Method of driving liquid discharge apparatus and liquid discharge apparatus

Abstract

To appropriately set the amplitude of a minute vibration pulse.SOLUTION: The first drive signal includes a first ejection pulse having a first ejection waveform element that changes in potential so as to cause a pressure fluctuation in the liquid in the first pressure chamber, the pressure fluctuation causing the liquid to be ejected from the first nozzle, and a first micro-vibration pulse having a first micro-vibration waveform element that changes in potential so as to cause a pressure fluctuation in the liquid in the first pressure chamber without causing the liquid to be ejected from the first nozzle. And a setting step of setting a potential change width of the potential change waveform element in the first micro-vibration waveform element based on a maximum potential change width in the first ejection waveform element of the first ejection pulse determined in the determination step and a first upper limit threshold value, in which the first upper limit threshold value is an upper limit value of the potential change width of the potential change waveform element in the micro-vibration waveform element capable of stabilizing the ejection of the liquid.SELECTED DRAWING: Figure 9

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, liquid ejection devices have been widely used, each having a nozzle that ejects a liquid such as ink onto a medium such as printing paper, a pressure chamber connected to the nozzle, and a drive element that drives the nozzle to generate pressure fluctuations in the liquid in the pressure chamber in response to a supplied drive signal. The drive signal has an ejection pulse having an ejection waveform element whose potential changes so as to generate pressure fluctuations in the liquid in the pressure chamber that cause the liquid to be ejected from the nozzle. For example, Patent Document 1 discloses correcting the amplitude of the drive signal to correct for differences in the characteristics of the drive element. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-184572 Summary of the Invention [Problem to be solved by the invention]

[0004] In a liquid ejection device, in order to mitigate thickening of the liquid in the nozzle due to evaporation of a solvent such as water contained in the liquid, the drive signal includes, in addition to the ejection pulse, a micro-vibration pulse that eliminates local thickening near the nozzle by micro-vibrating the liquid in the nozzle. Even if the amplitude of the micro-vibration pulse is corrected in accordance with the correction of the amplitude of the ejection pulse by applying the above-mentioned conventional technology, there are cases where the amplitude of the micro-vibration pulse after correction is inappropriate. [Means for solving the problem]

[0005] A preferred aspect of the present disclosure provides a method for driving a liquid ejection device including a first ejection section having a first nozzle that ejects liquid onto a medium, a first pressure chamber that communicates with the first nozzle, and a first drive element that drives the first nozzle to generate a pressure fluctuation in the liquid in the first pressure chamber in response to a supplied first drive signal, and a first drive signal generation circuit that generates the first drive signal, wherein the first drive signal includes a first ejection pulse having a first ejection waveform element that changes in potential so as to generate a pressure fluctuation in the liquid in the first pressure chamber that causes the liquid to be ejected from the first nozzle, and a first drive signal generation circuit that generates the first drive signal. and a first micro-vibration pulse having a first micro-vibration waveform element that changes potential so as to cause a pressure fluctuation in the liquid in the first pressure chamber without ejecting the liquid, the method comprising: a determining step of determining a waveform shape of the first ejection pulse; and a setting step of setting a potential change width of a potential change waveform element in the first micro-vibration waveform element based on a maximum potential change width in the first ejection waveform element of the first ejection pulse determined by the determining step and a first upper limit threshold, the first upper limit threshold being an upper limit value of the potential change width of the potential change waveform element in the micro-vibration waveform element that is capable of stabilizing the ejection of the liquid.

[0006] A liquid ejection device according to a preferred aspect of the present disclosure includes a first ejection section having a first nozzle that ejects liquid onto a medium, a first pressure chamber that communicates with the first nozzle, and a first drive element that drives the first pressure chamber to generate a pressure fluctuation in the liquid in the first pressure chamber in response to a supplied first drive signal; a first drive signal generation circuit that generates the first drive signal; and a control circuit that controls the first drive signal generation circuit, wherein the first drive signal is a first ejection pulse having a first ejection waveform element that changes in potential so as to generate a pressure fluctuation in the liquid in the first pressure chamber that ejects the liquid from the first nozzle. and a first micro-vibration pulse having a first micro-vibration waveform element that changes potential so as to cause a pressure fluctuation in the liquid in the first pressure chamber without ejecting liquid from the first nozzle, wherein the control circuit determines the waveform shape of the first ejection pulse and sets the potential change width of the potential change waveform element in the first micro-vibration waveform element based on the maximum potential change width in the first ejection waveform element of the determined first ejection pulse and a first upper limit threshold, and the first upper limit threshold is the upper limit value of the potential change width of the potential change waveform element in the micro-vibration waveform element that is capable of stabilizing the ejection of liquid. [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 cross-sectional view showing an example of a head chip 51. [Figure 4] FIG. 3 is a diagram for explaining a switching circuit 52. [Figure 5] 3 is a diagram for explaining a drive signal Com for generating a supply signal Vin that is supplied to a head chip 51. FIG. [Figure 6] FIG. 10 is a flowchart showing an example of a method for adjusting a drive signal Com. [Figure 7] FIG. 10 is a flowchart showing an example of a determination process. [Figure 8] FIG. 10 is a flowchart showing an example of a setting process. [Figure 9] FIG. 10 is a diagram for explaining a candidate value ΔVhB-C. [Figure 10] FIG. 2 is a diagram showing the electrical configuration of the liquid ejection device 100A. [Figure 11] FIG. 4 is a diagram for explaining a drive signal ComA. [Figure 12] FIG. 10 is a flowchart showing an example of a method for adjusting a drive signal ComA. [Figure 13] FIG. 10 is a flowchart showing an example of a threshold value changing process. [Figure 14] 10A and 10B are diagrams for explaining examples of changes to the micro-vibration upper limit threshold value BP1th and the micro-vibration upper limit threshold value BP2th. [Figure 15] FIG. 10 is a flowchart showing an example of a setting process according to the second embodiment. [Figure 16] 10A and 10B are diagrams for explaining an example of an adjustment result of a drive signal ComA. [Figure 17] FIG. 10 is a diagram showing the electrical configuration of a liquid ejection device 100B according to a first modified example. [Figure 18] FIG. 10 is a diagram for explaining an example of an adjustment result of a drive signal ComB. [Figure 19] FIG. 11 is a flowchart showing an example of a determination process in a second modified example. [Figure 20] 10A and 10B are diagrams for explaining an example of an adjustment result of the drive signal Com in the second 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] In the following description, the mutually intersecting X-axis, Y-axis, and Z-axis will be used 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 opposite directions along the Y-axis are the Y1 direction and the Y2 direction. The opposite directions along the Z-axis are the Z1 direction and the Z2 direction.

[0010] Here, the Z axis is typically 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. Furthermore, the X axis, Y axis, and Z axis are typically perpendicular to each other, but are not limited to this. For example, they may intersect at an angle between 80° and 100°.

[0011] A: First embodiment A1: Overall configuration of the liquid ejection device 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 ink, an example of a liquid, 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.

[0012] As shown in FIG. 1, the liquid ejection device 100 includes a liquid container 10, a control unit 20, a transport mechanism 30, a moving mechanism 40, and a liquid ejection head 50.

[0013] The liquid container 10 stores ink. Specific examples of the liquid container 10 include a cartridge that is detachable from the liquid ejection device 100, a bag-shaped ink pack made of flexible film, and an ink tank that can be refilled with ink. The type of ink stored in the liquid container 10 is arbitrary.

[0014] 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. The detailed configuration of the control unit 20 will be described later with reference to FIG. 2.

[0015] The transport mechanism 30 transports the medium PP in the Y1 direction under the control of the control unit 20. The movement mechanism 40 reciprocates the liquid ejection head 50 along the X axis under the control of the control unit 20. The movement mechanism 40 has a substantially box-shaped carriage 41 that houses the liquid ejection head 50, and an endless transport belt 42 to which the carriage 41 is fixed. Note that the number of liquid ejection heads 50 mounted on the carriage 41 is not limited to one, and may be multiple. In addition to the liquid ejection head 50, the carriage 41 may also be equipped with the aforementioned liquid container 10.

[0016] The liquid ejection head 50 ejects ink supplied from the liquid container 10 onto the medium PP from each of the multiple nozzles N under the control of the control unit 20. This ejection is performed in parallel with the transport of the medium PP by the transport mechanism 30 and the reciprocating movement of the liquid ejection head 50 by the movement mechanism 40, thereby forming an ink image on the surface of the medium PP.

[0017] 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, the liquid ejection head 50 has one head chip 51. However, the liquid ejection head 50 may have multiple head chips 51.

[0018] The head chip 51 has a switching circuit 52 and M ejection units D. Hereinafter, when the number of ejection units D in the head chip 51 is M, the ejection units D may be written as ejection unit D[m] using the subscript [m] to distinguish between the M ejection units D. However, M is an integer of 2 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.

[0019] Under the control of the control unit 20, the switching circuit 52 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 M discharge sections D. Note that, although the switching circuit 52 is included in the head chip 51 in this embodiment, the switching circuit 52 may not be included in the head chip 51.

[0020] 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.

[0021] 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. Note that the control circuit 21 may include a programmable logic device such as an FPGA 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.

[0022] In addition, by executing the program, the control circuit 21 generates a control signal Sk1, a control signal Sk2, a print data signal SI, a waveform designation signal dCom, a latch signal LAT, a change signal CH, and a clock signal CLK as signals for controlling the operation of each part of the liquid ejection device 100.

[0023] The control signal Sk1 is a signal for controlling the driving of the transport mechanism 30. The control signal Sk2 is a signal for controlling the driving of the movement mechanism 40. The print data signal SI is a digital signal for specifying the operating state of the drive element E. The latch signal LAT and the change signal CH are timing signals that are used in conjunction with the print data signal SI and define the timing of ink ejection from each nozzle N of the head chip 51.

[0024] Furthermore, the control circuit 21 reads out a program stored in the storage circuit 22 and executes the read out program, thereby functioning as a determination unit 211 and a setting unit 213. The determination unit 211 and the setting unit 213 will be described later.

[0025] 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.

[0026] 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.

[0027] 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. 5.

[0028] The liquid ejection device 100 also has an imaging device 45 for measuring the amount of liquid ejected from the ejection section D. The imaging device 45 is a device that captures images of the liquid ejected from the ejection section D in flight. Specifically, the imaging device 45 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.

[0029] The control circuit 21 transmits an image capture instruction Sk3 to the image capture device 45. When the image capture instruction Sk3 is received, the image capture device 45 transmits image information GI indicating an image of the liquid in flight to the control circuit 21. Based on the image information GI, the control circuit 21 obtains the weight of the droplets in flight as the discharge amount.

[0030] 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 part D, instead of using the imaging device 45.

[0031] A3: Specific structure of head chip 51 Fig. 3 is a cross-sectional view showing an example of a head chip 51. As shown in Fig. 3, the head chip 51 has M nozzles N arranged in a direction along the Y axis. The M nozzles N are divided into a first row L1 and a second row L2 arranged at intervals in a direction along the X axis. Each of the first row L1 and the second row L2 is a collection of 0.5 × M nozzles N arranged linearly in the direction along the Y axis.

[0032] The head chips 51 are configured to be approximately symmetrical with respect to each other in the direction along the X-axis. However, the positions of the multiple nozzles N in the first row L1 and the multiple nozzles N in the second row L2 in the direction along the Y-axis may or may not match. Figure 3 illustrates a configuration in which the positions of the multiple nozzles N in the first row L1 and the multiple nozzles N in the second row L2 in the direction along the Y-axis match each other.

[0033] As shown in FIG. 3, the head chip 51 has a flow path substrate 51a, a pressure chamber substrate 51b, a nozzle plate 51c, a vibration absorber 51d, a vibration plate 51e, a plurality of drive elements 51f, a protective plate 51g, a case 51h, and a wiring substrate 51i.

[0034] The flow path substrate 51a and the pressure chamber substrate 51b are stacked in this order in the Z1 direction to form a flow path for supplying ink to M nozzles N. A diaphragm 51e, M drive elements 51f, a protective plate 51g, a case 51h, and a wiring substrate 51i are disposed in an area positioned in the Z1 direction from the stack of the flow path substrate 51a and the pressure chamber substrate 51b. On the other hand, a nozzle plate 51c and a vibration absorber 51d are disposed in an area positioned in the Z2 direction from the stack. Each element of the head chip 51 is roughly a plate-like member that is elongated in the Y direction, and is joined to one another by, for example, an adhesive. Each element of the head chip 51 will be described in order below.

[0035] The nozzle plate 51c is a plate-like member having M nozzles N arranged in each of a first row L1 and a second row L2. Each of the M nozzles N is a through-hole that allows ink to pass through. The nozzle plate 51c is manufactured by processing a silicon single crystal substrate using semiconductor manufacturing techniques such as dry etching or wet etching. However, other known methods and materials may be used as appropriate for manufacturing the nozzle plate 51c. Furthermore, the cross-sectional shape of the nozzles N is typically circular, but is not limited thereto and may be a non-circular shape such as a polygonal or elliptical shape.

[0036] The flow path substrate 51a is provided with a space R1, M supply flow paths Ra, and M communication flow paths Na for each of the first row L1 and the second row L2. The space R1 is an elongated opening extending in the direction along the Y axis in a plan view seen in the direction along the Z axis. Each of the supply flow paths Ra and the communication flow paths Na is a through hole formed for each nozzle N. Each supply flow path Ra is in communication with the space R1.

[0037] The pressure chamber substrate 51b is a plate-like member in which M pressure chambers C, called cavities, are provided in each of a first row L1 and a second row L2. The M pressure chambers C are arranged in a direction along the Y axis. Each pressure chamber C is formed for each nozzle N and is an elongated space extending in a direction along the X axis in a plan view. Like the nozzle plate 51c described above, the flow path substrate 51a and the pressure chamber substrate 51b are each manufactured by processing a silicon single crystal substrate using semiconductor manufacturing technology, for example. However, other known methods and materials may also be used as appropriate to manufacture the flow path substrate 51a and the pressure chamber substrate 51b.

[0038] The pressure chambers C are spaces located between the flow path substrate 51a and the vibration plate 51e. M pressure chambers C are arranged in the direction along the Y axis in each of the first row L1 and the second row L2. The pressure chambers C are also connected to the communication flow path Na and the supply flow path Ra. Therefore, the pressure chambers C are connected to the nozzle N via the communication flow path Na and to the space R1 via the supply flow path Ra.

[0039] A diaphragm 51e is disposed on the surface of the pressure chamber substrate 51b facing the Z1 direction. The diaphragm 51e is a plate-like member that can vibrate elastically. The diaphragm 51e has, for example, a first layer and a second layer, which are stacked in this order in the Z1 direction. The first layer is, for example, an elastic film made of silicon oxide (SiO2). The elastic film is formed, for example, by thermally oxidizing one surface of a silicon single crystal substrate. The second layer is, for example, an insulating film made of zirconium oxide (ZrO2). The insulating film is formed, for example, by forming a zirconium layer by sputtering and then thermally oxidizing the layer. Note that the diaphragm 51e is not limited to the configuration of the stack of the first and second layers described above, and may be, for example, a single layer or three or more layers.

[0040] On the surface of the vibration plate 51e facing the Z1 direction, M drive elements 51f corresponding to the nozzles N are arranged in each of the first row L1 and the second row L2. Each drive element 51f is a passive element that deforms when a drive signal Com is supplied. Each drive element 51f has an elongated shape extending in the direction along the X axis in a plan view. The M drive elements 51f are arranged in the direction along the Y axis so as to correspond to the M pressure chambers C. The drive elements 51f overlap the pressure chambers C in a plan view.

[0041] Each drive element 51f is a piezoelectric element and includes a first electrode, a piezoelectric layer, and a second electrode (not shown), which are stacked in this order in the Z1 direction. One of the first and second electrodes is an individual electrode spaced apart from one another for each drive element 51f, and a supply signal Vin is applied to the one electrode. The other of the first and second electrodes is a strip-shaped common electrode extending continuously along the Y-axis across 0.5×M drive elements 51f, and an offset potential VBS is supplied to the other electrode. Examples of metal materials for these electrodes include platinum (Pt), aluminum (Al), nickel (Ni), gold (Au), and copper (Cu). These metal materials can be used singly or in combination of two or more in the form of an alloy or a laminate. The piezoelectric layer is made of a piezoelectric material such as lead zirconate titanate (Pb(Zr,Ti)O3) and has a strip shape extending continuously along the Y-axis across the 0.5×M driving elements 51f. However, the piezoelectric layer may be integral across the 0.5×M driving elements 51f. In this case, through-holes are provided in the piezoelectric layer extending along the X-axis in areas corresponding to the gaps between adjacent pressure chambers C in a plan view. When the vibration plate 51e vibrates in conjunction with the deformation of the driving elements 51f, the pressure in the pressure chambers C fluctuates, causing ink to be ejected from the nozzles N.

[0042] Protective plate 51g is a plate-like member placed on the surface of diaphragm 51e facing the Z1 direction, and protects M driving elements 51f and reinforces the mechanical strength of diaphragm 51e. M driving elements 51f are housed between protective plate 51g and diaphragm 51e. Protective plate 51g is made of, for example, a resin material.

[0043] The case 51h is a member for storing ink to be supplied to the M pressure chambers C. The case 51h is made of, for example, a resin material. A space R2 is provided in the case 51h for each of the first row L1 and the second row L2. The space R2 is a space that communicates with the above-mentioned space R1, and together with the space R1, functions as a reservoir R that stores ink to be supplied to the M pressure chambers C. The case 51h is provided with an inlet IH for supplying ink to each reservoir R. The ink in each reservoir R is supplied to the pressure chamber C via each supply flow path Ra.

[0044] The vibration absorber 51d is also called a compliance substrate and is a flexible resin film that forms the wall surface of the reservoir R, and absorbs pressure fluctuations of the ink inside the reservoir R. The vibration absorber 51d may also be a flexible thin metal plate. The surface of the vibration absorber 51d facing the Z1 direction is bonded to the flow path substrate 51a with an adhesive or the like.

[0045] The wiring board 51i is mounted on the surface of the diaphragm 51e facing the Z1 direction, and is a mounting component for electrically connecting the control unit 20 and the head chip 51. The wiring board 51i is a flexible wiring board such as a COF (Chip On Film), an FPC (Flexible Printed Circuit), or an FFC (Flexible Flat Cable). A switching circuit 52 for supplying a drive voltage to each drive element 51f is mounted on the wiring board 51i of this embodiment.

[0046] As illustrated in FIG. 3, one ejection section D includes one drive element 51f, one pressure chamber C, and one nozzle N. That is, the M drive elements 51f correspond one-to-one to the M pressure chambers C. As can be understood from FIG. 3 and other figures, the drive element 51f corresponding to a pressure chamber C refers to the drive element 51f that overlaps part or all of the pressure chamber C in a plan view in the Z2 direction. When a drive signal Com is supplied to the drive element 51f 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 51f with the drive signal Com.

[0047] A4: Driving the driving element 51f 4 is a diagram for explaining the switching circuit 52. The driving element 51f is driven by a supply signal Vin from the switching circuit 52. The switching circuit 52 will be explained below with reference to FIG.

[0048] As shown in FIG. 4, a line LHa is connected to the switching circuit 52. The line LHa is a signal line that transmits a drive signal Com. In FIG. 4, for each integer m from 1 to M, one of the first electrode and the second electrode of the drive element 51f is shown as electrode Zd[m], and the other is shown as electrode Zu[m]. A line LHd is connected to the electrode Zd[m]. The line LHd is a power supply line to which an offset potential VBS is supplied.

[0049] The switching circuit 52 has M switches SWa, ie, switches SWa[1] to SWa[M], and a connection state designation circuit 52a that designates the connection states of these switches.

[0050] The switch SWa[m] is a switch that switches between conduction and non-conduction between the wiring LHa for transmitting the drive signal Com and the electrode Zu[m] of the drive element 51f[m], where m is an integer from 1 to M. Each of these switches is, for example, a transmission gate.

[0051] The connection state designation circuit 52a generates connection state designation signals SLa[1] to SLa[M] that designate the on / off states of the switches SWa[1] to SWa[M] based on the clock signal CLK, print data signal SI, latch signal LAT, and change signal CH supplied from the control circuit 21.

[0052] For example, although not shown, the connection state designation circuit 52a 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, shown in FIG. 5, for each drive element E. The individual designation signal Sd is supplied serially 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 the 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] for each integer m between 1 and M based on the individual designation signal Sd and the latch signal LAT.

[0053] For each integer m between 1 and M, the switch SWa[m] is switched on and off according to the connection state designation signal SLa[m] generated as described above. 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. As described above, the switching circuit 52 supplies part or all of the waveform included in the drive signal Com as the supply signal Vin to the drive elements 51f of one or more discharge units D selected from the M discharge units D.

[0054] A5: Drive signal Com 5 is a diagram illustrating the drive signal Com for generating the supply signal Vin supplied to the head chip 51. In this embodiment, the operating period of the liquid ejection device 100 includes one or more unit periods Tu. Generally, the liquid ejection device 100 forms an image represented by the image data Img by ejecting liquid from each ejection section D one or more times over a plurality of continuous or intermittent unit periods Tu.

[0055] As shown in Fig. 5, the control circuit 21 outputs a latch signal LAT having a pulse PlsL and a change signal CH having a pulse PlsC. The control circuit 21 thereby defines a unit period Tu as the period from the rising edge of one pulse PlsL to the rising edge of the next pulse PlsL. The specific length or cycle of the unit period Tu is not particularly limited. The control circuit 21 also divides the unit period Tu into two control periods Tu1 and Tu2 using the pulse PlsC.

[0056] The print data signal SI includes individual designation signals Sd[1] to Sd[M] that designate the drive mode of the discharge sections D[1] to D[M] in each unit period Tu. As described above, the connection state designation circuit 52a generates a connection state designation signal SLa[m] based on the individual designation signal Sd[m] for each unit period Tu, where m is an integer from 1 to M.

[0057] The individual designation signal Sd[m] is a signal that designates one of two drive modes, ink ejection and micro-vibration, for the ejection section D[m] during each unit period Tu. The micro-vibration drive mode is to drive the drive element E so that ink is not ejected from the nozzle N, thereby micro-vibrating the liquid surface in the nozzle N, in order to prevent the ink in the nozzle N from thickening, etc. Hereinafter, the liquid surface in the nozzle N may be referred to as a "meniscus."

[0058] 5, the drive signal generating circuit 24 outputs a drive signal Com having a start potential maintaining element as, a slight vibration pulse PB, a connecting element ai, an ejection pulse PA, and an end potential maintaining element ae in this order in one unit period Tu. The start potential maintaining element as, the slight vibration pulse PB, and a portion including the start point of the connecting element ai are provided within a control period Tu1. The portion including the end point of the connecting element ai, the ejection pulse PA, and the end potential maintaining element ae are provided within a control period Tu2.

[0059] The start potential maintaining element as is an element that maintains the reference potential V0 from the start of one unit period Tu to the start of the vibration pulse PB. The connection element ai is an element that maintains the reference potential V0 from the end of the vibration pulse PB to the start of the ejection pulse PA. The end potential maintaining element ae is an element that maintains the reference potential V0 from the end of the ejection pulse PA to the end of one unit period Tu.

[0060] The minute vibration pulse PB has a minute vibration waveform element BE. The minute vibration waveform element BE is a trapezoidal wave, and changes in potential so as to cause pressure fluctuations in the ink in the pressure chamber C without causing ink to be ejected from the nozzle N. The minute vibration waveform element BE has an expansion element e1, a sustain element e2, and a contraction element e3, in this order. The expansion element e1 changes in potential from the reference potential V0 to the minimum potential VLB of the minute vibration pulse PB. The minimum potential VLB is the lowest potential within the minute vibration pulse PB. However, as can be seen from Figure 5, the minimum potential VLB is a potential higher than the minimum potential VLA. The sustain element e2 is an element that maintains the minimum potential VLB. The contraction element e3 is an element that returns from the minimum potential VLB to the reference potential V0.

[0061] The ejection pulse PA has, in this order, an ejection waveform element DR and a residual vibration suppression element ED. The ejection waveform element DR changes in potential so as to generate pressure fluctuations in the ink inside the pressure chamber C that cause ink to be ejected from the nozzle N. The residual vibration suppression element ED attenuates pressure fluctuations in the liquid remaining inside the pressure chamber C after a droplet is ejected from the nozzle N.

[0062] The ejection waveform element DR 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 V0 to a minimum potential VLA, generating a negative pressure in the pressure chamber C. The minimum potential VLA is the minimum potential in the ejection pulse PA. 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 VLA. The end of the potential maintaining element pwh1 is connected to the ejection element c1. The ejection element c1 changes from the minimum potential VLA to a maximum potential VHA, generating a positive pressure in the pressure chamber C. The maximum potential VHA is the highest potential in the ejection pulse PA. When the drive element E receives the ejection waveform element DR, it generates a negative pressure in the pressure chamber C using the fill 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.

[0063] The residual vibration suppression element ED has a vibration suppression maintaining element pwh2 and a vibration suppression expansion element d2, in this order. The vibration suppression maintaining element pwh2 maintains a constant potential from the end of the ejection element c1. In the example of FIG. 5, it maintains the maximum potential VHA. The vibration suppression expansion element d2 starts changing its potential from the end of the vibration suppression maintaining element pwh2, expanding the pressure chamber C. The vibration suppression expansion element d2 changes its potential from the maximum potential VHA to the reference potential V0.

[0064] For each integer m between 1 and M, when the individual designation signal Sd[m] designates a slight vibration for the ejection section D[m], the connection state designation circuit 52a is set to a high level during the control period Tu1 and to a low level during the control period Tu2. In this case, the ejection section D[m] is driven by the slight vibration pulse PB during the control period Tu1, causing the ink near the nozzle N to vibrate slightly.

[0065] For each integer m between 1 and M, when the individual designation signal Sd[m] designates the ejection unit D[m] to eject ink, the connection state designation circuit 52a is set to a low level during the control period Tu1 and to a high level during the control period Tu2. In this case, the ejection unit D[m] is driven by the ejection pulse PA during the control period Tu2 to eject ink.

[0066] In the following description, the maximum potential change width within the ejection waveform element DR, in the first embodiment, the absolute value of the potential difference between the minimum potential VLA and the maximum potential VHA, may be referred to as the potential difference ΔVhA. Similarly, the maximum potential change width within the micro-vibration waveform element BE, in the first embodiment, the absolute value of the potential difference between the minimum potential VLB and the reference potential V0, may be referred to as the potential difference ΔVhB.

[0067] The waveform information CI shown in FIG. 2 indicates the waveform shape of the drive signal Com. Specifically, the waveform information CI includes end information, which includes information indicating the end time of each element of the drive signal Com and information indicating the end potential. For example, the waveform information CI includes end information for a start potential sustaining element as, end information for an expansion element e1, end information for a sustaining element e2, end information for a contraction element e3, end information for a connection element ai, end information for a filling element d1, end information for a potential sustaining element pwh1, end information for an ejection element c1, end information for a vibration suppression sustaining element pwh2, end information for a vibration suppression expansion element d2, and end information for an end potential sustaining element ae. The information indicating the end time included in the end information for the end potential sustaining element ae indicates one unit period Tu.

[0068] The manufacturer of head chips 51 mass-produces head chips 51, and stores in memory circuit 22 reference waveform information CI for generating a reference drive signal Com having an ejection pulse PA that ejects an ejection amount assumed by the manufacturer of head chip 51 for an average head chip 51 among the mass-produced head chips 51, and a micro-vibration pulse PB that vibrates the ink in nozzles N to an extent that stabilizes the ejection of ink. Hereinafter, this reference drive signal Com may be referred to as a "reference drive signal Com-S."

[0069] Furthermore, the manufacturer of the head chip 51 may be referred to as the "head manufacturer." Furthermore, the ejection amount assumed by the head manufacturer may be referred to as the "estimated ejection amount." Furthermore, the ejection pulse PA of the reference drive signal Com-S may be referred to as the "reference ejection pulse PA-S," and the vibration pulse PB of the reference drive signal Com-S may be referred to as the "reference vibration pulse PB-S." Furthermore, the potential difference ΔVhA of the reference ejection pulse PA-S may be referred to as the reference potential difference ΔVhA-S. Furthermore, the potential difference ΔVhB of the reference vibration pulse PB-S may be referred to as the reference potential difference ΔVhB-S. The estimated ejection amount is an example of a "predetermined amount." The ejection waveform element DR of the reference ejection pulse PA-S is an example of a "reference ejection waveform element."

[0070] The drive signal Com is an example of a "first drive signal." The drive signal generating circuit 24 is an example of a "first drive signal generating circuit." The ejection pulse PA included in the drive signal Com is an example of a "first ejection pulse," and the micro-vibration pulse PB included in the drive signal Com is an example of a "first micro-vibration pulse." The ejection waveform element DR included in the ejection pulse PA is an example of a "first ejection waveform element." The micro-vibration waveform element BE included in the micro-vibration pulse PB is an example of a "first micro-vibration waveform element."

[0071] A6: Adjusting the drive signal Com A certain degree of manufacturing error may occur in the head chip 51. The manufacturing error may cause the expected ejection amount to differ from the ejection amount of the head chip 51. In order to make the ejection amount of the head chip 51 match the expected ejection amount, it may be possible to correct the ejection pulse PA.

[0072] One possible method for correcting the ejection pulse PA is to correct the potential difference ΔVhA so that the expected ejection amount is ejected. For example, if a first amount of ink less than the expected ejection amount is ejected from a nozzle N when a reference ejection pulse PA-S is supplied to the head chip 51 to be corrected, the control circuit 21 can increase the ejection amount by correcting the ejection pulse PA to obtain a potential difference ΔVhA obtained by multiplying the reference potential difference ΔVhA-S by a value greater than 1 based on the first amount and the expected ejection amount. Furthermore, if a second amount of ink exceeding the expected ejection amount is ejected from a nozzle N when a reference ejection pulse PA-S is supplied to the head chip 51 to be corrected, the control circuit 21 can reduce the ejection amount by correcting the ejection pulse PA to obtain a potential difference ΔVhA obtained by multiplying the reference potential difference ΔVhA-S by a value less than 1 based on the second amount and the expected ejection amount.

[0073] On the other hand, since the micro-vibration pulse PB does not eject ink, the same method as the correction of the ejection pulse PA cannot be applied. Therefore, a mode can be considered in which the micro-vibration pulse PB is corrected to obtain a potential difference ΔVhB obtained by multiplying the ratio of the potential difference ΔVhA to the reference potential difference ΔVhA-S by using the correction result of the potential difference ΔVhA to the reference potential difference ΔVhA-S. However, in this mode, the potential difference ΔVhB of the micro-vibration pulse PB after correction may not be appropriate. Specifically, if the diameter of the nozzle N is larger than the shape assumed by the manufacturer of the head chip 51 due to manufacturing errors, the meniscus is likely to vibrate and the ejection amount at the reference potential difference ΔVhA-S is likely to increase. Therefore, the ratio of the potential difference ΔVhA of the assumed ejection amount to the reference potential difference ΔVhA-S is relatively low, and the potential difference ΔVhB of the micro-vibration pulse PB after correction, which is obtained by multiplying the ratio by the reference potential difference ΔVhB-S, may not be enough to vibrate the ink in the nozzle N due to the micro-vibration pulse PB, and the ink may not become thicker. Furthermore, if the diameter of the nozzle N is smaller than the shape assumed by the manufacturer of the head chip 51 due to manufacturing errors, the meniscus is less likely to vibrate and the ejection amount at the reference potential difference ΔVhA-S is likely to be small, so the ratio of the potential difference ΔVhA of the assumed ejection amount to the reference potential difference ΔVhA-S is relatively high, and the potential difference ΔVhB of the micro-vibration pulse PB after correction, which is obtained by multiplying the reference potential difference ΔVhB-S by this ratio, may cause excessive vibration of the ink in the nozzle N due to the micro-vibration pulse PB, and thereafter, it may not be possible to ensure stable ejection of ink from the nozzle by the ejection pulse PA. The inability to ensure stable ejection of ink means, for example, that the ink ejection direction deviates from the predetermined direction, that ink is not ejected from the nozzle N, and that the amount of ink ejection varies.

[0074] Therefore, the control circuit 21 adjusts the potential change width of the potential change waveform element included in the micro vibration pulse PB based on the potential difference ΔVhA of the ejection pulse PA and the micro vibration upper limit threshold BPth. The micro vibration upper limit threshold BPth is the upper limit value of the potential difference ΔVhB, which is the potential change width of the potential change waveform element included in the micro vibration pulse PB, that can stabilize the ejection of ink when the drive element E is driven by the ejection pulse PA in the next unit period Tu starting from the end of the unit period Tu in which the drive element E is driven by the micro vibration pulse PB. Preferably, it is the largest potential change width among the potential change widths of the potential change waveform elements included in the micro vibration pulse PB. For example, the head manufacturer stores the micro vibration upper limit threshold BPth corresponding to the potential change waveform element with the largest potential change width among the potential change waveform elements included in the micro vibration pulse PB in the memory circuit 22. In the first embodiment, the potential change waveform element with the largest potential change width among the potential change waveform elements included in the micro vibration pulse PB will be described as being the expansion element e1 and the contraction element e3. That is, in the first embodiment, the control circuit 21 sets the potential change width in the expansion element e1 and the contraction element e3, that is, the potential difference ΔVhB, based on the potential difference ΔVhA and the micro-vibration upper limit threshold BPth. The expansion element e1 and the contraction element e3 are examples of "potential change waveform elements." If the potential difference ΔVhB exceeds the micro-vibration upper limit threshold BPth, the vibration of the meniscus due to the micro-vibration pulse PB will not be attenuated to an extent that ink can be stably ejected within the unit period Tu that continues, or it will be amplified, and ink may not be ejected from the nozzle N by the micro-vibration pulse PB, or stable ink ejection may not be ensured when the drive element E is driven by the ejection pulse PA after the drive element E is driven by the micro-vibration pulse PB.

[0075] Furthermore, in this embodiment, the control circuit 21 sets the potential difference ΔVhB based on the potential difference ΔVhA of the ejection pulse PA, the micro-vibration upper threshold BPth, and the micro-vibration lower threshold BUth. The micro-vibration lower threshold BUth is the lower limit of the potential difference ΔVhB, which is the potential change width of the potential change waveform element included in the micro-vibration pulse PB that can eliminate ink viscosity. If the potential difference ΔVhB falls below the micro-vibration lower threshold BUth, it may not be possible to eliminate the ink viscosity in the nozzle N. If the ink viscosity is not eliminated, the ink ejection speed from the nozzle N will decrease, and there is a possibility that ink will not be ejected from the nozzle N. If the ink ejection speed decreases or ink is not ejected, the quality of the image formed on the medium PP will decrease. In the first embodiment, the head manufacturer stores the micro-vibration upper threshold BPth and the micro-vibration lower threshold BUth of the potential change waveform elements included in the micro-vibration pulse PB, which are the expansion element e1 and the contraction element e3, in the memory circuit 22.

[0076] The micro-vibration upper threshold BPth and the micro-vibration lower threshold BUth are set by the head manufacturer's experience and / or experiments. The micro-vibration upper threshold BPth is, for example, 6.3 [V]. The micro-vibration lower threshold BUth is, for example, 3.0 [V]. The micro-vibration upper threshold BPth is an example of a "first upper threshold." The micro-vibration lower threshold BUth is an example of a "first lower threshold." The micro-vibration upper threshold BPth is greater than the micro-vibration lower threshold BUth. A method for adjusting the drive signal Com will be described using Figure 6.

[0077] A7: How to adjust the drive signal Com Fig. 6 is a flowchart showing an example of a method for adjusting the drive signal Com. The flowchart shown in Fig. 6 is executed when the power of the liquid ejection apparatus 100 is turned on or when an instruction from the user of the liquid ejection apparatus 100 is received.

[0078] Prior to the processing of step S2, the control circuit 21 stores the value of the reference potential difference ΔVhA-S in the memory circuit 22. There are two modes for storing the value of the reference potential difference ΔVhA-S. In the first mode, the control circuit 21 acquires the value of the reference potential difference ΔVhA-S from the reference waveform information CI stored in the memory circuit 22 and stores the acquired value in the memory circuit 22. In the first mode, the control circuit 21 corrects the candidate waveform information CI stored in the memory circuit 22 in the processing from step S2 onwards. In the second mode, the control circuit 21 stores a preset value of the reference potential difference ΔVhA-S in the memory circuit 22. In the second mode, the control circuit 21 corrects the candidate waveform information CI stored in the memory circuit 22 in the processing from step S2 onwards. In FIG. 6, the mode for storing the value of the reference potential difference ΔVhA-S will be described as the second mode.

[0079] The control circuit 21 functions as a determination unit 211, and executes a determination process for determining the waveform shape of the ejection pulse PA in step S2. Step S2 is an example of a "determination step." The determination process will be described with reference to FIG. 7.

[0080] After the process of step S2 is completed, in step S4, the control circuit 21 functions as the setting unit 213 and executes a setting process for setting the potential difference ΔVhB. Step S4 is an example of a "setting step." The setting process will be described with reference to FIG. 8.

[0081] 7 is a flowchart showing an example of the determination process. The determination process is a process for determining the waveform shape of the ejection pulse PA so that the amount of ink ejected from the nozzle N when the ejection pulse PA is supplied to the drive element E is the expected ejection amount.

[0082] In step S12, the control circuit 21 supplies a reference drive signal Com-S to the ejection unit D[m1] for any integer m1 between 1 and M. Specifically, the control circuit 21 generates candidate waveform information CI that is a copy of the reference waveform information CI, generates a waveform designation signal dCom based on the candidate waveform information CI that indicates the reference drive signal Com-S, and outputs the generated waveform designation signal dCom to the drive signal generation circuit 24. Furthermore, the control circuit 21 supplies an individual designation signal Sd[m1] that indicates the ejection of ink to the head chip 51.

[0083] The discharge section D[m1] is an example of a "first discharge section." The nozzle N included in the discharge section D[m1] is an example of a "first nozzle," the pressure chamber C included in the discharge section D[m1] is an example of a "first pressure chamber," and the drive element E included in the discharge section D[m1] is an example of a "first drive element."

[0084] Furthermore, in step S14, the control circuit 21 transmits an image capturing instruction Sk3 to the image capturing device 45 at a timing when an image of the ink ejected from the ejection section D[m1] can be captured.

[0085] After completing the process of step S14, in step S16, the control circuit 21 acquires image information GI from the imaging device 45. Then, in step S18, the control circuit 21 analyzes the image information GI to acquire information indicating the amount of ink ejected from the ejection section D[m1]. Hereinafter, the ink ejection amount indicated by the information acquired in step S18 may be referred to as the "measured amount."

[0086] After the process of step S18 is completed, the control circuit 21 determines in step S20 whether the measured amount matches the estimated ejection amount. The term "the measured amount matches the estimated ejection amount" includes not only the case where the measured amount and the estimated ejection amount match perfectly, but also the case where dots formed by the measured amount of ink and dots formed by the estimated ejection amount of ink can be considered to be the same when error is taken into account.

[0087] If the determination result in step S20 is negative, the control circuit 21 changes the potential difference ratio RtA and corrects the candidate waveform information CI in step S22. The potential difference ratio RtA is the ratio of the potential difference ΔVhA to the reference potential difference ΔVhA-S. The potential difference ratio RtA is an example of a "first ratio." If the measured amount is less than the expected ejection amount, the control circuit 21 increases the potential difference ratio RtA to correct the candidate waveform information CI. On the other hand, if the measured amount is more than the expected ejection amount, the control circuit 21 decreases the potential difference ratio RtA to correct the candidate waveform information CI. Specifically, the candidate waveform information CI is generated by multiplying the terminal potential of each waveform element of the drive signal Com contained in the reference waveform information CI by the potential difference ratio RtA, and setting the terminal potential of each element to that value. Note that the information indicating the terminal time of each waveform element in the candidate waveform information CI is consistent with the reference waveform information CI.

[0088] After completing step S22, the control circuit 21 supplies the drive signal Com based on the corrected candidate waveform information CI to the discharge section D[m1] in step S24. After completing step S24, the control circuit 21 executes step S14 again. If the determination result in step S20 is positive, the control circuit 21 ends the series of processes shown in FIG. 7 and executes step S4 shown in FIG. 6.

[0089] Fig. 8 is a flowchart showing an example of the setting process of step 4 shown in Fig. 6. The setting process is a process for setting the potential difference ΔVhB based on the potential difference ΔVhA determined by the determination process, the micro-vibration upper threshold BPth, and the micro-vibration lower threshold BUth.

[0090] In step S52, the control circuit 21 calculates a candidate value ΔVhB-C for the potential difference ΔVhB based on the potential difference ratio RtA of the candidate waveform information CI at the end of the determination process S2, i.e., the positive determination result in step S20. Specifically, the control circuit 21 calculates the candidate value ΔVhB-C indicated by the candidate waveform information CI, which is the value obtained by multiplying the potential difference ratio RtA by the reference potential difference ΔVhB-S. The candidate value ΔVhB-C is an example of a "first candidate value." An example of the candidate value ΔVhB-C will be described with reference to FIG. 9.

[0091] FIG. 9 is a diagram illustrating the candidate value ΔVhB-C. In FIG. 9, elements related to the reference drive signal Com-S are denoted with "-S." Furthermore, in FIG. 9, the reference drive signal Com-S is indicated by a dashed line, and the candidate drive signal Com indicated by the candidate waveform information CI after the processing of step S20 is indicated by a solid line. In step S22 of the determination process, the control circuit 21 generates candidate waveform information CI from the value obtained by multiplying the terminal potential of each element of the reference drive signal Com-S by the potential difference ratio RtA, using the minimum potential of the reference drive signal Com-S—in the example of FIG. 9, the minimum potential VLA-S—in other words, the terminal potential of the potential sustain element pwh1 of the ejection waveform element DR of the reference waveform signal CI as a reference. Note that the potential used as a reference when generating the candidate waveform information CI is not limited to the minimum potential VLA-S. For example, the control circuit 21 may generate candidate waveform information CI using the reference potential V0-S as a reference, or may generate candidate waveform information CI using the offset potential VBS as a reference. In the example of FIG. 9, an example in which the potential difference ratio RtA is greater than 1 is shown.

[0092] As can be understood from the definition of the potential difference ratio RtA, the potential difference from the reference potential V0 to the minimum potential VLA indicated by the candidate waveform information CI is the potential difference from the reference potential V0-S to the minimum potential VLA indicated by the reference waveform information CI multiplied by the potential difference ratio RtA.

[0093] 9 shows the candidate value ΔVhB-C. The minimum potential VLB-C shown in FIG. 9 shows the terminal potential of the expansion element e1 when the candidate value ΔVhB-C is set to the potential difference ΔVhB. The potential difference from the minimum potential VLB-C to the minimum potential VLA is the value obtained by multiplying the potential difference from the minimum potential VLB-S to the minimum potential VLA by the potential difference ratio RtA.

[0094] Returning to FIG. 8 for the explanation, after the processing of step S52 is completed, the control circuit 21 determines in step S54 whether the candidate value ΔVhB-C is equal to or less than the micro-vibration upper threshold BPth. If the determination result in step S54 is positive, the control circuit 21 determines in step S56 whether the candidate value ΔVhB-C is equal to or greater than the micro-vibration lower threshold BUth. If the determination result in step S56 is positive, the control circuit 21 sets the candidate value ΔVhB-C to the potential difference ΔVhB in step S58. The control circuit 21 sets the current candidate waveform information CI to be used as the waveform information CI to be used during printing.

[0095] If the determination result in step S54 is negative, i.e., if the candidate value ΔVhB-C exceeds the micro-vibration upper limit threshold BPth, the control circuit 21 sets the micro-vibration upper limit threshold BPth to the potential difference ΔVhB in step S60, and sets the terminal potential of the expansion element e1 and the terminal potential of the sustain element e2 of the micro-vibration waveform element BE of the candidate waveform information CI to the set potential difference ΔVhB. Specifically, the control circuit 21 sets the terminal potential of the expansion element e1 of the candidate waveform information CI to a potential obtained by subtracting the micro-vibration upper limit threshold BPth from the reference potential V0. Furthermore, the control circuit 21 sets the terminal potential of the sustain element e2 of the candidate waveform information CI to a potential obtained by subtracting the micro-vibration upper limit threshold BPth from the reference potential V0. The control circuit 21 sets the candidate waveform information CI to be used as waveform information CI to be used during printing.

[0096] If the determination result in step S56 is negative, i.e., if the candidate value ΔVhB-C is lower than the micro-vibration lower-limit threshold BUth, the control circuit 21 sets the micro-vibration lower-limit threshold BUth to the potential difference ΔVhB in step S62, and sets the terminal potential of the expansion element e1 and the terminal potential of the sustain element e2 of the micro-vibration waveform element BE of the candidate waveform information CI to the set potential difference ΔVhB. Specifically, the control circuit 21 sets the terminal potential of the expansion element e1 of the candidate waveform information CI to a potential obtained by subtracting the micro-vibration lower-limit threshold BUth from the reference potential V0. Furthermore, the control circuit 21 also sets the terminal potential of the sustain element e2 of the candidate waveform information CI to a potential obtained by subtracting the micro-vibration lower-limit threshold BUth from the reference potential V0. The control circuit 21 sets the candidate waveform information CI to be used as the waveform information CI to be used during printing.

[0097] After the process of step S58 is completed, after the process of step S60 is completed, or after the process of step S62 is completed, the control circuit 21 ends the series of processes shown in FIG. 8, and further ends the series of processes shown in FIG.

[0098] 9 shows a case where the candidate value ΔVhB-C exceeds the micro-vibration upper limit threshold BPth. Because the candidate value ΔVhB-C exceeds the micro-vibration upper limit threshold BPth, the control circuit 21 sets the micro-vibration upper limit threshold BPth to the potential difference ΔVhB. In FIG. 9, the portion of the drive signal Com where the potential has changed due to the micro-vibration upper limit threshold BPth being set to the potential difference ΔVhB is shown by a dashed line. The minimum potential VLB shown in FIG. 9 is the terminal potential of the expansion element e1, and is the potential obtained by subtracting the potential difference ΔVhB from the reference potential V0.

[0099] A8: Summary of the first embodiment The first embodiment will be summarized below using the ejection unit D[m1]. The disclosure of the first embodiment can be defined as a method for driving a liquid ejection device. The liquid ejection device 100 includes a nozzle N[m1] that ejects ink onto a medium PP, a pressure chamber C[m1] that communicates with the nozzle N[m1], and a drive element E[m1] that drives the pressure chamber C[m1] to generate pressure fluctuations in the ink in the pressure chamber C[m1] in response to a supplied drive signal Com. The drive signal Com includes an ejection pulse PA having an ejection waveform element DR that changes in potential to generate pressure fluctuations in the ink in the pressure chamber C[m1], causing ink to be ejected from the nozzle N[m1], and a micro-vibration pulse PB having a micro-vibration waveform element BE that changes in potential to generate pressure fluctuations in the ink in the pressure chamber C[m1] without ejecting ink from the nozzle N[m1]. The driving method includes step S2 of determining the waveform shape of the ejection pulse PA, and step S4 of setting the potential difference ΔVhB in the micro-vibration waveform element BE based on the potential difference ΔVhA in the ejection waveform element DR determined by step S2 and the micro-vibration upper limit threshold BPth. According to the first embodiment, compared to the aspect in which the potential difference ΔVhB is set without using the micro-vibration upper threshold BPth, it is possible to prevent the micro-vibration pulse PB from causing excessive vibration of the ink in the nozzle N, which then causes the ejection pulse PA to become unstable, i.e., it is possible to appropriately set the potential difference ΔVhB, which is the amplitude within the micro-vibration waveform element BE.

[0100] In step S2, the control circuit 21 determines the waveform shape of the ejection pulse PA so that the amount of ink ejected from the nozzle N[m1] when the ejection pulse PA is supplied to the drive element E[m1] is the expected ejection amount. In step S4, the control circuit 21 calculates a candidate value ΔVhB-C that is a candidate value for the potential difference ΔVhB in the micro-vibration waveform element BE based on the potential difference ratio RtA, and if the candidate value ΔVhB-C exceeds the micro-vibration upper limit threshold BPth, sets the micro-vibration upper limit threshold BPth to the potential difference ΔVhB. According to the first embodiment, it is possible to prevent the ink ejection from becoming unstable while adapting to the manufacturing error of the ejection section D[m1].

[0101] Furthermore, in step S4, if the candidate value ΔVhB-C is equal to or less than the micro-vibration upper limit threshold BPth, the control circuit 21 sets the candidate value ΔVhB-C as the potential difference ΔVhB in the micro-vibration waveform element BE. According to the first embodiment, the potential difference ΔVhB can be set to a value that corresponds to the manufacturing error of the discharge section D[m1].

[0102] Furthermore, in step S4, if the candidate value ΔVhB-C is lower than the micro-vibration lower-limit threshold BUth, the control circuit 21 sets the micro-vibration lower-limit threshold BUth to the potential difference ΔVhB. According to the first embodiment, it is possible to suppress ink viscosity increase while adapting to manufacturing errors of the ejection section D[m1]. By suppressing ink viscosity increase, it is possible to maintain the quality of the image formed on the medium PP.

[0103] As can be seen from FIG. 9, when the candidate value ΔVhB-C is equal to or less than the micro-vibration upper threshold BPth and equal to or greater than the micro-vibration lower threshold BUth, the control circuit 21 sets the candidate value ΔVhB-C to the potential difference ΔVhB. According to the first embodiment, it is possible to maintain the quality of the image formed on the medium PP and achieve ejection stability while adapting to manufacturing errors in the ejection section D[m1].

[0104] B: Second embodiment Since the viscosity of ink varies depending on the temperature, it is conceivable to change the micro-vibration upper threshold value BPth and the micro-vibration lower threshold value BUth in accordance with the temperature of the ink. A second embodiment will now be described.

[0105] B1: Electrical configuration of the liquid ejection device 100A according to the second embodiment 10 is a diagram showing the electrical configuration of liquid ejection device 100A. Liquid ejection device 100A differs from liquid ejection device 100 in that it has a temperature sensor 47, a control circuit 21A instead of control circuit 21, and a drive signal generation circuit 24A instead of drive signal generation circuit 24.

[0106] The temperature sensor 47 measures the temperature of the liquid ejector 100A as the temperature of the ink in the ejection section D, and generates temperature information KI indicating the measurement result. The temperature sensor 47 transmits the generated temperature information KI to the control circuit 21A. The temperature information KI is an example of "temperature information related to the temperature of the liquid in the first ejection section."

[0107] In the second embodiment, it is assumed that temperature sensor 47 is mounted on an electronic circuit on a board provided within liquid ejection device 100A and detects the temperature of liquid ejection device 100, but the present disclosure is not limited to this. For example, temperature sensor 47 may be provided inside liquid ejection head 50 or inside liquid container 10.

[0108] Control circuit 21A differs from control circuit 21 in that it reads a program stored in memory circuit 22 and executes the read program to function as a determination unit 211, a setting unit 213, an acquisition unit 215, a first change unit 217, and a second change unit 219. Furthermore, control circuit 21A differs from control circuit 21 in that control circuit 21A generates control signal Sk1, control signal Sk2, print data signal SI, waveform designation signal dCom, latch signal LAT, and clock signal CLK.

[0109] Drive signal generation circuit 24A differs from drive signal generation circuit 24 in that it generates drive signals ComAa and ComAb. For example, drive signal generation circuit 24A generates drive signals ComAa and ComAb using two independent circuits internally. Hereinafter, drive signals ComAa and ComAb may be referred to as drive signal ComA without distinction. Drive signal ComA will be described with reference to FIG. 11.

[0110] B2: Drive signal ComA 11 is a diagram for explaining the drive signal ComA. The drive signal ComAa has, in one unit period Tu, a start potential sustaining element asAa, an ejection pulse PA, and an end potential sustaining element aeAa, in this order. The drive signal ComAb has, in one unit period Tu, a start potential sustaining element asAb, a micro-vibration pulse PBA, and an end potential sustaining element aeAb, in this order.

[0111] The start potential maintaining element asAa is an element that maintains the reference potential V0 from the start of one unit period Tu to the start of the ejection pulse PA. The end potential maintaining element aeAa is an element that maintains the reference potential V0 from the end of the ejection pulse PA to the end of one unit period Tu.

[0112] The start potential maintaining element asAb is an element that maintains the reference potential V0 from the start of one unit period Tu to the start of the vibration pulse PBA. The end potential maintaining element aeAb is an element that maintains the reference potential V0 from the end of the vibration pulse PBA to the end of one unit period Tu.

[0113] The micro vibration pulse PBA has a micro vibration waveform element BEA. The micro vibration waveform element BEA has an expansion element e4, a sustain element e5, a contraction element e6, a sustain element e7, an expansion element e8, a sustain element e9, and a contraction element e10 in this order. The expansion element e4 changes potential from the reference potential V0 to the minimum potential V1. The minimum potential V1 is the minimum potential in the micro vibration pulse PBA. The sustain element e5 maintains the minimum potential V1. The contraction element e6 changes potential from the minimum potential V1 to the maximum potential V2. The maximum potential V2 is the highest potential in the micro vibration pulse PBA. The sustain element e7 maintains the maximum potential V2. The expansion element e8 changes potential from the maximum potential V2 to the minimum potential V1. The sustain element e9 maintains the minimum potential V1. The contraction element e10 is an element that returns from the minimum potential V1 to the reference potential V0.

[0114] In the second embodiment, the drive signal ComA is an example of a "first drive signal." The drive signal generating circuit 24A is an example of a "first drive signal generating circuit." The ejection pulse PA included in the drive signal ComAa is an example of a "first ejection pulse," and the minute vibration pulse PBA included in the drive signal ComAb is an example of a "first minute vibration pulse." The ejection waveform element DR included in the ejection pulse PA is an example of a "first ejection waveform element." The minute vibration waveform element BEA included in the minute vibration pulse PBA is an example of a "first minute vibration waveform element."

[0115] 11, in the second embodiment, the drive signal ComAa having the ejection pulse PA and the drive signal ComAb having the minute vibration pulse PBA are separated into separate drive signals, and are generated in parallel in time within the unit period Tu, but this is not limited to this. For example, similar to the first embodiment, the ejection pulse PA and the minute vibration pulse PBA may be configured to be arranged in time series order within the unit period Tu of the same drive signal ComA.

[0116] B3: How to adjust the drive signal ComA In the second embodiment, the control circuit 21A sets the potential difference ΔV1, which is the potential change width of an arbitrary period within the micro vibration pulse PBA, in the second embodiment, the expansion element e4 period, based on the potential difference ΔVhA of the ejection pulse PA, the micro vibration upper threshold BP1th, and the micro vibration lower threshold BU1th. Similarly, the control circuit 21 sets the potential difference ΔVhBA, which is the potential change width of the contraction element e6 period within the micro vibration pulse PBA, based on the potential difference ΔVhA, the micro vibration upper threshold BP2th, and the micro vibration lower threshold BU2th. The potential difference ΔVhBA coincides with the maximum potential change width within the micro vibration pulse PBA.

[0117] In the second embodiment, when correcting the potential change width during the period of the expansion element e4, the control circuit 21A changes the terminal potential of the expansion element e4. Furthermore, the control circuit 21A sets the terminal potential of the sustain element e5, the terminal potential of the expansion element e8, and the terminal potential of the sustain element e9 to the same potential as the terminal potential of the expansion element e4. Furthermore, when correcting the potential change width during the period of the contraction element e6, the control circuit 21A changes the terminal potential of the contraction element e6. Furthermore, the control circuit 21A sets the terminal potential of the sustain element e7 to the same potential as the terminal potential of the contraction element e6.

[0118] When the expansion element e4 and the contraction element e10 correspond to the "potential change waveform elements," the micro-vibration upper threshold BP1th corresponds to the "first upper threshold," and the micro-vibration lower threshold BU1th corresponds to the "first lower threshold." When the contraction element e6 and the expansion element e8 correspond to the "potential change waveform elements," the micro-vibration upper threshold BP2th corresponds to the "first upper threshold," and the micro-vibration lower threshold BU2th corresponds to the "first lower threshold." Below, a method for adjusting the drive signal ComA will be explained using FIG. 12.

[0119] FIG. 12 is a flowchart showing an example of a method for adjusting the drive signal ComA. The flowchart shown in FIG. 12 differs from the flowchart shown in FIG. 6 in that step S4A is executed instead of step S4, and step S6 is executed between the processing of step S2 and the processing of step S4A, but is otherwise the same. Below, only the differences from the flowchart shown in FIG. 6 will be described. Note that in step S2 of the second embodiment, the reference waveform information CI includes reference waveform information CIa corresponding to the drive signal ComAa and reference waveform information CIb corresponding to the drive signal ComAb. Furthermore, the candidate waveform information CI includes candidate waveform information CIa corresponding to the drive signal ComAa and candidate waveform information CIb corresponding to the drive signal ComAb.

[0120] After the process of step S2 is completed, the control circuit 21A executes a threshold value changing process in step S6. The process of step S6 may be executed before the process of step S2. The threshold value changing process will be described with reference to FIG.

[0121] 13 is a flowchart showing an example of threshold value changing processing. In step S102, the control circuit 21A functions as the acquisition unit 215 and acquires temperature information KI from the temperature sensor 47. Next, in step S104, the control circuit 21A functions as the first change unit 217 and changes the microvibration upper limit threshold BP1th and the microvibration upper limit threshold BP2th according to the temperature information KI. A specific example of changing the microvibration upper limit threshold BP1th and the microvibration upper limit threshold BP2th will be described with reference to FIG. 14. Step S102 is an example of an "acquisition step." Step S104 is an example of a "first change step."

[0122] 14 is a diagram illustrating an example of changing the micro-vibration upper limit threshold BP1th and the micro-vibration upper limit threshold BP2th. The memory circuit 22 stores a table h1 shown in FIG. 14. Table h1 is information that associates the micro-vibration upper limit threshold BP1th and the micro-vibration upper limit threshold BP2th with each temperature. More specifically, Table h1 shows the micro-vibration upper limit threshold BP1th and the micro-vibration upper limit threshold BP2th for the cases of 35 degrees Celsius or less, 36 degrees Celsius, 37 degrees Celsius, 38 degrees Celsius, 39 degrees Celsius, and when the temperature information KI is 40 degrees Celsius or more.

[0123] Returning to FIG. 13 for the explanation. After the processing of step S104 is completed, in step S106, the control circuit 21A functions as the second changing unit 219 and changes the micro-vibration lower limit threshold BU1th and the micro-vibration lower limit threshold BU2th in accordance with the temperature information KI. Step S106 is an example of a "second changing step." The method of changing the micro-vibration lower limit threshold BU1th and the micro-vibration lower limit threshold BU2th is the same as the method of changing the micro-vibration upper limit threshold BP1th and the micro-vibration upper limit threshold BP2th except that the tables referenced are different, and therefore description thereof will be omitted. After the processing of step S106 is completed, the control circuit 21A ends the series of processes shown in FIG. 13.

[0124] The description will return to Fig. 12. After step S6 is completed, the control circuit 21A executes the setting process in the second embodiment. The setting process in the second embodiment will be described with reference to Fig. 15.

[0125] FIG. 15 is a flowchart showing an example of the setting process in the second embodiment. The process from step S112 to step S122 shown in FIG. 15 is the same as the process from step S52 to step S62 shown in FIG. 8, except that the potential difference ΔVhB is replaced with the potential difference ΔV1, the candidate value ΔVhB-C is replaced with the candidate value ΔV1-C, the microvibration upper threshold BPth is replaced with the microvibration upper threshold BP1th, and the microvibration lower threshold BUth is replaced with the microvibration lower threshold BU1th. Therefore, a description thereof will be omitted. Note that in S112 of the second embodiment, the potential difference ratio RtA corresponding to the candidate waveform information CIa at the end of the determination process S2, i.e., the positive determination result in step S20, is multiplied by the potential at the end of each element of the drive signal Com included in the reference waveform information CIb, and the product is set to the potential at the end of each element of the candidate waveform information CIb. Note that the information indicating the end time of each waveform element of the candidate waveform information CIb is consistent with the reference waveform information CIb. Furthermore, the processing from step S132 to step S142 shown in FIG. 15 is the same as the processing except that the potential difference ΔVhB is replaced with the potential difference ΔVhBA, the candidate value ΔVhB-C is replaced with the candidate value ΔVhBA-C, the micro-vibration upper threshold BPth is replaced with the micro-vibration upper threshold BP2th, and the micro-vibration lower threshold BUth is replaced with the micro-vibration lower threshold BU2th, and therefore the explanation thereof will be omitted.

[0126] As a specific example of the process of step S120, the control circuit 21A sets the terminal potential of the expansion element e4, the terminal potential of the sustain element e5, the terminal potential of the expansion element e8, and the terminal potential of the sustain element e9 of the candidate waveform information CIb to a potential obtained by subtracting the micro-vibration upper limit threshold BP1th from the reference potential V0. Similarly, as a specific example of the process of step S122, the control circuit 21A sets the terminal potential of the expansion element e4, the terminal potential of the sustain element e5, the terminal potential of the expansion element e8, and the terminal potential of the sustain element e9 of the candidate waveform information CIb to a potential obtained by subtracting the micro-vibration lower limit threshold BU1th from the reference potential V0.

[0127] Furthermore, as a specific example of the processing of step S140, the control circuit 21A sets the terminal potential of the contraction element e6 and the terminal potential of the sustain element e7 of the candidate waveform information CIb to a potential obtained by adding the terminal potential of the expansion element e4 to the micro-vibration upper limit threshold BP2th. Similarly, as a specific example of the processing of step S142, the control circuit 21A sets the terminal potential of the contraction element e6 and the terminal potential of the sustain element e7 of the candidate waveform information CIb to a potential obtained by adding the terminal potential of the expansion element e4 to the micro-vibration lower limit threshold BU2th.

[0128] In addition, the potential change waveform elements included in the micro vibration pulse PBA are the expansion element e4, the contraction element e6, the expansion element e8, and the contraction element e10, and when the potential change waveform elements that adjust the potential change width are the expansion element e4 and the contraction element e10, the candidate value ΔV1-C corresponds to the "first candidate value". Also, when the potential change waveform elements that adjust the potential change width are the contraction element e6 and the expansion element e8, the candidate value ΔVhBA-C corresponds to the "first candidate value".

[0129] FIG. 16 is a diagram illustrating an example of the adjustment results of drive signal ComA. In FIG. 16, elements related to reference drive signal ComAa-S and reference drive signal ComAb-S are marked with "-S." Furthermore, in FIG. 16, reference drive signal ComAa-S and reference drive signal ComAb-S are shown with dashed lines, and drive signal ComA indicated by candidate waveform information CI after completion of determination process S2 is shown with a solid line. The example in FIG. 16 shows an example in which potential difference ratio RtA is less than 1.

[0130] As can be understood from the definition of the potential difference ratio RtA, the potential difference from the reference potential V0 to the minimum potential VLA indicated by the candidate waveform information CI is the potential difference from the reference potential V0-S to the minimum potential VLA indicated by the reference waveform information CI multiplied by the potential difference ratio RtA.

[0131] A candidate value ΔV1-C is shown in Fig. 16. In step S112, the control circuit 21A calculates the candidate value ΔV1-C by multiplying the potential difference ratio RtA by the reference potential difference ΔV1-S. The minimum potential V1-C shown in Fig. 16 indicates the terminal potential of the expansion element e4 when the candidate value ΔV1-C is set to the potential difference ΔV1.

[0132] FIG. 16 shows a case where the candidate value ΔV1-C is lower than the micro-vibration lower-limit threshold BU1th. Because the candidate value ΔV1-C is lower than the micro-vibration lower-limit threshold BU1th, the control circuit 21A sets the micro-vibration lower-limit threshold BU1th to a potential difference ΔV1. In FIG. 16, the portion of the drive signal Com where the potential has changed due to the micro-vibration lower-limit threshold BU1th being set to the potential difference ΔV1 is shown by a dashed line. The minimum potential V1 shown in FIG. 16 is the terminal potential of the expansion element e4, and is the potential obtained by subtracting the potential difference ΔV1 from the reference potential V0. The control circuit 21A sets the terminal potentials of the expansion element e4, the sustain element e5, the expansion element e8, and the sustain element e9 of the micro-vibration waveform element BEA included in the candidate waveform information CIb to the minimum potential V1.

[0133] B4: Summary of the second embodiment The second embodiment will be summarized below using an example in which the expansion element e4 and contraction element e10 correspond to the "potential change waveform element," the micro-vibration upper threshold BP1th corresponds to the "first upper threshold," the micro-vibration lower threshold BU1th corresponds to the "first lower threshold," and the candidate value ΔV1-C corresponds to the "first candidate value." The disclosure of the second embodiment can be defined as a driving method for a liquid ejection device. The driving method further includes step S102 of acquiring temperature information KI relating to the temperature of ink in the ejection element D[m1] and step S104 of changing the micro-vibration upper threshold BP1th in accordance with the temperature information KI. In step S4A, if the candidate value ΔV1-C exceeds the micro-vibration upper threshold BP1th changed in step S104, the control circuit 21A sets the micro-vibration upper threshold BP1th to the potential difference ΔV1 in the micro-vibration waveform element BEA. According to the second embodiment, even when the temperature of the ink fluctuates, it is possible to prevent the ink ejection from becoming unstable while taking into account the manufacturing error of the ejection section D[m1].

[0134] The driving method further includes the above-mentioned step S102 and step S106 of changing the micro-vibration lower-limit threshold BU1th in accordance with the temperature information KI. In step S4A, if the candidate value ΔV1-C is lower than the micro-vibration lower-limit threshold BU1th changed in step S106, the control circuit 21A sets the micro-vibration lower-limit threshold BU1th to the potential difference ΔV1 in the micro-vibration waveform element BEA. According to the second embodiment, even if the temperature of the ink fluctuates, it is possible to suppress the viscosity of the ink while taking into account the manufacturing error of the ejection section D[m1].

[0135] Furthermore, in step S4A, if the candidate value ΔV1-C is equal to or less than the micro-vibration upper threshold BP1th and equal to or greater than the micro-vibration lower threshold BU1th, the control circuit 21A sets the candidate value ΔV1-C to the potential difference ΔV1. According to the second embodiment, it is possible to maintain the quality of the image formed on the medium PP and achieve ejection stability while adapting to manufacturing errors in the ejection section D[m1].

[0136] 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.

[0137] C1: First modified example In each of the above-described embodiments, the liquid ejection device 100 has one head chip 51, but may have two or more head chips 51. A first modified example will be described below.

[0138] 17 is a diagram showing the electrical configuration of a liquid ejection device 100B according to a first modified example. The liquid ejection device 100B differs from the liquid ejection device 100 in that it has a control unit 20B instead of the control unit 20, and a liquid ejection head 50B instead of the liquid ejection head 50.

[0139] Control unit 20B differs from control unit 20 in that it has a drive signal generation circuit 24B instead of drive signal generation circuit 24. Drive signal generation circuit 24B differs from drive signal generation circuit 24 in that it has drive signal generation circuits 24-1 and 24-2. Liquid ejection head 50B differs from liquid ejection head 50 in that it has head chips 51-1 and 51-2 instead of head chip 51.

[0140] Drive signal generation circuit 24-1 generates drive signal ComB-1. Drive signal ComB-1 is supplied to head chip 51-1. Drive signal generation circuit 24-2 generates drive signal ComB-2. Drive signal ComB-2 is supplied to head chip 51-2. In the following description, drive signal ComB-1 and drive signal ComB-2 may be referred to indistinguishably as drive signal ComB.

[0141] As described above, manufacturing errors may occur in the head chip 51. Therefore, the control circuit 21 executes the series of processes shown in FIG. 6 for each of the drive signals ComB-1 and ComB-2. Before executing the series of processes shown in FIG. 6, the control circuit 21 stores the value of the reference potential difference ΔVhA-S in the memory circuit 22, as in the first embodiment. In the first modification, the control circuit 21 generates candidate waveform information CIB-1 corresponding to the drive signal ComB-1 and candidate waveform information CIB-2 corresponding to the drive signal ComB-2 from the reference waveform information CIB stored in the memory circuit 22. Then, the control circuit 21 corrects the first candidate waveform information CIB-1 when adjusting the drive signal ComB-1, and corrects the second candidate waveform information CIB-2 when adjusting the drive signal ComB-2. Below, using Figure 18, we will explain the case where, for any integer m1 between 1 and M, drive signal ComB-1 is supplied to discharge section D[m1] of head chip 51-1 to adjust drive signal ComB-1, and for any integer m2 between 1 and M, drive signal ComB-2 is supplied to discharge section D[m2] of head chip 51-2 to adjust drive signal ComB-2.

[0142] When performing the process of step S22 on drive signal ComB-1, control circuit 21 changes the potential difference ratio RtA-1 and corrects first candidate waveform information CIB-1. The potential difference ratio RtA-1 is the ratio of the potential difference ΔVhA-1 to the reference potential difference ΔVhA-S. Similarly, when performing the process of step S22 on drive signal ComB-2, control circuit 21 changes the potential difference ratio RtA-2 and corrects second candidate waveform information CIB-2. The potential difference ratio RtA-2 is the ratio of the potential difference ΔVhA-2 to the reference potential difference ΔVhA-S. In the first modified example, the potential difference ratio RtA-1 is an example of a "first ratio," and the potential difference ratio RtA-2 is an example of a "second ratio."

[0143] Furthermore, when performing the process of step S52 on drive signal ComB-1, control circuit 21 calculates a candidate value ΔVhB-1C for the potential difference ΔVhB-1 based on the potential difference ratio RtA-1. Similarly, when performing the process of step S52 on drive signal ComB-2, control circuit 21 calculates a candidate value ΔVhB-2C for the potential difference ΔVhB-2 based on the potential difference ratio RtA-2. In the first modified example, candidate value ΔVhB-C for the potential difference ΔVhB-1 is an example of a "first candidate value," and candidate value ΔVhB-C for the potential difference ΔVhB-2 is an example of a "second candidate value."

[0144] FIG. 18 is a diagram illustrating an example of the adjustment results of the drive signal ComB. In FIG. 18, elements related to the reference drive signal Com-S are marked with "-S." Similarly, elements related to the drive signal ComB-1 are marked with "-1," and elements related to the drive signal ComB-2 are marked with "-2." Furthermore, in FIG. 18, the reference drive signal Com-S is shown with a dashed line, the drive signal ComB-1 is shown with a solid line, and the drive signal ComB-2 is shown with a dashed line.

[0145] 18 shows an example in which the potential difference ΔVhA-2 is larger than the potential difference ΔVhA-1, and the potential difference ΔVhA-1 is larger than the reference potential difference ΔVhA-S. Furthermore, FIG. 18 shows an example in which, as a result of adjusting the drive signal ComB, the potential difference ΔVhB-2 is larger than the potential difference ΔVhB-1, and the potential difference ΔVhB-1 is larger than the reference potential difference ΔVhB-S.

[0146] 18, when the potential difference ratios RtA-1 and RtA-2 are different, the potential differences ΔVhA-1 and ΔVhA-2 are different, and the candidate values ​​ΔVhB-1C and ΔVhB-2C calculated in step S52 are different. However, when the potential differences ΔVhA-1 and ΔVhA-2 are different, the potential differences ΔVhB-1 and ΔVhB-2 are not necessarily different. For example, when the candidate value ΔVhB-1C for the potential difference ΔVhB-1 and the candidate value ΔVhB-2C for the potential difference ΔVhB-2 both exceed the micro-vibration upper limit threshold BPth, the potential differences ΔVhB-1 and ΔVhB-2 match the micro-vibration upper limit threshold BPth. Furthermore, when the candidate value ΔVhB-1C for the potential difference ΔVhB-1 and the candidate value ΔVhB-2C for the potential difference ΔVhB-2 are both below the micro-vibration lower-limit threshold BUth, the potential differences ΔVhB-1 and ΔVhB-2 match the micro-vibration lower-limit threshold BUth. Note that when at least one of the candidate values ​​ΔVhB-1C and ΔVhB-2C is the value between the micro-vibration upper-limit threshold BPth and the micro-vibration lower-limit threshold BUth, the potential differences ΔVhB-1 and ΔVhB-2 are different.

[0147] In the first modified example, the drive signal ComB-1 is an example of a "first drive signal." The drive signal generating circuit 24-1 is an example of a "first drive signal generating circuit." The ejection pulse PA-1 included in the drive signal ComB-1 is an example of a "first ejection pulse," and the micro-vibration pulse PB-1 included in the drive signal ComB-1 is an example of a "first micro-vibration pulse." The ejection waveform element DR-1 included in the ejection pulse PA-1 is an example of a "first ejection waveform element." The micro-vibration waveform element BE-1 included in the micro-vibration pulse PB-1 is an example of a "first micro-vibration waveform element." The ejection section D[m1] of the head chip 51-1 is an example of a "first ejection section."

[0148] Moreover, in the first modified example, the drive signal ComB-2 is an example of a "second drive signal." The drive signal generating circuit 24-2 is an example of a "second drive signal generating circuit." The ejection pulse PA-2 included in the drive signal ComB-2 is an example of a "second ejection pulse," and the minute vibration pulse PB-2 included in the drive signal ComB-2 is an example of a "second minute vibration pulse." The ejection waveform element DR-2 included in the ejection pulse PA-2 is an example of a "second ejection waveform element." The minute vibration waveform element BE-2 included in the minute vibration pulse PB-2 is an example of a "second minute vibration waveform element." The ejection section D[m2] of the head chip 51-2 is an example of a "second ejection section." The nozzle N included in the ejection section D[m2] of the head chip 51-2 is an example of a "second nozzle," the pressure chamber C included in the ejection section D[m2] is an example of a "second pressure chamber," and the drive element E included in the ejection section D[m2] is an example of a "second drive element."

[0149] The above describes a summary of the first modified example using the ejection unit D[m1] of head chip 51-1 and the ejection unit D[m2] of head chip 51-2. Liquid ejection device 100B further includes: an ejection unit D[m2] having a nozzle N[m2] that ejects ink onto medium PP, a pressure chamber C[m2] that communicates with nozzle N[m2], and a drive element E[m2] that drives in response to a supplied drive signal ComB-2 to generate a pressure fluctuation in the ink in pressure chamber C[m2]; and a drive signal generation circuit 24-2 that generates drive signal ComB-2. The drive signal ComB-2 has an ejection pulse PA-2 having an ejection waveform element DR-2 that changes potential to cause a pressure fluctuation in the ink in the pressure chamber C[m2] that causes ink to be ejected from the nozzle N[m2], and a minute vibration pulse PB-2 having a minute vibration waveform element BE-2 that changes potential to cause a pressure fluctuation in the ink in the pressure chamber C[m2] without causing ink to be ejected from the nozzle N[m2]. In step S2, the control circuit 21 determines the waveform shape of the ejection pulse PA-2 so that the amount of ink ejected from the nozzle N[m2] when the ejection pulse PA-2 is supplied to the drive element E[m2] is the expected ejection amount. In step S4, the control circuit 21 calculates a candidate value ΔVhB-2C for the potential difference ΔVhB-2 in the micro vibration waveform element BE-2 based on the potential difference ratio RtA-2, and if the candidate value ΔVhB-2C for the potential difference ΔVhB-2 exceeds the micro vibration upper limit threshold BPth, the control circuit 21 sets the micro vibration upper limit threshold BPth to the potential difference ΔVhB-2 of the micro vibration pulse PB-2. Also, if the candidate value ΔVhB-2C is below the micro vibration lower limit threshold BUth, the control circuit 21 sets the micro vibration lower limit threshold BUth to the potential difference ΔVhB-2. When the potential difference ΔVhA-1 in the ejection waveform element DR-1 is different from the potential difference ΔVhA-2 in the ejection waveform element DR-2, the potential difference ΔVhB-1 of the micro-vibration pulse PB-1 is different from the potential difference ΔVhB-2 in the micro-vibration pulse PB-2, the potential difference ΔVhB-1 and the potential difference ΔVhB-2 match the micro-vibration upper threshold BPth, or the potential difference ΔVhB-1 and the potential difference ΔVhB-2 match the micro-vibration lower threshold BUth. As described above, according to the first modified example, the amplitude in the minute vibration waveform element BE can be appropriately set for each of the ejection section D[m1] and the ejection section D[m2] having different manufacturing errors.

[0150] C2: Second modified example In the above-described embodiments, the micro-vibration upper threshold value BPth and the micro-vibration lower threshold value BUth are used for the micro-vibration pulse PB, but the upper threshold value and the lower threshold value may also be used for the ejection pulse PA. A second modified example will be described below.

[0151] Fig. 19 is a flowchart showing an example of a determination process in the second modified example. The flowchart shown in Fig. 19 is the same as the flowchart shown in Fig. 7 except that a process is added for when the determination result of step S20 is positive. Therefore, only the process for when the determination result of step S20 is positive will be described below. Note that the waveform shape of the drive signal Com indicated by the candidate waveform information CI when the determination result of step S20 is positive is a candidate for the waveform shape of the ejection pulse PA, and is an example of the "first shape."

[0152] If the determination result in step S20 is positive, the control circuit 21 determines in step S32 whether the potential difference ΔVhA is equal to or less than the upper discharge threshold APth. The upper discharge threshold APth is the upper limit of the maximum potential change width within the discharge waveform element DR that can stabilize the discharge of ink. If the potential difference ΔVhA exceeds the upper discharge threshold APth, it may not be possible to ensure stable discharge of ink. The upper discharge threshold APth is an example of a "second upper threshold."

[0153] If the determination result in step S32 is negative, the control circuit 21 sets the upper discharge threshold APth to the potential difference ΔVhA in step S34. Specifically, the control circuit 21 corrects the candidate waveform information CI so that the value obtained by adding the upper discharge threshold APth to the minimum potential VLA becomes the maximum potential VHA. After completing the process of step S34, the control circuit 21 ends the series of processes shown in FIG. 19.

[0154] If the determination result in step S32 is positive, the control circuit 21 determines in step S36 whether the potential difference ΔVhA is equal to or greater than the lower-limit discharge threshold AUth. The lower-limit discharge threshold AUth is the lower limit of the maximum potential change width within the discharge waveform element DR that allows the discharged droplet to be discharged at a predetermined discharge speed that allows the droplet to land at a predetermined position. If the potential difference ΔVhA falls below the lower-limit discharge threshold AUth, the ink discharge speed may decrease. The lower-limit discharge threshold AUth is an example of a "second lower-limit threshold."

[0155] If the determination result of step S36 is positive, the control circuit 21 ends the series of processes shown in Fig. 19. If the determination result of step S36 is negative, the control circuit 21 sets the discharge lower limit threshold AUth to the potential difference ΔVhA in step S38. Specifically, the control circuit 21 corrects the candidate waveform information CI so that the value obtained by adding the discharge lower limit threshold AUth to the minimum potential VLS becomes the maximum potential VHA. After completing the process of step S38, the control circuit 21 ends the series of processes shown in Fig. 19.

[0156] FIG. 20 is a diagram illustrating an example of the adjustment result of the drive signal Com in the second modified example. In FIG. 20, elements related to the reference drive signal Com-S are marked with "-S." Furthermore, in FIG. 20, the reference drive signal Com-S is indicated by a dashed line, and the drive signal ComA indicated by the candidate waveform information CI after the determination result of step S20 of the determination process is positive is indicated by a solid line. The example in FIG. 20 shows an example in which the potential difference ratio RtA is greater than 1. Furthermore, for ease of understanding, in FIG. 20, the potential difference ΔVhA, which is the maximum potential change width of the ejection waveform element DR after the determination result of step S20 of the determination process is positive, is indicated as a potential difference ΔVhA-C, and the terminal potential of the ejection element c1 is indicated as a maximum potential VHA-C.

[0157] FIG. 20 shows a case where the potential difference ΔVhA-C exceeds the upper discharge threshold APth. Because the potential difference ΔVhA-C exceeds the upper discharge threshold APth, the control circuit 21 sets the upper discharge threshold APth to the potential difference ΔVhA. In FIG. 20, the portion of the drive signal Com where the potential has changed due to the upper discharge threshold APth being set to the potential difference ΔVhA is shown by a dashed line. The maximum potential VHA shown in FIG. 20 is the terminal potential of the discharge element c1, and is the potential obtained by adding the minimum potential VLA to the upper discharge threshold APth.

[0158] As in the second embodiment, the control circuit 21 may change the upper discharge threshold APth and the lower discharge threshold AUth in accordance with the temperature of the ink.

[0159] The above will summarize the second modified example using the ejection unit D[m1]. In the processes from step S12 to step S20, the control circuit 21 sets a first shape, which is a candidate for the waveform shape of the ejection pulse PA, so that the amount of ink ejected from the nozzle N[m1] when the ejection pulse PA is supplied to the drive element E[m1] is the expected ejection amount. Then, in steps S32 and S34, if the potential difference ΔVhA, which is the maximum potential change width of the ejection waveform element DR of the first shape, exceeds the upper ejection threshold APth, the control circuit 21 determines the waveform shape of the ejection pulse PA so that the potential difference ΔVhA in the ejection waveform element DR is equal to the upper ejection threshold APth. According to the second modified example, it is possible to prevent the potential difference ΔVhA that causes the ink ejection to become unstable from being supplied to the ejection section D[m1] while taking into account the manufacturing error of the ejection section D[m1].

[0160] Also, in steps S36 and S38, if the potential difference ΔVhA of the ejection waveform element DR of the first shape is below the ejection lower limit threshold AUth, the waveform shape of the ejection pulse PA is determined so that the potential difference ΔVhA of the ejection waveform element DR is equal to the ejection lower limit threshold AUth. According to the second modified example, it is possible to suppress the potential difference ΔVhA, which reduces the ink ejection speed and causes landing deviation, from being supplied to the ejection section D[m1] while taking into account manufacturing errors of the ejection section D[m1].

[0161] C3: Third modified example In each of the above-described aspects, if the determination result of step S54 is positive, the control circuit 21 may execute the process of step S58 without executing the process of step S56. In other words, a lower limit value for the potential difference ΔVhB may not be set. In other words, the control circuit 21 may set the potential difference ΔVhA based on the potential difference ΔVhA of the ejection pulse PA and the micro-vibration upper limit threshold BPth. This makes it possible to ensure at least ejection stability.

[0162] For example, in the first modified example and the modified example of the first modified example, the control circuit 21 does not have to compare the candidate values ​​ΔVhB-1C and ΔVhB-2C with the micro-vibration lower limit threshold BUth. In this modified example, when the potential difference ΔVhA-1 in the ejection waveform element DR-1 and the potential difference ΔVhA-2 in the ejection waveform element DR-2 are different, the potential difference ΔVhA-1 of the micro-vibration pulse PB-1 and the potential difference ΔVhA-2 in the micro-vibration pulse PB-2 are different, or the potential difference ΔVhB-1 and the potential difference ΔVhB-2 match the micro-vibration upper limit threshold BPth.

[0163] C4: Fourth variant In the second modification and the modification of the second modification, similarly to the third modification, when the determination result of step S32 is positive, the control circuit 21 may not execute the processes of step S36 and step S38. In other words, a lower limit value of the potential difference ΔVhA may not be set.

[0164] C5: Fifth variant In the second embodiment and the modified example of the second embodiment, the control circuit 21A may execute the process of step S106 after completing the process of step S102 without executing the process of step S104. Alternatively, in the second embodiment and the modified example of the second embodiment, the control circuit 21A may execute the process of step S104 but not execute the process of step S106, and end the series of processes shown in FIG.

[0165] C6. Sixth Variation In the first embodiment and the first modified example, the ejection pulse PA and the minute vibration pulse PB were configured to be arranged in chronological order within the unit period Tu of the same drive signal Com, but this is not limited to this, and as in the second embodiment, the ejection pulse PA and the minute vibration pulse PB may be separated into different drive signals and generated in parallel in time within the unit period Tu. Also, in the second embodiment, the ejection pulse PA and the minute vibration pulse PBA were configured to be separated into different drive signals and generated in parallel in time within the unit period Tu, but this is not limited to this, and as in the first embodiment, the ejection pulse PA and the minute vibration pulse PBA may be configured to be arranged in chronological order within the unit period Tu of the same drive signal Com.

[0166] C7. 7th Variation In the first embodiment and the first modified example, the micro-vibration waveform element BE of the micro-vibration pulse PB was a trapezoidal wave, but is not limited to this, and may be a configuration including a plurality of expansion elements and contraction elements, or a configuration including a plurality of either expansion elements or contraction elements, like the micro-vibration waveform element BEA of the micro-vibration pulse PBA of the second embodiment. Also, in the second embodiment, the micro-vibration waveform element BEA of the micro-vibration pulse PBA was a configuration including a plurality of expansion elements and contraction elements, but is not limited to this, and may be a trapezoidal wave configuration including one expansion element and one contraction element, or a configuration including a plurality of either expansion elements and contraction elements.

[0167] C8. Eighth Variation In the above-described embodiment and modified example, the ejection pulse PA is composed of an ejection waveform element DR having a filling element d1, a potential maintaining element pwh1, and an ejection element c1, and a residual vibration suppression element ED having a vibration suppression maintaining element pwh2 and a vibration suppression expansion element d2, but is not limited to this, and ejection pulses of various known waveform shapes can be used for the first ejection pulse and the second ejection pulse.

[0168] C9. 9th Variation In the above-described embodiment and modified example, in steps S12 and S24 of the determination process in step S2 of the method for adjusting the drive signal Com, the reference drive signal Com-S is supplied to the discharge unit D[m1] for any integer m1 between 1 and M. However, this is not limited to this, and the reference drive signal Com-S may be supplied to all discharge units D from 1 to M, or the reference drive signal Com-S may be supplied to some of the discharge units D from 1 to M. In this case, the discharge unit D to which the reference drive signal Com-S is supplied is an example of a "first discharge unit," the nozzle N included in the discharge unit D to which the reference drive signal Com-S is supplied is an example of a "first nozzle," the pressure chamber C included in the discharge unit D to which the reference drive signal Com-S is supplied is an example of a "first pressure chamber," and the drive element E included in the discharge unit D to which the reference drive signal Com-S is supplied is an example of a "first drive element." Furthermore, in steps S14, S16, and S18, the average value of the ejection amounts of ink ejected from the plurality of ejection sections D to which the reference drive signal Com-S is supplied may be acquired as the measurement amount.

[0169] C10. 10th Variation In the second embodiment, the reference driving signal ComA corresponding to the common reference waveform information CI was used regardless of the temperature information K acquired by the temperature sensor 47, but the present invention is not limited to this, and the reference waveform information CI corresponding to the temperature information K can also be used. For example, the information of the reference waveform information CI can be corrected according to the temperature information K acquired by the temperature sensor 47 so that the ratio of the reference potential difference ΔVhBA-S of the micro-vibration pulse PBA to the reference potential difference ΔVhA-S of the ejection pulse PA when the temperature information KI indicates a second temperature higher than the first temperature is smaller than the ratio of the reference potential difference ΔVhBA-S of the micro-vibration pulse PBA to the reference potential difference ΔVhA-S of the ejection pulse PA when the temperature information KI indicates a first temperature.

[0170] C11. 11th Variation In the second embodiment, the micro vibration waveform element BEA of the micro vibration pulse PBA has potential change waveform elements with different potential change widths, namely, the expansion element e4 and contraction element e10 of the potential change width of the potential difference ΔV1, and the contraction element e6 and expansion element e8 of the potential change width of the potential difference ΔVhBA, and the potential difference ΔV1 and the potential difference ΔVhBA were adjusted based on the micro vibration upper threshold BP1th, the micro vibration lower threshold BU1th, the micro vibration upper threshold BP2th, the micro vibration lower threshold BU2th, and the potential difference ΔVhA of the ejection pulse PA, but this is not limited to this. For example, when the micro vibration waveform element BEA of the micro vibration pulse PBA has potential change waveform elements with different potential change widths, the potential change width can be set based on the potential difference ΔVhA of the ejection pulse PA, the first upper threshold, and the first lower threshold for the potential change waveform element with the largest potential change width. For example, it is also possible to perform steps S132 to S142 without performing steps S112 to S122 in the flowchart shown in FIG. 15, and to set ΔV1 together with setting the potential difference ΔVhBA. Specifically, in step S140, at least one of the terminal potentials of the expansion element e4, the sustain element e5, the expansion element e8, and the sustain element e9 (minimum potential V1) and the terminal potential of the contraction element e6 and the sustain element e7 (maximum potential V2) of the candidate waveform information CIb can be changed so that the potential difference ΔVhBA becomes the micro-vibration upper limit threshold BP2th. Note that it is preferable that the ratio of the reference potential difference ΔV1-S to the reference potential difference ΔVhBA-S is equal to the ratio of the potential difference ΔV1-S to the potential difference ΔVhBA after setting. Similarly, in step S142, at least one of the terminal potentials of the expansion element e4, the sustain element e5, the expansion element e8, and the sustain element e9 (minimum potential V1) and the terminal potential of the contraction element e6 and the sustain element e7 (maximum potential V2) of the candidate waveform information CIb can be changed so that the potential difference ΔVhBA becomes the micro-vibration lower limit threshold BU2th. Note that it is preferable that the ratio of the reference potential difference ΔV1-S to the reference potential difference ΔVhBA-S is equal to the ratio of the potential difference ΔV1-S to the potential difference ΔVhBA after setting.

[0171] C12: 12th variant In each of the above-mentioned embodiments, a serial-type liquid ejection device 100 in which a carriage 41 carrying a liquid ejection head 50 moves back and forth has been exemplified, but the present disclosure can also be applied to a line-type liquid ejection device in which multiple nozzles N are distributed across the entire width of the medium PP.

[0172] C13: 13th variant 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]

[0173] 10...liquid container, 20, 20B...control unit, 21, 21A...control circuit, 22...memory circuit, 23...power supply circuit, 24, 24-1, 24-2, 24A, 24B...drive signal generation circuit, 30...transport mechanism, 40...movement mechanism, 41...carriage, 42...transport belt, 45...imaging device, 47...temperature sensor, 50, 50B...liquid ejection head, 51, 51-1, 51-2...head chip, 51a...flow path substrate, 51b...pressure chamber substrate, 51c...nozzle plate, 51d...vibration absorber, 51e...vibration plate, 51f...drive element, 51g...protective plate, 51h...case, 51i...wiring board, 52...cut switching circuit, 52a...connection state designation circuit, 100, 100A, 100B...liquid ejection device, 200...external device, 211...determining unit, 213...setting unit, 215...acquiring unit, 217...first changing unit, 212...second changing unit, APth...ejection upper limit threshold, AUth...ejection lower limit threshold, BE, BE-1, BE-2, BEA...micro-vibration waveform elements, BP1th, BP2th, BPth...micro-vibration upper limit threshold, BU1th, BU2th, BUth...micro-vibration lower limit threshold, C...pressure chamber, CH...change signal, CI...waveform information, CLK...clock signal, Com, ComA, ComAa, ComAb, Com B, ComB-1, ComB-2... drive signal, ComAa-S, Com-S, ComAb-S... reference drive signal, D... discharge unit, DR, DR-1, DR-2... discharge waveform element, E... drive element, ED... residual vibration suppression element, GI... image information, IH... inlet, Img... image data, KI... temperature information, L1... first row, L2... second row, LAT... latch signal, LHa, LHd... wiring, N... nozzle, Na... communication flow path, PA, PA-1, PA-2... discharge pulse, PA-S... reference discharge pulse, PB, PB-1, PB-2, PBA... micro-vibration pulse, PB-S... reference micro-vibration pulse, PP ...medium, PlsC, PlsL...pulse, R...reservoir, R1, R2...space, Ra...supply flow path, RtA, RtA-1, RtA-2...potential difference ratio, SI...print data signal, SLa, SLb, SLc...connection status designation signal, SWa...switch, Sd...individual designation signal, Sk1, Sk2...control signal, Sk3...imaging instruction, Tu...unit period, Tu1, Tu2...control period, V0, V0-S...reference potential, V1, V1-C...minimum potential, V2...maximum potential, VBS...offset potential, VHA, VHA-C...maximum potential, VHV...power supply potential, VLA, VLA-S, VLB, VLB-C,VLS...minimum potential, Vin...supply signal, Zd, Zu...electrode, ae, aeAa, aeAb...final potential maintenance element, ai...connection element, as, asAa, asAb...starting potential maintenance element, c1...ejection element, d1...filling element, d2...vibration suppression expansion element, dCom...waveform designation signal, e1...expansion element, e10...contraction element, e2...maintenance element, e3...contraction element, e4...expansion element, e5...maintenance element, e6...contraction element , e7...maintenance element, e8...expansion element, e9...maintenance element, pwh1...potential maintenance element, pwh2...vibration suppression maintenance element, ΔV1...potential difference, ΔV1-C...candidate value, ΔV1-S...reference potential difference, ΔVhA, ΔVhA-1, ΔVhA-2, ΔVhA-C, ΔVhB, ΔVhB-1, ΔVhB-2, ΔVhBA...potential difference, ΔVhA-S, ΔVhB-S...reference potential difference, ΔVhB-C, ΔVhBA-C...candidate value. ,

Claims

1. a first ejection unit having a first nozzle that ejects liquid onto a medium, a first pressure chamber that communicates with the first nozzle, and a first drive element that drives the first nozzle in response to a supplied first drive signal so as to generate a pressure fluctuation in the liquid in the first pressure chamber; a first drive signal generating circuit that generates the first drive signal; A method for driving a liquid ejection device comprising: the first drive signal includes a first ejection pulse having a first ejection waveform element that changes in potential so as to cause a pressure fluctuation in the liquid in the first pressure chamber to eject the liquid from the first nozzle, and a first minute vibration pulse having a first minute vibration waveform element that changes in potential so as to cause a pressure fluctuation in the liquid in the first pressure chamber without ejecting the liquid from the first nozzle, a determining step of determining a waveform shape of the first ejection pulse; a setting step of setting a potential change width of a potential change waveform element in the first micro-vibration waveform element based on a maximum potential change width in the first ejection waveform element of the first ejection pulse determined in the determining step and a first upper limit threshold value, the first upper limit threshold is an upper limit of the potential change width of the potential change waveform element in the micro-vibration waveform element that can stabilize the ejection of liquid; Drive method.

2. The determining step determining a waveform shape of the first ejection pulse so that the amount of liquid ejected from the first nozzle when the first ejection pulse is supplied to the first drive element is a predetermined amount; The setting step includes: calculate a first candidate value that is a candidate value of the potential change width of the potential change waveform element in the first micro-vibration waveform element based on a first ratio that is a ratio of the maximum potential change width in the first ejection waveform element to the maximum potential change width in a reference ejection waveform element; When the first candidate value exceeds the first upper limit threshold, the first upper limit threshold is set to a potential change width of the potential change waveform element in the first micro-vibration waveform element. The driving method according to claim 1 .

3. The liquid ejection device further comprises: a second ejection unit including a second nozzle that ejects liquid onto the medium, a second pressure chamber that communicates with the second nozzle, and a second drive element that drives the second nozzle in response to a supplied second drive signal so as to generate a pressure fluctuation in the liquid in the second pressure chamber; a second drive signal generating circuit that generates the second drive signal; Equipped with the second drive signal has a second ejection pulse having a second ejection waveform element that changes in potential so as to cause a pressure fluctuation in the liquid in the second pressure chamber to eject the liquid from the second nozzle, and a second minute vibration pulse having a second minute vibration waveform element that changes in potential so as to cause a pressure fluctuation in the liquid in the second pressure chamber without ejecting the liquid from the second nozzle, The determining step determining a waveform shape of the second ejection pulse so that the amount of liquid ejected from the second nozzle when the second ejection pulse is supplied to the second drive element is the predetermined amount; The setting step includes: calculate a second candidate value that is a candidate value of the potential change width of the potential change waveform element in the second micro-vibration waveform element based on a second ratio that is a ratio of the maximum potential change width in the second ejection waveform element to the maximum potential change width in the reference ejection waveform element; If the second candidate value exceeds the first upper limit threshold, the first upper limit threshold is set to a potential change width of the potential change waveform element in the second micro-vibration waveform element, When the maximum potential change width in the first ejection waveform element is different from the maximum potential change width in the second ejection waveform element, the potential change width of the potential change waveform element in the first micro-vibration waveform element is different from the potential change width of the potential change waveform element in the second micro-vibration waveform element, or the potential change width of the potential change waveform element in the first micro-vibration waveform element and the potential change width of the potential change waveform element in the second micro-vibration waveform element match the first upper limit threshold. The driving method according to claim 2 .

4. The setting step includes: When the first candidate value is equal to or less than the first upper limit threshold, the first candidate value is set to a potential change width of the potential change waveform element in the first microvibration waveform element. The driving method according to claim 2 .

5. an acquiring step of acquiring temperature information relating to the temperature of the liquid in the first discharge portion; a first changing step of changing the first upper limit threshold in accordance with the temperature information, The setting step includes: If the first candidate value exceeds the first upper limit threshold changed by the first changing step, the first upper limit threshold is set to the potential change width of the potential change waveform element in the first micro-vibration waveform element. The driving method according to claim 2 .

6. The setting step includes: When the first candidate value is lower than a first lower threshold, the first lower threshold is set to a potential change width of the potential change waveform element in the first micro-vibration waveform element; The first lower limit threshold is a lower limit of the potential change width of the potential change waveform element in the micro-vibration waveform element that can eliminate the thickening of the liquid. The driving method according to claim 2 .

7. an acquiring step of acquiring temperature information relating to the temperature of the liquid in the first discharge portion; a second changing step of changing the first lower limit threshold in accordance with the temperature information, The setting step includes: When the first candidate value is lower than the first lower limit threshold changed by the second changing step, the first lower limit threshold is set to a potential change width of the potential change waveform element in the first micro-vibration waveform element. The driving method according to claim 6.

8. The determining step setting a first shape that is a candidate for a waveform shape of the first ejection pulse so that the amount of liquid ejected from the first nozzle when the first ejection pulse is supplied to the first drive element is a predetermined amount; When the maximum potential change width of the first ejection waveform element of the first shape exceeds a second upper limit threshold, the waveform shape of the first ejection pulse is determined so that the maximum potential change width in the first ejection waveform element is the second upper limit threshold; the second upper limit threshold is an upper limit of a maximum potential change width within an ejection waveform element that can stabilize the ejection of liquid; The driving method according to claim 1 .

9. The determining step When the maximum potential change width of the first ejection waveform element of the first shape is below a second lower limit threshold, determining the waveform shape of the first ejection pulse so that the maximum potential change width of the first ejection waveform element is the second lower limit threshold; the second lower limit threshold is a lower limit of a maximum potential change width within an ejection waveform element that allows the liquid to be ejected from the first nozzle at a predetermined ejection speed; The driving method according to claim 8.

10. a first ejection unit having a first nozzle that ejects liquid onto a medium, a first pressure chamber that communicates with the first nozzle, and a first drive element that drives the first nozzle in response to a supplied first drive signal so as to generate a pressure fluctuation in the liquid in the first pressure chamber; a first drive signal generating circuit that generates the first drive signal; a control circuit for controlling the first drive signal generation circuit; Equipped with the first drive signal includes a first ejection pulse having a first ejection waveform element that changes in potential so as to cause a pressure fluctuation in the liquid in the first pressure chamber to eject the liquid from the first nozzle, and a first minute vibration pulse having a first minute vibration waveform element that changes in potential so as to cause a pressure fluctuation in the liquid in the first pressure chamber without ejecting the liquid from the first nozzle, The control circuit determining a waveform shape of the first ejection pulse; A potential change width of a potential change waveform element in the first micro-vibration waveform element is set based on the determined maximum potential change width in the first ejection waveform element of the first ejection pulse and a first upper limit threshold value; the first upper limit threshold is an upper limit of the potential change width of the potential change waveform element in the micro-vibration waveform element that can stabilize the ejection of liquid; Liquid discharge device.

Images