment, the liquid ejection head HU includes a recording head HD having M ejection portions D, and a switching circuit 10. In the present embodiment, M is an integer of one or more.

[0055] Hereinafter, in order to distinguish each of the M ejection portions D provided on the recording head HD, the ejection portions D are sometimes referred to as the 1st, 2nd, …, Mth in order. Further, the ejection portion D of the mth is sometimes referred to as the ejection portion D[m]. The variable m is an integer satisfying the condition of one or more and M or less. Further, in the case where a constituent element or a signal or the like of the inkjet printer 1 corresponds to the order m of the ejection portion D[m], the order m corresponding to the order m is sometimes expressed by marking a suffix [m] to a symbol representing the constituent element or the signal or the like.

[0056] In the present embodiment, a case where the inkjet printer 1 is a serial printer is assumed. Specifically, as shown in Figure 2 , the inkjet printer 1 performs a print process by ejecting ink from the ejection portion D while conveying the recording paper P in the sub-scanning direction and moving the liquid ejection head HU in the main scanning direction. In the present embodiment, as shown in Figure 2 , it is assumed that the +X direction and the -X direction opposite to the +X direction are the main scanning direction, and the +Y direction is the sub-scanning direction. Hereinafter, the +X direction and the -X direction are collectively referred to as the "X-axis direction", and the +Y direction and the -Y direction opposite to the +Y direction are collectively referred to as the "Y-axis direction". Further, a direction perpendicular to the X-axis direction and the Y-axis direction, and a direction as the ejection direction of the ink is referred to as the -Z direction. The -Z direction and the +Z direction opposite to the -Z direction are collectively referred to as the "Z-axis direction". The +Z direction is one example of the "pull-in direction".

[0057] While referring to Figure 3 , the recording head HD and the ejection section D provided on the recording head HD will be described.

[0058] Figure 3 is a schematic partial cross-sectional view of the recording head HD, which has been cut in a manner including the ejection section D.

[0059] As shown in Figure 3 , the ejection section D is provided with a piezoelectric element PZ that is displaced by being supplied with a drive signal Vin having a waveform selected from a plurality of waveforms possessed by a drive waveform signal Com, a chamber 320 that increases and decreases the pressure inside according to the displacement of the piezoelectric element PZ, a nozzle N that communicates with the chamber 320 and is capable of ejecting ink filled inside the chamber 320 in the form of a droplet in the -Z direction according to the increase and decrease of the pressure inside the chamber 320, and a vibrating plate 310. The piezoelectric element PZ is an example of a "drive element". The chamber 320 is an example of a "pressure chamber". The chamber 320 is a space divided by a chamber plate 340, a nozzle plate 330 on which the nozzle N is formed, and the vibrating plate 310. The chamber 320 communicates with a reservoir 350 via an ink supply port 360. The reservoir 350 communicates with the liquid container 14 corresponding to the ejection section D via an ink take-in port 370.

[0060] In the present embodiment, as the piezoelectric element PZ, a single wafer type as shown in Figure 3 is employed. Note that the piezoelectric element PZ is not limited to the single wafer type, and a dual piezoelectric wafer type or a stacked type or the like can be employed.

[0061] The piezoelectric element PZ has an upper electrode Zu, a lower electrode Zd, and a piezoelectric body Zm provided between the upper electrode Zu and the lower electrode Zd. The piezoelectric element PZ is a passive element that deforms according to a change in potential of the drive signal Vin. When the lower electrode Zd is electrically connected to a power supply line LHb set to a fixed potential Vbs and the drive signal Vin is supplied to the upper electrode Zu, so that a voltage is applied between the upper electrode Zu and the lower electrode Zd, the piezoelectric element PZ is displaced in the +Z direction or the -Z direction according to the applied voltage, and as a result of the displacement, the piezoelectric element PZ vibrates.

[0062] On the upper opening portion of the chamber plate 340, a vibrating plate 310 is provided. On the vibrating plate 310, a lower electrode Zd is joined. Therefore, when the piezoelectric element PZ is driven according to the drive signal Vin so as to vibrate, the vibrating plate 310 also vibrates. Then, the volume of the chamber 320 is changed by the vibration of the vibrating plate 310, so that the ink filled in the chamber 320 is ejected from the nozzle N. In a case where the ink in the chamber 320 is reduced by the ejection of the ink, the ink is supplied from the reservoir 350.

[0063] The conveyance mechanism 7 conveys the recording paper P in the +Y direction. Specifically, the conveyance mechanism 7 is provided with a conveyance roller (not shown) whose rotation axis is parallel to the X axis direction, and a motor (not shown) that rotates the conveyance roller under the control by the control section 6.

[0064] The moving mechanism 8 reciprocally moves the liquid ejection head HU along the X axis under the control by the control section 6. As exemplified in Figure 2 The moving mechanism 8 is provided with a conveyance body 82 of a substantially box shape that houses the liquid ejection head HU, and a jointless belt 81 on which the conveyance body 82 is fixed.

[0065] The storage section 5 is configured in a manner that includes a volatile memory such as a RAM and a non-volatile memory such as a ROM, an EEPROM, or a PROM, and stores various information such as print data Img supplied from a host computer, and a control program of the inkjet printer 1. RAM is an abbreviation for Random Access Memory. ROM is an abbreviation for Read Only Memory. EEPROM is an abbreviation for Electrically Erasable Programmable Read-Only Memory. PROM is an abbreviation for Programmable ROM.

[0066] The control section 6 is configured in a manner that includes a CPU. CPU is an abbreviation for Central Processing Unit. However, in the control section 6, instead of the CPU, a programmable logic device such as an FPGA can be provided. FPGA is an abbreviation for Field Programmable Gate Array.

[0067] The control section 6 causes the inkjet printer 1 to perform a print process by causing the CPU provided in the control section 6 to act in accordance with the control program stored in the storage section 5.

[0068] The control section 6 generates a print signal SI for controlling the liquid ejection head HU, a waveform designation signal dCom for controlling the drive waveform signal generation circuit 2, a signal for controlling the conveyance mechanism 7, and a signal for controlling the movement mechanism 8.

[0069] Here, the waveform designation signal dCom is a digital signal that designates the waveform of the drive waveform signal Com. Further, the drive waveform signal Com is an analog signal for driving the ejection section D. The drive waveform signal generation circuit 2 includes a DA conversion circuit, and generates the drive waveform signal Com having the waveform designated by the waveform designation signal dCom.

[0070] Further, the print signal SI is a digital signal for designating the kind of the action of the ejection section D. Specifically, the print signal SI is a signal that designates whether or not ink is ejected from the ejection section D when the ejection section D is driven, by designating whether or not the drive waveform signal Com is supplied to the ejection section D.

[0071] 1.2. Structure of the liquid ejection head HU

[0072] Hereinafter, the structure of the liquid ejection head HU will be described while referring to Figure 4

[0073] Figure 4 is a block diagram showing one example of the structure of the liquid ejection head HU. As described above, the liquid ejection head HU is provided with the recording head HD and the switching circuit 10. Further, the liquid ejection head HU is provided with the internal wiring LHa to which the drive waveform signal Com is supplied from the drive waveform signal generation circuit 2.

[0074] As shown in Figure 4 , in the switching circuit 10, the switches SWa[l] to SWa[M] are provided as M switches SWa, and the connection state designation circuit 11 that designates the connection state of each switch. In addition, as each switch, for example, a transmission gate can be employed.

[0075] The switch SWa[m] switches the conduction and non-conduction of the internal wiring LHa and the upper electrode Zu[m] of the piezoelectric element PZ[m] provided on the ejection section D[m], according to the connection state designation signal SLa[m]. For example, the switch SWa[m] is set to be in conduction in the case where the connection state designation signal SLa[m] is at a high level, and is set to be in non-conduction in the case where it is at a low level.

[0076] 1.3. Action of the head unit

[0077] Hereinafter, the action of the liquid ejection head HU will be described while referring to Figures 5-7 .​

[0078] In the present embodiment, the operation period of the inkjet printer 1 includes a plurality of recording periods Tu. In the inkjet printer 1 related to the present embodiment, a case is assumed in which the driving of each of the ejection sections D in the printing process is performed within each of the recording periods Tu. In the following description, the operation period of the inkjet printer 1 has I recording periods Tu. I is an integer of 2 or more. Further, the ith recording period Tu is sometimes referred to as a recording period Tu[i]. I is an integer from 1 to I.

[0079] In addition, in general, the inkjet printer 1 forms an image representing the print data Img by repeatedly performing the printing process from each of the ejection sections D once or a plurality of times by across and continuous or intermittent plurality of recording periods Tu.

[0080] Figure 5 is a timing chart for explaining the operation in the recording period Tu[i] of the inkjet printer 1.

[0081] As shown in Figure 5 , the control section 6 outputs the latch signal LAT having the pulse PLsL and the conversion signal CH having the pulse PLsC. Thereby, the control section 6 defines the recording period Tu[i] as the period from the rising of the pulse PLsL to the rising of the next pulse PLsL. Further, the control section 6 divides the recording period Tu[i] into the control period Tcu1, the control period Tcu2, the control period Tcu3, the control period Tcu4, and the control period Tcu5 in accordance with the pulse PLsC.

[0082] As shown in Figure 5 , the drive waveform signal generation circuit 2 outputs the drive waveform signal Com. The drive waveform signal Com has the drive pulse PL1 provided within the control period Tcu1, the drive pulse PL2 provided within the control period Tcu2, the drive pulse PL3 provided within the control period Tcu3, the drive pulse PL4 provided within the control period Tcu4, and the drive pulse PL5 provided within the control period Tcu5. In the present embodiment, the drive pulse PL supplied to the piezoelectric element PZ within the control period Tcu1 to the control period Tcu3 from the nozzle N is referred to as a waveform PH1, and the drive pulse PL supplied to the piezoelectric element PZ within the control period Tcu4 to the control period Tcu5 from the nozzle N is referred to as a waveform PH2. In the following description, the waveform PH1 and the waveform PH2 are sometimes collectively referred to as "waveform PH", and the drive pulses PL1 to PL5 are sometimes collectively referred to as "drive pulse PL".

[0083] The drive pulse PL1 has a drive component DC1 and a drive component DC2. The drive pulse PL2 has a drive component DC3 and a drive component DC4. The drive pulse PL3 has a drive component DC5 and a drive component DC6. The drive pulse PL4 has a drive component DC7 and a drive component DC8. The drive pulse PL5 has a drive component DC9 and a drive component DC10. The drive components DC1, DC3, DC5, DC7, and DC9 decrease the pressure of the chamber 320. The drive components DC2, DC4, DC6, DC8, and DC10 increase the pressure of the chamber 320. In the following description, the drive components DC1 to DC10 are sometimes collectively referred to as "drive components DC".

[0084] As shown in Figure 5 , the potential at the start and the potential at the end of the drive pulses PL1, PL2, PL3, PL4, and PL5 are each set to a reference potential V0. In the present embodiment, the reference potential V0 is also the highest potential of the drive pulses PL1 to PL5. Figure 5 The potential VL1 shown in

[0085] As exemplified in Figure 5 , the difference between the highest potential and the lowest potential in the drive pulses PL1 to PL5 is a potential difference Vh. That is, the difference between the highest potential and the lowest potential in the waveform PH1 is the potential difference Vh. Similarly, the difference between the highest potential and the lowest potential in the waveform PH2 is the potential difference Vh. In the following description, the difference between the highest potential and the lowest potential in the waveform PH is sometimes referred to as "the potential difference of the waveform PH". The potential difference of the waveform PH1 and the potential difference of the waveform PH2 are approximately equal. By the expression "approximately equal", it is meant that, in addition to the case of being exactly equal, the case where it can be considered to be equal if an error in measurement is taken into account is also included. The potential difference of the waveform PH is 80% or more of the maximum potential difference that can be supplied to the piezoelectric element PZ. Since the greater the potential difference of the waveform PH is, the more the amount of ejection increases, it is more preferable that the potential difference of the waveform PH be closer to the maximum potential difference that can be supplied to the piezoelectric element PZ. The designer of the inkjet printer 1 adjusts the potential difference of the waveform PH in such a way that it is close to the maximum potential difference that can be supplied to the piezoelectric element PZ.

[0086] The print signal SI includes individual designation signals Sd[1] to Sd[M] that designate the drive mode of the ejection sections D[1] to D[M] in each recording period Tu. Also, when the print processing is performed in the recording period Tu[i], the control section 6 supplies the individual designation signal Sd[i] to the ejection section D[i] and supplies the individual designation signal Sd[j] to the ejection section D[j] (i ≠ j). Figure 5As shown, the print signal SI including the individual designation signal Sd[l] to Sd[M] is supplied to the connection state designation circuit 11 in synchronization with the clock signal CL before the start of the recording period Tu[i]. In this case, the connection state designation circuit 11 generates the connection state designation signal SLa[m] based on the individual designation signal Sd[m] during the recording period Tu[i].

[0087] In addition, the individual designation signal Sd[m] according to the present embodiment is a signal that designates any one of five drive modes shown below, drive mode al to drive mode a5, in each recording period Tu. In the present embodiment, a case is assumed as an example in which the individual designation signal Sd[m] is a five-bit digital signal.

[0088] Figure 6 is a diagram for describing the five drive modes available for the individual designation signal Sd[m]. The individual designation signal Sd[m] indicates any one of the values that are a value (1, 1, 1, 1, 1) indicating the drive mode al, a value (0, 0, 0, 1, 1) indicating the drive mode a2, a value (0, 0, 1, 1, 1) indicating the drive mode a3, a value (0, 1, 1, 1, 1) indicating the drive mode a4, and a value (0, 0, 0, 0, 0) indicating the drive mode a5. When the x-th bit of the individual designation signal Sd[m] is "1", the connection state designation circuit 11 sets the connection state designation signal SLa[m] to a high level during the control period Tcux, and when the x-th bit is "0", sets the connection state designation signal SLa[m] to a low level during the control period Tcux. x is an integer from 1 to 5.

[0089] Specifically, the connection state specifying circuit 11 sets the connection state specifying signal SLa[m] to the high level within the control period Tcu1, the control period Tcu2, the control period Tcu3, the control period Tcu4, and the control period Tcu5 when the individual designation signal Sd[m] indicates the drive mode α1. The connection state specifying circuit 11 sets the connection state specifying signal SLa[m] to the low level within the control period Tcu1, the control period Tcu2, and the control period Tcu3, and sets the connection state specifying signal SLa[m] to the high level within the control period Tcu4 and the control period Tcu5 when the individual designation signal Sd[m] indicates the drive mode α2. The connection state specifying circuit 11 sets the connection state specifying signal SLa[m] to the low level within the control period Tcu1 and the control period Tcu2, and sets the connection state specifying signal SLa[m] to the high level within the control period Tcu3, the control period Tcu4, and the control period Tcu5 when the individual designation signal Sd[m] indicates the drive mode α3. The connection state specifying circuit 11 sets the connection state specifying signal SLa[m] to the low level within the control period Tcu1, and sets the connection state specifying signal SLa[m] to the high level within the control period Tcu2, the control period Tcu3, the control period Tcu4, and the control period Tcu5 when the individual designation signal Sd[m] indicates the drive mode α4. The connection state specifying circuit 11 sets the connection state specifying signal SLa[m] to the low level within the control period Tcu1, the control period Tcu2, the control period Tcu3, the control period Tcu4, and the control period Tcu5 when the individual designation signal Sd[m] indicates the drive mode α5. As one example of the drive signal Vin, use is made of Figure 7 to indicate the drive signal Vin based on the individual designation signal Sd[m] of the drive mode α2.

[0090] In the present embodiment, although the details will be described later, when the ejection section D in the state where the reference potential V0 is supplied to the piezoelectric element PZ and the position of the meniscus MS is stationary at the initial position Z0, the drive signal Vin based on the individual designation signal Sd[m] of the drive mode α1 is supplied to the piezoelectric element PZ, the liquid droplet DR is ejected from the nozzle N within the control period Tcu4 to the control period Tcu5. Figure 7FIG. 2 is a diagram for explaining the drive signal Vin for the individually designated signal Sd[m] based on the drive mode a2. The drive signal Vin includes a drive signal Vinl and a drive signal Vin2. The drive signal Vinl is the drive signal Vin from the start of the control period Tcu1 to the end of the control period Tcu3. The drive signal Vin2 is the drive signal Vin from the start of the control period Tcu4 to the end of the control period Tcu5. As shown in FIG. 2, the drive signal Vinl included in the drive signal Vin for the individually designated signal Sd[m] based on the drive mode a2 sets the ejection section D to non-driving from the start of the control period Tcu1 to the end of the control period Tcu3. The drive signal Vin2 included in the drive signal Vin for the individually designated signal Sd[m] based on the drive mode a2 drives the ejection section D from the start of the control period Tcu4 to the end of the control period Tcu5. In other words, the drive signal Vin for the individually designated signal Sd[m] based on the drive mode a2 does not have the waveform PHl, but has the waveform PH2. Figure 7

[0091] In addition, the drive signal Vinl is one example of the "first drive signal". The drive signal Vin2 is one example of the "second drive signal".

[0092] 1.4. Relationship between the drive signal Vin and the liquid surface of the ejection section D

[0093] Next, the following example is explained with reference to FIG. 3. Figures 8-17 Thus, the following example is explained, in which, in a state in which the position of the meniscus MS is stationary at the initial position Z0 in the stationary state of the ejection section D in which the reference potential Vo is supplied to the piezoelectric element PZ in the positive direction, in a case in which the drive signal Vin for the individually designated signal Sd[m] based on the drive mode a2 to the drive mode a5 is supplied to the piezoelectric element PZ, the droplet DR is not ejected from the nozzle N, and in a case in which the drive signal Vin for the individually designated signal Sd[m] based on the drive mode al is supplied to the piezoelectric element PZ, the droplet DR is ejected from the nozzle N, due to the high viscosity of the ink. The state of the liquid surface of the ejection section D at each of the time point tl, the time point t2, the time point t3, the time point t4, the time point t5, the time point t6, the time point t7, the time point t8, the time point t9, and the time point tlO shown in FIG. 3 is explained. Figure 5 Figures 8-17 ​​The diagram shows a cross-sectional view taken along the XZ plane at time points t1 to t10, showing the area near nozzle N. The liquid surface within the ejection section D represents the liquid surface within nozzle N. The liquid surface within nozzle N is defined as the liquid surface located inside the wall of nozzle N when viewing ejection section D along the -Z direction. Therefore, if the liquid surface located on the outer side of the wall of nozzle N when viewing ejection section D in a direction perpendicular to the -Z direction, such as along the Y-axis—that is, the liquid surface protruding from nozzle N in the -Z direction—is also located inside the wall of nozzle N when viewing ejection section D along the -Z direction, it is also included within the liquid surface within nozzle N. Hereinafter, the liquid surface within nozzle N will be referred to as the "curved surface MS".

[0094] In the first embodiment, even when the ejector portion D, which is supplied with a reference potential V0 from the positive piezoelectric element PZ, is in a static state and the position of the meniscus MS is... Figure 8 Starting from the initial position Z0, which is in a static state, a drive signal Vin with only one drive pulse PL is supplied to the piezoelectric element PZ. Due to the high viscosity of the liquid, the pressure variation of the ink within the chamber 320 cannot increase, and therefore the ejector section D does not eject droplets DR. The initial position Z0 is such that, in the Z-axis direction, the position of the meniscus MS is approximately aligned with the -Z direction surface of the nozzle plate 330. In practice, to maintain a proper negative pressure state for the ink within the ejector section D and prevent it from drooping from the nozzle N, the center of the meniscus MS is formed as a concave surface recessed towards the chamber 320. In the first embodiment, by supplying the piezoelectric element PZ with a drive signal Vin having drive pulses PL1, PL2, PL3, PL4, and PL5, the ejector section D ejects droplets. Furthermore, even if a drive signal Vin with drive pulses PL1, PL2, PL3, and PL4 but without drive pulse PL5 is supplied to the piezoelectric element PZ, the ejector section D will still eject droplets. By supplying the piezoelectric element PZ with drive signals Vin having drive pulses PL1, PL2, PL3, PL4 and PL5, a more stable ejection can be achieved compared to supplying the piezoelectric element PZ with drive signals Vin having drive pulses PL1, PL2, PL3 and PL4 but without drive pulse PL5.

[0095] Figure 8Fig. 6 is a view for explaining the meniscus MS at the time point t1. The time point t1 is a time point at which the supply of the drive component DC1 ends within the control period Tcu1. The piezoelectric element PZ is supplied with the drive signal Vin having the drive component DC1 by the switching circuit 10, whereby the meniscus MS is pulled in the +Z direction while being elongated in the Z-axis direction in the concave curved surface shape having the central portion of the meniscus MS recessed toward the chamber 320, that is, the +Z direction side. At this time, the portion of the meniscus MS pulled in the +Z direction the most is pulled in to the pull-in position Zp1. The portion of the meniscus MS pulled in the +Z direction the most is the central portion of the meniscus MS in the Z-axis direction view and corresponds to the bottom portion of the concave curved surface shape. The central portion of the meniscus MS is substantially coincident with the central portion of the nozzle N in the Z-axis direction view. Hereinafter, the central portion of the meniscus MS in the Z-axis direction view is simply referred to as the "central portion of the meniscus MS" for the sake of simplicity of explanation. Further, the periphery of the central portion of the meniscus MS is simply referred to as the "peripheral portion of the meniscus MS". The pull-in position Zp1 is located in the +Z direction from the initial position Z0.

[0096] Figure 9 Fig. 7 is a view for explaining the meniscus MS at the time point t2. The time point t2 is a time point at which the control period Tcu1 ends and the supply of the drive component DC2 ends. The piezoelectric element PZ is supplied with the drive signal Vin having the drive component DC2 by the switching circuit 10, whereby the meniscus MS is extruded in the -Z direction, and further, a liquid column LC2 protruding in the -Z direction is formed at the central portion of the meniscus MS. In the following description, the liquid column is defined as a protruding columnar or hammer-shaped liquid surface in the meniscus MS from the position closest to the +Z direction side to the position closest to the -Z direction side. The top end of the liquid column LC2 in the -Z direction is located at the extrusion position Zm1. The extrusion position Zm1 is located in the -Z direction from the initial position Z0.

[0097] Figure 10Fig. 6 is a diagram for explaining the meniscus MS at the time point t3. The time point t3 is a time point at which the supply of the drive component DC3 ends within the control period Tcu2. The piezoelectric element PZ is supplied with the drive signal Vin having the drive component DC3 by the switching circuit 10, so that the meniscus MS, which is a meniscus having a concave shape recessed into the +Z direction at the peripheral portion of the meniscus MS and having a liquid column LC3 protruding in the -Z direction at the central portion of the meniscus MS, is pulled in the +Z direction. At this time, the portion of the meniscus MS pulled in the most in the +Z direction is pulled in up to the pulled-in position Zp2. The pulled-in position Zp2 at the time point t3 is located at the +Z direction compared with the initial position Z0, and is located at the -Z direction compared with the pulled-in position Zp1 at the time point t1. That is, by supplying the piezoelectric element PZ with the drive component DC3, the ink in the nozzle N is pulled in the +Z direction although the pressure of the ink in the chamber 320 is reduced, but the liquid column LC3 protruding in the -Z direction is formed at the central portion of the meniscus MS at the time point t3 as shown in Fig. 6. The liquid column LC3 is formed at the central portion of the meniscus MS. When viewed in the -Z direction from the pulled-in position Zp2, it can be said that the central portion of the meniscus MS forms a convex shape. The liquid surface around the liquid column LC3 is recessed into the +Z direction. Figure 10

[0098] Figure 11 Fig. 7 is a diagram for explaining the meniscus MS at the time point t4. The time point t4 is a time point at which the control period Tcu2 ends and the supply of the drive component DC4 ends. The piezoelectric element PZ is supplied with the drive signal Vin having the drive component DC4 by the switching circuit 10, so that the meniscus MS is extruded in the -Z direction, and the liquid column LC4 protruding in the -Z direction is formed at the central portion of the meniscus MS. The tip of the liquid column LC4 in the -Z direction is located at the extruded position Zm2. The extruded position Zm2 at the time point t4 is located at the -Z direction compared with the extruded position Zm1 at the time point t2.

[0099] Figure 12 ​Fig. 6 is a view for explaining the meniscus MS at the time point t5. The time point t5 is a time point at which the supply of the drive component DC5 ends within the control period Tcu3. The piezoelectric element PZ is supplied with the drive signal Vin having the drive component DC5 by the switching circuit 10, so that the meniscus MS, which is a meniscus having a concave shape recessed into the +Z direction at the peripheral portion of the meniscus MS and having the liquid column LC5 protruding in the -Z direction at the central portion of the meniscus MS, is pulled in the +Z direction. At this time, the portion of the meniscus MS, which is pulled in the +Z direction the most, is pulled in up to the pull-in position Zp3. The pull-in position Zp3 at the time point t5 is located at the +Z direction compared with the initial position Z0, and is located at the -Z direction compared with the pull-in position Zp2 at the time point t3. That is, by supplying the piezoelectric element PZ with the drive component DC5, the ink in the nozzle N is pulled in the +Z direction although the pressure of the ink in the chamber 320 is reduced, but the liquid column LC5 protruding in the -Z direction is formed at the central portion of the meniscus MS at the time point t5 as shown in Fig. 6. Further, the liquid column LC5 at the time point t5 is larger than the liquid column LC3 at the time point t3. The liquid column LC5 is formed at the central portion of the meniscus MS. When viewed in the -Z direction from the pull-in position Zp3, it can be said that the central portion of the meniscus MS forms a convex shape. The liquid surface around the liquid column LC5 is recessed into the +Z direction. Figure 12

[0100] Figure 13 Fig. 6 is a view for explaining the meniscus MS at the time point t5. The time point t5 is a time point at which the supply of the drive component DC5 ends within the control period Tcu3. The piezoelectric element PZ is supplied with the drive signal Vin having the drive component DC5 by the switching circuit 10, so that the meniscus MS, which is a meniscus having a concave shape recessed into the +Z direction at the peripheral portion of the meniscus MS and having the liquid column LC5 protruding in the -Z direction at the central portion of the meniscus MS, is pulled in the +Z direction. At this time, the portion of the meniscus MS, which is pulled in the +Z direction the most, is pulled in up to the pull-in position Zp3. The pull-in position Zp3 at the time point t5 is located at the +Z direction compared with the initial position Z0, and is located at the -Z direction compared with the pull-in position Zp2 at the time point t3. That is, by supplying the piezoelectric element PZ with the drive component DC5, the ink in the nozzle N is pulled in the +Z direction although the pressure of the ink in the chamber 320 is reduced, but the liquid column LC5 protruding in the -Z direction is formed at the central portion of the meniscus MS at the time point t5 as shown in Fig. 6. Further, the liquid column LC5 at the time point t5 is larger than the liquid column LC3 at the time point t3. The liquid column LC5 is formed at the central portion of the meniscus MS. When viewed in the -Z direction from the pull-in position Zp3, it can be said that the central portion of the meniscus MS forms a convex shape. The liquid surface around the liquid column LC5 is recessed into the +Z direction.

[0101] Figure 14 ​The diagram illustrates the meniscus MS at time point t7. Time point t7 is the point within the control period Tcu4 where the supply of the driving component DC7 ends. A driving signal Vin containing the driving component DC7 is supplied to the piezoelectric element PZ via the switching circuit 10, thereby pulling the meniscus MS in the +Z direction. The meniscus MS has a concave shape at its periphery that is recessed towards the +Z direction and a liquid column LC5 protruding towards the -Z direction at its central portion. At this time, the portion of the meniscus MS that is pulled in the +Z direction the most is pulled in until the pull-in position Zp4 is reached. The pull-in position Zp4 at time point t7 is located closer to the +Z direction than the pull-in position Zp3 at time point t5, and closer to the -Z direction than the pull-in position Zp1 at time point t1. In other words, by supplying the driving component DC7 to the piezoelectric element PZ, even though the ink pressure in the chamber 320 decreases and the ink in the nozzle N is pulled in the +Z direction, it still... Figure 14 As shown, at time point t7, a liquid column LC7 protruding in the -Z direction forms in the central portion of the meniscus MS. The liquid column LC7 at time point t7 is larger than the liquid column LC5 at time point t5. Furthermore, at... Figure 14 The figure shows the meniscus MS at time point t7 when drive signals Vin with drive pulses PL1, PL2, PL3, PL4, and PL5 are supplied to the piezoelectric element PZ. That is, Figure 14 The state of the meniscus MS shown is the case where drive pulses PL1 to PL3 are supplied to the piezoelectric element PZ before drive pulse PL4 is supplied to it. Assuming that a drive signal Vin consisting only of drive pulse PL4 is supplied to the piezoelectric element PZ, and the ejector portion D, which is currently supplied with a reference potential V0, is in a stationary state while the meniscus MS is stationary at its initial position Z0, drive pulse PL4 is supplied to the piezoelectric element PZ. Therefore, at time point t7, the meniscus MS will be in the same state as... Figure 8 The meniscus MS at time point t1 is equivalent. That is, when the drive signal Vin with only the drive pulse PL4 is supplied to the piezoelectric element PZ, the meniscus MS has a concave curved surface shape that is recessed in the +Z direction at its central part, and the position of the part of the meniscus MS that is pulled in the +Z direction the most is the pull-in position Zp1.

[0102] Figure 15Fig. 8 is a view for explaining the meniscus MS at time point t8. The time point t8 is the end time point of the control period Tcu4 and is the time point at which the supply of the drive component DC8 is ended. The piezoelectric element PZ is supplied with the drive signal Vin having the drive component DC8 by the switching circuit 10, so that the meniscus MS is extruded in the -Z direction, and further a liquid column LC8 is formed which protrudes in the -Z direction at the central portion of the meniscus MS. The length of the liquid column LC8 in the Z axis direction at the time point t8 is shorter than that of the liquid column LC7 at the time point t7. For the liquid column LC8, the tip end thereof in the -Z direction is in a spherical shape, and a neck portion is generated at the middle of the liquid column LC8.

[0103] Figure 16 Fig. 9 is a view for explaining the meniscus MS at time point t9. The time point t9 is within the control period Tcu5 and is the time point at which the supply of the drive component DC9 is ended. The piezoelectric element PZ is supplied with the drive signal Vin having the drive component DC9 by the switching circuit 10, so that the meniscus MS is pulled in in the +Z direction, which is a meniscus having a concave shape which is recessed in the +Z direction side at the peripheral portion of the meniscus MS and having a liquid column LC9 which protrudes in the -Z direction at the central portion of the meniscus MS. At this time, the portion of the meniscus MS which is pulled in the most in the +Z direction is pulled in to the +Z direction side from the initial position Z0. On the other hand, by supplying the piezoelectric element PZ with the drive component DC9, the ink in the nozzle N is pulled in in the +Z direction by the decrease in the pressure of the ink in the chamber 320, but the tip end of the liquid column LC8 which is formed at the time point t8 in the meniscus MS continues to move in the -Z direction, and a liquid column LC9 is formed at the central portion of the meniscus MS. When the neck portion of the liquid column LC9 is made thin and long, the tip end portion of the liquid column LC9 in the -Z direction is separated from the meniscus MS, and flies in the -Z direction as a droplet DR. Since the tip end of the liquid column LC8 which is formed at the time point t8 continues to move in the -Z direction, the ink in the nozzle N is pulled in in the +Z direction by the decrease in the pressure of the ink in the chamber 320 and the peripheral portion of the meniscus MS moves in the +Z direction by supplying the piezoelectric element PZ with the drive signal Vin having the drive component DC9, the droplet DR is torn off from the liquid column LC9. In Figure 16 Fig. 10 is a view for explaining the meniscus MS at time point t10. The time point t10 is within the control period Tcu5 and is the time point at which the supply of the drive component DC10 is ended. The piezoelectric element PZ is supplied with the drive signal Vin having the drive component DC10 by the switching circuit 10, so that the meniscus MS approaches the initial position Z0. As shown in Fig. 10, the meniscus MS is pulled in in the +Z direction by the drive component DC10, so that the liquid column LC9 is pulled in in the +Z direction and the liquid column LC8 is pulled in in the +Z direction. The liquid column LC8 is pulled in in the +Z direction by the drive component DC10, so that the neck portion of the liquid column LC8 is made thin and long, and the tip end portion of the liquid column LC8 in the -Z direction is separated from the meniscus MS, and flies in the -Z direction as a droplet DR. The droplet DR is torn off from the liquid column LC8 by the drive component DC10. The droplet DR which is torn off from the liquid column LC8 is not shown in Fig. 10.

[0104] Figure 17 Fig. 11 is a view for explaining the meniscus MS at time point tl l. The time point tl l is within the control period Tcu6 and is the time point at which the supply of the drive component DC11 is ended. The piezoelectric element PZ is supplied with the drive signal Vin having the drive component DC11 by the switching circuit 10, so that the meniscus MS is pulled in in the -Z direction. The meniscus MS is pulled in in the -Z direction by the drive component DC11, so that the liquid column LC9 is pulled in in the -Z direction and the liquid column LC8 is pulled in in the -Z direction. The liquid column LC8 is pulled in in the -Z direction by the drive component DC11, so that the neck portion of the liquid column LC8 is made thin and long, and the tip end portion of the liquid column LC8 in the -Z direction is separated from the meniscus MS, and flies in the -Z direction as a droplet DR. The droplet DR is torn off from the liquid column LC8 by the drive component DC11. The droplet DR which is torn off from the liquid column LC8 is not shown in Fig. 11.Figure 17 As shown, a liquid column LC10 is formed in which the central portion of the meniscus MS protrudes in the -Z direction. However, the meniscus MS is vibrated, and after the time point t10, the central portion of the meniscus MS is pulled in in the +Z direction. In Figure 17 In the figure, a droplet DR is shown that is separated after the time point t9.

[0105] Since the position of the meniscus MS is returned to the initial position Z0 without further continuing the ejection of the droplet DR from the ejection portion D by supplying the drive component DC10 to the piezoelectric element PZ, the amount of change in the potential per unit period in the drive component DC10 is smaller compared to the drive components DC2, DC4, DC6, and DC8. Further, although in the first embodiment, the amount of change in the potential per unit period in the drive component DC10 is fixed during the period in which the drive component DC10 is supplied, it can also be varied during the period in which the drive component DC10 is supplied. The amount of change in the potential per unit period in the drive components DC1, DC3, DC5, DC7, and DC9 is substantially equal. The amount of change in the potential per unit period in the drive components DC2, DC4, DC6, and DC8 is substantially equal.

[0106] As Figures 8-17 As shown, when the drive signal Vin based on the individual designation signal Sd[m] that designates the drive pattern al is supplied to the piezoelectric element PZ, in a case where the drive component DC1 of the initial drive pulse PL1 is supplied to the piezoelectric element PZ, the meniscus MS is pulled in the most in the +Z direction, and thereafter, each time the drive pulse PL2 and the drive pulse PL3 are supplied to the piezoelectric element PZ, the meniscus MS is pushed out in the -Z direction, and the liquid column formed at the central portion of the meniscus MS also grows along the Z axis direction. Further, when the drive pulse PL4 is supplied to the piezoelectric element PZ, the liquid column further grows thin and long in the Z axis direction, and a part of the liquid column LC9 flies in the -Z direction as the droplet DR. In addition, when the drive signal Vin based on the individual designation signal Sd[m] that designates the drive pattern a5 is supplied to the piezoelectric element PZ, the droplet DR does not fly. With regard to examples in which the drive signal Vin based on the individual designation signal Sd[m] that designates any one of the drive pattern a2, the drive pattern a3, and the drive pattern a4 is supplied to the piezoelectric element PZ, the following will be described. Figures 21-25 Hereinafter.

[0107] 1.5. Pressure variation generated by the drive signal Vin

[0108] Although in the Figures 8-17In the present embodiment, the operation of the meniscus MS when the drive pulses PL1 to PL5 are supplied to the piezoelectric element PZ in this order is described, but the variation in the pressure of the chamber 320 generated by the drive signal Vin will be described next using Figure 18 Figure 18 The graphs G1 and G2 shown in the drawing indicate the variation in the pressure in the chamber 320 obtained by fluid analysis simulation. The horizontal axes of the graphs G1 and G2 indicate the time, and the vertical axes of the graphs G1 and G2 indicate the pressure. The pressure of the chamber 320 in the rest state of the ejection section D in which the reference potential Vo is supplied to the piezoelectric element PZ is set as the zero point of the vertical axes of the graphs G1 and G2. The unit of the pressure is Pascal, and is indicated in the graphs G1 and G2 in the form of "Pa". In the case where the pressure is positive, the case where the volume of the chamber 320 is reduced and the pressure in the interior of the chamber 320 is increased is shown, and in the case where the pressure is negative, the case where the volume of the chamber 320 is expanded and the pressure in the interior of the chamber 320 is decreased is shown. "E+0i" in the graphs G1 and G2 indicates the pressure of the chamber 320 in the case where the drive signal Vin is not supplied to the piezoelectric element PZ, and "E+0i" is 10 +i i is 5 or 6.

[0109] Figure 18 ​This is a graph used to illustrate the pressure variation characteristics generated by the drive signal Vin. Graph G1 shows the pressure variation characteristics Pa1 and Pn1 of the piezoelectric element PZ on the ink in chamber 320, respectively, when a drive signal Vin with drive pulse PL4 but without drive pulses PL1, PL2, PL3, and PL5 is supplied to the piezoelectric element PZ. In other words, graph G1 corresponds to the pressure variation characteristics Pa1 of the ink in chamber 320 and Pn1 of the ink in nozzle N when a drive signal Vin with only waveform PH2 and without waveform PH1 is supplied to the piezoelectric element PZ. Point Pn1p within the pressure variation characteristic Pn1 represents the highest pressure that can be applied to the ink in nozzle N when only drive pulse PL4 is supplied to the piezoelectric element PZ, and the time point at which this pressure is generated. The pressure represented by point Pn1p is approximately 1.2 × 1006 Pascals. Furthermore, the pressure represented by point Pn1p corresponds to the increase in pressure of the ink within nozzle N when only the drive pulse PL4 is supplied to the piezoelectric element PZ, representing the change in pressure towards the positive pressure side from the pressure of the ink within nozzle N in the static state of the ejection section D. Point Pn1m within the pressure variation characteristic Pn1 represents the minimum pressure that can be applied to the ink within nozzle N, and the time point at which that pressure is generated. The pressure represented by point Pn1m is approximately -1.2 × 10⁻⁶. 06 Pascal. Furthermore, the pressure represented by point Pn1m is equivalent to the amount of change, i.e., the reduction, in the pressure of the ink in nozzle N from the stationary state of the ejection section D when only the drive pulse PL4 is supplied to the piezoelectric element PZ, towards the negative pressure side.

[0110] The graph G2 indicates the pressure fluctuation characteristics Pa2 representing the behavior of the pressure fluctuation of the ink in the chamber 320 caused by the piezoelectric element PZ and the pressure fluctuation characteristics Pn2 representing the behavior of the pressure fluctuation of the ink in the nozzle N caused by the piezoelectric element PZ in a case where the driving signal Vin having the driving pulses PL1, PL2, PL3, and PL4 is supplied to the piezoelectric element PZ. That is, the graph G2 corresponds to the pressure fluctuation characteristics Pa2 of the ink in the chamber 320 and the pressure fluctuation characteristics Pn2 of the ink in the nozzle N in a case where the driving signal Vin including the waveform PH1 and the waveform PH2 together is supplied to the piezoelectric element PZ. The point Pn2p in the pressure fluctuation characteristics Pn2 represents the highest pressure that can be applied to the ink in the nozzle N during the period in which the driving pulse PL4 is supplied to the piezoelectric element PZ among the period in which the driving signal Vin having the driving pulses PL1, PL2, PL3, and PL4 is supplied to the piezoelectric element PZ, and the time point at which the pressure is generated. The pressure represented by the point Pn2p is about 1.2 x 10 06 Pascals. Further, the pressure represented by the point Pn2p corresponds to the amount of fluctuation, i.e., the increase, to the positive pressure side from the pressure of the ink in the nozzle N in the stationary state of the ejection section D of the pressure of the ink in the nozzle N in a case where the driving pulse PL4 is supplied to the piezoelectric element PZ among the period in which the driving signal Vin having the driving pulses PL1, PL2, PL3, and PL4 is supplied to the piezoelectric element PZ.

[0111] The point Pn2m in the pressure fluctuation characteristics Pn2 represents the lowest pressure that can be applied to the ink in the nozzle N during the period in which the driving pulse PL4 is supplied to the piezoelectric element PZ among the period in which the driving signal Vin having the driving pulses PL1, PL2, PL3, and PL4 is supplied to the piezoelectric element PZ, and the time point at which the pressure is generated. The pressure represented by the point Pn2m is about -1.2 x 10 06 Pascals. Further, the pressure represented by the point Pn2m corresponds to the amount of fluctuation, i.e., the decrease, to the negative pressure side from the pressure of the ink in the nozzle N in the stationary state of the ejection section D of the pressure of the ink in the nozzle N in a case where the driving pulse PL4 is supplied to the piezoelectric element PZ among the period in which the driving signal Vin having the driving pulses PL1, PL2, PL3, and PL4 is supplied to the piezoelectric element PZ.

[0112] In addition, the time point represented by the point Pn1m and the time point represented by the point Pn2m coincide with the time point at which the supply of the driving component DC7 ends. Further, the time point represented by the point Pn1p and the time point represented by the point Pn2p coincide with the time point at which the supply of the driving component DC8 ends.

[0113] AsFigure 18 The amount of variation in the pressure on the positive pressure side and the negative pressure side in the nozzle N in the case where the piezoelectric element PZ is supplied with the drive signal Vin having only the drive pulse PL4 is approximately equal to the amount of variation in the pressure of the ink in the nozzle N in the case where the piezoelectric element PZ is supplied with the drive signal Vin having the drive pulses PL1, PL2, PL3, and PL4, as indicated by the graph G1. The amount of variation in the pressure is the sum of the amount of increase in the pressure and the amount of decrease in the pressure. Specifically, the pressure indicated by the point Pnlp is approximately equal to the pressure indicated by the point Pn2p, as indicated by the line segment LPnp of approximately 1.2 x 10 06 Pascals. In addition, the pressure indicated by the point Pnlm is approximately equal to the pressure indicated by the point Pn2m, as indicated by the line segment LPnm of approximately -1.2 x 10 06 Pascals.

[0114] Generally, in the case where an ink having a viscosity of less than 20 millipascal seconds is used, by setting the interval of the plurality of drive pulses to the resonance timing, the pressure variation generated by the following drive pulse and the pressure variation generated by the preceding drive pulse resonate to become larger, and in conjunction therewith, the amount of variation in the pressure of the liquid in the nozzle at the time when the following drive pulse is supplied to the piezoelectric element becomes larger than the amount of variation in the pressure of the liquid in the nozzle at the time when the preceding drive pulse is supplied to the piezoelectric element. However, in the present embodiment, the amount of variation in the pressure of the liquid in the nozzle at the time when only the drive pulse PL4 indicated in the graph G1 is supplied and the amount of variation in the pressure of the liquid in the nozzle at the time when the drive pulses PL1, PL2, PL3, and PL4 indicated in the graph G2 are continuously supplied to the piezoelectric element PZ are approximately equal, as described above. This can be considered to show that, since the ink of the present embodiment is high viscosity, the pressure variation generated by the preceding drive pulse PL and the pressure variation generated by the following drive pulse PL do not resonate.

[0115] 1.6. Volumetric velocity generated by drive signal Vin

[0116] Next, the volumetric velocity of the ink in the nozzle N generated by the drive signal Vin will be described using Figure 19 The volumetric velocity of the ink in the nozzle N is the moving speed of the ink in the nozzle N in the Z-axis direction. Figure 19 The graph G3 and the graph G4 indicated in FIG. 9 indicate the volumetric velocity calculated by the fluid analysis simulation. The horizontal axis of the graph G3 and the horizontal axis of the graph G4 indicate the time, and the vertical axis of the graph G3 and the vertical axis of the graph G4 indicate the volumetric velocity of the ink in the nozzle N. The unit of the volumetric velocity is cubic meters per second, and in the graph G3 and the graph G4, it is indicated in "m3 / s".3 The volume velocity of the ink in the nozzle N is the volume of the ink in the nozzle N that moves per unit period. In the case where the volume velocity of the ink in the nozzle N is positive, it indicates a case where the ink moves in the +Z direction, and in the case where the volume velocity of the ink in the nozzle N is negative, it indicates a case where the ink moves in the -Z direction. "E-06" in the graph G3 and the graph G4 indicates 10 -06 .

[0117] Figure 19 Fig. 3 is a graph that illustrates the variation characteristic of the volume velocity of the ink in the nozzle N. The graph G3 indicates a variation characteristic Vn3 that indicates the behavior of the volume velocity of the ink in the nozzle N in the case where the drive signal Vin having the drive pulse PL4 and not having the drive pulses PL1, PL2, PL3, and PL5 is supplied to the piezoelectric element PZ. The point Vn3p in the variation characteristic Vn3 indicates the volume velocity of the ink in the nozzle N that is the largest in the +Z direction and the time point at which this volume velocity is generated. The volume velocity indicated by the point Vn3p is approximately 2.7 x 10 -6 cubic meters per second. The point Vn3m in the variation characteristic Vn3 indicates the volume velocity that is the largest in the -Z direction and the time point at which this volume velocity is generated. The volume velocity indicated by the point Vn3m is approximately -3.3 x 10 -6 cubic meters per second.

[0118] The graph G4 indicates a variation characteristic Vn4 that indicates the behavior of the volume velocity of the ink in the nozzle N in the case where the drive signal Vin having the drive pulses PL1, PL2, PL3, and PL4 is supplied to the piezoelectric element PZ. The point Vn4p in the variation characteristic Vn4 indicates the volume velocity of the ink in the nozzle N that is the largest in the +Z direction and the time point at which this volume velocity is generated in the case where the drive pulse PL4 is supplied to the piezoelectric element PZ. The volume velocity indicated by the point Vn4p is approximately 2.7 x 10 -06 cubic meters per second. The point Vn4m in the variation characteristic Vn4 indicates the volume velocity that is the largest in the -Z direction and the time point at which this volume velocity is generated in the case where the drive pulse PL4 is supplied to the piezoelectric element PZ. The volume velocity indicated by the point Vn4m is approximately -3.3 x 10 -6 cubic meters per second.

[0119] In addition, the time point indicated by the point Vn3p and the time point indicated by the point Vn4p coincide with the time point at which the supply of the drive component DC7 ends. Further, the time point indicated by the point Vn3m and the time point indicated by the point Vn4m coincide with the time point at which the supply of the drive component DC8 ends.

[0120] As Figure 19As shown, the volumetric velocity of the ink in nozzle N when a drive signal Vin with only drive pulse PL4 is supplied to the piezoelectric element PZ is approximately equal to the volumetric velocity of the ink in nozzle N when a drive signal Vin with drive pulses PL1, PL2, PL3, and PL4 is supplied to the piezoelectric element PZ. Specifically, the volumetric velocity represented by point Vn3p is approximately 2.7 × 10⁻⁶. -06 The volume velocity represented by the line segment LVnp, in cubic meters per second, is approximately equal to the volume velocity represented by the point Vn4p. Furthermore, the volume velocity represented by the point Vn3m is approximately -3.3 × 10⁻⁶. 6 The velocity represented by the line segment LVnm in cubic meters per second is approximately equal to the volume velocity represented by the point Vn4m.

[0121] This can be considered as demonstrating the following situation, namely, compared with the reference. Figure 18 As previously described, the pressure variation characteristics generated by the drive signal Vin are the same. Since the ink in this embodiment is of high viscosity, the pressure variation generated by the preceding drive pulse PL and the pressure variation generated by the subsequent drive pulse PL do not resonate.

[0122] 1.7. Appropriate conditions for the driving waveform signal Com

[0123] Return to the instructions Figure 5 .like Figure 5 As shown, the periods Pw24 from time point tDC2 to time point tDC4, Pw46 from time point tDC4 to time point tDC6, and Pw68 from time point tDC6 to time point tDC8 are approximately the same. "Approximately the same" means that, in addition to being completely identical, they also include cases where measurement errors are taken into account. In the following description, periods Pw24, Pw46, and Pw68 will sometimes be collectively referred to as "period Pw". Time point tDC2 is the starting time of the supply of drive component DC2. Time point tDC4 is the starting time of the supply of drive component DC4. Time point tDC6 is the starting time of the supply of drive component DC6. Time point tDC8 is the starting time of the supply of drive component DC8. Alternatively, period Pw can be described as the timing interval of the start of the drive component DC in the continuous drive pulses PL that increase the pressure in chamber 320. Figure 20 This section explains the relationship between Pw and ejection performance values ​​during the period.

[0124] Figure 20 This is a graph used to illustrate the relationship between Pw and ejection performance values ​​during the period. The ejection performance values ​​are obtained by multiplying the volume of the droplet DR by the velocity of the droplet DR ejected from nozzle N. The unit of the ejection performance values ​​is Newton-second.Figure 20 The curve shown in the graph G5 is expressed in the form of "Ns". "E-10" in the graph G5 indicates 10 -10 As shown in the graph G5, the horizontal axis is a value obtained by dividing the period Pw by the natural vibration period TC of the discharge portion D. Figure 20

[0125] The natural vibration period TC is the reciprocal of the number of natural vibrations of the discharge portion D, and in general, can be expressed by the following (1).

[0126] Mathematical expression 1

[0127]

[0128] In the above (1), M represents the inertia of the flow passage, and C represents the compliance C V of the vibration plate 310 and the compressibility C L of the ink. ζ is a value less than 1, and can be expressed by the following (2).

[0129] Mathematical expression 2

[0130]

[0131] In the above (2), R represents the viscous resistance of the flow passage, and is proportional to the viscosity of the ink.

[0132] Hereinafter, the value obtained by dividing the period Pw by the natural vibration period TC of the discharge portion D will be referred to as a "pulse interval ratio". The vertical axis of the graph G5 represents the above-described discharge performance value. The plurality of black dots in the graph G5 respectively represent the pulse interval ratio and the discharge performance value obtained through experiments. Furthermore, in the graph G5, a characteristic CPw of the pulse interval ratio calculated on the basis of the pulse interval ratio and the discharge performance value obtained through experiments is shown. The characteristic CPw is calculated, for example, on the basis of the least squares method.

[0133] As shown in the graph G5, in a manner in which the pulse interval ratio is 1 or more and 2 or less, the discharge performance value becomes approximately 1.8 x 10 -10 ​The ejection performance value can be increased in the case where the pulse interval ratio is less than 1 and in the case where the pulse interval ratio is more than 2, compared to the case where the pulse interval ratio is 1 or more and less than 2 with respect to the period Pw68. For example, in the case where the pulse interval ratio is less than 1 during the period Pw68, the drive component DC8 is started while the volume of the chamber 320 is still in the state of being expanded. That is, since the drive component DC8 is started in the state where the volume of the chamber 320 is smaller than the volume of the chamber 320 at the time point tDC8 at which the drive component DC8 is started in the case where the pulse interval ratio is 1 or more and less than 2 with respect to the period Pw68, the ejection performance value is decreased. The ejection performance value is approximately 2.3 x 10 -10 The ejection performance value can be increased in the case where the pulse interval ratio is less than 1.2 and in the case where the pulse interval ratio is more than 1.6, compared to the case where the pulse interval ratio is 1 or more and less than 2 with respect to the period Pw68. In addition, the ejection performance value is approximately 1.8 x 10 -10 1 Newton second corresponds to 20 ng x 9 m / s, 2.3 x 10 -10 1 Newton second corresponds to 23 ng x 10 m / s. 1 ng indicates 10 -9 grams.

[0134] 1.8. Recording method using the drive waveform signal Com

[0135] As Figure 17As shown, after the ejection of the liquid droplet DR, there is also a liquid column on the meniscus MS. When the liquid droplet DR is ejected within the recording period Tu[i], even within the recording period Tu[j] that is started at the end time point of the recording period Tu[i], there is a possibility that the liquid column on the meniscus MS continues to exist. j is an integer from 2 to I, and is larger than i by 1. In the case where the liquid column exists on the meniscus MS within the recording period Tu[j], when the drive signal Vin based on the individual designation signal Sd[m] that designates the drive mode al is supplied to the piezoelectric element PZ, there is a possibility that the liquid droplet DR is ejected before the drive component DC8 is supplied. Since the liquid ejection head HU and the recording paper P are being relatively moved at a predetermined speed, if the liquid droplet DR is ejected at a timing that is not originally supposed to eject, the position on the recording paper P where the liquid droplet DR lands deviates from the position that is originally supposed to land, thereby degrading the print quality. In order to make the liquid droplet DR land on the position that is originally supposed to land, in the first embodiment, when the liquid droplet DR is caused to be ejected within the recording period Tu[j], the waveform of the drive signal Vin supplied to the piezoelectric element PZ within the recording period Tu[j] is decided based on the waveform of the drive signal Vin supplied to the piezoelectric element PZ within a predetermined recording period Tux that precedes the recording period Tu[j]. More specifically, the control section 6 generates the individual designation signal Sd[m] of the recording period Tu[j] based on the individual designation signal Sd[m] within the predetermined recording period Tux that precedes the recording period Tu[j].

[0136] More specifically, the processing of the control section 6 will be described. When the droplet DR is ejected from the nozzle N during the recording period Tu[j], the control section 6 generates the individual designation signal Sd[m] of the recording period Tu[j] based on the individual designation signal Sdx of the predetermined recording period Tux preceding the recording period Tu[j], that is, the individual designation signal Sd[m] of the recording period Tu[j-1], the individual designation signal Sd[m] of the recording period Tu[j-2], and the individual designation signal Sd[m] of the recording period Tu[j-3]. More specifically, when the droplet DR is ejected from the nozzle N during the recording period Tu[j], the control section 6 decides whether to select the drive pulse PLl, the drive pulse PL2, and the drive pulse PL3, respectively, in the drive signal Vinl of the drive signal Vin supplied to the recording period Tu[j], based on the individual designation signal Sdx of the predetermined recording period Tux preceding the recording period Tu[j], that is, the individual designation signal Sd[m] of the recording period Tu[j-1], the individual designation signal Sd[m] of the recording period Tu[j-2], and the individual designation signal Sd[m] of the recording period Tu[j-3]. On the other hand, when the droplet DR is ejected during the recording period Tu[j], the control section 6 decides the drive signal Vin2 of the drive signal Vin supplied to the recording period Tu[j] to be the waveform PH2 including the drive pulse PL4 and the drive pulse PL5, irrespective of the individual designation signal Sdx of the predetermined recording period Tux preceding the recording period Tu[j], that is, the individual designation signal Sd[m] of the recording period Tu[j-1], the individual designation signal Sd[m] of the recording period Tu[j-2], and the individual designation signal Sd[m] of the recording period Tu[j-3]. For a more specific recording method, the use of Figure 21 and Figure 22 will be described.

[0137] Figure 21 and Figure 22 is a flowchart showing an example of generation of the individual designation signals Sd[l] to Sd[m] in the recording period Tu[j]. In addition, in the flowcharts shown in Figure 21 and Figure 22 , the illustration is made in a manner limited only to the case where the value of j is 4 or more for the sake of simplification of the illustration. For the case where the value of j is 2, and the case where the value of j is 3, the description will be made after the description of the flowcharts shown in Figure 21 and Figure 22 .

[0138] The control section 6 substitutes 1 in the variable m in step S2. Next, in step S4, the control section 6 judges whether or not the ejection section D[m] ejects a droplet during the recording period Tu[j] based on the print data Img. When the judgment result of step S4 is affirmative, in step S6, the control section 6 acquires the individual designation signal Sd[m] of the recording period Tu[i], i.e., the recording period Tu[j-1] from the storage section 5. Next, in step S8, the control section 6 judges whether or not the ejection section D[m] ejects a droplet DR during the recording period Tu[j-1] based on the individual designation signal Sd[m] of the recording period Tu[j-1]. For example, in the case where the individual designation signal Sd[m] of the recording period Tu[j-1] designates any one of the drive modes αl, α2, α3, and α4, the control section 6 judges that the ejection section D[m] ejects a droplet DR during the recording period Tu[j-1]. On the other hand, in the case where the individual designation signal Sd[m] of the recording period Tu[j-1] designates the drive mode α5, the control section 6 judges that the ejection section D[m] does not eject a droplet DR during the recording period Tu[j-1].

[0139] When the judgment result of step S8 is negative, in step S10, the control section 6 acquires the individual designation signal Sd[m] of the recording period Tu[j-2] from the storage section 5. Next, in step S12, the control section 6 judges whether or not the ejection section D[m] ejects a droplet DR during the recording period Tu[j-2] based on the individual designation signal Sd[m] of the recording period Tu[j-2].

[0140] When the judgment result of step S12 is negative, in step S14, the control section 6 acquires the individual designation signal Sd[m] of the recording period Tu[j-3] from the storage section 5. Next, in step S16, the control section 6 judges whether or not the ejection section D[m] ejects a droplet DR during the recording period Tu[j-3] based on the individual designation signal Sd[m] of the recording period Tu[j-3].

[0141] When the result of the determination in step S16 is negative, that is, when the ejection section D[m] does not eject the droplet DR in the three preceding recording periods Tu, namely, the recording period Tu[j-1], the recording period Tu[j-2], and the recording period Tu[j-3], in step S18, the control section 6 generates the individually designated signal Sd[m] of the drive mode αl. It can also be said that in the processing in step S18, the control section 6 determines the drive signal Vinl to be the waveform PHl including the three drive pulses PLl, PL2, and PL3. After the processing in step S18 is completed, in step S32, the control section 6 causes the storage section 5 to store the generated individually designated signal Sd[m].

[0142] When the result of the determination in step S4 is negative, that is, when the ejection section D[m] does not eject the droplet DR in the recording period Tu[j], in step S20, the control section 6 generates the individually designated signal Sd[m] of the drive mode α5. Then, in step S32, the control section 6 causes the storage section 5 to store the generated individually designated signal Sd[m].

[0143] When the result of the determination in step S8 is positive, that is, when the ejection section D[m] is ejecting the droplet DR in the recording period Tu[j-1], in step S22, the control section 6 generates the individually designated signal Sd[m] of the drive mode α2. It can also be said that in the processing in step S22, the control section 6 determines the drive signal Vinl to be a signal having no waveform PHl, that is, the number of drive pulses PL is 0. Further, in the processing in step S8, the control section 6 determines whether the waveform PHl is included in the drive signal Vin to be supplied to the piezoelectric element PZ in the recording period Tu[j] based on the waveform of the drive signal Vin to be supplied to the piezoelectric element PZ in the predetermined recording period Tux.

[0144] After the processing in step S22 is completed, in step S32, the control section 6 causes the storage section 5 to store the generated individually designated signal Sd[m].

[0145] When the result of the determination in step S12 is positive, that is, when the ejection section D[m] does not eject the droplet DR in the recording period Tu[j-1], but ejects the droplet DR in the recording period Tu[j-2], in step S24, the control section 6 generates the individually designated signal Sd[m] of the drive mode α3. It can also be said that in the processing in step S24, the control section 6 determines the drive signal Vinl to be the waveform PHl including the one drive pulse PL3. After the processing in step S22 is completed, in step S32, the control section 6 causes the storage section 5 to store the generated individually designated signal Sd[m].

[0146] When the result of the determination in step S16 is affirmative, that is, when the ejection section D[m] did not eject the droplet DR during the recording period Tu[j-1] and the recording period Tu[j-2], but the ejection section D[m] ejected the droplet DR during the recording period Tu[j-3], the control section 6 generates the individual designation signal Sd[m] of the drive pattern α4 in step S26. It can also be said that the control section 6 determines the drive signal Vinl to be the waveform PHl including both the drive pulse PL2 and the drive pulse PL3 in the processing in step S26. After the processing in step S26 ends, the control section 6 causes the storage section 5 to store the generated individual designation signal Sd[m] in step S32.

[0147] In the processing in steps S12 and S16, when the control section 6 determines that the waveform PHl is included in the drive signal Vinl supplied to the piezoelectric element PZ during the recording period Tu[j] based on the waveform of the drive signal Vin supplied to the piezoelectric element PZ during a predetermined recording period Tux, the number of drive pulses PL included in the waveform PHl is further determined.

[0148] Further, in the processing in steps S8, S12, and S16, the control section 6 determines the waveform of the drive signal Vin supplied to the piezoelectric element PZ during the recording period Tu[j] in such a manner that the number of drive pulses PL included in the drive signal Vinl supplied to the piezoelectric element PZ during the recording period Tu[j] when the droplet DR is not ejected from the ejection section D during the recording period Tu[j-1] is larger than the number of drive pulses PL included in the drive signal Vinl supplied to the piezoelectric element PZ during the recording period Tu[j] when the droplet DR is ejected from the ejection section D during the recording period Tu[j-1].

[0149] After the processing in step S32 ends, the control section 6 determines whether the variable m has reached M, which is the number of ejection sections D, in step S34. When the result of the determination in step S34 is negative, the control section 6 increments the value of the variable m by 1 in step S38, and returns the processing to step S4. When the result of the determination in step S34 is affirmative, the control section 6 outputs the individual designation signals Sd[1] to Sd[M] to the switching circuit 10 in step S36. After the processing in step S36 ends, the control section 6 ends the series of processing shown in FIG. 8. Figure 21 and Figure 22 After the processing in step S32 ends, the control section 6 determines whether the variable m has reached M, which is the number of ejection sections D, in step S34. When the result of the determination in step S34 is negative, the control section 6 increments the value of the variable m by 1 in step S38, and returns the processing to step S4. When the result of the determination in step S34 is affirmative, the control section 6 outputs the individual designation signals Sd[1] to Sd[M] to the switching circuit 10 in step S36. After the processing in step S36 ends, the control section 6 ends the series of processing shown in FIG. 8.

[0150] The case where variable j has a value of 2 will be explained. If the judgment result of step S8 is negative, control unit 6 will execute step S18 instead of step S10. Next, the case where variable j has a value of 3 will be explained. If the judgment result of step S12 is negative, control unit 6 will execute step S18 instead of step S14. After the processing of step S18 is completed, since... Figure 21 as well as Figure 22 The series of processes shown are the same, so the explanation after the processing of step S18 is omitted. Furthermore, during the recording period Tu[1], the control unit 6 determines whether the ejector D[m] ejects droplets during the recording period Tu[1] based on the printing data Img. When the ejector D[m] ejects droplets, the control unit 6 generates a separate designation signal Sd[m] for drive mode α1. When the ejector D[m] does not eject droplets, the control unit 6 generates a separate designation signal Sd[m] for drive mode α5.

[0151] Figure 23 The diagram illustrates a specific example of a recording method using the drive waveform signal Com. Figure 23 In the diagram, four ejection methods are shown in the ejection section D[m]. Figure 23 In the diagram, below each recording period Tu, black dots or white dots drawn with dashed lines are shown. Black dots indicate that droplets DR were ejected during that recording period Tu, while white dots drawn with dashed lines indicate that droplets DR were not ejected during that recording period Tu. Additionally, in... Figure 23 The future Figure 25 , Figure 27 , Figure 28 The black dots shown and the white dots depicted with dashed lines also have the same characteristics as... Figure 23 The black dots shown and the white dots depicted with dashed lines have the same meaning. Hereinafter, the recording period Tu during which droplets DR are ejected is sometimes referred to as "ejection recording period Tu-D", and the recording period Tu during which droplets DR are not ejected is referred to as "non-ejection recording period Tu-N".

[0152] Figure 23 The first stage of the ejection method is to eject droplets DR during the recording period Tu[1] and the recording period Tu[2]. For the recording period Tu[1], the control unit 6 generates a separate designated signal Sd[m] for the driving mode α1 and outputs the generated separate designated signal Sd[m] to the switching circuit 10. Thus, in the ejection section D[m], during the recording period Tu[1], a driving signal Vin with driving pulses PL1, PL2, PL3, PL4 and PL5 is supplied.

[0153] For the recording period Tu[2], the control section 6 executes the flowchart shown in Figs. 8 and 9 in a state where the value of the variable j is 2. Since the recording period Tu[2] is the non-ejection recording period Tu-N, the result of the determination of step S4 is negative, and the control section 6 generates the individual designation signal Sd[m] of the drive mode α5 by the process of step S20, and outputs the generated individual designation signal Sd[m] to the switching circuit 10. As a result, in the ejection section D[m], the drive signal Vin which sets the ejection section D to the non-drive is supplied during the recording period Tu[2]. Figure 21 and Figure 22 Since the result of the determination of step S8 is affirmative, the control section 6 generates the individual designation signal Sd[m] of the drive mode α2 by the process of step S22, and outputs the generated individual designation signal Sd[m] to the switching circuit 10. As a result, in the ejection section D[m], the drive signal Vin having the drive pulses PL4 and PL5 is supplied during the recording period Tu[l].

[0154] Figure 23 The ejection mode shown in the third stage of the ejection mode table of Fig. 6 is a mode in which the liquid droplets DR are ejected during the recording period Tu[l] and the recording period Tu[4], and the liquid droplets DR are not ejected during the recording period Tu[2] and the recording period Tu[3]. With respect to the recording periods Tu[l] and Tu[2], since the recording periods Tu[l] and Tu[2] are the same as the recording periods Tu[l] and Tu[2] of the first stage of the ejection mode table of Fig. 6, the description is omitted. Figure 23 For the recording period Tu[2], the control section 6 executes the flowchart shown in Figs. 8 and 9 in a state where the value of the variable j is 2. Since the recording period Tu[2] is the non-ejection recording period Tu-N, the result of the determination of step S4 is negative, and the control section 6 generates the individual designation signal Sd[m] of the drive mode α5 by the process of step S20, and outputs the generated individual designation signal Sd[m] to the switching circuit 10. As a result, in the ejection section D[m], the drive signal Vin which sets the ejection section D to the non-drive is supplied during the recording period Tu[2]. Figure 21 and Figure 22 Since the recording period Tu[2] is the non-ejection recording period Tu-N, the result of the determination of step S4 is negative, and the control section 6 generates the individual designation signal Sd[m] of the drive mode α5 by the process of step S20, and outputs the generated individual designation signal Sd[m] to the switching circuit 10. As a result, in the ejection section D[m], the drive signal Vin which sets the ejection section D to the non-drive is supplied during the recording period Tu[2].

[0155] For the recording period Tu[3], the control section 6 executes the flowchart shown in Figs. 10 and 11 in a state where the value of the variable j is 3. Since the result of the determination of step S12 is affirmative, the control section 6 generates the individual designation signal Sd[m] of the drive mode α3 by the process of step S24, and outputs the generated individual designation signal Sd[m] to the switching circuit 10. As a result, in the ejection section D[m], the drive signal Vin having the drive pulses PL3, PL4 and PL5 is supplied during the recording period Tu[3]. Figure 21 Figure 22 Since the result of the determination of step S12 is affirmative, the control section 6 generates the individual designation signal Sd[m] of the drive mode α3 by the process of step S24, and outputs the generated individual designation signal Sd[m] to the switching circuit 10. As a result, in the ejection section D[m], the drive signal Vin having the drive pulses PL3, PL4 and PL5 is supplied during the recording period Tu[3].

[0156] Figure 23 The ejection mode shown in the third stage of the ejection mode table of Fig. 6 is a mode in which the liquid droplets DR are ejected during the recording period Tu[l] and the recording period Tu[4], and the liquid droplets DR are not ejected during the recording period Tu[2] and the recording period Tu[3]. With respect to the recording periods Tu[l] and Tu[2], since the recording periods Tu[l] and Tu[2] are the same as the recording periods Tu[l] and Tu[2] of the first stage of the ejection mode table of Fig. 6, the description is omitted. Figure 23 ​The recording period Tu[l] and the recording period Tu[2] shown in the second stage of the fourth stage are the same, and therefore the explanation is omitted. For the recording period Tu[3], the control section 6 executes the process shown in the flowchart of Fig. 6 in the state where the value of the variable j is 3. Since the recording period Tu[3] is the non-ejection recording period Tu-N, the result of the determination of step S4 is negative, and the control section 6 generates the individual designation signal Sd[m] of the drive mode α5 through the process of step S20, and outputs the generated individual designation signal Sd[m] to the switching circuit 10. As a result, in the ejection section D[m], the drive signal Vin that sets the ejection section D to non-drive is supplied during the recording period Tu[3]. Figure 21 and Figure 22 The recording period Tu[l] and the recording period Tu[2] shown in the second stage of the fourth stage are the same, and therefore the explanation is omitted. For the recording period Tu[3], the control section 6 executes the process shown in the flowchart of Fig. 6 in the state where the value of the variable j is 3. Since the recording period Tu[3] is the non-ejection recording period Tu-N, the result of the determination of step S4 is negative, and the control section 6 generates the individual designation signal Sd[m] of the drive mode α5 through the process of step S20, and outputs the generated individual designation signal Sd[m] to the switching circuit 10. As a result, in the ejection section D[m], the drive signal Vin that sets the ejection section D to non-drive is supplied during the recording period Tu[3].

[0157] Figure 23 The ejection mode shown in the fourth stage of the fourth stage is a mode that ejects the droplet DR during the recording period Tu[l] and the recording period Tu[5], and does not eject the droplet DR during the recording period Tu[2], the recording period Tu[3], and the recording period Tu[4]. For the recording period Tu[l], the recording period Tu[2], and the recording period Tu[3], since the recording period Tu[l] and the recording period Tu[2] are the same, and the recording period Tu[3] is the non-ejection recording period Tu-N, the result of the determination of step S4 is negative, and the control section 6 generates the individual designation signal Sd[m] of the drive mode α5 through the process of step S20, and outputs the generated individual designation signal Sd[m] to the switching circuit 10. As a result, in the ejection section D[m], the drive signal Vin that sets the ejection section D to non-drive is supplied during the recording period Tu[l], the recording period Tu[2], and the recording period Tu[3]. Figure 23 The recording period Tu[l], the recording period Tu[2], and the recording period Tu[3] shown in the third stage of the fourth stage are the same, and therefore the explanation is omitted. Since the recording period Tu[4] is the non-ejection recording period Tu-N, the result of the determination of step S4 is negative, and the control section 6 generates the individual designation signal Sd[m] of the drive mode α5 through the process of step S20, and outputs the generated individual designation signal Sd[m] to the switching circuit 10. As a result, in the ejection section D[m], the drive signal Vin that sets the ejection section D to non-drive is supplied during the recording period Tu[4].

[0158] For the recording period Tu[5], since the result of the determination of step S16 is negative, the control section 6 generates the individual designation signal Sd[m] of the drive mode αl through the process of step S18, and outputs the generated individual designation signal Sd[m] to the switching circuit 10. As a result, in the ejection section D[m], the drive signal Vin that has the drive pulses PLl, PL2, PL3, PL4, and PL5 is supplied during the recording period Tu[5].

[0159] 1.9. Summary of the first embodiment

[0160] Hereinafter, a summary of the first embodiment is described.

[0161] 1.9.1. Summary on the waveform PH1 and the waveform PH2

[0162] As described above, the liquid ejection head HU in the first embodiment has M ejection portions D. The ejection portion D has a piezoelectric element PZ that is displaced by being supplied with a drive signal Vin, a chamber 320 that increases and decreases the pressure in the inside thereof in accordance with the displacement of the piezoelectric element PZ, and a nozzle N that communicates with the chamber 320 and is able to eject the ink filled in the inside of the chamber 320 as a droplet in the -Z direction in accordance with the increase and decrease of the pressure in the inside of the chamber 320. The liquid ejection head HU executes a drive method having the first step and the second step shown below. In the first step, by supplying the drive signal Vin1 having the waveform PH1 including the drive pulses PL1, PL2, PL3 having the drive components DC1, DC3, DC5 that decrease the pressure in the inside of the chamber 320 and the drive components DC2, DC4, DC6 that increase the pressure in the inside of the chamber 320 to the piezoelectric element PZ, the meniscus MS is caused to form the liquid column LC6 that protrudes in the -Z direction. In the second step, after the liquid column LC8 that protrudes in the -Z direction is caused to form by supplying the drive signal Vin2 having the waveform PH2 including the drive pulses PL4, PL5 having the drive components DC7, DC9 that decrease the pressure in the inside of the chamber 320 and the drive components DC8, DC10 that increase the pressure in the inside of the chamber 320 to the piezoelectric element PZ in the state where the liquid column LC6 is formed, a part or all of the ink constituting the liquid column LC8 is caused to be ejected as a droplet DR. When the drive signal Vin having the waveform PH1 and not having the waveform PH2 is supplied to the piezoelectric element PZ, the droplet DR is not ejected from the ejection portion D, and when the drive signal Vin having the waveform PH2 and not having the waveform PH1 is supplied to the piezoelectric element PZ, the droplet DR is not ejected from the ejection portion D.

[0163] Specifically, the drive signal Vin having the waveform PH1 is the drive signal Vin based on the individual designation signal Sd[m] that designates the drive mode al, the drive mode a3, and the drive mode a4.

[0164] Further, in the section "Summary on Waveform PH1 and Waveform PH2", the waveform PH1 is an example of the "first waveform". The waveform PH2 is an example of the "second waveform". The liquid column LC6 is an example of the "first liquid column". The liquid column LC8 is an example of the "second liquid column". Further, the drive pulses PL1, PL2, and PL3 are an example of the "first drive pulse", and the drive pulses PL4 and PL5 are an example of the "second drive pulse". Further, the drive components DC1, DC3, and DC5 are an example of the "first drive component that decreases the pressure inside the pressure chamber", the drive components DC2, DC4, and DC6 are an example of the "second drive component that increases the pressure inside the pressure chamber", the drive components DC7 and DC9L are an example of the "third drive component that decreases the pressure inside the pressure chamber", and the drive components DC8 and DC10 are an example of the "fourth drive component that increases the pressure inside the pressure chamber".

[0165] Here, when the viscosity of the ink becomes 20 millipascal seconds or more, the ink in the ejection section D has a possibility that the liquid droplet DR cannot be ejected in one drive pulse PL1 while being kept in a standby state under a fixed negative pressure. Although it is possible to consider increasing the difference between the highest potential and the lowest potential of the drive signal Vin in order to eject the ink of high viscosity, there is a physical limit. Further, although it is possible to consider increasing the excluded volume of the chamber 320, when the capacity of the chamber 320 is increased, the structure of the ejection section D becomes easy to deform due to the force applied to the structure, that is, the compliance of the flow path inside the ejection section D becomes large. The meaning of the excluded volume means the amount of variation of the volume of the pressure chamber caused by the vibration of the vibrating plate 310. When the compliance of the flow path inside the ejection section D becomes large, the pressure variation caused by the displacement of the piezoelectric element PZ becomes easy to be moderated by the deformation of the structure of the ejection section D, and thus it becomes difficult to eject the liquid droplet DR. Further, when the capacity of the chamber 320 is increased, the pressure caused by the displacement of the piezoelectric element PZ becomes easy to be absorbed by the compression of the ink, and thus it becomes difficult to eject the liquid droplet DR.

[0166] Therefore, according to the first embodiment, in a case where the liquid column LC6 is formed by the drive signal Vin1 having the waveform PH1, the liquid column formed on the meniscus MS is grown by supplying the drive signal Vin2 having the waveform PH2 to the piezoelectric element PZ, and further it is possible to eject a part or all of the ink constituting the liquid column LC8 as the liquid droplet DR.

[0167] Further, the amount of variation of the pressure of the ink in the nozzle N to the negative pressure side, i.e., the first reduction amount, when the driving component DC7 of the waveform PH2 included in the driving signal Vin is supplied to the piezoelectric element PZ in the case where the driving signal Vin having the waveform PH2 and not having the waveform PH1 is supplied to the piezoelectric element PZ, is substantially equal to the amount of variation of the pressure of the ink in the nozzle N to the negative pressure side, i.e., the second reduction amount, when the driving component DC7 of the waveform PH2 included in the driving signal Vin is supplied to the piezoelectric element PZ in the case where the driving signal Vin having the waveform PH1 and the waveform PH2 is supplied to the piezoelectric element PZ. Further, the amount of variation of the pressure of the ink in the nozzle to the positive pressure side, i.e., the first increase amount, when the driving component DC8 of the waveform PH2 included in the driving signal Vin is supplied to the piezoelectric element PZ in the case where the driving signal Vin having the waveform PH2 and not having the waveform PH1 is supplied to the piezoelectric element PZ, is substantially equal to the amount of variation of the pressure of the ink in the nozzle N to the positive pressure side, i.e., the second increase amount, when the driving component DC8 of the waveform PH2 included in the driving signal Vin is supplied to the piezoelectric element PZ in the case where the driving signal Vin having the waveform PH1 and the waveform PH2 is supplied to the piezoelectric element PZ.

[0168] When the viscosity of the ink becomes high, the residual vibration is attenuated in advance. Therefore, at the time point when the waveform PH2 is supplied to the piezoelectric element PZ after the waveform PH1 is supplied to the piezoelectric element PZ, the residual vibration generated by the waveform PH1 is attenuated, and thus the waveform PH2 and the residual vibration generated by the waveform PH1 cannot be synchronized to resonate. In the first embodiment, since the first reduction amount and the second reduction amount are substantially equal, and further, the first increase amount and the second increase amount are substantially equal, the residual vibration generated by the waveform PH1 and the pressure vibration generated by the waveform PH2 do not resonate. However, in the first embodiment, since the liquid column formed on the meniscus MS is formed by the plurality of driving pulses PL, and thus the droplet DR is ejected, the waveform PH1 and the waveform PH2 are not adjusted in such a manner that the waveform PH2 is generated in such a manner that the residual vibration generated by the waveform PH1 resonates, but are adjusted in such a manner that the meniscus MS is formed by the plurality of driving pulses PL. Therefore, according to the first embodiment, even if the ink having a high viscosity, the liquid column formed on the meniscus MS can be formed by using the waveform PH1 and the waveform PH2, and thus the droplet DR can be ejected.

[0169] The position of the portion of the meniscus MS in the ejection section D that is pulled in the +Z direction the most when the driving component DC7 of the waveform PH2 is supplied to the piezoelectric element PZ, i.e., the pull-in position Zp4, is located in the +Z direction compared to the pull-in position Zp1 of the meniscus MS that corresponds to the portion pulled in the +Z direction the most when the driving component DC7 of the waveform PH2 is supplied to the piezoelectric element PZ under the condition that the driving signal Vin1 having the waveform PH1 is not supplied to the piezoelectric element PZ.

[0170] In this way, in the first embodiment, since the portion of the meniscus MS pulled in the +Z direction the most is moved in the -Z direction by supplying the plurality of driving pulses PL to the piezoelectric element PZ, the liquid column formed on the meniscus MS is also moved in the -Z direction. Since the tip of the liquid column in the -Z direction is moved away from the initial position Z0 in the -Z direction by moving the liquid column in the -Z direction, a part or the whole of the liquid column becomes easy to separate, and thus the liquid droplet DR separated from the liquid column can be ejected.

[0171] Further, in the second step, the driving component DC9 that the driving pulse PL5 of the driving signal Vin has is supplied to the piezoelectric element PZ in the case where the tip of the liquid column LC8 is moved in the -Z direction.

[0172] In the case where the tip of the liquid column LC8 is moved in the -Z direction, the liquid droplet DR can be torn off from the liquid column LC9 by supplying the driving signal Vin having the driving component DC9 to the piezoelectric element PZ. According to the present embodiment, compared to the case where the driving signal Vin having no driving component DC9 is supplied to the piezoelectric element PZ, more stable ejection can be achieved.

[0173] The waveform PH1 includes the driving pulses PL1, PL2, and PL3. The driving pulse PL1 includes the driving component DC1 and the driving component DC2. The driving pulse PL2 includes the driving component DC3 and the driving component DC4. The driving pulse PL3 includes the driving component DC5 and the driving component DC6.

[0174] As described above with reference to Figures 8-17As explained above, as indicated by the behavior of the meniscus MS when the drive signal Vin based on the individual designation signal Sd[m] designating the drive mode al is supplied to the piezoelectric element PZ, in the case of an ink of high viscosity, it is not possible to cause the ejection section D to generate a pressure variation of the degree that the droplet DR is ejected from the nozzle N with only one drive pulse PL. That is, by successively supplying a plurality of drive pulses PL to the piezoelectric element PZ and repeatedly reducing and increasing the pressure inside the chamber 320, a liquid column is formed on the meniscus MS and the liquid column is further grown, whereby a part or all of the liquid column can be caused to fly as a droplet DR from the nozzle N in the -Z direction.

[0175] In the present embodiment, since the waveform PH1 has three drive pulses PL, even in the case where the droplet DR cannot be ejected with one drive pulse PL, by supplying the drive signal Vin of the waveform PH1 having two or three drive pulses PL to the piezoelectric element PZ, the liquid column formed on the meniscus MS is grown, and further, a part or all of the ink constituting the liquid column LC8 by the waveform PH2 can be caused to be ejected as a droplet DR.

[0176] As explained above with reference to Figure 21 and Figure 22 As explained above, when the predetermined recording period Tux preceding the recording period Tu[j] is the non-ejection recording period Tu-N, the drive signal Vin including the drive pulse PL2 and the drive pulse PL3, or the drive pulse PL1, PL2 and PL3 is supplied to the piezoelectric element PZ within the recording period Tu[j] so that the droplet DR is ejected from the ejection section D after the drive component DC8 of the waveform PH2 is supplied to the piezoelectric element PZ within the recording period Tu[j].

[0177] Further, the viscosity of the ink in the liquid ejection head HU is 20 millipascal seconds or more, and preferably, 40 millipascal seconds. Although there is a possibility that the droplet DR cannot be ejected with only one drive pulse PL4 of the waveform PH2 when the viscosity of the ink becomes 20 millipascal seconds or more, by the driving method realized by the present embodiment having the waveform PH1 before the waveform PH2, even the ink having a viscosity of 20 millipascal seconds or more can be caused to eject the droplet DR.

[0178] The difference between the maximum potential and the minimum potential in the waveform PH1 is substantially equal to the difference between the maximum potential and the minimum potential in the waveform PH2. More specifically, the minimum potential in the waveform PH1 and the minimum potential in the waveform PH2 are substantially equal to the potential VL1, and the maximum potential in the waveform PH1 and the maximum potential in the waveform PH2 are substantially equal to the reference potential V0. By setting the maximum potential that can be realized in the inkjet printer 1 to the maximum potential of the waveform PH1 and the waveform PH2, and setting the minimum potential that can be realized in the inkjet printer 1 to the minimum potential of the waveform PH1 and the waveform PH2, even if the ink is of high viscosity, the liquid column can be grown on the meniscus MS by the waveform PH1, and thus the droplet DR can be ejected in the waveform PH2.

[0179] 1.9.2. Summary of appropriate conditions of the drive waveform signal Com

[0180] As explained above, the liquid ejection head HU in the first embodiment executes the drive method having the first step and the second step described above. The waveform PH1 has three drive pulses PL, i.e., the three drive pulses PL having the drive components DC1, DC3, DC5 that decrease the pressure inside the chamber 320 and the drive components DC2, DC4, DC6 that increase the pressure inside the chamber 320. The waveform PH2 has two drive pulses PL, i.e., the two drive pulses PL having the drive components DC7, DC9 that decrease the pressure inside the chamber 320 and the drive components DC8, DC10 that increase the pressure inside the chamber 320. The waveform PH2 is started to be implemented at the end time point of the waveform PH1. The interval, i.e., the period Pw68, between the last drive pulse PL3 in the drive pulses PL of the waveform PH1 and the first drive pulse PL4 in the drive pulses PL of the waveform PH2 is one time or more and two times or less of the natural vibration period TC of the ejection section D. The period Pw68 is a period from the time point tDC6 at which the supply of the drive component DC6 possessed by the last drive pulse PL3 of the three drive pulses PL possessed by the waveform PH1 is started to the time point tDC8 at which the supply of the drive component DC8 possessed by the first drive pulse PL4 of the two drive pulses PL possessed by the waveform PH2 is started.

[0181] Since the period Pw68 is one time or more and two times or less of the natural vibration period TC, compared with a manner in which the period Pw68 is less than one time of the natural vibration period TC and a manner in which the period Pw68 is more than two times of the natural vibration period TC, it is possible to increase the ejection performance value.

[0182] Further, the driving pulses PL1, PL2, and PL3 included in the waveform PH1 are an example of "first driving pulses". The driving components DC1, DC3, and DC5 are an example of "first driving components". The driving components DC2, DC4, and DC6 are an example of "second driving components". The driving pulses PL4 and PL5 included in the waveform PH2 are an example of "second driving pulses". The driving components DC7 and DC9 are an example of "third driving components". The driving components DC8 and DC10 are an example of "fourth driving components". The period Pw68 corresponds to "a first period".

[0183] Further, the period Pw68 is 1.2 times or more and 1.6 times or less than the natural vibration period TC. Since the period Pw68 is 1.2 times or more and 1.6 times or less than the natural vibration period TC, the ejection performance value can be increased as compared with a case where the period Pw68 is less than 1.2 times the natural vibration period TC and a case where the period Pw68 is more than 1.6 times the natural vibration period TC.

[0184] Further, the intervals of the pulses of the driving pulses PL1 to PL3 included in the waveform PH1, i.e., the periods Pw24 and Pw46, are 1 time or more and 2 times or less than the natural vibration period TC. The period Pw24 is a period from a time point tDC2 at which the supply of the driving component DC2 included in the driving pulse PL1 among the three driving pulses PL included in the waveform PH1 is started until a time point tDC4 at which the supply of the driving component DC4 included in the next driving pulse PL2 of the driving pulse PL1 is started. The period Pw46 is a period from a time point tDC4 at which the supply of the driving component DC4 included in the driving pulse PL2 among the three driving pulses PL included in the waveform PH1 is started until a time point tDC6 at which the supply of the driving component DC6 included in the next driving pulse PL3 of the driving pulse PL2 is started.

[0185] Since the periods Pw24 and Pw46 are 1 time or more and 2 times or less than the natural vibration period TC, the ejection performance value can be increased as compared with a case where the periods Pw24 and Pw46 are less than 1 time the natural vibration period TC and a case where the periods Pw24 and Pw46 are more than 2 times the natural vibration period TC.

[0186] Further, the period Pw24 and the period Pw46 are each an example of the "second period". In the case where the period Pw24 is an example of the "second period", the drive pulse PL1 corresponds to "one first drive pulse", and the drive pulse PL2 corresponds to "one first drive pulse next first drive pulse". In the case where the period Pw46 is an example of the "second period", the drive pulse PL2 corresponds to "one first drive pulse", and the drive pulse PL3 corresponds to "one first drive pulse next first drive pulse".

[0187] Further, the period Pw24 and the period Pw46 are each an example of the "second period". In the case where the period Pw24 is an example of the "second period", the drive pulse PL1 corresponds to "one first drive pulse", and the drive pulse PL2 corresponds to "one first drive pulse next first drive pulse". In the case where the period Pw46 is an example of the "second period", the drive pulse PL2 corresponds to "one first drive pulse", and the drive pulse PL3 corresponds to "one first drive pulse next first drive pulse".

[0188] 1.9.3. Summary of recording method using drive waveform signal Com

[0189] As described above, the liquid ejection head HU in the first embodiment has the M ejection portions D. The ejection portion D has the piezoelectric element PZ, the chamber 320, and the nozzle N. The piezoelectric element PZ is displaced in accordance with the drive signal Vin including the drive signal Vin1 and the drive signal Vin2 supplied in each of the plurality of recording periods Tu including the recording period Tu[j]. The control section 6 executes the recording method having the first step. In the first step, when the liquid droplet is ejected from the nozzle N in the recording period Tu[j], the waveform of the drive signal Vin supplied to the piezoelectric element PZ in the recording period Tu[j] is decided on the basis of the waveforms of the drive signal Vin supplied to the piezoelectric element PZ in the recording periods Tu preceding the recording period Tu[j], i.e., the recording periods Tu[j-1] to Tu[j-3]. When the drive signal Vin having the waveform decided in the first step has the waveform PH1 in the drive signal Vin1 and the waveform PH2 in the drive signal Vin2, the meniscus MS is caused to form the liquid column LC6 projecting in the -Z direction by supplying the drive signal Vin1 to the piezoelectric element PZ in the recording period Tu[j], and in the case where the liquid column LC6 is formed, a part or all of the ink constituting the liquid column LC8 is caused to be ejected as a liquid droplet by supplying the drive signal Vin2 to the piezoelectric element PZ after the meniscus MS is caused to form the liquid column LC8 projecting in the -Z direction.

[0190] For example, when the drive signal Vin based on the individual designation signal Sd[m] designating the drive mode al is supplied to the piezoelectric element PZ in the stationary state of the ejection section D, in the ink of the viscosity at which the degree of ejection of the droplet DR at the timing at which the waveform PH2 is supplied, if the droplet DR is ejected within the recording period Tu[j-1] preceding the recording period Tu[j] and the drive signal Vin based on the individual designation signal Sd[m] designating the drive mode al is supplied to the piezoelectric element PZ within the recording period Tu[j], there is a possibility that the droplet DR is ejected at the timing at which it should not be ejected, for example, while the waveform PHI is being supplied, thereby degrading the print quality.

[0191] The state of the meniscus MS at the start point of the recording period Tu[j] can be inferred from the waveform of the drive signal Vin supplied to the piezoelectric element PZ within the predetermined recording period Tux preceding the recording period Tu[j]. Therefore, since the waveform of the drive signal Vin supplied to the piezoelectric element PZ within the recording period Tu[j] is determined based on the waveform of the drive signal Vin supplied to the piezoelectric element PZ within the predetermined recording period Tux preceding the recording period Tu[j], the ejection can be performed in a manner close to the timing at which the droplet DR should be ejected, thereby degrading the print quality.

[0192] In addition, the recording period Tu[j] is an example of the "first recording period", and the predetermined recording period Tux preceding the recording period Tu[j], the recording periods Tu[j-1] to Tu[j-3] in the present embodiment, used in the determination of the drive signal Vin supplied to the piezoelectric element PZ within the recording period Tu[j] are examples of the "predetermined recording period preceding the first recording period".

[0193] The predetermined recording period Tux preceding the recording period Tu[j] used in the determination of the drive signal Vin supplied to the piezoelectric element PZ during the recording period Tu[j] includes the recording period Tu[j-1] ending at the start of the recording period Tu[j]. Among the two or more recording periods Tu ending before the start of the recording period Tu[j], the waveform of the drive signal Vin supplied to the piezoelectric element PZ during the recording period Tu[j-1] has the greatest influence on the meniscus MS at the start point of the recording period Tu[j]. Therefore, by determining the separate designation signal Sd[m] of the recording period Tu[j] based on the separate designation signal Sd[m] of the predetermined recording period Tux preceding the recording period Tu[j] including the recording period Tu[j-1], it is possible to more suppress the deterioration of the print quality compared to a case where the separate designation signal Sd[m] of the recording period Tu[j] is determined based on the separate designation signal Sd[m] of the predetermined recording period Tu preceding the recording period Tu[j] not including the recording period Tu[j-1].

[0194] In addition, the recording period Tu[j-1] is an example of the "second recording period".

[0195] In the first step in the section "Summary of the recording method using the drive waveform signal Com", the predetermined recording period Tux preceding the recording period Tu[j] used in the determination of the drive signal Vin supplied to the piezoelectric element PZ during the recording period Tu[j] includes the recording period Tu[j-1], and includes the consecutive recording periods Tu[j-1] to Tu[j-3] ending before the start of the recording period Tu[j].

[0196] Although the waveform of the drive signal Vin supplied to the piezoelectric element PZ during the recording period Tu[j-1] has the greatest influence on the meniscus MS at the start point of the recording period Tu[j], the waveform of the drive signal Vin supplied to the piezoelectric element PZ during the recording period Tu preceding the recording period Tu[j-1] also has an influence on the meniscus MS at the start point of the recording period Tu[j]. Therefore, according to the present embodiment, since it is possible to more accurately estimate the state of the meniscus MS at the start point of the recording period Tu[j], it is possible to more suppress the deterioration of the print quality compared to a case where the waveform of the drive signal Vin supplied to the piezoelectric element PZ during the recording period Tu[j] is determined based on only the waveform of the drive signal Vin supplied to the piezoelectric element PZ during the recording period Tu[j-1].

[0197] Further, the recording periods Tu[j-1] ~ Tu[j-3] are an example of "two or more consecutive recording periods including the second recording period and ending before the start of the first recording period."

[0198] In the first step in the section "Summary of the recording method using the drive waveform signal Com", the waveform of the drive signal Vin1 supplied to the piezoelectric element PZ during the recording period Tu[j] is decided based on the waveform of the drive signal Vin supplied to the piezoelectric element PZ during a predetermined recording period Tux preceding the recording period Tu[j].

[0199] Since the ejection is performed in a manner close to the timing at which the liquid droplet DR should originally be ejected by adjusting the waveform of the drive signal Vin1, the deterioration of the print quality can be further suppressed.

[0200] Further, in the first step in the section "Summary of the recording method using the drive waveform signal Com", whether or not the waveform PH1 is included in the drive signal Vin1 supplied to the piezoelectric element PZ during the recording period Tu[j] is decided based on the waveform of the drive signal Vin supplied to the piezoelectric element PZ during a predetermined recording period Tux preceding the recording period Tu[j] used in the decision of the drive signal Vin supplied to the piezoelectric element PZ during the recording period Tu[j].

[0201] Further, in the first step in the section "Summary of the recording method using the drive waveform signal Com", the number of drive pulses PL included in the waveform PH1 is further decided in the case where the waveform PH1 is included in the drive signal Vin1 supplied to the piezoelectric element PZ during the recording period Tu[j] based on the waveform of the drive signal Vin supplied to the piezoelectric element PZ during a predetermined recording period Tux preceding the recording period Tu[j] used in the decision of the drive signal Vin supplied to the piezoelectric element PZ during the recording period Tu[j].

[0202] As in this embodiment, the method of adjusting the number of drive pulses PL included in the drive signal Vinl can be realized by an easier structure than the method of adjusting the minimum potential and the maximum potential of the drive pulses PL included in the drive signal Vinl. The method of adjusting the minimum potential and the maximum potential of the drive pulses PL can be realized by, for example, the following structure. The drive waveform signal generating circuit 2 generates a first drive waveform signal Com-A and a second drive waveform signal Com-B. The difference between the minimum potential and the maximum potential of the drive pulses PL corresponding to the drive signal Vinl of the first drive waveform signal Com-A is larger than the difference between the minimum potential and the maximum potential of the drive pulses PL corresponding to the drive signal Vinl of the second drive waveform signal Com-B. The switching circuit 10 supplies one of the first drive waveform signal Com-A and the second drive waveform signal Com-B to the piezoelectric element PZ. However, the above structure results in a large drive waveform generating circuit if the number of drive waveform signals Com is to be increased, and becomes a more complicated structure than in this embodiment. Furthermore, although there is a limit to the minimum potential and the maximum potential that can be supplied to the piezoelectric element PZ in the inkjet printer 1, as described above, by repeatedly reducing and increasing the internal pressure of the chamber 320 by supplying a plurality of drive pulses PL to the piezoelectric element PZ, even an ink of high viscosity can be made to grow a liquid column and be ejected as a droplet DR.

[0203] Therefore, according to this embodiment, the waveform of the drive signal Vinl that conforms to the state of the meniscus MS at the start point of the recording period Tu[j] can be generated by an easier structure than the method of adjusting the minimum potential and the maximum potential of the drive pulses PL included in the drive signal Vinl.

[0204] The predetermined recording period Tux preceding the recording period Tu[j] used in the determination of the drive signal Vin supplied to the piezoelectric element PZ in the recording period Tu[j] includes the recording period Tu[j-1]. In the first step of the "Summary of the recording method using the drive waveform signal Com" section, the waveform of the drive signal Vinl supplied to the piezoelectric element PZ in the recording period Tu[j] is determined in such a manner that the first number of drive pulses PL included in the drive signal Vinl supplied to the piezoelectric element PZ in the recording period Tu[j] in the case where no droplet DR is ejected from the ejection portion D in the recording period Tu[j-1] is larger than the second number of drive pulses PL included in the drive signal Vinl supplied to the piezoelectric element PZ in the recording period Tu[j] in the case where a droplet DR is ejected from the ejection portion D in the recording period Tu[j-1].

[0205] The liquid column formed on the meniscus MS at the start time point of the recording period Tu[j] is smaller in the first condition in which the recording period Tu[j-1] is a non-ejection recording period Tu-N than in the second condition in which the recording period Tu[j-1] is an ejection recording period Tu-D. Therefore, in order to cause the liquid droplet DR to be ejected at the timing at which it should originally be ejected in the first condition, it is necessary to supply the piezoelectric element PZ with a drive signal Vinl having more drive pulses PL than in the second condition. Therefore, by determining the waveform of the drive signal Vinl supplied to the piezoelectric element PZ during the recording period Tu[j] in such a manner that the first number is larger than the second number, it is possible to cause the liquid droplet DR to be ejected at the timing at which it should originally be ejected.

[0206] When the liquid droplet is ejected from the nozzle N during the recording period Tu[j], the drive signal Vin2 of the drive signals Vin supplied to the piezoelectric element PZ during the recording period Tu[j] has a waveform PH2 that is predetermined regardless of the waveform of the drive signal Vin supplied to the piezoelectric element PZ during a predetermined recording period Tux preceding the recording period Tu[j] that is used in the determination of the drive signal Vin supplied to the piezoelectric element PZ during the recording period Tu[j]. Therefore, in the case where the drive signal Vin is generated so as to conform to the state of the meniscus MS at the start time point of the recording period Tu[j], it is possible to adjust only the waveform of the drive signal Vinl and not to adjust the waveform of the drive signal Vin2.

[0207] 1.9.4. Summary of the relationship between the drive signal Vin and the meniscus MS

[0208] As explained above, it can also be said that the liquid ejection head HU executes a driving method having the first step and the second step shown below. In the first step, by supplying the driving signal having the waveform PHI to the piezoelectric element PZ, the meniscus MS is formed to protrude in the ejection direction, and the liquid column LC6 is formed. In the second step, in a case where the liquid column LC6 is formed, by supplying the driving signal having the waveform PH2 to the piezoelectric element PZ, after the liquid column LC8 is formed in which the meniscus MS is formed to protrude in the -Z direction, a part or all of the ink constituting the liquid column LC8 is ejected as the droplet DR. The waveform PH2 includes the driving component DC7 that reduces the pressure inside the chamber 320, and the driving component DC8 that increases the pressure inside the chamber 320. In the second step, by supplying the driving component DC7 to the piezoelectric element PZ before the liquid column LC8 is formed, the liquid column LC7 is formed in which the meniscus MS is formed to protrude in the -Z direction. In the second step, in a case where the liquid column LC7 is formed, by supplying the driving component DC8 to the piezoelectric element PZ, the liquid column LC8 is formed.

[0209] According to the first embodiment, in a case where the liquid column LC6 is formed, by supplying the driving signal Vin having the driving component DC7 to the piezoelectric element PZ, it is possible to grow the liquid column formed on the meniscus MS, and further, in a case where the liquid column LC7 is formed, by supplying the driving signal Vin having the driving component DC8 to the piezoelectric element PZ, it is possible to eject a part or all of the ink constituting the liquid column LC8 as the droplet DR.

[0210] In addition, in the section "Summary of the relationship between the driving signal Vin and the meniscus MS", the waveform PHI is an example of the "first waveform". The waveform PH2 is an example of the "second waveform". The driving component DC7 is an example of the "first pull-in driving component". The driving component DC8 is an example of the "first squeeze-out driving component". The liquid column LC6 is an example of the "first liquid column". The liquid column LC7 is an example of the "third liquid column". The liquid column LC8 is an example of the "second liquid column".

[0211] The waveform PH1 has three driving pulses PL having a first driving component that reduces the pressure of the inside of the chamber 320 and a second driving component that increases the pressure of the inside of the chamber 320. In the first step of the section "Summary of the relationship between the driving signal Vin and the meniscus MS", in the case where the driving signal having the driving component DC1 of the first driving pulse PL1 of the three driving pulses PL that the waveform PH1 has has been supplied to the piezoelectric element PZ, the meniscus having the concave curved surface shape inside the ejection portion D is pulled in the +Z direction, and by supplying the driving signal having the driving component DC5 of the last driving pulse PL3 of the three driving pulses PL that the waveform PH1 has to the piezoelectric element PZ, the meniscus MS that forms the liquid column LC5 that protrudes in the -Z direction is pulled in the +Z direction.

[0212] According to the first embodiment, in the state where the driving signal having the driving component DC1 of the first driving pulse PL1 of the waveform PH1 has been supplied to the piezoelectric element PZ, although the liquid column is not generated on the meniscus MS, but a concave curved surface shape in which the central portion of the meniscus MS is recessed into the +Z direction side, by supplying the driving components DC2 of the driving pulse PL1, the driving components DC3 and DC4 of the driving pulse PL2 to the piezoelectric element PZ, and by supplying the driving component DC5 of the driving pulse PL3 to the piezoelectric element PZ, it is possible to form the liquid column LC5 at the central portion of the meniscus MS.

[0213] In addition, in the section "Summary of the relationship between the driving signal Vin and the meniscus MS", the driving components DC1, DC3, and DC5 are one example of the "first driving component". The driving components DC2, DC4, and DC6 are one example of the "second driving component". The meniscus MS that forms the liquid column LC5 is one example of "the meniscus that protrudes in the ejection direction by supplying the first driving component of the last driving pulse of the plurality of driving pulses that the first waveform has to the driving element".

[0214] In the first step of the section "Summary of the relationship between the driving signal Vin and the meniscus MS", by supplying the driving signal having the driving component DC3 of the driving pulse PL2 between the first driving pulse PL1 and the last driving pulse PL3 of the three driving pulses PL that the waveform PH1 has to the piezoelectric element PZ, the meniscus MS that forms the liquid column LC3 is pulled in the +Z direction. The liquid column LC3 formed by the driving component DC3 of the driving pulse PL2 is smaller than the liquid column LC6 formed by the driving component DC5 of the driving pulse PL3.

[0215] In this way, by repeating the drive pulse PL and supplying it to the piezoelectric element PZ, it is possible to make the liquid column grow gradually larger. By making the liquid column grow larger, even an ink of high viscosity can be ejected as a droplet DR when the waveform PH2 is supplied to the piezoelectric element PZ.

[0216] In addition, the liquid column LC3 is an example of a "fourth liquid column".

[0217] 2. Modification

[0218] Each of the above-described modes can be variously modified. Specific modified modes are exemplified below. Two or more modes selected arbitrarily from the following examples can be appropriately combined within a range in which they do not contradict each other. In addition, with respect to elements that function or function in the same manner as in the embodiments in the modification examples exemplified below, the same symbols as those referred to in the above description will be used, and detailed description of each will be appropriately omitted.

[0219] 2.1. First Modification

[0220] Although in the first embodiment, the control section 6 generates the individual designation signal Sd[m] of the drive mode α5 in the case where Tu[j] is the non-ejection recording period Tu-N during recording, an individual designation signal Sd[m] of a drive mode other than the drive mode α5 can also be generated.

[0221] Figure 24 is a diagram for explaining five drive modes that can be individually designated by the individual designation signal Sd[m] in the first modification. In the first modification, the individual designation signal Sd[m] is a signal that designates any one of the five drive modes of the drive mode αl to the drive mode α4 and the drive mode α6. The individual designation signal Sd[m] of the drive mode α6 is generated in a case where the ejection section D[m] is not caused to eject a droplet. That is, in the first modification, the control section 6 generates the individual designation signal Sd[m] of the drive mode α6 instead of the individual designation signal Sd[m] of the drive mode α5 in a case where the ejection section D[m] is not caused to eject a droplet, which is different from the first embodiment in this point. The value of the individual designation signal Sd[m] that indicates the drive mode α6 is (0, 0, 0, 1, 0). The connection state designation circuit 11 sets the connection state designation signal SLa[m] to the low level within the control period Tcui, the control period Tcu2, the control period Tcu3, and the control period Tcu5 and sets the connection state designation signal SLa[m] to the high level within the control period Tcu4 in a case where the individual designation signal Sd[m] indicates the drive mode α6.

[0222] Figure 25is a diagram showing a specific example of the recording method using the drive waveform signal Com in the first modification. If compared with the recording period Tu[1] shown in the first embodiment, Figure 23 In the first modification, the individual designation signal Sd[m] during the recording period Tu in which no droplet DR is ejected is replaced from the drive mode α5 to the drive mode α6. More specifically, Figure 25 the recording period Tu[2] shown in the second stage of the drive mode α5, Figure 25 the recording period Tu[2] and the recording period Tu[3] shown in the third stage of the drive mode α5, Figure 25 the recording period Tu[2], the recording period Tu[3], and the recording period Tu[4] shown in the fourth stage of the drive mode α5 are replaced from the drive mode α5 to the drive mode α6.

[0223] According to the first modification, even in the recording period Tu[j] which is the non-ejection recording period Tu-N, by supplying the drive pulse PL to the extent that no droplet DR is ejected to the piezoelectric element PZ, it is possible to maintain the meniscus MS at the start time point of the next recording period Tu[j+1] of the non-ejection recording period Tu-N or it is possible to easily form the liquid column during the recording period Tu[j]. When the next recording period Tu[j+1] is the ejection recording period Tu-D, it is possible to utilize the variation of the meniscus MS during the recording period Tu[j-1].

[0224] In the first modification example, although the driving pulse PL having the driving pulse PL4 is selected as the driving pulse PL of the driving signal Vin2 to be supplied to the piezoelectric element PZ within the non-ejection recording period Tu-N as the degree of not ejecting the liquid droplet DR, the selected driving pulse PL is not limited to this. For example, either one of the driving pulses PL1, PL2, PL3, PL4, and PL5 or a plurality of driving pulses PL can be selected. However, for the driving pulse PL selected within the recording period Tu[j] as the non-ejection recording period Tu-N, it is preferable that the driving pulse PL be the driving pulse PL close to the driving pulse PL4 of the next recording period Tu[j+1]. This is because, in the case where the next recording period Tu[j+1] is the ejection recording period Tu-D, by selecting the driving pulse PL close to the driving pulse PL4 included in the waveform PH2 at the ejection timing of the liquid droplet DR as the recording period Tu[j+1] as the driving signal Vin of the non-ejection recording period Tu-N, i.e., the recording period Tu[j], the interval between the driving pulse PL selected within the recording period Tu[j] and the driving pulse PL selected within the recording period Tu[j+1] becomes short, and the possibility of being able to utilize the liquid column formed on the meniscus MS or the variation of the meniscus MS within the recording period Tu[j] within the recording period Tu[j+1] becomes high. Further, when the recording period Tu[j-1] before the recording period Tu[j] as the non-ejection recording period Tu-N is the ejection recording period Tu-D, by selecting the driving pulse PL distant from the driving pulse PL4 included in the waveform PH2 at the ejection timing of the liquid droplet DR as the recording period Tu[j-1] as the driving signal Vin of the recording period Tu[j], it is possible to suppress the case where the liquid droplet DR is ejected within the non-ejection recording period Tu-N, i.e., the recording period Tu[j] due to the liquid column or the variation of the meniscus MS formed after the liquid droplet DR is ejected within the recording period Tu[j-1].

[0225] Further, when no droplet is ejected from the nozzle N during the recording period Tu[j], a drive signal Vin having at least one of the waveform PH1 including at least one of the drive pulses PL1, PL2, and PL3, and the waveform PH2 including at least one of the drive pulses PL4 and PL5 is supplied to the piezoelectric element PZ so as to increase and decrease the pressure of the ink inside the chamber 320 to an extent that no droplet is ejected from the nozzle N during the recording period Tu[j]. With the above processing, even during the recording period Tu[j] in which no droplet is ejected from the nozzle N, by supplying the drive signal Vin having at least one of the waveform PH1 and the waveform PH2 to the piezoelectric element PZ, it is possible to maintain the vibration of the ink inside the ejection section D during the recording period Tu[j] and utilize the vibration during the recording period Tu[j+1]. Further, when a droplet DR is ejected from the nozzle N during the recording period Tu[j+1], in the case where the vibration is applied by the waveform PH2 closer to the recording period Tu[j+1] during the recording period Tu[j], compared to the case where the vibration is applied only by the waveform PH1 during the recording period Tu[j], it is possible to utilize the vibration applied during the recording period Tu[j] before the vibration is reduced during the recording period Tu[j+1]. Further, when a droplet DR is ejected from the nozzle N during the recording period Tu[j-1], in the case where the drive signal Vin not including the waveform PH1 closer to the recording period Tu[j+1] is supplied during the recording period Tu[j], it is possible to prevent the case where ejection is performed even during the recording period Tu[j].

[0226] 2.2. Second Modification Example

[0227] Although in the first embodiment and the first modification example, the control section 6 always generates the individual designation signal Sd[m] of the same drive mode when the recording period Tu[j] is the non-ejection recording period Tu-N, it is also possible to generate the individual designation signals Sd[m] of mutually different drive modes between a plurality of non-ejection recording periods Tu-N.

[0228] Figure 26Fig. 6 is a diagram for explaining six drive modes obtainable by the individually specified signal Sd[m] in the second modification. In the second modification, the individually specified signal Sd[m] is a signal that specifies any one of the six drive modes of the drive mode al to the drive mode a4, the drive mode a7, and the drive mode a8. The individually specified signal Sd[m] of the drive mode a7 and the individually specified signal Sd[m] of the drive mode a8 are generated without causing the ejection section D[m] to eject a droplet. That is, in the second modification, the control section 6 generates the individually specified signal Sd[m] of the drive mode a7 or the individually specified signal Sd[m] of the drive mode a8 instead of the individually specified signal Sd[m] of the drive mode a5 without causing the ejection section D[m] to eject a droplet, unlike the first embodiment.

[0229] The value of the individually specified signal Sd[m] of the drive mode a7 is (0, 1, 0, 0, 0). The connection state specifying circuit 11 sets the connection state specifying signal SLa[m] to the low level within the control period Tcui, the control period Tcu3, the control period Tcu4, and the control period Tcu5 and sets the connection state specifying signal SLa[m] to the high level within the control period Tcu2 when the individually specified signal Sd[m] indicates the drive mode a7. The value of the individually specified signal Sd[m] of the drive mode a8 is (1, 0, 1, 0, 0). The connection state specifying circuit 11 sets the connection state specifying signal SLa[m] to the low level within the control period Tcu2, the control period Tcu4, and the control period Tcu5 and sets the connection state specifying signal SLa[m] to the high level within the control period Tcui and the control period Tcu3 when the individually specified signal Sd[m] indicates the drive mode a8.

[0230] As to which one of the individually specified signal Sd[m] of the drive mode a7 and the individually specified signal Sd[m] of the drive mode a8 is generated, in the second modification, a case where there are consecutive non-ejection recording periods Tu-N is assumed. The control section 6 generates the individually specified signal Sd[m] of the drive mode a7 within the k-th non-ejection recording period Tu-N among the consecutive non-ejection recording periods Tu-N and generates the individually specified signal Sd[m] of the drive mode a8 within the (k+1)-th non-ejection recording period Tu-N. The variable k is an integer from 1 to the consecutive non-ejection recording periods Tu-N.

[0231] Figure 27 Fig. 6 is a diagram for explaining six drive modes obtainable by the individually specified signal Sd[m] in the second modification. In the second modification, the individually specified signal Sd[m] is a signal that specifies any one of the six drive modes of the drive mode al to the drive mode a4, the drive mode a7, and the drive mode a8. The individually specified signal Sd[m] of the drive mode a7 and the individually specified signal Sd[m] of the drive mode a8 are generated without causing the ejection section D[m] to eject a droplet. That is, in the second modification, the control section 6 generates the individually specified signal Sd[m] of the drive mode a7 or the individually specified signal Sd[m] of the drive mode a8 instead of the individually specified signal Sd[m] of the drive mode a5 without causing the ejection section D[m] to eject a droplet, unlike the first embodiment. Figure 23In the second modification, the individual designation signal Sd[m] during the recording period Tu in which the droplet DR is not ejected is replaced from the drive pattern α5 to the drive pattern α7 or the drive pattern α8. More specifically, Figure 27 the recording period Tu[2] shown in the second stage of the first modification, Figure 27 the recording period Tu[2] shown in the third stage of the first modification, and Figure 27 the recording period Tu[2] and the recording period Tu[4] shown in the fourth stage of the first modification, the individual designation signal Sd[m] is replaced from the drive pattern α5 to the drive pattern α7, Figure 27 the recording period Tu[3] shown in the third stage of the first modification, and Figure 27 the recording period Tu[3] shown in the fourth stage of the first modification, the individual designation signal Sd[m] is replaced from the drive pattern α5 to the drive pattern α8. In addition, it is also possible to set a mode in which the control section 6 selects any one of the drive patterns α5 to α8 in the individual designation signal Sd[m] during the non-ejection recording period Tu-N. Furthermore, it is also possible to set a mode in which one or more drive pulses PL are included from the drive pulses PL1 to PL4 as the drive signal Vin supplied during the non-ejection recording period Tu-N.

[0232] As in the second modification, the control section 6 can adjust the number of drive pulses PL supplied during the non-ejection recording period Tu-N to the extent that the droplet DR is not ejected. As to the specific number of drive pulses PL, the designer of the inkjet printer 1 specifies the relationship between the viscosity and the number of drive pulses PL by experiment, and stores a table showing the relationship between the viscosity of the ink and the number of drive pulses PL, or a calculation formula for calculating the number of drive pulses PL from the viscosity of the ink in the storage section 5.

[0233] Furthermore, as a modification of the second modification, the control section 6 can vary the drive pulse PL supplied during the non-ejection recording period Tu-N to the extent that the droplet DR is not ejected. For example, the control section 6 can generate the individual designation signal Sd[m] in which the drive signal Vin having only the drive pulse PL3 is generated during the k-th non-ejection recording period Tu-N among the continuous non-ejection recording periods Tu-N, and generate the individual designation signal Sd[m] in which the drive signal Vin having only the drive pulse PL4 is generated during the (k+1)-th non-ejection recording period Tu-N. The variable k is an integer from 1 to the number of continuous non-ejection recording periods Tu-N.

[0234] 2.3. Third Modification

[0235] Although in the first embodiment, the first modification example, and the second modification example, the viscosity of the ink is such a degree that, in a state where the ejection section D is supplied with the reference potential Vo of the positive piezoelectric element PZ in a stationary state and the position of the meniscus MS is stationary at the initial position Z0, the droplet DR can be ejected within one recording period Tu[i] in a case where the drive signal Vin based on the individually designated signal Sd[m] of the drive mode al is supplied to the piezoelectric element PZ within one recording period Tu[i], there is also a high viscosity of the ink that is such a degree that, even in a case where the drive signal Vin based on the individually designated signal Sd[m] of the drive mode al is supplied to the piezoelectric element PZ within one recording period Tu[i], the ink cannot be ejected within one recording period Tu[i]. In the third modification example, in a case where the printing process is started from the recording period Tu[l], by supplying the drive signal that generates the out-of-print micro-vibration to the piezoelectric element PZ before the recording period Tu[l], the droplet DR can be ejected within the recording period Tu[l], and thereafter, by using the liquid column formed on the meniscus MS or the variation of the meniscus MS of the recording period Tu[j-1], the droplet DR can be ejected within the recording period Tu[j].

[0236] Figure 28 FIG. 6 is a diagram for explaining the drive signal Vin used in the case where the droplet DR is ejected in the third modification example. Figure 28 The ejection mode shown in the first stage of the first modification example is a mode in which the droplet DR is ejected within the recording period Tu[l] at the beginning of the printing process and the recording period Tu[2] thereafter. In a period before the recording period Tu[l], that is, a period Tbu, the control section 6 supplies the drive signal Vin that generates the out-of-print micro-vibration to the piezoelectric element PZ. Thereby, on the ejection section D[m], the drive signal Vin that generates the out-of-print micro-vibration is supplied within the period Tbu. The drive signal Vin that generates the out-of-print micro-vibration includes a waveform that includes a plurality of pulses including a drive component that reduces the pressure inside the chamber 320 and a drive component that increases the pressure inside the chamber 320.

[0237] For the recording period Tu[l], the control section 6 generates the individually designated signal Sd[m] of the drive mode al, and outputs the generated individually designated signal Sd[m] to the switching circuit 10. Thereby, on the ejection section D[m], the drive signal Vin having the drive pulses PL1, PL2, PL3, PL4, and PL5 is supplied within the recording period Tu[l]. Since, at the start time point of the recording period Tu[l], the liquid column is formed on the meniscus MS or the meniscus MS is varied by the out-of-print micro-vibration, the ejection section D can eject the droplet DR within the recording period Tu[l].

[0238] For the recording period Tu[2], the control unit 6 generates a separate designated signal Sd[m] for the driving mode α2 and outputs the generated separate designated signal Sd[m] to the switching circuit 10. Thus, during the recording period Tu[2], the ejector D[m] is supplied with a driving signal Vin having driving pulses PL4 and PL5. Since the driving signal Vin having driving pulses PL1, PL2, PL3, PL4 and PL5 is supplied during the recording period Tu[1], a liquid column is formed on the meniscus MS at the beginning of the recording period Tu[2], or the meniscus MS is changed, so the ejector D can eject droplets DR during the recording period Tu[1].

[0239] Figure 28 The second stage shows an ejection method in which droplets DR are ejected during the recording period Tu[1] and the recording period Tu[3], but no droplets DR are ejected during the recording period Tu[2]. Regarding the period Tbu and the recording period Tu[1], since... Figure 28 The first stage shows the same period Tbu and recording period Tu[1], so the explanation is omitted. Since the recording period Tu[2] is the non-ejection recording period Tu-N, a drive signal Vin with a drive pulse PL that includes the degree of non-ejection droplet DR is supplied, such as a drive signal Vin with drive pulses PL2 and PL3.

[0240] For the recording period Tu[3], since the prior predetermined recording period Tux is the non-ejection recording period Tu-N, it is supplied with the same... Figure 28 The first stage shown has a driving signal Vin with more driving pulses PL compared to the previous recording period Tu[1] of the ejection recording period Tu-D, such as driving signals Vin with driving pulses PL3, PL4 and PL5. Since driving signals Vin with driving pulses PL2 and PL3 are supplied during the recording period Tu[2], a liquid column is formed on the meniscus MS or the meniscus MS is changed at the beginning of the recording period Tu[3], so that the ejection part D can eject droplets DR during the recording period Tu[3].

[0241] In addition, in the third modification example, the waveform PH1 included in the drive signal Vin during the recording period Tu[l] in the initial recording period Tu[l] of the printing process is another example of the "first waveform" described in the foregoing embodiments and modification examples, and the waveform PH2 included in the drive signal Vin during the recording period Tu[l] is another example of the "second waveform" described in the foregoing embodiments and modification examples. Further, the waveform PH1 included in the drive signal Vin during the recording period Tu[j-1] and the waveform PH1 included in the drive signal Vin during the recording period Tu[j] in the recording period Tu after the initial recording period Tu[l] of the printing process is another example of the "first waveform" described in the foregoing embodiments and modification examples, and the waveform PH2 included in the drive signal Vin during the recording period Tu[j] is another example of the "second waveform" described in the foregoing embodiments and modification examples. Further, the plurality of pulses included in the drive signal Vin that causes the extraneous vibration during the recording period Tu[l] in the initial recording period Tu[l] of the printing process, and the drive pulse PL included in the waveform PH1 included in the drive signal Vin during the recording period Tu[l] is another example of the "first drive pulse" described in the foregoing embodiments and modification examples, and the drive pulse PL included in the waveform PH2 included in the drive signal Vin during the recording period Tu[l] is another example of the "second drive pulse" described in the foregoing embodiments and modification examples. Further, the drive pulse PL included in the drive signal Vin during the recording period Tu[j-1] and the drive pulse PL included in the waveform PH1 included in the drive signal Vin during the recording period Tu[j] in the recording period Tu after the initial recording period Tu[l] of the printing process is another example of the "first drive pulse" described in the foregoing embodiments and modification examples, and the drive pulse PL of the waveform PH2 included in the drive signal Vin during the recording period Tu[j] is another example of the "second waveform" described in the foregoing embodiments and modification examples.

[0242] 2.4. Fourth Modification Example

[0243] Although in the third modification example, an example is explained in which, when the viscosity of the ink is so high that the ink cannot be ejected within one recording period Tu[i] even if the driving signal Vin based on the individually designated signal Sd[m] of the driving mode al is supplied to the piezoelectric element PZ during the recording period Tu[i], the driving signal that causes the printing outer microvibration is supplied to the piezoelectric element PZ before the initial recording period Tu[1] of the printing process, and thus the droplet DR is ejected within the recording period Tu[1], the present application is not limited to this example. In the fourth modification example, the driving signal Vin is supplied to the piezoelectric element PZ across a plurality of recording periods Tu[i] from a state in which the rest state of the ejection section D in which the reference potential V0 is supplied to the piezoelectric element PZ in the forward direction and the position of the meniscus MS is at the initial position Z0, and thus one droplet DR can be ejected from the ejection section D within the plurality of recording periods Tu[i].

[0244] Figure 29 is a graph for explaining the driving signal Vin when the droplet DR is ejected in the fourth modification example. In order to make the ejection interval, in other words, the dot interval uniform among the plurality of ejection sections D, the control section 6 makes a predetermined number of recording periods Tu correspond to one dot. The predetermined number is an integer of 2 or more. In Figure 29 In the example in which the predetermined number is 2, the control section 6 controls the moving mechanism 8 so that the moving speed of the liquid droplet ejection head HU becomes a value obtained by dividing the moving speed of the liquid droplet ejection head HU in the first embodiment by the predetermined number.

[0245] In Figure 29 In the example in which the predetermined number is 2, the control section 6 controls the moving mechanism 8 so that the moving speed of the liquid droplet ejection head HU becomes a value obtained by dividing the moving speed of the liquid droplet ejection head HU in the first embodiment by the predetermined number.

[0246] Next, one dot printing is performed even within two recording periods Tu[i+2] and a recording period Tu[i+3] that follow the recording period Tu[i+1]. Within the recording period Tu[i+2], the control section 6 generates the individually designated signal Sd[m] of the value (1, 1, 1, 0, 0), and within the recording period Tu[i+3], the control section 6 generates the individually designated signal Sd[m] of the driving mode al.

[0247] In addition, in the fourth modification example, the waveform PH1 included in the drive signal Vin during the recording period Tu[i] and the drive signal Vin during the recording period Tu[i+1] is another example of the "first waveform" described in the foregoing embodiments and modification examples, and the waveform PH2 included in the drive signal Vin during the recording period Tu[i+1] is another example of the "second waveform" described in the foregoing embodiments and modification examples. Furthermore, the waveform PH1 included in the drive signal Vin during the recording period Tu[i+2] and the drive signal Vin during the recording period Tu[i+3] is another example of the "first waveform" described in the foregoing embodiments and modification examples, and the waveform PH2 included in the drive signal Vin during the recording period Tu[i+3] is another example of the "second waveform" described in the foregoing embodiments and modification examples. Furthermore, the drive pulse PL included in the drive signal Vin during the recording period Tu[i] and the drive pulse PL included in the waveform PH1 of the drive signal Vin during the recording period Tu[i+1] is another example of the "first drive pulse" described in the foregoing embodiments and modification examples, and the drive pulse PL included in the waveform PH2 of the drive signal Vin during the recording period Tu[i+1] is another example of the "second drive pulse" described in the foregoing embodiments and modification examples. Furthermore, the drive pulse PL included in the drive signal Vin during the recording period Tu[i+2] and the drive pulse PL included in the waveform PH1 of the drive signal Vin during the recording period Tu[i+3] is another example of the "first drive pulse" described in the foregoing embodiments and modification examples, and the drive pulse PL included in the waveform PH2 of the drive signal Vin during the recording period Tu[i+3] is another example of the "second drive pulse" described in the foregoing embodiments and modification examples.

[0248] As explained in the first embodiment, when the liquid droplet DR is ejected in the two recording periods Tu[j] and Tu[j+1], the waveform of the drive signal Vin supplied to the piezoelectric element PZ in the predetermined recording period Tux preceding the two recording periods Tu[j] and Tu[j+1] is based on, and the waveform of the drive signal Vin supplied to the piezoelectric element PZ in the two recording periods Tu[j] and Tu[j+1] is determined. In order to eject the liquid droplet DR in the recording period Tu[i+1] preceding the two recording periods Tu[i+2] and Tu[i+3], the number of drive pulses PL included in the drive signal Vin in the recording period Tu[i+2] is made smaller than the number of drive pulses PL included in the drive signal Vin in the recording period Tu[i] in the preceding period in which the liquid droplet DR is not ejected.

[0249] Further, in the fourth modification example, as in the third modification example, the drive signal that causes the off-print micro-vibration to occur can be supplied to the piezoelectric element PZ before the start of the printing process. By causing the off-print micro-vibration to occur before the first recording period Tu[1] of the printing process, the number of recording periods Tu corresponding to one dot can be reduced compared to the case where the off-print micro-vibration does not occur, and the case where the moving speed of the liquid ejection head HU is reduced can be suppressed.

[0250] 2.5. Fifth Modification Example

[0251] Although in the first embodiment and the first to fourth modification examples, when the liquid droplet DR is ejected in the recording period Tu[j], the waveform of the drive signal Vin supplied to the piezoelectric element PZ in the predetermined recording period Tux preceding the recording period Tu[j] is based on, and the waveform of the drive signal Vin supplied to the piezoelectric element PZ in the recording period Tu[j] is determined, specifically, the waveform of the drive signal Vin supplied to the piezoelectric element PZ in the predetermined recording period Tux is based on, and which one of the drive modes α1 to α4 is selected in the recording period Tu[j] is determined, it is not limited thereto. In the fifth modification example, the waveform of the drive signal Vin can be determined based on the viscosity of the ink, specifically, the number of drive pulses PL included in the drive signal Vin is varied.

[0252] Figure 30 Fig. 1 is a functional block diagram showing one example of the structure of the inkjet printer la in the fifth modification example. The inkjet printer la differs from the inkjet printer 1 in that it has the control section 6a instead of the control section 6 and has the viscosity information acquisition section 9.

[0253] The viscosity information acquisition unit 9 acquires viscosity information VI, which represents the viscosity of the liquid in the liquid ejector head HU. Viscosity information VI is an example of "physical property information".

[0254] The viscosity information acquisition unit 9 acquires viscosity information VI, for example, by any one of the three methods shown below. In the first method, the viscosity information acquisition unit 9 acquires viscosity information VI based on the waveform of the residual vibration of the vibrating plate 310. In the second method, the viscosity information acquisition unit 9 acquires the viscosity information VI of the ink held in the liquid container 14. In the third method, the user inputs the viscosity information VI of the ink, and the viscosity information acquisition unit 9 acquires the viscosity information VI input by the user.

[0255] The control unit 6a determines the waveform of the drive signal Vin based on the viscosity information VI. Specifically, the control unit 6a determines the number of drive pulses PL of the waveform PH1 included in the drive signal Vin1 based on the viscosity information VI. Figure 31 The following example illustrates the determination of the number of drive pulses PL of waveform PH1 contained in drive signal Vin1.

[0256] Figure 31 This is a diagram illustrating an example of determining the number of drive pulses PL for the waveform PH1 contained in the drive signal Vin1. (See diagram for example.) Figure 31 As shown, when the viscosity represented by viscosity information VI is less than 20 mPa·s, the control unit 6a sets the number of drive pulses PL of waveform PH1 included in the drive signal Vin1 to 0. When the viscosity represented by viscosity information VI is 20 mPa·s or more but less than 30 mPa·s, the control unit 6a sets the number of drive pulses PL of waveform PH1 included in the drive signal Vin1 to 1. When the viscosity represented by viscosity information VI is 30 mPa·s or more but less than 50 mPa·s, the control unit 6a sets the number of drive pulses PL of waveform PH1 included in the drive signal Vin1 to 2. When the viscosity represented by viscosity information VI is 50 mPa·s or more but less than 70 mPa·s, the control unit 6a sets the number of drive pulses PL of waveform PH1 included in the drive signal Vin1 to 3.

[0257] When the number of drive pulses PL for the waveform PH1 contained in the drive signal Vin1 is determined to be 1, the control unit 6a determines the waveform of the drive signal Vin1 to be a waveform PH1 having any one of the drive pulses PL1, PL2, and PL3 selected from the drive pulses PL1, PL2, and PL3. For example, the waveform of the drive signal Vin1 is determined to be a waveform PH1 having a drive pulse PL3.

[0258] Likewise, when the number of drive pulses PL included in the drive signal Vinl is determined to be two, the control section 6a determines the waveform possessed by the drive signal Vinl to be the waveform PHl having any two drive pulses PL selected from among the drive pulses PLl, PL2, and PL3. For example, the waveform possessed by the drive signal Vinl is determined to be the waveform PHl having the drive pulses PL2 and PL3.

[0259] Further, regardless of the viscosity information VI, the control section 6a determines the waveform possessed by the drive signal Vin2 to be the waveform PH2.

[0260] In addition, when the drive pulses PL included in the waveform PHl are selected from among the drive pulses PLl, PL2, and PL3, by selecting the drive pulses PL close to the waveform PH2, it is possible to easily cause the liquid droplet DR to be ejected from the nozzle N when the waveform PH2 is supplied to the piezoelectric element PZ.

[0261] Returning the explanation to Figure 30 , the control section 6a generates the individual designation signal Sd[m] in a manner that the drive signal Vinl having the determined waveform and the drive signal Vin2 having the determined waveform can be generated. For example, when it is determined that the drive signal Vinl includes the waveform PHl having only the drive pulse PL3, the control section 6a generates the individual designation signal Sd[m] of the drive mode α3 shown in FIG. 27. The control section 6a outputs the generated individual designation signal Sd[m] to the switching circuit 10. Figure 6

[0262] Further, in the fifth modification example, as explained in the first embodiment, when the liquid droplet DR is caused to be ejected within the recording period Tu[j], the waveform of the drive signal Vin supplied to the piezoelectric element PZ within a predetermined recording period Tux preceding the recording period Tu[j] is also taken into consideration, and thus it is also possible to determine the waveform of the drive signal Vin supplied to the piezoelectric element PZ within the recording period Tu[j].

[0263] 2.5.1. Summary of the fifth modification example

[0264] ​As explained above, in the inkjet printer 1a in the fifth modification example, the control section 6 executes the recording method having the first step, the second step, the third step, and the fourth step. In the first step, the viscosity information VI indicating the viscosity of the ink in the liquid ejection head HU is acquired. In the second step, the waveform of the drive signal Vin is decided based on the viscosity information VI. In the third step, the meniscus MS protruding in the -Z direction is formed by supplying the waveform PH1 included in the drive signal Vin1 among the drive signals Vin having the waveform decided in the second step to the piezoelectric element PZ. In the fourth step, when the liquid column LC6 is formed, the waveform PH2 included in the drive signal Vin2 among the drive signals Vin having the waveform decided in the second step is supplied to the piezoelectric element PZ, so that the liquid column LC8 is formed with the meniscus MS protruding in the -Z direction, and then a part or all of the liquid constituting the liquid column LC8 is ejected as the droplet DR.

[0265] If the number of drive pulses PL of the waveform PH1 is increased even though the state where the viscosity of the ink is low, the case where the droplet DR is ejected earlier than the timing at which the droplet DR should be ejected is caused. On the other hand, if the number of drive pulses PL of the waveform PH1 is decreased even though the state where the viscosity of the ink is high, the case where the droplet DR is ejected later than the timing at which the droplet DR should be ejected or the droplet DR is not ejected is caused.

[0266] Since the waveform of the drive signal Vin is decided based on the viscosity indicated by the viscosity information VI, the ejection can be performed in a manner close to the timing at which the droplet DR should be ejected, so that the deterioration of the print quality can be suppressed.

[0267] In the second step in the "Summary of the fifth modification example", the waveform of the drive signal Vin1 is decided based on the viscosity information VI.

[0268] By adjusting the waveform of the drive signal Vin1, the ejection can be performed in a manner close to the timing at which the droplet DR should be ejected.

[0269] In the second step in the "Summary of the fifth modification example", the number of drive pulses PL of the waveform PH1 included in the drive signal Vin1 is decided based on the viscosity information VI.

[0270] As described in the "Summary of the recording method using the drive waveform signal Com" section in the first embodiment, the manner of adjusting the number of drive pulses PL becomes a relatively easy structure compared to the manner of adjusting the minimum potential and the maximum potential of the drive pulse PL.

[0271] According to the fifth modification example, therefore, the waveform of the drive signal Vinl that matches the viscosity of the ink can be generated with an easier configuration.

[0272] In the fifth modification example, the drive signal Vin2 has a waveform PH2 that is prescribed in advance regardless of the viscosity information VI. Therefore, in the case of generating a drive signal Vin that matches the viscosity of the ink, it is only necessary to adjust the waveform of the drive signal Vinl, and it is not necessary to adjust the waveform of the drive signal Vin2.

[0273] In the second step in the section "Summary of the fifth modification example", the waveform of the drive signal Vinl is decided in such a manner that the third number of drive pulses PL of the waveform PHl included in the drive signal Vinl is larger than the fourth number of drive pulses PL of the waveform PHl included in the drive signal Vinl in the case where the viscosity information VI indicates a first viscosity than in the case where the viscosity information VI indicates a second viscosity that is lower than the first viscosity.

[0274] Since the first viscosity is higher than the second viscosity, the drive signal Vinl that has more drive pulses PL needs to be supplied to the piezoelectric element PZ in the case where the viscosity information VI indicates the first viscosity than in the case where the viscosity information VI indicates the second viscosity. Therefore, by deciding the waveform of the drive signal Vinl in such a manner that the third number is larger than the fourth number, it is possible to perform ejection at the timing at which the droplet DR should originally be ejected.

[0275] 2.6. Sixth Modification Example

[0276] Although the case where one example of the physical property information is the viscosity information VI is described in the fifth modification example, the physical property information is not limited to the viscosity information VI. For example, the physical property information can be any one of information indicating the surface tension of the ink, information indicating the bulk modulus of the ink, and information indicating the specific gravity of the ink.

[0277] In the case where the physical property information is the information indicating the surface tension of the ink, the control section 6 decides the waveform of the drive signal Vinl in such a manner that the number of drive pulses PL included in the drive signal Vinl is larger in the case where the surface tension of the ink indicates a first value than in the case where the surface tension of the ink indicates a second value that is smaller than the first value.

[0278] In a case where the physical property information is information indicating the bulk modulus of the ink, the control section 6 determines the waveform of the drive signal Vinl in such a manner that the number of drive pulses PL included in the drive signal Vinl is larger in a case where the bulk modulus of the ink indicates a third value than in a case where the bulk modulus of the ink indicates a fourth value lower than the third value.

[0279] In a case where the physical property information is information indicating the specific gravity of the ink, the control section 6 determines the waveform of the drive signal Vinl in such a manner that the number of drive pulses PL included in the drive signal Vinl is larger in a case where the bulk modulus of the ink indicates a fifth value than in a case where the bulk modulus of the ink indicates a sixth value larger than the fifth value.

[0280] 2.7. Seventh Modification Example

[0281] Although the drive waveform signal Com has the waveform PH2 having the drive pulses PL4 and PL5 in the first embodiment and the first to sixth modification examples, the present application is not limited to this. The drive waveform signal Comb in the seventh modification example has the waveform PH2b having only the drive pulse PL4.

[0282] Figure 32 Fig. 7 is a diagram for describing the drive waveform signal Comb in the seventh modification example. The drive waveform signal Comb has the waveform PHl and the waveform PH2b. The waveform PH2b has the drive pulse PL4b. The drive pulse PL4b has the drive component DC7 and a drive component DC8b. Since the amount of change in potential per unit period in the drive component DC8b is larger than the amount of change in potential per unit period in the drive components DC2, DC4, and DC6, the energy of the -Z direction movement of the liquid column LC8 formed by supplying the drive component DC8b to the piezoelectric element PZ becomes large, so that even in the absence of a drive pulse PL after the drive pulse PL4b, a part or all of the liquid column can be ejected as the droplet DR.

[0283] 2.8. Eighth Modification Example

[0284] Although the potential difference between the highest potential and the lowest potential in the drive pulse PL included in the waveform PH1 and the waveform PH2 is the potential difference Vh in the first embodiment and the first modification to the seventh modification, it is not limited thereto. The potential difference of the waveform PH1 only needs to be 0.5 times or more of the potential difference of the waveform PH2. In the eighth modification, the potential difference Vh2a of the drive pulse PL4a included in the waveform PH2a is larger than the potential difference Vhl of the drive pulses PL1, PL2, and PL3 of the waveform PH1, and the potential difference Vh3a of the drive pulse PL5a included in the waveform PH2 is smaller than the potential difference Vhl of the drive pulses PL1, PL2, and PL3 of the waveform PH1.

[0285] Figure 33 FIG. 8 is a diagram for explaining the drive waveform signal Coma in the eighth modification. The drive waveform signal Coma has the waveform PH1 and the waveform PH2a. The waveform PH2a has the drive pulse PL4a and the drive pulse PL5a. The drive pulse PL5a has the drive component DC9a and the drive component DC10a. The lowest potential of the drive pulse PL4a is the potential VL2a. The potential VL2a is lower than the potential VL1. The potential difference of the drive pulse PL4a is the potential difference Vh2a. The potential difference Vh2a is larger than the potential difference Vhl of the drive pulses PL1, PL2, and PL3. In more detail, for the drive component DC7a of the drive pulse PL4a, the potential at the start is set to the reference potential V0, and the potential at the end is set to the potential VL2a. For the drive component DC8a of the drive pulse PL4a, the potential at the start is set to the potential VL2a, and the potential at the end is set to the reference potential V0. Further, the lowest potential of the drive pulse PL5a is the potential VL3a. The potential VL3a is higher than the potential VL1. The potential difference of the drive pulse PL5a is the potential difference Vh3a. The potential difference Vh3a is smaller than the potential difference Vhl of the drive pulses PL1, PL2, and PL3. In more detail, for the drive component DC9a of the drive pulse PL5a, the potential at the start is set to the reference potential V0, and the potential at the end is set to the potential VL3a. For the drive component DC10a of the drive pulse PL5a, the potential at the start is set to the potential VL3a, and the potential at the end is set to the reference potential V0.

[0286] The potential difference Vhl of the drive pulses PL1, PL2, and PL3 of the waveform PH1 can be set to an arbitrary potential suitable for growing the liquid column appropriately and not causing the unnecessary ink to leak out from the nozzle N. In addition, since the liquid column will not grow when the potential difference Vhl is small, it is preferable that the potential difference Vhl of the drive pulses PL1, PL2, and PL3 be 0.5 times or more of the potential difference Vh2a of the drive pulse PL4a of the waveform PH2a.

[0287] Further, in the present modification example, the potential difference Vh3a of the drive pulse PL5a of the waveform PH2a is made smaller than the potential difference Vhl and the potential difference Vh2a. In this way, it is possible to suppress the possibility of the ink seeping out to the -Z direction face of the nozzle plate 330 due to the drive component DC10a of the drive pulse PL5a. In addition, in a case where it is difficult for the ink to seep out to the -Z direction face of the nozzle plate 330 due to the drive component DC10a of the drive pulse PL5a, it is also possible to set the potential difference Vh3a of the drive pulse PL5a to be equal to or larger than the potential difference Vh2a.

[0288] Further, it is also possible to set the potential difference of each of the drive pulses PL1, PL2, and PL3 of the waveform PH1 to be different values.

[0289] 2.9. Ninth Modification Example

[0290] Although in the first embodiment and from the first modification example to the eighth modification example, the potential difference between the highest potential and the lowest potential of the drive pulse PL included in the waveform PH1 and the waveform PH2 is substantially equal to the potential difference Vh, it is not limited thereto. The potential difference of the waveform PH1 only needs to be 0.5 times or more of the potential difference of the waveform PH2. In the ninth modification example, the potential difference of the drive pulse PL5 included in the waveform PH2 is larger than the potential difference of the waveform PH1.

[0291] Figure 34 FIG. 9 is a diagram for describing a drive waveform signal Comc in the ninth modification example. The drive waveform signal Comc has a waveform PH1 and a waveform PH2c. The waveform PH2c has drive pulses PL4 and PL5c. The drive pulse PL5c has drive components DC9c and DC10c. The lowest potential of the drive pulse PL5c is a potential VL2. The potential VL2 is lower than the potential VLl. The potential difference of the drive pulse PL5c is a potential difference Vh2. More specifically, with respect to the drive component DC9c, the potential at the start is set to the reference potential V0, and the potential at the end is set to the potential VL2. With respect to the drive component DC10c, the potential at the start is set to the potential VL2, and the potential at the end is set to the reference potential V0. The potential difference Vh2 is larger than the potential difference Vh of the drive pulses PL1, PL2, PL3, and PL4. By making the potential difference Vh2 of the drive pulse PL5c larger than the potential difference Vh, it is possible to make the force for pulling the droplet DR off the liquid column LC9 larger.

[0292] According to the ninth modification example, since the potential difference of the waveform PH1 is set to be 0.5 times or more of the potential difference of the waveform PH2c, compared with the case where the potential difference of the waveform PH1 and the potential difference of the waveform PH2 are substantially equal, the degree of freedom in designing the drive waveform signal Com can be increased. For example, by setting the potential difference of the waveform PH2 to be larger than the potential difference of the waveform PH1, the force to pull the liquid droplet DR from the liquid column LC9 can be increased. More preferably, the drive pulse PL5c of the waveform PH2c has a drive component DC9c that is supplied to the piezoelectric element PZ when the tip of the liquid column LC8 moves in the -Z direction, and by making the difference between the maximum potential and the minimum potential of the drive pulse PL5c larger than the difference between the maximum potential and the minimum potential in the waveform PH1, the force to pull the liquid droplet DR from the liquid column LC9 can be increased.

[0293] In addition, the drive pulse PL5c is an example of "one drive pulse included in the second drive pulse of the second waveform", and the drive component DC9c is an example of "a third drive component that is supplied to the drive element when the tip of the second liquid column moves in the ejection direction".

[0294] On the other hand, by making the potential difference of the waveform PH1 smaller than the potential difference of the waveform PH2c, the liquid droplet DR can not be ejected from the ejection portion D when the waveform PH1 is supplied to the piezoelectric element PZ, and the liquid droplet DR can be reliably ejected when the waveform PH2c is supplied to the piezoelectric element PZ. In addition, although in the case where the potential difference of the waveform PH2c is larger than the potential difference of the waveform PH1, the liquid droplet is not excessively ejected under the waveform PH2, there is a possibility that the ink seeps to the -Z direction face of the nozzle plate 330. By making the potential difference of the waveform PH1 larger than the potential difference of the waveform PH2, the possibility that the ink seeps to the -Z direction face of the nozzle plate 330 can be suppressed. The designer of the inkjet printer 1 can design the drive waveform signal Com taking into account the viscosity of the ink.

[0295] 2.10. Tenth Modification Example

[0296] Although in the first embodiment, and the first to ninth modification examples, the period from the time point at which the supply of the drive component DC9, DC9a, DC9c included in the drive pulse PL5, PL5a, PL5c is started to the time point at which the supply of the drive component DC10, DC10a, DC10c is ended is longer than the period from the time point at which the supply of the first drive component DC1, DC3, DC5, DC7 included in any one of the other drive pulses PL included in the drive waveform signal Com, Coma, Comc is started to the time point at which the supply of the second drive component DC2, DC4, DC6, DC8 is ended, it is not limited thereto.

[0297] Figure 35 FIG. 10 is a diagram for explaining a drive waveform signal Comd in the tenth modification. The drive waveform signal Comd has a waveform PH1 and a waveform PH2d. The waveform PH2d has a drive pulse PL4 and a PL5d. The drive pulse PL5d has a drive component DC9d and a drive component DC10d. A period Pw5 from a time point at which the supply of the drive component DC9d is started to a time point at which the supply of the drive component DC10d is ended is shorter than, for example, a period Pwl from a time point at which the supply of the drive component DC1 of the drive pulse PL1 is started to a time point at which the supply of the drive component DC2 is ended. The period Pw5 is shorter than a period of an inherent vibration cycle TC of the ejection section D, for example, 0.25 times the inherent vibration cycle TC. By the period Pw5 being shorter than the period Pwl, an opportunity to pull off the liquid droplet DR from the liquid column LC9 can be generated.

[0298] Further, although the drive pulse PL that generates the tearing is one drive pulse PL5, the drive pulse PL can be a plurality of drive pulses PL.

[0299] 2.11. Eleventh Modification

[0300] Although the highest potential and the initial potential of the drive pulse PL are the same in the first embodiment and the first to tenth modifications, the highest potential and the initial potential can be made different.

[0301] Figure 36 FIG. 11 is a diagram for explaining a drive waveform signal Come in the eleventh modification. The drive waveform signal Come has a waveform PH1e and a waveform PH2e. The waveform PH1e has drive pulses PL1e, PL2, and PL3. The waveform PH2e has a drive pulse PL4 and a PL5e.

[0302] For the drive pulse PL1e, a potential at the start is set to the reference potential V0, and a potential at the end is set to the highest potential Vh1. The highest potential Vh1 is higher than the reference potential V0. The drive pulse PL1e has a drive component DC1e and a DC2. For the drive component DC1e, a potential at the start is set to the reference potential V0, and a potential at the end is set to the lowest potential VL1. For the drive pulses PL2, PL3, and PL4, a potential at the start and a potential at the end are set to the highest potential Vh1. For the drive pulse PL5e, a potential at the start is set to the highest potential Vh1, and a potential at the end is set to the reference potential V0. The drive pulse PL5e has a drive component DC9 and a DC10e. For the drive component DC10e, a potential at the start is set to the lowest potential VL1, and a potential at the end is set to the reference potential V0.

[0303] According to the eleventh modification example, since the potential difference between the highest potential and the lowest potential of the drive component DC10e is smaller than the potential difference between the highest potential and the lowest potential of the drive component DC10, compared with the aforementioned embodiment and modification examples, it is possible to suppress unnecessary ejection. Or, in the embodiment, even if a droplet DR is not ejected by the drive component DC10, there is a possibility that the ink seeps to the -Z direction surface of the nozzle plate 330. In the tenth modification example, compared with the embodiment, it is possible to suppress the case where the ink seeps to the -Z direction surface of the nozzle plate 330.

[0304] 2.12. Twelfth Modification Example

[0305] Although in the eleventh modification example, the reference potential V0 is between the highest potential Vhl and the lowest potential VLI, it is also possible to make the reference potential V0 coincide with the lowest potential VLI.

[0306] Figure 37 FIG. 12 is a diagram for explaining a drive waveform signal Comf in the twelfth modification example. The drive waveform signal Comf has a waveform PHIf and a waveform PH2f. The waveform PHIf has drive pulses PLIf, PL2, and PL3. The waveform PH2f has drive pulses PL4 and PL5f.

[0307] For the drive pulse PLIf, the potential at the start is set to the reference potential V0, and the potential at the end is set to the highest potential Vhl. The highest potential Vhl is higher than the reference potential V0. The drive pulse PLIf has the drive component DC2, and does not have the drive component DC1. For the drive pulses PL2, PL3, and PL4, the potential at the start and the potential at the end are set to the highest potential Vhl. For the drive pulse PL5f, the potential at the start is set to the highest potential Vhl, and the potential at the end is set to the reference potential V0. The drive pulse PL5e has the drive component DC9, and does not have the drive component DC10.

[0308] According to the twelfth modification example, since the drive component DC10 is not present, compared with the tenth modification example, it is possible to suppress unnecessary ejection. Or, even in the eleventh modification example, even if a droplet DR is not ejected by the drive component DC10, there is a possibility that the ink seeps to the -Z direction surface of the nozzle plate 330. According to the eleventh modification example, since the drive component DC10 is not present, compared with the tenth modification example, it is possible to suppress the case where the ink seeps to the -Z direction surface of the nozzle plate 330.

[0309] 2.13. Thirteenth Modification Example

[0310] Although in the first modification, the control section 6 decides the waveform of the individual designation signal Sd[m] of the recording period Tu[j] based on the individual designation signal Sd[m] of the recording periods Tu[j-1] to Tu[j-3] which are the predetermined recording periods Tux preceding the recording period Tu[j], it is not limited thereto. For example, the control section 6 can decide the individual designation signal Sd[m] of the recording period Tu[j] based on the individual designation signal Sd[m] of two or more recording periods Tu including the recording period Tu[j-1] and consecutive to the recording period Tu[j-1] and ending before the start of the recording period Tu[j]. Further, for example, the control section 6 can decide the individual designation signal Sd[m] of the recording period Tu[j] based on only the individual designation signal Sd[m] of the recording period Tu[j-1].

[0311] 2.14. Fourteenth modification

[0312] Although in the fourteenth modification, it is described that the control section 6 decides the individual designation signal Sd[m] of the recording period Tu[j] based on the individual designation signal Sd[m] of two or more recording periods Tu including the recording period Tu[j-1] and preceding the recording period Tu[j], it can decide the individual designation signal Sd[m] of the recording period Tu[j] based on the individual designation signal Sd[m] of one or more recording periods Tu not including the recording period Tu[j-1] and preceding the recording period Tu[j].

[0313] 2.15. Fifteenth modification

[0314] The control section 6 can decide the waveform of the drive signal Vin of the recording period Tu[j] based on the proportion of the number of the recording periods Tu in which the droplet DR is ejected from the ejection section D to the number of the predetermined recording periods Tux among the predetermined recording periods Tux including the recording period Tu[j-1] and including two or more recording periods Tu consecutive to the recording period Tu[j-1] and ending before the start of the recording period Tu[j]. For example, the control section 6 calculates the following (3).

[0315] Ejection proportion = number of recording periods Tu in which the droplet DR is ejected from the ejection section D / number of predetermined recording periods Tux (3)

[0316] Further, the control section 6 makes the number of the drive pulses PL of the recording period Tu in the case where the calculated ejection proportion is the first proportion smaller than the number of the drive pulses PL of the recording period Tu in the case where the ejection proportion is the second proportion. The first proportion is larger than the second proportion.

[0317] When the ejection ratio is large, the liquid column formed on the meniscus MS at the start time point of the recording period Tu[j] becomes large. Therefore, since the waveform of the drive signal Vin of the recording period Tu[j] is decided based on the ejection ratio, so that the liquid droplet DR can be ejected in a manner close to the timing at which it should originally be ejected, it is possible to suppress the deterioration of the print quality.

[0318] 2.16. Sixteenth modification example

[0319] Although the waveform PH1 has three drive pulses PL in the first embodiment, the first to fifteenth modification examples, it is not limited thereto, and the waveform PH1 can have only one drive pulse PL or four or more drive pulses PL. In the case where the waveform PH1 has four or more drive pulses PL, in the fifth modification example, when the viscosity indicated by the viscosity information VI is 70 millipascal seconds or more, the control section 6a decides the number of drive pulses PL included in the drive signal Vin1 to be four or more. For example, when the viscosity indicated by the viscosity information VI is 70 millipascal seconds or more and less than 100 millipascal seconds, the control section 6a decides the number of drive pulses PL included in the drive signal Vin1 to be four.

[0320] 2.17. Seventeenth modification example

[0321] Although the liquid column is defined as a columnar or hammer-shaped liquid surface that protrudes from the position closest to the +Z direction toward the -Z direction among the meniscus MS in the first embodiment, in the case of a liquid droplet that is temporarily separated from the meniscus MS, the columnar or hammer-shaped liquid surface of the liquid droplet can also be the liquid column. The so-called liquid droplet that is temporarily separated from the meniscus MS refers to a liquid droplet that is separated at the time of supply of a certain drive component DC but is combined again at the time of supply of the next drive component DC. Specifically, Figure 14 The liquid column LC7 illustrated is in a state of being temporarily separated from the meniscus MS. The separated liquid column LC7 is combined again with the meniscus MS by the supply of the drive component DC8.

[0322] 2.18. Eighteenth modification example

[0323] Each of the above-described modes can also be applied to a mode in which a plurality of chambers 320 supply ink to one nozzle N.

[0324] Figure 38 Fig. 18 is a view that shows one example of the ejection section Dg in the eighteenth modification example. Figure 38 The illustrated view is a view that observes a plurality of ejection sections Dg in the -Z direction. For the sake of simplicity of explanation, in the view, the ejection section Dg is shown as a single line. Figure 38In the example shown in FIG. 19, the piezoelectric element PZ, the vibration plate 310, the nozzle plate 330, and the chamber plate 340 are omitted from the illustration. The discharge portion Dg has four chambers 320, a connection flow path 321, and a nozzle N. The four chambers 320 communicate with a common ink chamber not shown and are supplied with ink. The connection flow path 321 communicates with the nozzle N and further communicates with each of the four chambers 320 in the -X direction. Although the example shown in FIG. 19 has four chambers 320, the discharge portion Dg can have two chambers 320, three chambers 320, or more than five chambers 320. Since the number of chambers 320 per nozzle N can be increased by increasing the number of chambers 320 per discharge portion D, a higher viscosity ink can be discharged compared to the first embodiment. Figure 38 In the example shown in FIG. 19, the piezoelectric element PZ, the vibration plate 310, the nozzle plate 330, and the chamber plate 340 are omitted from the illustration. The discharge portion Dg has four chambers 320, a connection flow path 321, and a nozzle N. The four chambers 320 communicate with a common ink chamber not shown and are supplied with ink. The connection flow path 321 communicates with the nozzle N and further communicates with each of the four chambers 320 in the -X direction. Although the example shown in FIG. 19 has four chambers 320, the discharge portion Dg can have two chambers 320, three chambers 320, or more than five chambers 320. Since the number of chambers 320 per nozzle N can be increased by increasing the number of chambers 320 per discharge portion D, a higher viscosity ink can be discharged compared to the first embodiment.

[0325] 2.19. Nineteenth Modification Example

[0326] The above-described embodiments can also be applied to an inkjet printer 1 having a circulation mechanism that recovers ink discharged from the liquid discharge head HU to supply the recovered ink to the liquid discharge head HU while supplying ink to the liquid discharge head HU.

[0327] Figure 39 FIG. 19 is a view showing one example of the discharge portion Dh in the nineteenth modification example. Figure 39 The view shown in FIG. 19 is a view observed in the -Z direction of the plurality of discharge portions Dh. For simplicity of explanation, the piezoelectric element PZ, the vibration plate 310, the nozzle plate 330, and the chamber plate 340 are omitted from the illustration. Figure 39 In the example shown in FIG. 19, the piezoelectric element PZ, the vibration plate 310, the nozzle plate 330, and the chamber plate 340 are omitted from the illustration. The discharge portion Dg has four chambers 320, a connection flow path 321, and a nozzle N. The four chambers 320 communicate with a common ink chamber not shown and are supplied with ink. The connection flow path 321 communicates with the nozzle N and further communicates with each of the four chambers 320 in the -X direction. Although the example shown in FIG. 19 has four chambers 320, the discharge portion Dg can have two chambers 320, three chambers 320, or more than five chambers 320. Since the number of chambers 320 per nozzle N can be increased by increasing the number of chambers 320 per discharge portion D, a higher viscosity ink can be discharged compared to the first embodiment.

[0328] Since the nineteenth modification example also increases the discharge volume of the chambers 320 per nozzle N, a higher viscosity ink can be discharged compared to the first embodiment. Further, the nineteenth modification example uses a circulation mechanism, so that thickening of the ink in the chambers 320 and the connection flow path 321h can be suppressed.

[0329] 2.20. Twentieth Modification Example

[0330] Although in each of the above-described modes, the serial inkjet printer 1 in which the conveyance body 82 that houses the liquid ejection head HU is reciprocated in the X-axis direction is exemplified, the present application is not limited to such a mode. The inkjet printer can also be a line inkjet printer in which a plurality of nozzles N are distributed across the entire width of the recording paper P.

[0331] When the inkjet printer 1 is of the line type, the third modification example can also be applied. The control section 6 controls the conveyance mechanism 7 in such a manner that the conveyance speed of the recording paper P becomes a value obtained by dividing the conveyance speed of the recording paper P in the case where the twentieth modification example is applied to the first embodiment by a predetermined number.

[0332] 2.21. Twenty-First Modification Example

[0333] Although in each of the above-described modes, one example of the "driving element" is the piezoelectric element PZ, a heating element can also be provided instead of the piezoelectric element PZ.

[0334] 2.22. Twenty-Second Modification Example

[0335] The inkjet printer exemplified in each of the above-described modes can also be employed in various devices such as facsimile apparatuses and copiers in addition to devices dedicated to printing. Obviously, the use of the liquid ejection apparatus of the present application is not limited to printing. For example, a liquid ejection apparatus that ejects a solution of a color material can be utilized as a manufacturing apparatus for forming a color filter of a liquid crystal display device. Further, a liquid ejection apparatus that ejects a solution of a conductive material can be utilized as a manufacturing apparatus for forming a wiring and an electrode of a wiring substrate.

[0336] 3. Postscript

[0337] From the above-described modes, for example, the following structures can be grasped.

[0338] A driving method of a liquid ejection head according to Mode 1 as a preferred mode is a driving method of a liquid ejection head having an ejection section including a driving element that is displaced by being supplied with a driving signal, a pressure chamber that increases and decreases the pressure inside thereof in accordance with the displacement of the driving element, and a nozzle that communicates with the pressure chamber and is capable of ejecting liquid filled inside the pressure chamber as liquid droplets in an ejection direction in accordance with the increase and decrease of the pressure inside the pressure chamber, in which the driving method has: a first step of forming a first liquid column in which a liquid surface inside the ejection section is projected in the ejection direction, by supplying the driving element with a driving signal having a first waveform including a first driving pulse having a first driving component that decreases the pressure inside the pressure chamber and a second driving component that increases the pressure inside the pressure chamber; and a second step of, after forming the second liquid column in which the liquid surface inside the ejection section is projected in the ejection direction, ejecting a part or all of the liquid constituting the second liquid column as liquid droplets, by supplying the driving element with a driving signal having a second waveform including a second driving pulse having a third driving component that decreases the pressure inside the pressure chamber and a fourth driving component that increases the pressure inside the pressure chamber, in a case where the first liquid column is formed, in which liquid droplets are not ejected from the ejection section in a case where the driving element is supplied with a driving signal having the first waveform and not having the second waveform, and liquid droplets are not ejected from the ejection section in a case where the driving element is supplied with a driving signal having the second waveform and not having the first waveform.

[0339] According to Mode 1, in a case where the first liquid column is formed by the driving signal having the first waveform, the liquid column formed on the liquid surface inside the ejection section can be grown by supplying the driving element with the driving signal having the second waveform, and further a part or all of the liquid constituting the second liquid column can be ejected as liquid droplets.

[0340] In Mode 2 as a specific example of Mode 1, the amount of variation, i.e., the decrease, of the pressure of the liquid inside the nozzle to the negative pressure side at the time when the third driving component of the second waveform is supplied to the driving element in a case where the driving element is supplied with the driving signal having the second waveform and not having the first waveform is substantially equal to the amount of variation, i.e., the decrease, of the pressure of the liquid inside the nozzle to the negative pressure side at the time when the third driving component of the second waveform is supplied to the driving element in a case where the driving element is supplied with the driving signal having the first waveform and the second waveform.

[0341] In Mode 2, even if the liquid is high in viscosity, the liquid column formed on the liquid surface in the ejection portion is formed by using the first waveform and the second waveform, so that the liquid droplet can be ejected.

[0342] In Mode 3, which is a specific example of Mode 1 or 2, the amount of variation, i.e., the increase, of the pressure of the liquid in the nozzle to the positive pressure side when the fourth driving component of the second waveform is supplied to the driving element, in the case where the driving signal having the second waveform and not having the first waveform is supplied to the driving element, is substantially equal to the amount of variation, i.e., the increase, of the pressure of the liquid in the nozzle to the positive pressure side when the fourth driving component of the second waveform is supplied to the driving element, in the case where the driving signal having the first waveform and the second waveform is supplied to the driving element.

[0343] In Mode 3, which is a specific example of Mode 1 or 2, even if the liquid is high in viscosity, the liquid column formed on the liquid surface in the ejection portion is formed by using the first waveform and the second waveform, so that the liquid droplet can be ejected.

[0344] In Mode 4, which is a specific example of any one of Modes 1 to 3, in the case where the driving signal having the second waveform is supplied to the driving element after the driving signal having the first waveform, the portion of the liquid surface in the ejection portion that is pulled in the most in the pull-in direction opposite to the ejection direction when the fourth driving component of the second waveform included in the driving signal is supplied to the driving element is located in the ejection direction, compared to the portion of the liquid surface in the ejection portion that is pulled in the most in the pull-in direction when the driving signal having the second waveform is supplied to the driving element, in the case where the driving signal having the second waveform is supplied to the driving element without supplying the driving signal having the first waveform to the driving element.

[0345] In the first embodiment, since the portion of the liquid surface in the ejection portion that is pulled in the most in the pull-in direction is moved to the ejection direction when the driving signal having the first driving component is supplied to the driving element by supplying the first waveform and the second waveform to the piezoelectric element PZ, the liquid column formed on the liquid surface in the ejection portion is also moved to the ejection direction. Since the tip of the ejection direction of the liquid column is moved away from the initial position of the liquid surface in the ejection portion by moving the liquid column to the ejection direction, it becomes easy to separate a part or all of the liquid column, so that the liquid droplet separated from the liquid column can be ejected.

[0346] In Mode 5 which is a specific example of any one of Modes 1 to 4, in the second step, in a case where the top end of the second liquid column moves in the ejection direction, the third driving component of the second driving pulse of the driving signal is supplied to the driving element.

[0347] In a case where the top end of the second liquid column moves in the ejection direction, by supplying the driving signal having the second driving component to the driving element, a liquid droplet can be pulled off from the second liquid column. According to the present embodiment, compared with a mode in which the driving signal having no second driving component is supplied to the driving element, more stable ejection can be achieved.

[0348] In Mode 6 which is a specific example of any one of Modes 1 to 5, the first driving pulse of the first waveform includes a plurality of driving pulses.

[0349] Since the first waveform has a plurality of driving pulses, even in a case where a liquid droplet cannot be ejected by one driving pulse, by supplying the driving signal having the first waveform having a plurality of driving pulses to the driving element, a liquid column formed on the liquid surface in the ejection portion can be grown, and a part or all of the liquid constituting the second liquid column can be ejected as a liquid droplet by the second waveform.

[0350] In Mode 7 which is a specific example of any one of Modes 1 to 6, the viscosity of the liquid in the liquid ejection head is 20 millipascal seconds or more.

[0351] Although there is a possibility that a liquid droplet cannot be ejected by one driving pulse when the viscosity of the liquid becomes 20 millipascal seconds or more, by the driving method achieved by Mode 7 in which the first waveform is provided before the second waveform, even a liquid having a viscosity of 20 millipascal seconds or more can be ejected as a liquid droplet.

[0352] In Mode 8 which is a specific example of any one of Modes 1 to 7, the difference between the highest potential and the lowest potential in the first waveform and the difference between the highest potential and the lowest potential in the second waveform are substantially equal. More specifically, the highest potential in the first waveform and the highest potential in the second waveform are substantially equal, and the lowest potential in the first waveform and the lowest potential in the second waveform are substantially equal.

[0353] By setting the highest potential which can be achieved in the liquid ejection apparatus as the highest potential of the first waveform and the second waveform, and setting the lowest potential which can be achieved in the liquid ejection apparatus as the lowest potential of the first waveform and the second waveform, even a liquid having a high viscosity can be grown by the first waveform to grow a liquid column on the liquid surface in the ejection portion, and a liquid droplet can be ejected in the second waveform.

[0354] A liquid ejecting apparatus according to Mode 9 as a preferred mode includes a liquid ejecting head having an ejecting portion including a driving element that is displaced by being supplied with a driving signal, a pressure chamber that increases or decreases a pressure in the inside thereof in accordance with the displacement of the driving element, and a nozzle that communicates with the pressure chamber and that ejects a liquid filled in the inside of the pressure chamber as a liquid droplet in an ejecting direction in accordance with the increase or decrease of the pressure in the inside of the pressure chamber; and a control portion that controls the liquid ejecting head, the control portion performing control to form a first liquid column in which a liquid surface in the ejecting portion is projected in the ejecting direction by supplying the driving element with a driving signal having a first waveform including a first driving pulse having a first driving component that decreases the pressure in the inside of the pressure chamber and a second driving component that increases the pressure in the inside of the pressure chamber, and after the first liquid column is formed, ejecting a part or all of the liquid constituting the first liquid column as a liquid droplet after a second liquid column in which the liquid surface in the ejecting portion is projected in the ejecting direction is formed by supplying the driving element with a driving signal having a second waveform including a second driving pulse having a third driving component that decreases the pressure in the inside of the pressure chamber and a fourth driving component that increases the pressure in the inside of the pressure chamber, and in a case where the driving signal having the first waveform and not having the second waveform is supplied to the driving element, no liquid droplet is ejected from the ejecting portion, and in a case where the driving signal having the second waveform and not having the first waveform is supplied to the driving element, no liquid droplet is ejected from the ejecting portion.

[0355] According to Mode 9, in a case where the first liquid column is formed by the driving signal having the first waveform, the liquid column in which the liquid surface in the ejecting portion is formed can be grown by supplying the driving element with the driving signal having the second waveform, and a part or all of the liquid constituting the second liquid column can be ejected as a liquid droplet.

[0356] Symbol explanation

[0357] 1, 1a... inkjet printer; 2... drive waveform signal generating circuit; 5... storage section; 6, 6a... control section; 7... conveyance mechanism; 8... moving mechanism; 9... viscosity information obtaining section; 10... switching circuit; 11... connection state specifying circuit; 14... liquid container; 81... endless tape; 82... conveyance body; 310... vibration plate; 320... chamber; 321... link flow passage; 321h... link flow passage; 330... nozzle plate; 340... chamber plate; 350... reservoir; 360... ink supply port; 370... ink intake port; CH... conversion signal; CL... clock signal; CPw... characteristic; Com, Coma, Comb, Comc, Comd, Come, Comf... drive waveform signal; D, Dg, Dh... ejection section; DC1-DC10, DC7a, DC8a, DC8b, DC9a, DC9c, DC9d, DC10a, DC10c, DC10d, DC10e... drive component; DR... droplet; G1, G2, G3, G4, G5... graph; HD... recording head; HU... liquid ejection head; Img... print data; LAT... latch signal; LC2-LC10... liquid column; LHa... internal wiring; LHb... power supply wiring; LPnm, LPnp, LVnm, LVnp... line segment; MS... meniscus; N... nozzle; P... recording paper; PH, PH1, PH1e, PH1f, PH2, PH2a, PH2b, PH2c, PH2d, PH2e, PH2f... waveform; PL, PL1, PL1e, PL1f, PL2, PL3, PL4, PL4a, PL4b, PL5, PL5a, PL5c, PL5d, PL5e, PL5f... drive pulse; PZ... piezoelectric element; Pa1, Pa2... pressure variation characteristic; PLsC, PLsL... pulse; Pn1, Pn2... pressure variation characteristic; Pw, Pw1, Pw24, Pw46, Pw5, Pw68... period; SI... print signal; SLa... connection state specifying signal; SWa... switch; Sd... individual specifying signal; TC... natural vibration period; Tbu... period; Tcu1-Tcu5... control period; Tu... recording period; V0... reference potential; Vbs... fixed potential; Vh1... highest potential; VI... viscosity information; VL1... lowest potential; VL2, VL2a, VL3a... potential; Vh, Vh1, Vh2, Vh2a, Vh3a... potential difference; Vin, Vin1, Vin2... drive signal; Vn3, Vn4... variation characteristic; Z0... initial position; Zd... lower electrode; Zm... piezoelectric body; Zm1-Zm3... extrusion position; Zp1-Zp4... pull-in position; Zu... upper electrode; dCom... waveform specifying signal; α1-α8... drive mode.

Claims

1. A driving method, characterized in that, It is a method for driving a liquid ejector head having an ejection section, the ejection section comprising a drive element that is displaced by being supplied with a drive signal, a pressure chamber whose internal pressure is increased or decreased according to the displacement of the drive element, and a nozzle that communicates with the pressure chamber and is capable of ejecting liquid filled inside the pressure chamber as droplets in the ejection direction according to the increase or decrease of the internal pressure of the pressure chamber. The driving method includes: The first step involves supplying a drive signal with a first waveform to the drive element, thereby forming a first liquid column protruding from the ejection section in the ejection direction. The first waveform includes a first drive pulse having a first drive component that reduces the pressure inside the pressure chamber and a second drive component that increases the pressure inside the pressure chamber. The second step involves supplying a drive signal with a second waveform to the drive element after the formation of the first liquid column, thereby causing a portion or all of the liquid constituting the second liquid column to be ejected as droplets after the formation of the second liquid column where the liquid surface in the ejection section protrudes in the ejection direction. The second waveform includes a second drive pulse having a third drive component that reduces the pressure inside the pressure chamber and a fourth drive component that increases the pressure inside the pressure chamber. Furthermore, when a drive signal having the first waveform but not the second waveform is supplied to the drive element, droplets are not ejected from the ejection section. When a drive signal having the second waveform but not the first waveform is supplied to the drive element, droplets are not ejected from the ejection section. In the second step, as the tip of the second liquid column moves in the ejection direction, the third driving component of the second driving pulse of the driving signal is supplied to the driving element.

2. The driving method as described in claim 1, characterized in that, When a drive signal having the second waveform but not the first waveform is supplied to the drive element, and the third drive component of the second waveform is supplied to the drive element, the amount of pressure change (i.e., reduction) of the liquid in the nozzle toward the negative pressure side is approximately equal to the amount of pressure change (i.e., reduction) of the liquid in the nozzle toward the negative pressure side when a drive signal having both the first and second waveforms is supplied to the drive element, and the third drive component of the second waveform is supplied to the drive element, within the range of measurement error.

3. The driving method as described in claim 1 or 2, characterized in that, When a drive signal having the second waveform but not the first waveform is supplied to the drive element, and the fourth drive component of the second waveform is supplied to the drive element, the amount of change (increase) in the pressure of the liquid in the nozzle toward the positive pressure side is approximately equal to the amount of change (increase) in the pressure of the liquid in the nozzle toward the positive pressure side when a drive signal having both the first and second waveforms is supplied to the drive element, and the fourth drive component of the second waveform is supplied to the drive element, within the range of measurement error.

4. The driving method as described in claim 1, characterized in that, When a drive signal with the second waveform is supplied to the drive element following a drive signal with the first waveform, and the fourth drive component of the second waveform contained in the drive signal is supplied to the drive element, the portion of the liquid surface in the ejection section that is pulled in the most in the pull-in direction opposite to the ejection direction is located in the ejection direction, compared to the portion of the liquid surface in the ejection section that is pulled in the most in the pull-in direction when a drive signal with the second waveform is supplied to the drive element without supplying a drive signal with the first waveform to the drive element, and the fourth drive component of the second waveform is supplied to the drive element.

5. The driving method as described in claim 1, characterized in that, The first driving pulse of the first waveform includes multiple driving pulses.

6. The driving method as described in claim 1, characterized in that, The viscosity of the liquid in the liquid nozzle is above 20 millipascals.

7. The driving method as described in claim 1, characterized in that, The difference between the highest and lowest potentials in the first waveform and the difference between the highest and lowest potentials in the second waveform are approximately equal within the range of measurement error.

8. A liquid ejection device, characterized in that, have: A liquid ejector head has an ejection section comprising a drive element that is displaced by being supplied with a drive signal, a pressure chamber that increases or decreases the internal pressure according to the displacement of the drive element, and a nozzle that communicates with the pressure chamber and is capable of ejecting liquid filled inside the pressure chamber as droplets in the ejection direction according to the increase or decrease of the internal pressure of the pressure chamber. The control unit controls the liquid ejection head. The control unit performs the following control: By supplying a drive signal having a first waveform to the drive element, a first liquid column protruding from the ejection section in the ejection direction is formed, wherein the first waveform includes a first drive pulse having a first drive component that reduces the pressure inside the pressure chamber and a second drive component that increases the pressure inside the pressure chamber. When the first liquid column is formed, by supplying a drive signal having a second waveform to the drive element, after the formation of the second liquid column in the ejection section that protrudes in the ejection direction, a portion or all of the liquid constituting the second liquid column is ejected as droplets. The second waveform includes a second drive pulse having a third drive component that reduces the pressure inside the pressure chamber and a fourth drive component that increases the pressure inside the pressure chamber. Furthermore, when a drive signal having the first waveform but not the second waveform is supplied to the drive element, droplets are not ejected from the ejection section. When a drive signal having the second waveform but not the first waveform is supplied to the drive element, droplets are not ejected from the ejection section. The third driving component of the second driving pulse of the driving signal is supplied to the driving element when the tip of the second liquid column moves in the ejection direction.

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