Method of driving liquid discharge apparatus and liquid discharge apparatus

Abstract

To correct a discharge amount of a droplet to a desired amount.SOLUTION: A liquid ejecting apparatus includes an ejecting unit including a nozzle that ejects a liquid droplet, a pressure chamber that communicates with the nozzle, and a drive element that is driven so as to apply a pressure fluctuation to a liquid in the pressure chamber according to a supplied drive signal, and a drive signal generation circuit that generates a drive signal having at least one ejection pulse during one drive cycle. The at least one discharge pulse includes a discharge waveform element that applies a pressure fluctuation to the liquid in the pressure chamber so as to discharge the liquid droplet from the nozzle, and a residual vibration suppression element that attenuates the pressure fluctuation of the liquid in the pressure chamber according to a natural vibration cycle of the discharge unit, which remains after the liquid droplet is discharged from the nozzle, and by adjusting the residual vibration suppression element of the at least one discharge pulse, the drive signal is supplied to the drive element over a period of two or more drive cycles to correct the weight of the liquid droplet discharged from the nozzle when the liquid droplet is continuously discharged from the nozzle.SELECTED DRAWING: Figure 17

Description

[Technical Field]

[0001] The present invention relates to a method for driving a liquid ejection device, and to a liquid ejection device. [Background technology]

[0002] Conventionally, there has been provided a liquid ejection device having a nozzle that ejects droplets, a pressure chamber that communicates with the nozzle, and a drive element that is driven to apply pressure fluctuations to the liquid in the pressure chamber in response to a supplied drive signal. For example, Patent Document 1 discloses that the potential difference between the minimum and maximum potentials in the drive signal is adjusted to correct the amount of droplets ejected from the nozzle. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2010-184380 Summary of the Invention [Problem to be solved by the invention]

[0004] However, with the above-mentioned conventional technology, even if the potential difference of the drive signal is adjusted, it is sometimes difficult to correct the ejection amount of droplets to a desired amount. [Means for solving the problem]

[0005] A preferred aspect of the present disclosure provides a method for driving a liquid ejection device having a nozzle that ejects droplets, a pressure chamber connected to the nozzle, an ejection section having a drive element that is driven to impart pressure fluctuations to the liquid in the pressure chamber in response to a supplied drive signal, and a drive signal generation circuit that generates the drive signal, wherein the drive signal has at least one ejection pulse during one drive cycle, and the at least one ejection pulse has an ejection waveform element that imparts pressure fluctuations to the liquid in the pressure chamber so that droplets are ejected from the nozzle, and a residual vibration suppression element that attenuates pressure fluctuations of the liquid in the pressure chamber that remain after the droplets are ejected from the nozzle in accordance with the natural vibration period of the ejection section, and by adjusting the residual vibration suppression element of the at least one ejection pulse, the drive signal is supplied to the drive element over a period of two or more drive cycles, thereby correcting the weight of the droplets ejected from the nozzle when droplets are continuously ejected from the nozzle.

[0006] A liquid ejection device according to a preferred aspect of the present disclosure comprises an ejection section having a nozzle that ejects droplets, a pressure chamber connected to the nozzle, and a drive element that is driven to impart pressure fluctuations to the liquid in the pressure chamber in response to a supplied drive signal, and a drive signal generation circuit that generates the drive signal, wherein the drive signal has at least one ejection pulse during one drive cycle, and the at least one ejection pulse has an ejection waveform element that imparts pressure fluctuations to the liquid in the pressure chamber so that droplets are ejected from the nozzle, and a residual vibration suppression element that attenuates pressure fluctuations of the liquid in the pressure chamber that remain after the droplets are ejected from the nozzle in accordance with the natural vibration period of the ejection section, and by adjusting the residual vibration suppression element of the at least one ejection pulse, the drive signal is supplied to the drive element over a period of two or more drive cycles to correct the weight of the droplets ejected from the nozzle when droplets are continuously ejected from the nozzle. [Brief explanation of the drawings]

[0007] [Figure 1] 1 is a schematic diagram showing an example of the configuration of a liquid ejection device 100 according to a first embodiment. [Figure 2] FIG. 2 is a diagram showing the electrical configuration of the liquid ejection device 100 according to the first embodiment. [Figure 3] FIG. 3 is a bottom view of the liquid ejection head 50 shown in FIG. [Figure 4] 4 is a cross-sectional view showing a part of the head chip 51 shown in FIG. 3. [Figure 5] FIG. 3 is a diagram for explaining a supply mode of a drive signal Com. [Figure 6] FIG. 3 is a diagram for explaining a supply mode of a drive signal Com. [Figure 7] FIG. 2 is a diagram for explaining a switching circuit 18. [Figure 8] FIG. 4 is a diagram for explaining a drive signal Com for generating a supply signal Vin that is supplied to a head chip 51a1. [Figure 9] FIG. 4 is a diagram for explaining the relationship between the drive period Tu and the ejection amount Iw. [Figure 10] 10 is a diagram showing the relationship between the potential difference ΔVh and the liquid ejection amount Iw for each drive frequency in a method of adjusting the potential difference ΔVh. FIG. [Figure 11] FIG. 4 is a diagram for explaining a drive frequency characteristic. [Figure 12] 10A and 10B are diagrams for explaining why the amount of change in ejection amount differs depending on the driving frequency. [Figure 13] FIG. 10 is a diagram for explaining the drive frequency characteristic ChTc when the residual vibration suppression element ED is adjusted. [Figure 14] FIG. 10 is a flowchart showing an example of a discharge amount correction process. [Figure 15] FIG. 10 is a flowchart showing an example of a residual vibration suppression element adjustment process. [Figure 16] FIG. 10 is a diagram for explaining the relationship between the adjustment interval tA and the discharge amount Iw. [Figure 17] 10A and 10B are diagrams for explaining an example of adjustment of the residual vibration suppression element ED of the drive signal ComAa. [Figure 18] 10A and 10B are diagrams for explaining an example of adjustment of the residual vibration suppression element ED of the drive signal ComBa. [Figure 19] FIG. 10 is a diagram for explaining a drive signal Com in the second embodiment. [Figure 20] FIG. 13 is a diagram for explaining a drive signal Com in a fifth modified example. [Figure 21] FIG. 13 is a diagram for explaining a drive signal Com in a sixth modified example. DETAILED DESCRIPTION OF THE INVENTION

[0008] Preferred embodiments of the present disclosure will be described below with reference to the accompanying drawings. Note that the dimensions and scale of each part in the drawings may differ from the actual dimensions and are shown schematically to facilitate understanding. Furthermore, the scope of the present disclosure is not limited to these embodiments unless otherwise specified in the following description to the effect that the present disclosure is limited.

[0009] The following description will use the mutually intersecting X-axis, Y-axis, and Z-axis as appropriate. In the following description, one direction along the X-axis is the X1 direction, and the direction opposite the X1 direction is the X2 direction. Similarly, the Y1 and Y2 directions are opposite directions along the Y-axis. The Z1 and Z2 directions are opposite directions along the Z-axis. Typically, the Z-axis is a vertical axis, and the Z2 direction corresponds to the downward direction in the vertical direction. However, the Z-axis does not have to be a vertical axis. While the X-axis, Y-axis, and Z-axis are typically perpendicular to each other, this is not a limitation, and they may intersect at an angle between 80° and 100°. In this specification, the term "equal" not only refers to strict equality, but also includes manufacturing and assembly errors.

[0010] A: First embodiment A1: Overall configuration of the liquid ejection device 100 FIG. 1 is a schematic diagram showing an example of the configuration of a liquid ejection device 100 according to a first embodiment. The liquid ejection device 100 is an inkjet printing device that ejects liquid such as ink as droplets onto a medium PP. The medium PP is, for example, printing paper. Note that the medium PP is not limited to printing paper, and may be a printing target made of any material, such as a resin film or fabric.

[0011] As shown in FIG. 1, the liquid ejection device 100 includes a liquid container 10, a control unit 20, a transport mechanism 30, and a liquid ejection head 50.

[0012] The liquid container 10 stores liquid. Specific examples of the liquid container 10 include a cartridge that is detachable from the liquid ejection device 100, a bag-shaped liquid pack made of flexible film, and a liquid tank that can be refilled with liquid. The type of liquid that can be stored in the liquid container 10 is arbitrary.

[0013] The control unit 20 controls the operation of each element of the liquid ejection device 100. The control unit 20 includes, for example, one or more processing circuits such as a CPU (Central Processing Unit) or an FPGA (Field Programmable Gate Array), and one or more storage circuits such as a semiconductor memory.

[0014] The transport mechanism 30 transports the medium PP in the Y1 direction under the control of the control unit 20. The transport mechanism 30 includes, for example, a long transport roller along the X axis and a motor that rotates the transport roller. Note that the transport mechanism 30 is not limited to a configuration using a transport roller, and may be configured, for example, to use a drum or endless belt that transports the medium PP while adsorbed to the outer peripheral surface by electrostatic force or the like.

[0015] The multiple liquid ejection heads 50 are housed in a carriage 501. The multiple liquid ejection heads 50 are arranged so as to be distributed over the entire range of the medium PP in the direction along the X axis. Each liquid ejection head 50 ejects liquid supplied from a liquid container 10 onto the medium PP from each of multiple nozzles N under the control of a control unit 20 based on image data Img. This ejection is performed in parallel with the transport of the medium PP by a transport mechanism 30, so that an image corresponding to the image data Img is formed in droplets on the surface of the medium PP.

[0016] A2: Electrical configuration of the liquid ejection device 100 Fig. 2 is a diagram showing the electrical configuration of the liquid ejection device 100 according to the first embodiment. As shown in Fig. 2, each liquid ejection head 50 has a plurality of head chips 51. In this embodiment, six head chips 51 are provided as the plurality of head chips 51.

[0017] Each head chip 51 has a switching circuit 18 and M ejection units D. In the following, when the number of ejection units D in the head chip 51 is M, in order to distinguish between the M ejection units D, the ejection units D may be written as ejection unit D[m] using the subscript [m]. However, M is an integer of 1 or more, and m is an integer of 1 or more and M or less. In the liquid ejection device 100, the subscript [m] may also be used for elements included in the ejection unit D.

[0018] Under the control of the control unit 20, the switching circuit 18 switches whether or not to supply the drive signal Com output from the control unit 20 as the supply signal Vin to each of the plurality of discharge sections D. Note that, although the switching circuit 18 is included in the head chip 51 in this embodiment, the switching circuit 18 may not be included in the head chip 51.

[0019] The control unit 20 includes a control circuit 21, a memory circuit 22, a power supply circuit 23, and a drive signal generation circuit 24.

[0020] The control circuit 21 has a function to control the operation of each part of the liquid ejection device 100 and a function to process various data. The control circuit 21 includes, for example, one or more processors such as a CPU (Central Processing Unit). Note that the control circuit 21 may include a programmable logic device such as an FPGA (Field-Programmable Gate Array) instead of or in addition to a CPU. Furthermore, when the control circuit 21 is made up of multiple processors, the multiple processors may be mounted on different boards or the like.

[0021] Furthermore, the control circuit 21 generates a control signal Sk1, a print data signal SI, a waveform designation signal dCom, a latch signal LAT, and a clock signal CLK as signals for controlling the operation of each part of the liquid ejection device 100 by executing the program.

[0022] The control signal Sk1 is a signal for controlling the driving of the transport mechanism 30. The print data signal SI is a digital signal for specifying the operating state of the drive element E. The latch signal LAT is used in conjunction with the print data signal SI and is a timing signal that determines the timing of liquid ejection from each nozzle N of the head chip 51.

[0023] Furthermore, the control circuit 21 reads out a program stored in the memory circuit 22 and executes the read out program, thereby functioning as an acquisition unit 211 and an adjustment unit 213. The acquisition unit 211 and the adjustment unit 213 will be described later.

[0024] The memory circuit 22 stores various programs executed by the control circuit 21, various data such as image data Img processed by the control circuit 21, and waveform information CI for generating the waveform designation signal dCom. The memory circuit 22 includes, for example, one or both of semiconductor memories: a volatile memory such as a random access memory (RAM) and a non-volatile memory such as a read-only memory (ROM), an electrically erasable programmable read-only memory (EEPROM), or a programmable read-only memory (PROM). The image data Img is supplied from an external device 200 such as a personal computer or a digital camera. The memory circuit 22 may be configured as a part of the control circuit 21.

[0025] The power supply circuit 23 receives power from a commercial power supply (not shown) and generates various predetermined potentials. The generated potentials are supplied to various parts of the liquid ejection device 100 as appropriate. For example, the power supply circuit 23 generates a power supply potential VHV and an offset potential VBS. The offset potential VBS is supplied to the liquid ejection head 50. The power supply potential VHV is also supplied to the drive signal generation circuit 24.

[0026] The drive signal generation circuit 24 is a circuit that repeatedly generates a drive signal Com for driving each drive element E included in each ejection section D. Specifically, the drive signal generation circuit 24 has, for example, a DA conversion circuit and an amplifier circuit. In the drive signal generation circuit 24, the DA conversion circuit converts the waveform designation signal dCom from the control circuit 21 from a digital signal to an analog signal. The amplifier circuit amplifies the analog signal using the power supply potential VHV from the power supply circuit 23, thereby generating the drive signal Com. Of the waveforms included in the drive signal Com, the signal with the waveform actually supplied to the drive element E is the aforementioned supply signal Vin. The waveform designation signal dCom is a digital signal that defines the waveform of the drive signal Com. The control circuit 21 generates the waveform designation signal dCom based on waveform information CI. Details of the waveform information CI will be described later with reference to FIG. 8.

[0027] In this embodiment, it is assumed that the drive signal Com includes drive signals ComAa, ComAb, ComAc, ComBa, ComBb, ComBc, ComC1, and ComC2. For example, the drive signal generation circuit 24 generates drive signals ComAa, ComAb, ComAc, ComBa, ComBb, ComBc, ComC1, and ComC2 using eight independent internal circuits. Hereinafter, the drive signals ComAa, ComAb, and ComAc may be referred to as drive signals ComA without distinction. The drive signals ComBa, ComBb, and ComBc may be referred to as drive signals ComB without distinction. The drive signals ComC1 and ComC2 may be referred to as drive signals ComC without distinction.

[0028] The drive signal ComA is a signal that causes the discharge portion D to discharge an amount of liquid corresponding to a large dot. The drive signal ComB is a signal that causes the discharge portion D to discharge an amount of liquid corresponding to a small dot. The drive signal ComC is a signal that drives the drive element E so that liquid is not discharged. More specifically, the drive signal ComC is a signal that causes the liquid surface of the nozzle N to vibrate slightly by driving the drive element E so that liquid is not discharged in order to prevent the liquid in the nozzle N from thickening, etc. Hereinafter, the liquid surface of the nozzle N may be referred to as a "meniscus."

[0029] The liquid ejection device 100 also has an imaging device 40 for measuring the amount of liquid ejected from the ejection section D. The imaging device 40 is a device that captures images of the liquid ejected from the ejection section D in flight. Specifically, the imaging device 40 has, for example, an imaging optical system and an imaging element. The imaging optical system is an optical system that includes at least one imaging lens, and may include various optical elements such as a prism, or may include a zoom lens or a focus lens. The imaging element is, for example, a CCD image sensor or a CMOS image sensor. CCD is an abbreviation for Charge Coupled Device. CMOS is an abbreviation for Complementary MOS.

[0030] The control circuit 21 transmits an image capture instruction Sk2 to the image capture device 40. When the image capture instruction Sk2 is received, the image capture device 40 transmits image information GI indicating an image of the liquid in flight to the control circuit 21. The control circuit 21 obtains the weight of the droplet in flight based on the image information GI.

[0031] The method for measuring the discharge amount is not limited to the above-mentioned method. For example, the liquid discharger 100 can measure the discharge amount by using a device that captures an image of the liquid that has landed on the medium PP or the like, or by using an electronic balance that measures the mass of the liquid discharged from the discharge portion D, instead of using the imaging device 40.

[0032] A3: Arrangement of multiple head chips 51 FIG. 3 is a bottom view of the liquid ejection head 50 shown in FIG. 2. As described above, the liquid ejection head 50 has six head chips 51 spaced apart from one another. The six head chips 51 are fixed to a fixing plate 55. In FIG. 3, the liquid ejection head 50 is viewed from the Z2 direction to the Z1 direction, so the head chips 51 are not visible, but for convenience, the six head chips 51 are shown by dashed lines. Parts of the six head chips 51 are exposed through openings 55a provided in the fixing plate 55. Each head chip 51 is elongated and extends along an α-axis that intersects the X-axis and Y-axis when viewed in the Z1 direction.

[0033] In this embodiment, of the six head chips 51, the head chip 51 located at the end in the X1 direction and the end in the Y2 direction may be referred to as head chip 51a1. Similarly, the head chip 51 located at the end in the X1 direction and the end in the Y1 direction may be referred to as head chip 51a2. The head chip 51 located at the end in the X2 direction and the end in the Y2 direction may be referred to as head chip 51c1. The head chip 51 located at the end in the X2 direction and the end in the Y1 direction may be referred to as head chip 51c2. The head chip 51 located between head chip 51a1 and head chip 51c1 may be referred to as head chip 51b1. The head chip 51 located between head chip 51a2 and head chip 51c2 may be referred to as head chip 51b2.

[0034] The six head chips 51 have a total of M nozzles N included in each of the M discharge sections D. The M nozzles N are exposed by openings 55a. The M nozzles N are divided into either nozzle row L1 or nozzle row L2. Hereinafter, nozzle row L1 and nozzle row L2 may be referred to as nozzle row Ln without distinction. The nozzle row Ln is a collection of multiple nozzles N arranged in a straight line that intersects the X-axis and Y-axis. The nozzle row Ln is aligned along the α-axis.

[0035] The nozzles N are arranged at equal intervals along the β axis, which is perpendicular to the α axis.

[0036] A4: Partial configuration of each head chip 51 Fig. 4 is a cross-section showing a portion of the head chip 51 shown in Fig. 3. However, Fig. 4 also shows a portion of the fixing plate 55. As shown in Fig. 4, the head chip 51 has a nozzle plate 11, a vibration absorber 12, a flow path substrate 13, a pressure chamber substrate 14, a diaphragm 15, a wiring substrate 16, a housing unit 17, and a switching circuit 18. The nozzle plate 11, the vibration absorber 12, the flow path substrate 13, the pressure chamber substrate 14, the diaphragm 15, the wiring substrate 16, and the housing unit 17 are each a plate-like member that is elongated in the direction along the α-axis. The nozzle plate 11, the flow path substrate 13, the pressure chamber substrate 14, the diaphragm 15, and the wiring substrate 16 are arranged in this order in the Z1 direction.

[0037] The nozzle plate 11 is a plate-like member in which a plurality of nozzles N are formed. Each of the plurality of nozzles N is a circular through-hole that allows a liquid to pass through. The nozzles N eject the liquid by vibration of the vibration plate 15. The nozzle plate 11 is bonded to the flow path substrate 13 with, for example, an adhesive.

[0038] The flow path substrate 13 is formed with flow paths for supplying liquid to the multiple nozzles N. Specifically, the flow path substrate 13 is formed with a space Ra, multiple supply flow paths 131, multiple communication flow paths 132, and a supply liquid chamber 133. The space Ra is an elongated opening extending in a direction along the α-axis in a plan view seen along the Z-axis. Each of the supply flow path 131 and the communication flow path 132 is a through-hole formed for each nozzle N. The supply liquid chamber 133 is an elongated space extending in a direction along the α-axis across the multiple nozzles N, and connects the space Ra and the multiple supply flow paths 131 to each other. Each of the multiple communication flow paths 132 overlaps with one nozzle N corresponding to that communication flow path 132 in a plan view. A pressure chamber substrate 14 is bonded to the flow path substrate 13 with, for example, an adhesive.

[0039] A plurality of pressure chambers C are provided in the pressure chamber substrate 14. Each pressure chamber C is formed for each nozzle N and is an elongated space extending in a direction along the β-axis in a plan view. The plurality of pressure chambers C are arranged in a direction along the α-axis. The pressure chamber C is a space located between the flow path substrate 13 and the vibration plate 15. The pressure chamber C communicates with the nozzle N via a communication flow path 132, and also communicates with the space Ra via a supply flow path 131 and a supply liquid chamber 133.

[0040] The nozzle plate 11, the flow path substrate 13, and the pressure chamber substrate 14 are each manufactured by processing a silicon single crystal substrate using, for example, dry etching, wet etching, etc. However, other known methods may also be used as appropriate to manufacture the nozzle plate 11, the flow path substrate 13, and the pressure chamber substrate 14.

[0041] A diaphragm 15 is disposed on the surface facing the Z1 direction of the pressure chamber substrate 14. The diaphragm 15 is a plate-like member that can vibrate elastically.

[0042] A plurality of drive elements E corresponding to the nozzles N are arranged on the surface of the vibration plate 15 facing the Z1 direction. Each drive element E has an elongated shape extending in a direction along the β axis in a plan view. The plurality of drive elements E correspond to a plurality of pressure chambers C and are arranged in a direction along the α axis. The drive elements E are driven to change the volume of the pressure chambers C in accordance with the supply signal Vin generated from the drive signal Com. In other words, the drive elements E are deformed by the application of a voltage. When the vibration plate 15 vibrates in conjunction with this deformation, the pressure in the pressure chambers C fluctuates, causing liquid to be ejected from the nozzles N.

[0043] The housing 17 is a case for storing the liquid to be supplied to the multiple pressure chambers C. As shown in FIG. 4, a space Rb is formed in the housing 17. The space Rb in the housing 17 and the space Ra in the flow path substrate 13 are connected to each other. The space formed by the spaces Ra and Rb functions as a liquid storage chamber R, which is a reservoir that stores the liquid to be supplied to the multiple pressure chambers C. The liquid is supplied to the liquid storage chamber R via an inlet 171 formed in the housing 17. The liquid in the liquid storage chamber R is supplied to the pressure chambers C via the supply liquid chamber 133 and each supply flow path 131.

[0044] The vibration absorber 12 is a flexible film that forms the wall surface of the liquid storage chamber R. The vibration absorber 12 is a compliant substrate that absorbs pressure fluctuations of the liquid in the liquid storage chamber R.

[0045] The wiring board 16 is a plate-like member on which wiring is formed for electrically connecting the switching circuit 18 and the plurality of drive elements E. The wiring board 16 is, for example, a rigid board. The wiring board 16 has wiring formed on its surface facing the Z1 direction to electrically connect the switching circuit 18 mounted on the surface facing the Z2 direction to the plurality of bumps 16B required for driving each drive element E. The switching circuit 18 has an IC (Integrated Circuit) chip that outputs a supply signal Vin and an offset potential VBS based on a drive signal Com for driving each drive element E. A flexible wiring board (not shown) that is connected to the control unit 20 is also connected to the wiring board 16.

[0046] The wiring board 16 may be a flexible board such as an FFC (Flexible Flat Cable), or may be an FPC (Flexible Printed Circuits) or a COF (Chip On Film) on which the switching circuit 18 is mounted.

[0047] 4, one ejection section D includes one drive element E, one pressure chamber C, and one nozzle N. As can be seen from FIG. 4 and other figures, the pressure chamber C and drive element E included in one ejection section D are such that, in a plan view in the Z2 direction, the drive element E overlaps part or all of the pressure chamber C. When a drive signal Com is supplied to the drive element E based on a print data signal SI, the ejection section D ejects ink from the pressure chamber C from the nozzle N by driving the drive element E with the drive signal Com.

[0048] The configuration of each head chip 51 is not limited to the example shown in Fig. 4. Each head chip 51 may have, for example, a circulation flow path for circulating a liquid.

[0049] 5 and 6 are diagrams for explaining the manner in which the drive signal Com is supplied. As shown in FIG. 5, the same drive signal Com related to the ejection of liquid is supplied to the head chips 51 aligned in the Y1 direction, which is the transport direction of the medium PP. Specifically, drive signals ComAa and ComBa are supplied to the head chips 51a1 and 51a2. Drive signals ComAb and ComBb are supplied to the head chips 51b1 and 51b2. Drive signals ComAc and ComBc are supplied to the head chips 51c1 and 51c2.

[0050] 6, in this embodiment, the drive signal ComC that does not eject liquid from the nozzles N is common to the head chips 51 aligned in the X1 direction that intersects with the transport direction of the medium PP. Specifically, the same drive signal ComC1 is supplied to head chip 51a1, head chip 51b1, and head chip 51c1. The same drive signal ComC2 is supplied to head chip 51a2, head chip 51b2, and head chip 51c2.

[0051] However, the supply mode of the drive signal Com is not limited to the mode shown in Figures 5 and 6. For example, the drive signal generation circuit 24 may supply the same drive signal ComC to six head chips 51. In the following, the supply mode of the drive signal Com will be described as being the mode shown in Figures 5 and 6.

[0052] As can be understood from the above description, three drive signals Com can be supplied to one head chip 51. A mode in which the three drive signals Com are switched and supplied to one head chip 51 will be described with reference to FIG.

[0053] A5: Driving element E Fig. 7 is a diagram for explaining the switching circuit 18. Fig. 7 shows the switching circuit 18 of the head chip 51a1. The driving element E is driven by a supply signal Vin from the switching circuit 18. The switching circuit 18 will be explained below with reference to Fig. 7.

[0054] As shown in FIG. 7, the switching circuit 18 is connected to a wiring LHa, a wiring LHb, and a wiring LHc. The wiring LHa is a signal line that transmits the drive signal ComAa. The wiring LHb is a signal line that transmits the drive signal ComBa. The wiring LHc is a signal line that transmits the drive signal ComC1. Note that in FIG. 7, one of the first electrode and the second electrode of the drive element E described above is shown as electrode Zd[m], and the other is shown as electrode Zu[m]. The wiring LHd is connected to the electrode Zd[m]. The wiring LHd is a power supply line to which an offset potential VBS is supplied.

[0055] The switching circuit 18 has M switches SWa[1] to SWa[M], M switches SWb[1] to SWb[M], M switches SWb[1] to SWc[M], and a connection state designation circuit 18a that designates the connection state of these switches.

[0056] For each m from 1 to M, switch SWa[m] is a switch that switches between conduction and non-conduction between the wiring LHa for transmitting the drive signal ComAa and the electrode Zu[m] of the drive element E[m]. Switch SWb[m] is a switch that switches between conduction and non-conduction between the wiring LHb for transmitting the drive signal ComBa and the electrode Zu[m] of the drive element E[m]. Switch SWc[m] is a switch that switches between conduction and non-conduction between the wiring LHc for transmitting the drive signal ComC1 and the electrode Zu[m] of the drive element E[m]. Each of these switches is, for example, a transmission gate.

[0057] Based on the clock signal CLK, print data signal SI, and latch signal LAT supplied from the control circuit 21, the connection state designation circuit 18a generates connection state designation signals SLa[1] to SLa[M] that specify the on / off states of the switches SWa[1] to SWa[M], connection state designation signals SLb[1] to SLb[M] that specify the on / off states of the switches SWb[1] to SWb[M], and connection state designation signals SLc[1] to SLc[M] that specify the on / off states of the switches SWc[1] to SWc[M].

[0058] For example, although not shown, the connection state designation circuit 18a includes multiple transfer circuits, multiple latch circuits, and multiple decoders in one-to-one correspondence with the drive elements E[1] to E[M]. Of these, the transfer circuit receives a print data signal SI. The print data signal SI includes an individual designation signal Sd for each drive element E. The individual designation signals Sd are serially supplied and, for example, transferred sequentially to the multiple transfer circuits in synchronization with a clock signal CLK. The latch circuit latches the individual designation signal Sd supplied to the transfer circuit based on a latch signal LAT. The decoder generates a connection state designation signal SLa[m], a connection state designation signal SLb[m], and a connection state designation signal SLc[m], where m is 1 to M, based on the individual designation signal Sd and the latch signal LAT.

[0059] For each m ranging from 1 to M, the switch SWa[m] is switched on and off in response to the connection state designation signal SLa[m]. For example, the switch SWa[m] is turned on when the connection state designation signal SLa[m] is at a high level, and turned off when the connection state designation signal SLa[m] is at a low level. Similarly, the switch SWb[m] is switched on and off in response to the connection state designation signal SLb[m]. For example, the switch SWb[m] is turned on when the connection state designation signal SLb[m] is at a high level, and turned off when the connection state designation signal SLb[m] is at a low level. Furthermore, the switch SWc[m] is switched on and off in response to the connection state designation signal SLc[m]. For example, the switch SWc[m] is turned on when the connection state designation signal SLc[m] is at a high level, and turned off when the connection state designation signal SLc[m] is at a low level. As described above, the switching circuit 18 supplies part or all of the waveform included in the drive signal Com as the supply signal Vin to the drive elements E of one or more discharge units D selected from the M discharge units D.

[0060] In Figure 7, the switching circuit 18 of head chip 51a1 is illustrated, but for head chips 51 other than head chip 51a1, only one or more of the drive signals ComAa, drive signal ComBa, and drive signal ComC1 are different, so illustration and explanation are omitted.

[0061] A6: Drive signal Com 8 is a diagram illustrating the drive signal Com for generating the supply signal Vin supplied to the head chip 51a1. In this embodiment, the operating period of the liquid ejection device 100 includes one or more drive cycles Tu. Generally, the liquid ejection device 100 forms an image represented by image data Img by ejecting liquid from each ejection section D one or more times over multiple continuous or intermittent drive cycles Tu.

[0062] 8, the control circuit 21 outputs a latch signal LAT having a pulse PlsL. As a result, the control circuit 21 defines a drive period Tu as a period from the rising edge of one pulse PlsL to the rising edge of the next pulse PlsL. The specific length or period of the drive period Tu is not particularly limited.

[0063] The print data 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 drive cycle Tu. As described above, the connection state designation circuit 18a generates connection state designation signals SLa[m], SLb[m], and SLc[m] based on the individual designation signal Sd[m] for each of m from 1 to M in the drive cycle Tu.

[0064] The individual designation signal Sd[m] is a signal that designates one of three drive modes for the discharge section D[m] in each drive cycle Tu: discharge of liquid in an amount equivalent to a large dot, discharge of liquid in an amount equivalent to a small dot, or slight vibration. Hereinafter, the amount equivalent to a large dot may be referred to as a "large amount." Also, the amount equivalent to a small dot may be referred to as a "small amount."

[0065] First, the drive signal ComAa will be described. As shown in Fig. 8, the drive signal ComAa has, in one drive period Tu, a start potential sustain element asAa, an ejection pulse PAa for forming a large dot, and an end potential sustain element aeAa, in this order.

[0066] 8, the start potential maintaining element asAa is an element that maintains the reference potential V0Aa from the start of one drive period Tu to the start of the ejection pulse PAa, and the end potential maintaining element aeAa is an element that maintains the reference potential V0Aa from the end of the ejection pulse PAa to the end of one drive period Tu.

[0067] The ejection pulse PAa has an ejection waveform element DRAa and a residual vibration suppression element EDAa. The ejection waveform element DRAa applies pressure fluctuations to the liquid in the pressure chamber C so that a large amount of droplets are ejected from the nozzle N. The ejection waveform element DRAa has a fill element d1, a potential maintaining element pwh1, and an ejection element c1, in this order. The fill element d1 changes from a reference potential V0Aa to a minimum potential VLAa, generating negative pressure in the pressure chamber C. The minimum potential VLAa is the minimum potential within the ejection pulse PAa. The end of the fill element d1 is connected to the start of the potential maintaining element pwh1. The potential maintaining element pwh1 maintains the minimum potential VLAa. The end of the potential maintaining element pwh1 is connected to the ejection element c1. The ejection element c1 changes from the minimum potential VLAa to a maximum potential VHAa, generating positive pressure in the pressure chamber C. The maximum potential VHAa is the highest potential within the ejection pulse PAa. When the drive element E receives the ejection waveform element DRAa, it generates a negative pressure in the pressure chamber C using the filling element d1, and then generates a positive pressure in the pressure chamber C using the ejection element c1, thereby ejecting a droplet from the nozzle N.

[0068] 8 illustrates the state of the meniscus MN at the filling element d1 and the ejection element c1. At the filling element d1, the meniscus MN is retracted in the Z1 direction. At the ejection element c1, the meniscus MN is pushed out in the Z2 direction, and a large amount of droplet DL is ejected from the nozzle N.

[0069] The residual vibration suppression element EDAa attenuates pressure fluctuations of the liquid in the pressure chamber C that correspond to the natural vibration period of the ejection section D and remain after a droplet is ejected from the nozzle N. Hereinafter, the pressure fluctuations that remain after liquid is ejected from the nozzle N may be referred to as "residual vibration." The residual vibration suppression element EDAa includes a first vibration suppression maintaining element pwh2 and a first vibration suppression expansion element d2, in this order. The first vibration suppression maintaining element pwh2 maintains a constant potential from the end of the ejection element c1. In the example of Figure 8, it maintains the maximum potential VHAa. The first vibration suppression expansion element d2 starts changing its potential from the end of the first vibration suppression maintaining element pwh2 and expands the pressure chamber C. The first vibration suppression expansion element d2 changes its potential from the maximum potential VHAa to the reference potential V0Aa.

[0070] Next, the drive signal ComBa will be described. As shown in Fig. 8, the drive signal ComBa has, in this order, a start potential sustaining element asBa, an ejection pulse PBa for forming a small dot, and an end potential sustaining element aeBa.

[0071] 8, the start potential maintaining element asBa is an element that maintains the reference potential V0Ba from the start of one drive period Tu to the start of the ejection pulse PBa, and the end potential maintaining element aeBa is an element that maintains the reference potential V0Ba from the end of the ejection pulse PBa to the end of one drive period Tu.

[0072] The ejection pulse PBa has an ejection waveform element DRBa and a residual vibration suppression element EDBa. The ejection waveform element DRBa applies pressure fluctuations to the liquid in the pressure chamber C so that a small amount of droplet is ejected from the nozzle N. The ejection waveform element DRBa has, in this order, a filling element d4, a potential maintaining element pwh5, a contraction element c3, a potential maintaining element pwh6, and a separation element d5. The filling element d4 changes from the reference potential V0Ba to the minimum potential VLBa, generating negative pressure in the pressure chamber C. The minimum potential VLBa is the minimum potential in the ejection pulse PBa. The end of the filling element d4 connects to the start of the potential maintaining element pwh5. The potential maintaining element pwh5 maintains the minimum potential VLBa. The end of the potential maintaining element pwh5 connects to the start of the contraction element c3. The contraction element c3 changes from the minimum potential VLBa to a potential V1Ba, contracting the pressure chamber C and causing a liquid column to protrude from the nozzle N. The potential V1Ba is higher than the reference potential V0Ba. The end of the contraction element c3 is connected to the start of the potential maintaining element pwh6. The potential maintaining element pwh6 maintains the potential V1Ba. The end of the potential maintaining element pwh6 is connected to the start of the dividing element d5. The dividing element d5 changes from the potential V1Ba to the potential V2Ba, expanding the pressure chamber C after the contraction element c3 and dividing the liquid column into multiple parts.

[0073] The residual vibration suppression element EDBa attenuates residual vibration. The residual vibration suppression element EDBa has a third vibration suppression sustaining element pwh3, a second vibration suppression contraction element c2, a fourth vibration suppression sustaining element pwh4, and a second vibration suppression expansion element d3, in this order. The third vibration suppression sustaining element pwh3 maintains a potential V2Ba as a constant potential from the end of the decoupling element d5. The second vibration suppression contraction element c2 changes from the potential V2Ba to the highest potential VHBa, causing the pressure chamber C to contract from the end of the third vibration suppression sustaining element pwh3. The highest potential VHBa is the highest potential of the ejection pulse PBa. The fourth vibration suppression sustaining element pwh4 maintains a constant potential from the end of the second vibration suppression contraction element c2 as a constant potential from the end of the second vibration suppression contraction element c2, maintaining the highest potential VHBa. The second vibration suppression expansion element d3 changes from the highest potential VHBa to the reference potential V0Ba, causing the pressure chamber C to expand from the end of the fourth vibration suppression sustaining element pwh4.

[0074] 8 illustrates the state of the meniscus MN at the contraction element c3 and the dividing element d5. At the contraction element c3, the meniscus MN is pushed out in the Z2 direction by contracting the pressure chamber C, causing a liquid column DC to protrude from the nozzle N. At the dividing element d5, the meniscus MN is pulled in the Z1 direction, dividing the liquid column DC into multiple pieces, and each droplet resulting from the division of the liquid column DC is ejected from the nozzle N as a small droplet DS.

[0075] In the following description, pulses that cause liquid to be ejected from the nozzle N, including the ejection pulse PAa and the ejection pulse PBa, may be collectively referred to as the ejection pulse PD. The potential difference between the highest and lowest potentials of the ejection pulse PD may be referred to as the potential difference ΔVh. The potential difference ΔVh of the ejection pulse PAa shown in FIG. 8 is the potential difference ΔVhAa between the highest potential VHAa and the lowest potential VLAa. Furthermore, the potential difference ΔVh of the ejection pulse PBa shown in FIG. 8 is the potential difference ΔVhBa between the highest potential VHBa and the lowest potential VLBa.

[0076] Hereinafter, the ejection waveform elements included in the ejection pulse PD, including the ejection waveform element DRAa and the ejection waveform element DRBa, may be collectively referred to as the ejection waveform element DR. Similarly, the residual vibration suppression elements included in the ejection pulse PD, including the residual vibration suppression element EDAa and the residual vibration suppression element EDBa, may be collectively referred to as the residual vibration suppression element ED.

[0077] 8, the drive signal ComAa and the drive signal ComBa each have one ejection pulse PD during one drive period Tu. One ejection pulse PD is an example of "at least one ejection pulse."

[0078] Next, the driving signal ComC1 will be described. As shown in Fig. 8, the driving signal ComC1 has a start potential maintaining element asC1, a slight vibration pulse PC1 that generates slight vibration, and an end potential maintaining element aeC1.

[0079] 8, the start potential maintaining element asC1 is an element that maintains the reference potential V0C1 from the start of one drive period Tu to the start of the micro vibration pulse PC1. The end potential maintaining element aeC1 is an element that maintains the reference potential V0C1 from the end of the micro vibration pulse PC1 to the end of one drive period Tu.

[0080] The micro-vibration pulse PC1 is a trapezoidal wave and has an expansion element e1, a sustain element e2, and a contraction element e3 in this order. The expansion element e1 changes potential from the reference potential V0C1 to the minimum potential VLC1 of the micro-vibration pulse PC1. The minimum potential VLC1 is the minimum potential within the micro-vibration pulse PC1. The sustain element e2 is an element that maintains the minimum potential VLC1. The contraction element e3 is an element that returns from the minimum potential VLC1 to the reference potential V0C1.

[0081] In the following description, pulses that generate micro-vibrations, including the micro-vibration pulse PC1, may be referred to as micro-vibration pulse PC. Furthermore, the potential at the start of one drive period Tu and the potential at the end of one drive period Tu in each drive signal Com, including the reference potential V0Aa, reference potential V0Ba, and reference potential V0C1, may be referred to as the reference potential V0. The reference potential V0 is an example of a "first potential." Furthermore, elements that maintain the reference potential V0 from the start of one drive period Tu, including the start potential maintaining element asAa, the start potential maintaining element asBa, and the start potential maintaining element asC1, may be referred to as the start potential maintaining element as. Furthermore, elements that maintain the reference potential V0 until the end of one drive period Tu, including the end potential maintaining element aeAa, the end potential maintaining element aeBa, and the end potential maintaining element aeC1, may be referred to as the end potential maintaining element ae.

[0082] Although not shown, drive signals ComAb and ComAc have the same elements as drive signal ComAa. Therefore, each element of drive signals ComAb and ComAc may be described with a reference symbol, such as "start potential maintaining element as." Similarly, drive signals ComBb and drive signal ComBc are not shown, but have the same elements as drive signal ComBa. Therefore, each element of drive signals ComBb and drive signal ComBc may be described with a reference symbol, such as "start potential maintaining element as." Drive signal ComC2 has the same elements as drive signal ComC1. However, the duration or potential of each element may differ between drive signals ComAa, drive signal ComAb, and drive signal ComAc due to adjustment of drive signal Com, which will be described later.

[0083] The waveform information CI shown in FIG. 2 indicates the waveform shape of the drive signal Com. Specifically, the waveform information CI indicates the waveform shapes of each of the drive signals ComAa, ComAb, ComAc, ComBa, ComBb, ComBc, ComC1, and ComC2. For example, the waveform information CI includes termination information including information indicating the termination time and termination potential of each element of each drive signal Com. For example, for the drive signal ComAa, the waveform information CI includes termination information for the start potential sustaining element asAa, the fill element d1, the potential sustaining element pwh1, the ejection element c1, the first damping sustaining element pwh2, the first damping expansion element d2, and the end potential sustaining element aeAa. The information indicating the termination time included in the termination information for the end potential sustaining element a2 indicates one drive period Tu.

[0084] A7: Adjusting the drive signal Com The head chips 51 may have some manufacturing errors. These manufacturing errors may cause the ejection amounts of the two head chips 51 to differ from each other. For example, even if the same drive signal Com is applied to each of the two head chips 51, manufacturing errors may cause the shapes of the pressure chambers C to differ, resulting in different ejection amounts. Adjusting the drive signal Com may be considered to equalize the ejection amounts of the two head chips 51. In this embodiment, it is necessary to equalize the large amounts ejected from the six head chips 51 and the small amounts ejected from the six head chips 51. Therefore, it is necessary to adjust the drive signal ComAa so that the head chips 51a1 and 51a2 eject a uniform large amount, adjust the drive signal ComAb so that the head chips 51b1 and 51b2 eject a uniform large amount, and adjust the drive signal ComAc so that the head chips 51c1 and 51c2 eject a uniform large amount. Similarly, it is necessary to adjust the drive signal ComBa so that uniform small amounts are ejected from head tips 51a1 and 51a2, adjust the drive signal ComBb so that uniform small amounts are ejected from head tips 51b1 and 51b2, and adjust the drive signal ComBc so that uniform small amounts are ejected from head tips 51c1 and 51c2.

[0085] Furthermore, if the reference potential V0 of two or more drive signals Com that can be supplied to a given head chip 51 differs in potential, switching the drive signal Com supplied to this head chip 51 may result in ejection defects, such as unintended ejection of droplets. For example, since drive signals ComAa, ComBa, and ComC1 may be supplied to head chip 51a1, in order to prevent ejection defects from head chip 51a1 when the drive signal Com supplied to head chip 51a1 is switched, the reference potential V0Aa, reference potential V0Ba, and reference potential V0C1 must be the same potential. Similarly, since drive signals ComAa, ComBa, and drive signal ComC2 may be supplied to head chip 51a2, in order to prevent ejection defects from head chip 51a2 when the drive signal Com supplied to head chip 51a2 is switched, the reference potential V0Aa, reference potential V0Ba, and reference potential V0 of drive signal ComC2 must be the same potential. However, drive signal ComC1 can also be supplied to head chip 51b1 and head chip 51c1. Furthermore, drive signal ComC2 can also be supplied to head chip 51b2 and head chip 51c2. Therefore, in this embodiment, in order to prevent ejection defects from occurring from head chip 51 when the drive signal Com supplied to head chip 51 is switched, the reference potential V0 of all eight drive signals Com must be the same potential.

[0086] As described above, it is necessary to adjust the drive signals Com while maintaining the reference potentials V0 of all eight drive signals Com at the same potential.

[0087] One possible method for adjusting the drive signal Com is to adjust the potential difference ΔVh of the ejection pulse PD of the drive signal Com while keeping the reference potential V0 in the drive signal Com fixed. Generally, the ejection volume can be increased by increasing the potential difference ΔVh. However, the inventors' experiments have shown that even when the potential difference ΔVh is increased, the ejection volume does not necessarily increase if the drive period Tu is short. Hereinafter, the reciprocal of the drive period Tu may be referred to as the drive frequency. Furthermore, a state in which the drive period Tu is short, i.e., a state in which the drive frequency is high, may be referred to as high-frequency drive. On the other hand, a state in which the drive period Tu is long, i.e., a state in which the drive frequency is low, may be referred to as low-frequency drive. The relationship between the drive period Tu and the ejection volume will be explained using FIG. 9 .

[0088] FIG. 9 is a diagram illustrating the relationship between the drive period Tu and the ejection amount Iw. Graph g1 in FIG. 9 shows the ejection amount Iw corresponding to the drive period Tu. The horizontal axis of graph g1 indicates the length of the drive period Tu. [μs] in FIG. 9 indicates microseconds. The vertical axis of graph g1 indicates the magnitude of the ejection amount Iw. The ejection amount characteristic Ch50 shown in graph g1 indicates the characteristics of the ejection amount Iw when the ratio of the potential difference from the minimum potential to the reference potential V0 to the potential difference ΔVh is 50%. Hereinafter, the ratio of the potential difference from the minimum potential to the reference potential V0 to the potential difference ΔVh may be referred to as the "potential difference ratio." The ejection amount characteristic Ch40 shown in graph g1 indicates the characteristics of the ejection amount Iw when the potential difference ratio is 40%. A smaller potential difference ratio means a larger potential difference ΔVh.

[0089] As can be seen from Figure 9, by changing the potential difference ratio from 50% to 40%, i.e., by increasing the potential difference ΔVh, the liquid ejection volume Iw increases when the drive period Tu is 40 μs or longer. However, the change in the ejection volume when the drive period Tu is shorter than 40 μs is smaller than the change in the ejection volume when the drive period Tu is longer than 40 μs. In other words, the higher the drive frequency, the smaller the change in the ejection volume per 1 V of the potential difference ΔVh.

[0090] FIG. 10 shows the relationship between the potential difference ΔVh and the liquid ejection amount Iw for each drive frequency in a method for adjusting the potential difference ΔVh. Graph g2 in FIG. 10 shows the relationship between the potential difference ΔVh and the liquid ejection amount Iw for each drive frequency. The horizontal axis of graph g2 indicates the magnitude of the potential difference ΔVh. The vertical axis of graph g2 indicates the magnitude of the ejection amount Iw. [pl] in graph g2 indicates picoliters. The ejection amount characteristic Ch1 shown in graph g2 indicates the characteristics of the liquid ejection amount Iw corresponding to the potential difference ΔVh when the drive frequency is 5.0 kHz. [kHz] indicates kilohertz. The ejection amount characteristic Ch2 shown in graph g2 indicates the characteristics of the liquid ejection amount Iw corresponding to the potential difference ΔVh when the drive frequency is 31.5 kHz. The ejection amount characteristic Ch3 shown in graph g2 indicates the characteristics of the liquid ejection amount Iw corresponding to the potential difference ΔVh when the drive frequency is 63.0 kHz.

[0091] As can be seen from the ejection volume characteristics Ch1, Ch2, and Ch3, as the drive frequency increases, the change in ejection volume Iw is small even when the potential difference ΔVh is changed. In other words, the amount of change in ejection volume per volt of potential difference ΔVh is smaller in high-frequency drive than in low-frequency drive. Therefore, if the potential difference ΔVh is further adjusted to ensure the ejection volume in high-frequency drive, the droplet ejection speed becomes excessively faster than the desired speed in low-frequency drive. As a result, there is a risk of droplet impact deviation during low-frequency drive, such as when printing ruled lines. The drive frequency characteristics, which indicate the rate of change in ejection volume Iw corresponding to the drive period Tu, are explained using Figure 11.

[0092] FIG. 11 is a diagram illustrating the drive frequency characteristic. Graph g3 shown on the left side of FIG. 11 shows the drive frequency characteristic ChF, which indicates the rate of variation of the ejection volume Iw corresponding to the drive period Tu. The drive frequency characteristic ChF is the sum of the drive frequency characteristic ChTm due to the influence of the Tm vibration shown in graph g4 in the center of FIG. 11 and the drive frequency characteristic ChTc due to the influence of the Tc vibration shown in graph g5 on the right side of FIG. 11. The Tm vibration refers to the vibration of the meniscus MN. The Tc vibration refers to the natural vibration of the liquid in the flow path of the ejection unit D. In the following description, the natural vibration period of the ejection unit D may be referred to as the natural vibration period Tc.

[0093] The influence of Tm vibration is greater in high-frequency driving. Therefore, in low-frequency driving, the influence of residual vibration, which is Tc vibration after droplet ejection, and the influence of refill, which is Tm vibration after liquid ejection, are smaller than in high-frequency driving. In low-frequency driving, the next drive signal Com is applied after the meniscus MN has returned to its non-driven state. On the other hand, in high-frequency driving, the ejection volume is easily affected by the Tm vibration of the meniscus MN and the Tc vibration in the flow path of the ejection section D. The reason why the amount of change in the ejection volume differs depending on the drive frequency will be explained using Figure 12.

[0094] FIG. 12 is a diagram illustrating why the amount of change in the ejection amount differs depending on the drive frequency. Graph g6 in FIG. 12 shows the ejection amount characteristic ChD50 and the ejection amount characteristic ChD40. The ejection amount characteristic ChD50 indicates the rate of change in the ejection amount Iw according to the drive frequency when the potential difference ratio is 50%. The ejection amount characteristic ChD40 indicates the rate of change in the ejection amount Iw according to the drive frequency when the potential difference ratio is 40%. The vertical axis of graph g6 indicates the rate of change [%] of the ejection amount Iw when the ejection amount Iw in the low frequency range of the ejection amount characteristic ChD50 and the ejection amount characteristic ChD40 is set to 100%.

[0095] As can be seen from the discharge rate characteristics ChD40 and ChD50, when the potential difference ratio is 40%, the rate of change in the discharge rate is lower than when the potential difference ratio is 50%. In other words, with high-frequency driving, even if the correction amount for the potential difference ΔVh is increased without changing the reference potential V0, the discharge rate Iw is unlikely to increase. For this reason, with the method of adjusting the potential difference ΔVh without changing the reference potential V0, the higher the frequency of driving, the more difficult it is to increase the liquid discharge rate Iw.

[0096] As described above, the higher the driving frequency, the greater the influence of residual vibration. Therefore, in this embodiment, the weight of droplets ejected from the nozzle N when the drive signal Com is repeatedly supplied to the drive element E to continuously eject droplets from the nozzle N is corrected by adjusting the residual vibration suppression element ED of the ejection pulse PD. For example, by adjusting the residual vibration suppression element ED of a certain ejection pulse PD and supplying the next ejection pulse PD while leaving a large residual vibration, the next ejection pulse PD can utilize the residual vibration to increase the ejection amount. On the other hand, by supplying the next ejection pulse PD with the residual vibration largely attenuated, the next ejection pulse PD cannot utilize the residual vibration, and the ejection amount can be reduced.

[0097] As described above, the drive frequency characteristic is the sum of the drive frequency characteristic ChTm and the drive frequency characteristic ChTc, and is therefore affected by the natural vibration period Tc. The drive frequency characteristic ChTc when the residual vibration suppression element ED is adjusted will be described with reference to FIG.

[0098] Fig. 13 is a diagram for explaining the drive frequency characteristic ChTc when the residual vibration suppression element ED is adjusted. Graph g7 shown in Fig. 13 shows the drive frequency characteristic ChTc1 when the residual vibration suppression element ED is not adjusted, and the drive frequency characteristic ChTc2 when the residual vibration suppression element ED is adjusted.

[0099] As can be seen from the drive frequency characteristics ChTc1 and ChTc2, when the drive period Tu is (0.5×n−0.25) or (0.5×n+0.25) times the natural vibration period Tc, the discharge amount Iw does not change even if the residual vibration suppression element ED is adjusted. n is an integer greater than or equal to 1. For example, in the drive frequency characteristics ChTc1 and ChTc2, when n is 1, the fluctuation rates of the discharge amount Iw are the same at 0.25Tc and 0.75Tc. That is, when the drive period Tu is 0.25Tc or 0.75Tc, the discharge amount Iw does not change even if the residual vibration suppression element ED is adjusted. Therefore, in this embodiment, in order to change the discharge amount Iw, the drive period Tu satisfies the following formula (1): (0.5×n-0.2)×Tc <Tu<(0.5×n+0.2)×Tc …(1)

[0100] 13, the drive period Tu is longer than 0.3Tc and less than 0.7Tc, longer than 0.8Tc and less than 1.2Tc, or longer than 1.3Tc and less than 1.7Tc. Furthermore, as can be seen from the drive frequency characteristics ChTc1 and ChTc2, the closer the drive period Tu is to 0.5×n times the natural vibration period Tc, the easier it is to adjust the discharge amount Iw.

[0101] A8: Discharge volume correction process 14 is a flowchart showing an example of the discharge amount correction process. The discharge amount correction process is executed, for example, when the liquid discharger 100 is powered on or when an instruction is received from the user of the liquid discharger 100. In step S2, the control circuit 21 selects one drive signal Com from two or more drive signals Com having discharge pulses PD. Specifically, the control circuit 21 selects from drive signal ComAa, drive signal ComAb, drive signal ComAc, drive signal ComBa, drive signal ComBb, and drive signal ComBc, in order from the top. Hereinafter, the drive signal Com selected in step S2 may be referred to as the adjustment target drive signal Com-Adj.

[0102] Next, in step S4, the control circuit 21 causes the drive signal generation circuit 24 to supply the adjustment target drive signal Com-Adj to the head chip 51 for a period of two or more drive cycles Tu. Furthermore, in step S6, the control circuit 21 transmits an imaging instruction Sk2 to the imaging device 40 at a timing when the droplets ejected continuously by two or more drive cycles Tu can be imaged.

[0103] After the processing of step S6 is completed, in step S8, the control circuit 21 acquires image information GI from the imaging device 40. Then, in step S10, the control circuit 21 functions as an acquisition unit 211, analyzes the image information GI, and acquires information indicating the weight of droplets that have been continuously ejected as a result of the drive signal Com being supplied by the processing of step S4. Hereinafter, the weight of the droplets indicated by the information acquired in step S4 may be referred to as the "measured amount."

[0104] After completing the process of step S10, the control circuit 21 determines in step S12 whether the measured amount matches the desired amount corresponding to the drive signal Com-Adj to be adjusted. The desired amount corresponding to the drive signal Com-Adj to be adjusted is a large amount if the drive signal Com-Adj to be adjusted is drive signal ComA, and a small amount if the drive signal Com-Adj to be adjusted is drive signal ComB. The measured amount matching the desired amount includes not only the case where the measured amount and the desired amount match perfectly, but also the case where dots formed by droplets of the measured amount and dots formed by droplets of the desired amount can be considered to be the same when error is taken into account.

[0105] If the determination result in step S12 is positive, in step S14, the control circuit 21 updates the waveform information CI of the drive signal Com corresponding to the adjustment-target drive signal Com-Adj, and determines whether or not there is any drive signal Com that has not been selected as the adjustment-target drive signal Com-Adj. If the determination result in step S14 is positive, the control circuit 21 executes the process of step S2 again. If the determination result in step S14 is negative, the control circuit 21 ends the series of processes shown in FIG.

[0106] If the determination result in step S12 is negative, the control circuit 21 functions as the adjustment unit 213 in step S16 and executes the residual vibration suppression element adjustment process. After the process of step S16 ends, the control circuit 21 executes the process of step S4 again. The residual vibration suppression element adjustment process will be described with reference to FIG.

[0107] 15 is a flowchart showing an example of the residual vibration suppression element adjustment process. The residual vibration suppression element adjustment process is a process for correcting the weight of droplets ejected from the nozzle N when the drive signal Com is supplied to the drive element E over a period of two or more drive cycles Tu to continuously eject droplets from the nozzle N by adjusting the residual vibration suppression element ED.

[0108] In step S22, the control circuit 21 determines whether the measured amount is greater than the desired amount. If the determination result in step S22 is positive, the discharge rate needs to be reduced. In step S24, the control circuit 21 adjusts the residual vibration suppression element ED so that the adjustment interval t is set to a value closer to the natural vibration period Tc than the current value. After completing the process of step S24, the control circuit 21 ends the series of processes shown in FIG. 15. If the determination result in step S22 is negative, the discharge rate needs to be increased. In step S26, the control circuit 21 adjusts the residual vibration suppression element ED so that the adjustment interval t is set to a value farther from Tc than the current value. However, if the adjustment target drive signal Com-Adj is the drive signal ComB, the control circuit 21 compares the maximum vibration suppression interval (described later in FIG. 18) with the current value instead of the natural vibration period Tc in steps S24 and S26. After completing the process of step S26, the control circuit 21 ends the series of processes shown in FIG. 15 and returns to the process of step S4 in FIG. 14.

[0109] When the drive signal Com-Adj to be adjusted is the drive signal ComAa, the adjustment interval t is the adjustment interval tA shown in FIG. 8. The adjustment interval tA is the time interval between the center time of the period of the discharge element c1 in the drive signal ComAa and the center time of the period of the first damping expansion element d2. Furthermore, in the first embodiment, the control circuit 21 sets the adjustment interval tA to be longer than 0.5Tc and shorter than 1.5Tc. Note that when the drive signal Com-Adj to be adjusted is the drive signal ComAb or the drive signal ComAc, the adjustment interval tA is also the time interval between the center time of the period of the discharge element c1 and the center time of the period of the first damping expansion element d2. Note that the adjustment interval tA is an example of a "first interval." The relationship between the discharge amount Iw when the adjustment interval tA is changed will be described with reference to FIG. 16.

[0110] FIG. 16 is a diagram for explaining the relationship between the adjustment interval tA and the discharge amount Iw. Graph g8 shown in FIG. 16 shows the discharge amount Iw corresponding to the adjustment interval tA. The horizontal axis of graph g8 shows the length of the adjustment interval tA. The vertical axis of graph g8 shows the magnitude of the discharge amount Iw. The discharge amount characteristic ChIw shown in graph g8 shows the characteristic of the discharge amount Iw corresponding to the adjustment interval tA.

[0111] As shown by the discharge amount characteristic ChIw, when the period of the adjustment interval tA coincides with the natural vibration period Tc, the discharge amount Iw is smallest, and as the period of the adjustment interval tA deviates from the natural vibration period Tc, the discharge amount Iw increases.

[0112] When the adjustment target drive signal Com-Adj is the drive signal ComBa, the adjustment interval t is the adjustment interval tB shown in Fig. 8. The adjustment interval tB will be described later in the description of Fig. 18.

[0113] An example of adjusting the residual vibration suppression element ED when the drive signal Com-Adj to be adjusted is the drive signal ComAa will be explained using Figure 17, and an example of adjusting the residual vibration suppression element ED when the drive signal Com-Adj to be adjusted is the drive signal ComBa will be explained using Figure 18.

[0114] 17 is a diagram illustrating an example of adjusting the residual vibration suppression element ED of the drive signal ComAa. When adjusting the residual vibration suppression element ED, the control circuit 21 adjusts at least one of the period of the first vibration suppression maintaining element pwh2 and the potential change rate of the first vibration suppression expansion element d2. The potential change rate is the value obtained by dividing the potential change width by the length of the period during which the potential changes. When adjusting the potential change rate of the first vibration suppression expansion element d2, the control circuit 21 adjusts the potential change rate of the first vibration suppression expansion element d2 by shortening or lengthening the period of the first vibration suppression expansion element d2.

[0115] 17, it is assumed that the adjustment interval tA is shorter than the natural vibration period Tc. In FIG. 17, when the process of step S24 is executed, i.e., when the ejection rate is reduced, an example of the drive signal ComAa obtained by adjusting the residual vibration suppression element EDAa so that the adjustment interval tA is set to a value closer to the natural vibration period Tc than the current value is shown as drive signal ComAa-1. Furthermore, among the elements of the drive signal ComAa-1, elements that differ from the drive signal ComAa are indicated by the symbol "-1." Similarly, when the process of step S26 is executed, i.e., when the ejection rate is increased, an example of the drive signal ComAa obtained by adjusting the residual vibration suppression element EDAa so that the adjustment interval tA is set to a value farther from the natural vibration period Tc than the current value is shown as drive signal ComAa-2. Furthermore, among the elements of the drive signal ComAa-2, elements that differ from the drive signal ComAa are indicated by the symbol "-2."

[0116] The drive signal ComAa-1 is an example in which the potential change rate of the first vibration damping expansion element d2 is adjusted. In the example of the drive signal ComAa-1, the control circuit 21 sets the period of the first vibration damping expansion element d2-1 included in the drive signal ComAa-1 to be longer than the period of the first vibration damping expansion element d2, thereby setting the absolute value of the potential change rate of the first vibration damping expansion element d2-1 to be smaller than the absolute value of the potential change rate of the first vibration damping expansion element d2. Furthermore, in the drive signal ComAa-1, the period of the end potential maintaining element aeAa-1 is set shorter than the period of the end potential maintaining element aeAa by the amount that the period of the first vibration damping expansion element d2-1 is set longer than the period of the first vibration damping expansion element d2. 17, as a result of setting the absolute value of the potential change rate of the first vibration damping expansion element d2-1 small, the adjustment interval tA-1 in the drive signal ComAa-1 becomes longer than the adjustment interval tA and closer to the natural vibration period Tc, thereby reducing the influence of residual vibration on the next ejection pulse PD. In step S24, the control circuit 21 sets the end time of the first vibration damping expansion element d2-1 in the waveform information CI to a time later than the end time of the first vibration damping expansion element d2. Note that if the adjustment interval tA is set longer than the natural vibration period Tc, the control circuit 21 sets the duration of the first vibration damping expansion element d2-1 included in the drive signal ComAa-1 to be shorter than the duration of the first vibration damping expansion element d2, and sets the duration of the end potential sustaining element aeAa-1 to be longer than the duration of the end potential sustaining element aeAa.

[0117] The drive signal ComAa-2 is an example in which the period of the first vibration suppression sustain element pwh2 is adjusted. In the example of the drive signal ComAa-2, the control circuit 21 sets the period of the first vibration suppression sustain element pwh2-2 included in the drive signal ComAa-2 to be shorter than the period of the first vibration suppression sustain element pwh2. Furthermore, in the drive signal ComAa-2, the period of the first vibration suppression sustain element pwh2-2 is set shorter than the period of the first vibration suppression sustain element pwh2, and the period of the end potential sustain element aeAa-2 is set longer than the period of the end potential sustain element aeAa. As a result of setting the period of the first vibration suppression sustain element pwh2-2 shorter than the period of the first vibration suppression sustain element pwh2, as can be seen from FIG. 17, the adjustment interval tA-2 in the drive signal ComAa-2 is shorter than the adjustment interval tA and is farther away from the natural vibration period Tc, thereby increasing the influence of residual vibration on the next ejection pulse PD. However, as described above, the control circuit 21 sets the period of the first vibration suppression sustain element pwh2-2 so that the adjustment interval tA is longer than 0.5Tc. In step S26, the control circuit 21 sets the end time of the first vibration suppression sustain element pwh2-2 in the waveform information CI to a time earlier than the end time of the first vibration suppression sustain element pwh2. Note that if the adjustment interval tA is set longer than the natural vibration period Tc, the control circuit 21 sets the period of the first vibration suppression sustain element pwh2-2 included in the drive signal ComAa-1 to be longer than the period of the first vibration suppression expansion element d2, and sets the period of the end potential sustain element aeAa-1 to be shorter than the period of the end potential sustain element aeAa.

[0118] Although not shown in the figure, when the adjustment interval tA is longer than the natural vibration period Tc and the adjustment interval tA is set farther away from the natural vibration period Tc than the adjustment interval tA, the control circuit 21 sets the period of the first vibration control maintenance element pwh2 so that the adjustment interval tA is shorter than 1.5Tc.

[0119] 18 is a diagram illustrating an example of adjusting the residual vibration suppression element ED of the drive signal ComBa. The control circuit 21 adjusts at least one of the period of the third vibration suppression maintaining element pwh3 and the potential change rate of the second vibration suppression contraction element c2. When adjusting the potential change rate of the second vibration suppression contraction element c2, the control circuit 21 adjusts the potential change rate of the second vibration suppression contraction element c2 by shortening or lengthening the period of the second vibration suppression contraction element c2.

[0120] In the ejection pulse PBa, the length of the adjustment interval tB at which residual vibration can be most suppressed varies depending on the setting of the ejection waveform element DRBa. Therefore, the maximum vibration suppression interval at which residual vibration can be most suppressed is determined in advance through an experiment or the like, and a value slightly shifted from the maximum vibration suppression interval is set as the adjustment interval tB. 18, it is assumed that the adjustment interval tB is shorter than the maximum vibration suppression interval. In FIG. 18, when the processing of step S24 is performed, an example of the drive signal ComBa obtained by adjusting the residual vibration suppression element EDBa so that the adjustment interval tB is set to a value closer to the maximum vibration suppression interval than the current value is displayed as drive signal ComBa-1. Furthermore, among the elements of the drive signal ComBa-1, elements that are different from the drive signal ComBa are marked with the symbol "-1." Similarly, when the processing of step S26 is performed, an example of the drive signal ComBa obtained by adjusting the residual vibration suppression element EDBa so that the adjustment interval tB is set to a value farther from the maximum vibration suppression interval than the current value is displayed as drive signal ComBa-2. Furthermore, among the elements of the drive signal ComBa-2, elements that are different from the drive signal ComBa are marked with the symbol "-2."

[0121] The drive signal ComBa-1 is an example in which the potential change rate of the second vibration damping contraction element c2 is adjusted. In the example of the drive signal ComBa-1, the control circuit 21 sets the period of the second vibration damping contraction element c2-1 included in the drive signal ComBa-1 to be longer than the period of the second vibration damping contraction element c2, thereby setting the absolute value of the potential change rate of the second vibration damping contraction element c2-1 to be smaller than the absolute value of the potential change rate of the second vibration damping contraction element c2. Furthermore, in the drive signal ComBa-1, the period of the second vibration damping contraction element c2-1 is set to be longer than the period of the second vibration damping contraction element c2, and the period of the end potential sustain element aeBa-1 is set to be shorter than the period of the end potential sustain element aeBa. As a result of reducing the absolute value of the potential change rate of the second vibration damping contraction element c2-1, as can be seen from FIG. 17, the adjustment interval tB-1 in the drive signal ComBa-1 is closer to the maximum vibration damping interval than the adjustment interval tB, thereby reducing the influence of residual vibration on the next ejection pulse PD. In step S24, the control circuit 21 sets the end time of the second vibration damping contraction element c2-1 in the waveform information CI to a time later than the end time of the second vibration damping contraction element c2. If the adjustment interval tB is set longer than the maximum vibration damping interval, the control circuit 21 sets the period of the second vibration damping contraction element c2-1 included in the drive signal ComBa-1 to be shorter than the period of the second vibration damping contraction element c2, and sets the period of the end potential sustaining element aeBa-1 to be longer than the period of the end potential sustaining element aeBa.

[0122] The drive signal ComBa-2 is an example in which the period of the third vibration suppression sustain element pwh3 is adjusted. In the example of the drive signal ComBa-2, the control circuit 21 sets the period of the third vibration suppression sustain element pwh3-2 included in the drive signal ComBa-2 to be shorter than the period of the third vibration suppression sustain element pwh3. Furthermore, in the drive signal ComBa-2, the period of the third vibration suppression sustain element pwh3-2 is set shorter than the period of the third vibration suppression sustain element pwh3, and the period of the end potential sustain element aeBa-2 is set longer than the period of the end potential sustain element aeBa. As a result of setting the period of the third vibration suppression sustain element pwh3-2 shorter than the period of the third vibration suppression sustain element pwh3, as can be seen from FIG. 18, the adjustment interval tB-2 in the drive signal ComBa-2 is farther away from the maximum vibration suppression interval than the adjustment interval tB, thereby increasing the influence of residual vibration on the next ejection pulse PD. In addition, if the adjustment interval tB is set longer than the maximum vibration suppression interval, the control circuit 21 sets the period of the third vibration suppression sustain element pwh3-2 included in the drive signal ComBa-2 to be longer than the period of the third vibration suppression sustain element pwh3, and sets the period of the end potential sustain element aeBa-1 to be shorter than the period of the end potential sustain element aeBa.

[0123] A9: Summary of the first embodiment As described above, the liquid ejection device 100 in the first embodiment includes a nozzle N that ejects liquid, a pressure chamber C that communicates with the nozzle N, an ejection unit D that includes a drive element E that is driven to impart pressure fluctuations to the liquid in the pressure chamber C in response to a supplied drive signal Com, and a drive signal generation circuit 24 that generates the drive signal Com. The drive signal Com includes one ejection pulse PD within one drive period Tu. One ejection pulse PD includes an ejection waveform element DR that imparts pressure fluctuations to the liquid in the pressure chamber C so that the liquid is ejected from the nozzle N, and a residual vibration suppression element ED that attenuates pressure fluctuations in the liquid in the pressure chamber C that correspond to the natural vibration period Tc of the ejection unit D and remain after the liquid is ejected from the nozzle N. The control circuit 21 of the liquid ejection device 100 adjusts the residual vibration suppression element ED of one ejection pulse PD to supply a drive signal Com to the drive element E over a period of two or more drive periods Tu to correct the weight of droplets ejected from the nozzle N when droplets are continuously ejected from the nozzle N. According to the first embodiment, by adjusting the residual vibration suppression element ED, even in the case of high-frequency driving, it is possible to control the magnitude of the residual vibration that affects the next ejection pulse PD after the ejection pulse PD that includes this residual vibration suppression element ED, and therefore it is possible to correct the ejection amount of the next ejection pulse PD.

[0124] When the drive signal Com is the drive signal ComA, the ejection waveform element DRAa of one ejection pulse PAa has an ejection element c1 that contracts the pressure chamber C to eject a droplet from the nozzle N. The residual vibration suppression element ED of one ejection pulse PD has a first vibration suppression sustain element pwh2 that maintains a constant potential from the end of the ejection element c1, and a first vibration suppression expansion element d2 that starts a potential change from the end of the first vibration suppression sustain element pwh2 to expand the pressure chamber C. The control circuit 21 supplies the drive signal ComA to the drive element E over a period of two or more drive cycles Tu to correct the weight of droplets ejected from the nozzle N when droplets are continuously ejected from the nozzle N by adjusting at least one of the period of the first vibration suppression sustain element pwh2 and the potential change rate of the first vibration suppression expansion element d2 in the residual vibration suppression element ED of one ejection pulse PD. According to the first embodiment, the weight of a large amount of droplets can be corrected by adjusting at least one of the period of the first damping sustaining element pwh2 and the potential change rate of the first damping expansion element d2.

[0125] Furthermore, when the natural vibration period of the discharge section D is Tc, the adjustment interval tA between the center time of the period of the discharge element c1 and the center time of the first damping expansion element d2 is longer than 0.5Tc and shorter than 1.5Tc. When the adjustment interval tA is 0.5Tc or less, large residual vibrations remain, making the ejection by the next ejection pulse PD unstable. On the other hand, when the adjustment interval tB is 1.5Tc or more, the period of the ejection pulse PD becomes long, and there is a possibility that it will become longer than the drive period Tu. If the drive period Tu is made longer, high-frequency driving becomes difficult. As described above, in an embodiment in which the adjustment interval tA is longer than 0.5Tc and shorter than 1.5Tc, high-frequency driving is facilitated while suppressing the ejection by the next ejection pulse PD from becoming unstable.

[0126] When the drive signal Com is the drive signal ComB, the ejection waveform element DRBa of one ejection pulse PBa has a contraction element c3 that contracts the pressure chamber C to protrude a liquid column DC from the nozzle N, and a dividing element d5 that expands the pressure chamber C after the contraction element c3 to divide the liquid column DC into multiple pieces. The residual vibration suppression element EDBa of one ejection pulse PBa has a third vibration suppression sustain element pwh3 that maintains a constant potential from the end of the dividing element d5, and a second vibration suppression contraction element c2 that contracts the pressure chamber C from the end of the third vibration suppression sustain element. The control circuit 21 adjusts at least one of the period of the third vibration suppression sustain element pwh3 and the potential change rate of the second vibration suppression contraction element c2 in the residual vibration suppression element ED of one ejection pulse PD, thereby correcting the weight of droplets ejected from the nozzle N when droplets are continuously ejected from the nozzle N by supplying the drive signal ComB to the drive element E over a period of two or more drive cycles Tu. According to the first embodiment, the weight of a small amount of droplet can be corrected by adjusting at least one of the period of the third damping sustaining element pwh3 and the second damping contraction element c2.

[0127] The drive signal Com having the ejection pulse PD has, in one drive period Tu, one ejection pulse PD, a start potential maintaining element as that maintains the reference potential V0 from the start of one drive period Tu to the start of the ejection waveform element DR of one ejection pulse PD, and an end potential maintaining element ae that maintains the reference potential V0 from the end of the residual vibration suppression element ED of one ejection pulse PD to the end of one drive period Tu. When the natural vibration period of the ejection section D is Tc, the period of one drive period Tu satisfies equation (1). When the period of the drive cycle Tu satisfies the formula (1), the discharge amount Iw can be adjusted more easily than in a case where the period of the drive cycle Tu does not satisfy the formula (1).

[0128] Furthermore, when the drive signal Com is the drive signal ComA, the ejection waveform element DR of one ejection pulse PAa has an ejection element c1 that contracts the pressure chamber C to eject a droplet from the nozzle N. The residual vibration suppression element ED of one ejection pulse PAa has a first vibration suppression sustain element pwh2 that maintains a constant potential from the end of the ejection element c1, and a first vibration suppression expansion element d2 that starts a potential change from the end of the first vibration suppression sustain element pwh2 to expand the pressure chamber C. When the natural vibration period of the ejection section D is Tc, by adjusting at least one of the period of the first vibration-damping maintenance element pwh2 and the potential change rate of the first vibration-damping expansion element d2 within a range in which the adjustment interval tA between the center time of the period of the ejection element c1 and the center time of the period of the first vibration-damping expansion element d2 is longer than 0.5Tc and shorter than 1.5Tc, the weight of the droplets ejected from the nozzle N when a drive signal ComA is supplied to the drive element E over a period of two or more drive periods Tu and droplets are ejected continuously from the nozzle N is corrected. According to the first embodiment, it is possible to correct the weight of a large amount of droplets while suppressing the ejection by the next ejection pulse PD from becoming unstable and maintaining a state in which high frequency driving is easy.

[0129] Furthermore, when the drive signal Com is the drive signal ComA, and the drive signal ComA is supplied to the drive element E over a period of two or more drive cycles Tu to reduce the weight of droplets continuously ejected from the nozzle N, the control circuit 21 adjusts the adjustment interval tA to a value closer to the natural vibration period Tc than the current value. On the other hand, when the drive signal ComA is supplied to the drive element E over a period of two or more drive cycles Tu to increase the weight of droplets continuously ejected from the nozzle N, the control circuit 21 adjusts the adjustment interval tA to a value farther from the natural vibration period Tc than the current value. According to the first embodiment, when the drive signal ComA is supplied to reduce the weight of droplets continuously ejected from the nozzle N, the weight of the large amount of droplets can be corrected more efficiently than in the case where the weight of the large amount of droplets is corrected while fine-tuning the adjustment interval tA.

[0130] B1: Second embodiment The ejection pulse PD that ejects a large amount of droplets is not limited to the ejection pulse PAa shown in the first embodiment. A second embodiment will be described below.

[0131] FIG. 19 is a diagram for explaining the drive signal Com in the second embodiment. In the second embodiment, the drive signal generation circuit 24 generates the drive signal ComA2a instead of the drive signal ComAa, the drive signal ComA2b instead of the drive signal ComAb, and the drive signal ComA2c instead of the drive signal ComAc. Hereinafter, the drive signals ComA2a, ComA2b, and ComA2c may be referred to as the drive signal ComA2 without distinction. Note that the drive signals ComB and ComC are omitted from FIG. 19.

[0132] 19, the drive signal ComA2a differs from the drive signal ComA in that it has an ejection pulse PA2a for forming large dots instead of the ejection pulse PAa, and has an end potential sustaining element aeA2a instead of the end potential sustaining element aeAa. The ejection pulse PA2a differs from the ejection pulse PAa in that it has a residual vibration suppression element EDA2a instead of the residual vibration suppression element EDAa. The residual vibration suppression element EDA2a differs from the residual vibration suppression element EDAa in that it has a first vibration suppression expansion element d2A2 instead of the first vibration suppression expansion element d2, and further has a second vibration suppression sustaining element pwh7 and a first vibration suppression contraction element c4.

[0133] The first damping expansion element d2A2 differs from the first damping expansion element d2 in that its potential changes from the highest potential VHAa to a reference potential V3Aa. The reference potential V3Aa is a potential between the lowest potential VLAa and the reference potential V0Aa. The end of the first damping expansion element d2A2 is connected to the start of the second damping sustain element pwh7. The second damping sustain element pwh7 maintains the end potential of the first damping expansion element d2. The end of the second damping sustain element pwh7 is connected to the start of the first damping contraction element c4. The potential of the first damping contraction element c4 changes from the end of the second damping sustain element pwh7 to the reference potential V0Aa.

[0134] B2: Discharge amount correction process in the second embodiment In the second embodiment, as in the first embodiment, the control circuit 21 executes the discharge amount correction process shown in FIG. 14. In the second embodiment, the adjustment interval t in steps S24 and S26 is the adjustment interval tA2 shown in FIG. 19. The adjustment interval tA2 is the time interval between the center time of the period of the discharge element c1 in the drive signal ComAa and the center time of the period of the first damping expansion element d2A2. Furthermore, in the second embodiment, as in the first embodiment, the control circuit 21 sets the adjustment interval tA2 to be longer than 0.5Tc and shorter than 1.5Tc. Note that, even when the adjustment target drive signal Com-Adj is the drive signal ComA2b or the drive signal ComA2c, the adjustment interval tA2 is the time interval between the center time of the period of the discharge element c1 and the center time of the period of the first damping expansion element d2. Note that, in the second embodiment, the adjustment interval tA2 is an example of the "first interval."

[0135] In the second embodiment, similarly to the first embodiment, the control circuit 21 adjusts at least one of the period of the first vibration damping maintenance element pwh2 and the potential change rate of the first vibration damping expansion element d2A2 in steps S24 and S26.

[0136] As described above, according to the second embodiment, similar to the first embodiment, it is possible to correct the weight of a large amount of droplets even with high frequency driving.

[0137] C: Modified Example The above-described embodiments can be modified in various ways. Specific modifications that can be applied to the above-described embodiments are exemplified below. Two or more embodiments arbitrarily selected from the following examples can be combined as appropriate within the scope of not mutually contradictory.

[0138] C1: First modified example In the first embodiment, when adjusting the residual vibration suppression element ED of the drive signal ComA, the control circuit 21 adjusts at least one of the period of the first vibration suppression sustaining element pwh2 and the potential change rate of the first vibration suppression expansion element d2. However, this is not limiting. For example, the control circuit 21 may adjust at least one of the period of the first vibration suppression sustaining element pwh2, the potential change rate of the first vibration suppression expansion element d2, and the potential change width of the first vibration suppression expansion element d2. When adjusting the potential change width of the first vibration suppression expansion element d2, the control circuit 21 adjusts one or both of the starting potential and the ending potential of the first vibration suppression expansion element d2.

[0139] When adjusting the starting potential of the first vibration damping expansion element d2, the control circuit 21 matches the highest potential VHAa maintained by the first vibration damping sustain element pwh2 and the end potential of the ejection element c1 to the adjusted starting potential of the first vibration damping expansion element d2. Furthermore, as can be seen from FIG. 8, adjusting the starting potential of the first vibration damping expansion element d2 inevitably changes the potential difference ΔVh. In this way, in the first modified example, the potential difference ΔVh may be changed as a result of adjusting the residual vibration damping element ED.

[0140] Furthermore, when adjusting the terminal potential of the first vibration damping expansion element d2, the control circuit 21 matches the reference potential V0Aa maintained by the terminal potential maintaining element aeAa to the terminal potential of the adjusted first vibration damping expansion element d2. As described above, in the first modified example, as a result of adjusting the residual vibration suppression element ED of a certain drive signal Com, the reference potential V0 may differ from the reference potential V0 of another drive signal Com. Alternatively, when adjusting the terminal potential of the first vibration damping expansion element d2 to a potential lower than the reference potential V0Aa, the control circuit 21 may add an element whose potential changes from the terminal potential of the first vibration damping expansion element d2 to the reference potential V0Aa after the first vibration damping expansion element d2, thereby creating a waveform like the ejection pulse PA2a shown in FIG. 19.

[0141] Similarly, when adjusting the residual vibration suppression element ED of the drive signal ComB, the control circuit 21 adjusts at least one of the period of the third vibration suppression sustain element pwh3 and the potential change rate of the second vibration suppression contraction element c2. However, this is not limiting. For example, the control circuit 21 may adjust at least one of the period of the third vibration suppression sustain element pwh3, the potential change rate of the second vibration suppression contraction element c2, and the potential change width of the second vibration suppression contraction element c2. When adjusting the potential change width of the second vibration suppression contraction element c2, the control circuit 21 adjusts one or both of the starting potential and the ending potential of the second vibration suppression contraction element c2.

[0142] When adjusting the starting potential of the second vibration damping contraction element c2, the control circuit 21 matches the potential V2Ba maintained by the third vibration damping sustain element pwh3 and the terminal potential of the decoupling element d5 to the starting potential of the adjusted second vibration damping contraction element c2. When adjusting the terminal potential of the second vibration damping contraction element c2, the control circuit 21 matches the highest potential VHBa maintained by the fourth vibration damping sustain element pwh4 and the starting potential of the second vibration damping expansion element d3 to the terminal potential of the adjusted second vibration damping contraction element c2.

[0143] C2: Second modified example In the second embodiment, when adjusting the residual vibration suppression element ED of the drive signal ComA2, the control circuit 21 adjusts at least one of the period of the first vibration suppression maintaining element pwh2 and the potential change rate of the first vibration suppression expansion element d2A2. However, this is not limiting. For example, the control circuit 21 may adjust at least one of the period of the first vibration suppression maintaining element pwh2, the potential change rate of the first vibration suppression expansion element d2A2, and the potential change width of the first vibration suppression expansion element d2A2.

[0144] C3: Third modified example Furthermore, in the second embodiment and the modified example based on the second embodiment, when adjusting the residual vibration suppression element ED of the drive signal ComA2, the control circuit 21 may adjust at least one of the period of the first vibration suppression maintenance element pwh2, the potential change rate of the first vibration suppression expansion element d2A2, the potential change width of the first vibration suppression expansion element d2A2, the period of the second vibration suppression maintenance element pwh7, the potential change rate of the first vibration suppression contraction element c4, and the potential change width of the first vibration suppression contraction element c4.

[0145] Also, in the third modified example, similar to the above-described embodiments, the adjustment interval tA2 in the third modified example is longer than 0.5Tc and shorter than 1.5Tc.

[0146] As described above, according to the third modification, it is possible to correct the weight of a large amount of droplets even with high frequency drive, as in the second embodiment. Furthermore, in the third modification, the number of adjustable elements in the residual vibration suppression element ED of the drive signal ComA is greater than in the second embodiment, which improves the degree of freedom in setting the drive signal ComA.

[0147] C4: Fourth variant In the first modified example, when adjusting the residual vibration suppression element ED of the drive signal ComB, the control circuit 21 adjusts at least one of the period of the third vibration suppression sustaining element pwh3, the potential change rate of the second vibration suppression contraction element c2, and the potential change width of the second vibration suppression contraction element c2. However, this is not limiting. For example, the control circuit 21 may adjust at least one of the period of the third vibration suppression sustaining element pwh3, the potential change rate of the second vibration suppression contraction element c2, the potential change width of the second vibration suppression contraction element c2, the period of the fourth vibration suppression sustaining element pwh4, the potential change rate of the second vibration suppression expansion element d3, and the potential change width of the second vibration suppression expansion element d3. In this case, too, the relationship between the period of the third damping sustain element pwh3, the potential change rate of the second damping contraction element c2, the potential change width of the second damping contraction element c2, the period of the fourth damping sustain element pwh4, the potential change rate of the second damping expansion element d3, and the potential change width of the second damping expansion element d3 and the change in the residual vibration is confirmed in advance through experiments, etc., so that each element can be adjusted in response to a correction to increase or decrease the discharge rate. When adjusting the potential change rate of the second damping expansion element d3, the control circuit 21 adjusts at least one of the starting potential and ending potential of the second damping expansion element d3 and the period of the second damping expansion element d3. When adjusting the potential change width of the second damping expansion element d3, at least one of the starting potential and ending potential of the second damping expansion element d3 is adjusted.

[0148] As described above, according to the fourth modification, it is possible to correct the weight of a small amount of droplets even with high frequency drive, as in the first modification. Furthermore, in the fourth modification, the number of adjustable elements within the residual vibration suppression element ED of the drive signal ComB is greater than in the first modification, which improves the degree of freedom in setting the drive signal ComB.

[0149] C5: Fifth variant In the above-described embodiments, the drive signal Com has one ejection pulse PD in one drive period Tu, but this is not limited to this. For example, the drive signal Com may have two or more ejection pulses PD in one drive period Tu. A fifth modification will be described below.

[0150] FIG. 20 is a diagram illustrating the drive signal Com in the fifth modified example. In the fifth modified example, the drive signal generation circuit 24 generates drive signal ComA3a instead of drive signal ComAa, drive signal ComA3b instead of drive signal ComAb, and drive signal ComA3c instead of drive signal ComAc. Hereinafter, the drive signals ComA3a, ComA3b, and ComA3c may be referred to as drive signal ComA3 without distinction. Note that the drive signals ComB and ComC are omitted from FIG. 20.

[0151] 20, the drive signal ComA3a has, in one drive period Tu, a start potential maintaining element asA2a, an ejection pulse PAa_1, a connecting element aiA2a, an ejection pulse PAa_2, and an end potential maintaining element aeA2a, in this order. Thus, one drive period Tu has two ejection pulses PD, namely, an ejection pulse PAa_1 and an ejection pulse PAa_2. The two ejection pulses PD are an example of "at least one ejection pulse."

[0152] The ejection pulse PAa_1 and the ejection pulse PAa_2 have the same shape as the ejection pulse PAa. For the sake of simplicity, the ejection pulse PAa_1 and the ejection pulse PAa_2 are ejection pulses PD with the same shape in Fig. 20, but they may be ejection pulses PD with different shapes.

[0153] The start potential maintaining element asA2a maintains the reference potential V0Aa from the start of one drive period Tu to the start of the ejection waveform element DRAa of the ejection pulse PAa_1. The connection element aiA2a maintains and connects the reference potential V0Aa from the end point of the residual vibration suppression element EDAa of the ejection pulse PAa_1 to the start of the ejection waveform element DRAa of the ejection pulse PAa_2. The end potential maintaining element aeA2a maintains the reference potential V0Aa from the end of the ejection pulse PAa_2 to the end of one drive period Tu.

[0154] The start potential maintaining element asA2a is an example of "a start potential maintaining element that maintains the potential from the start of one drive cycle to the start of the ejection waveform element of the leading ejection pulse among two or more ejection pulses." The connection element aiA2a is an example of "a connection element that maintains the potential from the end point of the residual vibration suppression element of the leading ejection pulse of two or more consecutive ejection pulses to the start of the ejection waveform element of the trailing ejection pulse among two or more ejection pulses." The end potential maintaining element aeA2a is an example of "an end potential maintaining element that maintains the potential from the end point of the residual vibration suppression element of the last ejection pulse among two or more ejection pulses to the end of one drive cycle."

[0155] The period tC shown in FIG. 20 satisfies the following formula (2). (0.5×n-0.2)×Tc <tC<(0.5×n+0.2)×Tc …(2)

[0156] The period tC is the period from the start of the ejection waveform element DRAa of the ejection pulse PAa_1 to the start of the ejection waveform element DRAa of the ejection pulse PAa_2. The period tC is an example of "the period from the start of the ejection waveform element of the leading ejection pulse to the start of the ejection waveform element of the trailing ejection pulse." When the period tC satisfies formula (2), the ejection amount Iw can be easily adjusted compared to a case where the period tC does not satisfy formula (2).

[0157] In the fifth modified example, as in the first embodiment, if the determination result of step S22 is positive, the control circuit 21 adjusts the residual vibration suppression elements ED of the ejection pulses PAa_1 and PAa_2 in step S24 so that the adjustment intervals tA3_1 and tA3_2 are set to values ​​closer to the natural vibration period Tc than their current values. The adjustment interval tA3_1 is the time interval between the center time of the period of the ejection element c1 in the ejection pulse PAa_1 and the center time of the period of the first vibration suppression expansion element d2. The adjustment interval tA3_2 is the time interval between the center time of the period of the ejection element c1 in the ejection pulse PAa_2 and the center time of the period of the first vibration suppression expansion element d2. If the determination result of step S22 is negative, the control circuit 21 adjusts the residual vibration suppression elements ED of the ejection pulses PAa_1 and PAa_2 in step S26 so that the adjustment intervals tA3_1 and tA3_2 are set to values ​​farther from the natural vibration period Tc than their current values.

[0158] Furthermore, the control circuit 21 sets the adjustment intervals tA3_1 and tA3_2 to be longer than 0.5Tc and shorter than 1.5Tc. By setting the adjustment intervals tA3_1 and tA3_2 to be longer than 0.5Tc and shorter than 1.5Tc, high-frequency driving becomes easier while preventing the ejection by the next ejection pulse PD from becoming unstable.

[0159] C6: Sixth Variation In the fifth modified example, the drive signal ComA has one ejection pulse PD in one drive period Tu, but the drive signal ComB may have two ejection pulses PD in one drive period Tu. The sixth modified example will be described below.

[0160] FIG. 21 is a diagram illustrating the drive signal Com in the sixth modified example. In the sixth modified example, the drive signal generation circuit 24 generates drive signal ComB4a instead of drive signal ComBa, drive signal ComB4b instead of drive signal ComBb, and drive signal ComB4c instead of drive signal ComBc. Hereinafter, the drive signals ComB4a, ComB4b, and ComB4c may be referred to as drive signal ComA3 without distinction. Note that the drive signals ComA and ComC are omitted from FIG. 21.

[0161] 21, the driving signal ComB4a has, in one driving period Tu, a start potential maintaining element asB4a, an ejection pulse PBa_1, a connecting element aiB4a, an ejection pulse PBa_2, and an end potential maintaining element aeB4a, in this order. Thus, one driving period Tu has two ejection pulses PD, namely, the ejection pulse PBa_1 and the ejection pulse PBa_2. The two ejection pulses PD are an example of "at least one ejection pulse."

[0162] The ejection pulse PBa_1 and the ejection pulse PBa_2 have the same shape as the ejection pulse PBa. For the sake of simplicity, the ejection pulse PBa_1 and the ejection pulse PBa_2 are ejection pulses PD of the same shape in Fig. 21, but they may be ejection pulses PD of different shapes.

[0163] The start potential maintaining element asB4a is an element that maintains the reference potential V0Ba from the start of one drive period Tu to the start of the ejection waveform element DRBa of the ejection pulse PBa_1. The connection element aiB4a maintains and connects the reference potential V0Ba from the end point of the residual vibration suppression element ED of the ejection pulse PBa_1 to the start of the ejection waveform element DRBa of the ejection pulse PBa_2. The end potential maintaining element aeB4a is an element that maintains the reference potential V0Ba from the end of the ejection pulse PBa_2 to the end of one drive period Tu.

[0164] The start potential maintaining element asB4a is an example of "a start potential maintaining element that maintains a potential from the start of one drive cycle to the start of the ejection waveform element of the leading ejection pulse among two or more ejection pulses." The connection element aiB4a is an example of "a connection element that maintains a potential from the end point of the residual vibration suppression element of the leading ejection pulse of two or more consecutive ejection pulses to the start of the ejection waveform element of the trailing ejection pulse among two or more ejection pulses." The end potential maintaining element aeB4a is an example of "a residual vibration suppression element of the last ejection pulse among two or more ejection pulses."

[0165] The period tD shown in FIG. 21 satisfies the following formula (3). (0.5×n-0.2)×Tc <tD<(0.5×n+0.2)×Tc …(3)

[0166] The period tD is the period from the start of the ejection waveform element DRBa of the ejection pulse PBa_1 to the start of the ejection waveform element DRBa of the ejection pulse PBa_2. The period tD is an example of "the period from the start of the ejection waveform element of the front ejection pulse to the start of the ejection waveform element of the rear ejection pulse." When the period tD satisfies formula (3), the ejection amount Iw can be easily adjusted compared to a case where the period tC does not satisfy formula (3).

[0167] In the sixth modified example, as in the first embodiment, if the determination result of step S22 is positive, the control circuit 21 adjusts the residual vibration suppression elements ED of the ejection pulses PBa_1 and PBa_2 in step S24 so that the adjustment intervals tB4_1 and tB4_2 are set to values ​​closer to the maximum vibration suppression interval than their current values. If the determination result of step S22 is negative, the control circuit 21 adjusts the residual vibration suppression elements ED of the ejection pulses PBa_1 and PBa_2 in step S26 so that the adjustment intervals tB4_1 and tB4_2 are set to values ​​farther from the maximum vibration suppression interval than their current values.

[0168] C7: 7th variant In the above-described embodiments, the adjustment interval tA is set to be longer than 0.5Tc and shorter than 1.5Tc, but this is not limiting. For example, if the viscosity of the liquid is high, residual vibrations are rapidly attenuated, so the adjustment interval tA may be 0.5Tc or shorter. Furthermore, if high-frequency driving is not required, the adjustment interval tA may be 1.5Tc or longer.

[0169] C8: Eighth Variation In each of the above-described embodiments, the drive period Tu satisfies formula (1), but it does not have to satisfy formula (1). If the drive period Tu is not (0.5×n−0.25) or (0.5×n+0.25), the amount of fluctuation in the discharge amount Iw will be smaller than in the embodiment where formula (1) is satisfied, but correction of the discharge amount Iw itself is possible.

[0170] C9: 9th variant In each of the above-mentioned embodiments, the liquid ejection device 100 is a line type in which multiple nozzles N are distributed across the entire width of the medium PP, but the present disclosure can also be applied to a serial type liquid ejection device in which a carriage 501 carrying a liquid ejection head 50 moves back and forth.

[0171] C10: Other variations The liquid ejection device 100 exemplified in each of the above-described embodiments may be employed in various devices such as facsimile machines and copiers, in addition to devices dedicated to printing, and the applications of the present disclosure are not particularly limited. However, the applications of the liquid ejection device are not limited to printing. For example, a liquid ejection device that ejects a solution of a color material is used as a manufacturing device for forming color filters for display devices such as liquid crystal display panels. Furthermore, a liquid ejection device that ejects a solution of a conductive material is used as a manufacturing device for forming wiring and electrodes on a wiring board. Furthermore, a liquid ejection device that ejects a solution of an organic substance related to a living body is used as a manufacturing device for manufacturing biochips, for example. [Explanation of symbols]

[0172] 10...liquid container, 11...nozzle plate, 12...vibration absorber, 13...flow path substrate, 14...pressure chamber substrate, 15...diaphragm, 16...wiring board, 16B...bump, 17...casing, 18...switching circuit, 18a...connection state designation circuit, 20...control unit, 21...control circuit, 22...memory circuit, 23...power supply circuit, 24...drive signal generation circuit, 30...transport mechanism, 40...imaging device, 50...liquid ejection head, 51a1, 51a2, 51b1, 51b2, 51c1, 51c2...head chip, 55...fixing plate, 55a...opening, 100...liquid ejection device, 131...supply flow path, 132...communicating flow path, 1 33...supply liquid chamber, 171...inlet port, 200...external device, 211...acquisition unit, 213...adjustment unit, 501...carriage, C...pressure chamber, CI...waveform information, CLK...clock signal, Ch1, Ch2, Ch3, Ch40, Ch50, ChD40, ChD50...discharge amount characteristics, ChF...drive frequency characteristics, ChIw...discharge amount characteristics, ChTc, ChTc1, ChTc2, ChTm...drive frequency characteristics, Com...drive signal, ComA2a, ComA2b, ComA2c, ComA3a, ComA3b, ComA3c, ComAa-1, ComAa-2, ComAb, ComA c, ComB4a, ComB4b, ComB4c, ComBa, ComBa-1, ComBa-2, ComBb, ComBc, ComC1, ComC2... drive signal, D... ejection unit, DC... liquid column, DL... droplet, DRAa, DRBa... ejection waveform element, DS... droplet, E... drive element, EDA2a, EDAa, EDBa... residual vibration suppression element, GI... image information, Img... image data, Iw... ejection amount, L, L1, L2... nozzle array, LAT... latch signal, LHa, LHb, LHc, LHd... wiring, MN... meniscus, N... nozzle, PA2a, PAa, PAa_1, P Aa_2, PBa, PBa_1, PBa_2...ejection pulse, PP...medium, PlsL...pulse, R...liquid storage chamber, Ra, Rb...space, SI...print data signal, SLa, SLb, SLc...connection status designation signal, SWa, SWb, SWc...switch, Sd...individual designation signal, Sk1...control signal, Sk2...imaging instruction, Tc...natural vibration period, Tu...driving period, V0, V0Aa, V0Ba, V0C1...reference potential, V1Ba, V2Ba...potential, V3Aa...reference potential, VBS...offset potential, VHAa, VHBa...highest potential, VHV...power supply potential, VLAa, VLBa,VLC1...minimum potential, Vin...supply signal, Zd, Zu...electrode, a2...final potential maintaining element, aeA2a, aeAa, aeAa-1, aeAa-2, aeB4a, aeBa, aeBa-1, aeBa-2, aeC1...final potential maintaining element, aiA2a, aiB4a...connection element, asA2a, asAa, asB4a, asBa, asC1...starting potential maintaining element, c1...ejection element, c2, c2-1...second damping contraction element, c3...contraction element, c4...first damping contraction element, d1...filling element, d2, d2-1, d2A2...first damping expansion element, d3...second damping expansion element, d4...filling element, d5... Dividing element, dCom...waveform designation signal, e1...expansion element, e2...sustaining element, e3...contraction element, g1, g2, g3, g4, g5, g6, g7, g8...graph, pwh1...potential maintaining element, pwh2, pwh2-2...first vibration suppression maintaining element, pwh3, pwh3-2...third vibration suppression maintaining element, pwh4...fourth vibration suppression maintaining element, pwh5, pwh6...potential maintaining element, pwh7...second vibration suppression maintaining element, t, tA, tA-1, tA-2, tA2, tA3_1, tA3_2, tB, tB-1, tB-2, tB4_1, tB4_2...adjustment interval, tC, tD...period, ΔVhAa, ΔVhBa...potential difference.

Claims

1. a discharge unit having a nozzle for discharging droplets, a pressure chamber communicating with the nozzle, and a drive element that is driven to apply pressure fluctuations to the liquid in the pressure chamber in response to a supplied drive signal; a drive signal generating circuit that generates the drive signal; A method for driving a liquid ejection device having the drive signal has at least one ejection pulse during one drive period, The at least one ejection pulse comprises: an ejection waveform element that applies pressure fluctuation to the liquid in the pressure chamber so as to eject droplets from the nozzle; a residual vibration suppression element that attenuates pressure fluctuations of the liquid in the pressure chamber that remain after droplets are ejected from the nozzle and that correspond to the natural vibration period of the ejection unit, by adjusting the residual vibration suppression element of the at least one ejection pulse, the drive signal is supplied to the drive element over a period of two or more drive cycles, thereby correcting the weight of droplets ejected from the nozzle when droplets are continuously ejected from the nozzle; A method for driving a liquid ejection device.

2. an ejection waveform element of the at least one ejection pulse has an ejection element that contracts the pressure chamber to eject a droplet from the nozzle; the residual vibration suppression element of the at least one ejection pulse includes a first vibration suppression maintaining element that maintains a constant potential from an end of the ejection element, and a first vibration suppression expansion element that starts a potential change from an end of the first vibration suppression maintaining element and expands the pressure chamber, In the residual vibration suppression element of the at least one ejection pulse, at least one of the period of the first vibration suppression maintaining element, the potential change rate of the first vibration suppression expansion element, and the potential change width of the first vibration suppression expansion element is adjusted, thereby correcting the weight of droplets ejected from the nozzle when the drive signal is supplied to the drive element over a period of two or more drive cycles and droplets are continuously ejected from the nozzle. The driving method according to claim 1 .

3. When the natural vibration period of the ejection portion is Tc, a first interval between a center time of the period of the discharge element and a center time of the first damping expansion element is longer than 0.5Tc and shorter than 1.5Tc; The driving method according to claim 2 .

4. an ejection waveform element of the at least one ejection pulse has an ejection element that contracts the pressure chamber to eject a droplet from the nozzle; the residual vibration suppression element of the at least one ejection pulse includes a first vibration suppression maintaining element that maintains a constant potential from the end of the ejection element, a first vibration suppression expansion element that starts a potential change from the end of the first vibration suppression maintaining element and expands the pressure chamber, a second vibration suppression maintaining element that maintains the terminal potential of the first vibration suppression expansion element, and a first vibration suppression contraction element that changes in potential to a first potential from the end of the second vibration suppression maintaining element, In the residual vibration suppression element of the at least one ejection pulse, at least one of the period of the first damping maintenance element, the potential change rate of the first damping expansion element, the potential change width of the first damping expansion element, the period of the second damping maintenance element, the potential change rate of the first damping contraction element, and the potential change width of the first damping contraction element is adjusted to supply the drive signal to the drive element over a period of two or more drive cycles, thereby correcting the weight of droplets ejected from the nozzle when droplets are continuously ejected from the nozzle. The driving method according to claim 1 .

5. When the natural vibration period of the ejection portion is Tc, a first interval between a center time of the period of the discharge element and a center time of the first damping expansion element is longer than 0.5Tc and shorter than 1.5Tc; The driving method according to claim 4 .

6. an ejection waveform element of the at least one ejection pulse includes a contraction element that contracts the pressure chamber to cause a liquid column to protrude from the nozzle, and a dividing element that expands the pressure chamber after the contraction element to divide the liquid column into a plurality of parts; the residual vibration suppression element of the at least one ejection pulse includes a third vibration suppression maintaining element that maintains a constant potential from an end of the dividing element, and a second vibration suppression contraction element that contracts the pressure chamber from an end of the third vibration suppression maintaining element, In the residual vibration suppression element of the at least one ejection pulse, at least one of the period of the third vibration suppression maintaining element, the potential change rate of the second vibration suppression contraction element, and the potential change width of the second vibration suppression contraction element is adjusted to supply the drive signal to the drive element over a period of two or more drive cycles, thereby correcting the weight of droplets ejected from the nozzle when droplets are continuously ejected from the nozzle. The driving method according to claim 1 .

7. an ejection waveform element of the at least one ejection pulse includes a contraction element that contracts the pressure chamber to cause a liquid column to protrude from the nozzle, and a dividing element that expands the pressure chamber after the contraction element to divide the liquid column into a plurality of parts; the residual vibration suppression element of the at least one ejection pulse includes a third vibration suppression maintaining element that maintains a constant potential from an end of the dividing element, a second vibration suppression contraction element that contracts the pressure chamber from an end of the third vibration suppression maintaining element, a fourth vibration suppression maintaining element that maintains a constant potential from an end of the second vibration suppression contraction element, and a second vibration suppression expansion element that expands the pressure chamber from an end of the fourth vibration suppression maintaining element, In the residual vibration suppression element of the at least one ejection pulse, at least one of the period of the third damping sustain element, the potential change rate of the second damping contraction element, the potential change width of the second damping contraction element, the period of the fourth damping sustain element, the potential change rate of the second damping expansion element, and the potential change width of the second damping expansion element is adjusted to supply the drive signal to the drive element over a period of two or more drive cycles, thereby correcting the weight of droplets ejected from the nozzle when droplets are continuously ejected from the nozzle. The driving method according to claim 1 .

8. The drive signal includes the following signals in one drive cycle: one ejection pulse; a start potential maintaining element that maintains a first potential from the start point of the one drive cycle to the start of the ejection waveform element of the one ejection pulse; a final potential maintaining element that maintains the first potential from the end point of the residual vibration suppression element of the one ejection pulse to the end point of the one drive period; and When the natural vibration period of the ejection portion is Tc, The period Tu of one drive cycle satisfies the formula (1), (0.5×n-0.2)×Tc<Tu<(0.5×n+0.2)×Tc…(1) n is an integer of 1 or greater; The driving method according to claim 1 .

9. an ejection waveform element of the at least one ejection pulse has an ejection element that contracts the pressure chamber to eject a droplet from the nozzle; the residual vibration suppression element of the at least one ejection pulse includes a first vibration suppression maintaining element that maintains a constant potential from an end of the ejection element, and a first vibration suppression expansion element that starts a potential change from an end of the first vibration suppression maintaining element and expands the pressure chamber, When the natural vibration period of the ejection portion is Tc, and adjusting at least one of the period of the first vibration damping expansion element, the potential change rate of the first vibration damping expansion element, and the potential change width of the first vibration damping expansion element, within a range in which a first interval between the center time of the period of the ejection element and the center time of the period of the first vibration damping expansion element is longer than 0.5Tc and shorter than 1.5Tc, thereby correcting the weight of droplets ejected from the nozzle when the drive signal is supplied to the drive element over a period of two or more drive cycles and droplets are ejected continuously from the nozzle. The driving method according to claim 1 .

10. When the weight of droplets continuously ejected from the nozzle is reduced by supplying the drive signal to the drive element over a period of two or more drive cycles, the first interval is adjusted to a value closer to Tc than the current value, when the weight of droplets continuously ejected from the nozzle is increased by supplying the drive signal to the drive element over a period of two or more drive cycles, the first interval is adjusted to a value farther away from Tc than the current value; The driving method according to claim 9.

11. a discharge unit having a nozzle for discharging droplets, a pressure chamber communicating with the nozzle, and a drive element that is driven to apply pressure fluctuations to the liquid in the pressure chamber in response to a supplied drive signal; a drive signal generating circuit that generates the drive signal; and the drive signal has at least one ejection pulse during one drive period, The at least one ejection pulse comprises: an ejection waveform element that applies pressure fluctuation to the liquid in the pressure chamber so as to eject droplets from the nozzle; a residual vibration suppression element that attenuates pressure fluctuations of the liquid in the pressure chamber that remain after droplets are ejected from the nozzle and that correspond to the natural vibration period of the ejection unit, by adjusting the residual vibration suppression element of the at least one ejection pulse, the drive signal is supplied to the drive element over a period of two or more drive cycles, thereby correcting the weight of droplets ejected from the nozzle when droplets are continuously ejected from the nozzle; Liquid discharge device.

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