Liquid discharge apparatus and driving method

Abstract

A liquid ejecting apparatus and a driving method. Generation of ink mist is suppressed. The liquid ejecting apparatus includes: an ejecting section having a nozzle that ejects liquid, a pressure chamber that communicates with the nozzle, and a driving element that is driven in accordance with a supplied driving signal to cause a pressure variation of the liquid in the pressure chamber; and a driving signal generation circuit that generates the driving signal, the driving signal including a first ejection pulse that causes the liquid to be ejected from the nozzle, the first ejection pulse having: a first pressure reduction potential variation element that drives the driving element to reduce the liquid pressure in the pressure chamber; and a first pressure increase potential variation element that drives the driving element to increase the liquid pressure in the pressure chamber after the first pressure reduction potential variation element so that a liquid surface protrudes from the nozzle, a potential variation amplitude of the first pressure reduction potential variation element being 40% or more of a potential variation amplitude of the first pressure increase potential variation element, and a potential variation rate of the first pressure reduction potential variation element being 1 V / µsec or more and 2 V / µsec or less.

Description

Technical Field

[0001] This invention relates to a liquid ejection device and a driving method. Background Technology

[0002] Previously, the following liquid ejection devices were becoming popular. These devices had an ejection section that formed an image on a medium such as recording paper. The ejection section included: a nozzle that ejected liquid such as ink; a pressure chamber that communicated with the nozzle; and a drive element that was driven according to a supplied drive signal to generate pressure changes in the liquid within the pressure chamber.

[0003] Patent Document 1: Japanese Patent Application Publication No. 2017-95814

[0004] However, in liquid ejection devices, fine, mist-like droplets, known as ink mist, sometimes form due to the stringing of the ejected liquid. If ink mist occurs, it can degrade ejection performance and cause poor ejection as it adheres to the area around the nozzle. This degraded ejection performance and poor ejection result in a decrease in the quality of the image formed on the medium. Summary of the Invention

[0005] The preferred embodiment of this disclosure relates to a liquid ejection device comprising: an ejection section having a nozzle, a pressure chamber, and a drive element, wherein the nozzle ejects liquid, the pressure chamber is in communication with the nozzle, the drive element is driven according to a supplied drive signal to cause a pressure change in the liquid within the pressure chamber; and a drive signal generation circuit for generating the drive signal; the drive signal includes a first ejection pulse that causes liquid to be ejected from the nozzle, the first ejection pulse having: a first decompression potential change element that drives the drive element to reduce the pressure of the liquid within the pressure chamber; and a first pressurization potential change element that drives the drive element after the first decompression potential change element to increase the pressure of the liquid within the pressure chamber so that the liquid surface protrudes from the nozzle, wherein the potential change amplitude of the first decompression potential change element is 40% or more of the potential change amplitude of the first pressurization potential change element, and the potential change rate of the first decompression potential change element is 1V / µs or more and 2V / µs or less.

[0006] The preferred embodiment of this disclosure relates to a driving method for a liquid ejection device, the liquid ejection device comprising: an ejection section having a nozzle, a pressure chamber, and a driving element, the nozzle ejecting liquid, the pressure chamber communicating with the nozzle, the driving element being driven according to a supplied driving signal to cause a pressure change in the liquid within the pressure chamber; and a driving signal generation circuit generating the driving signal, the driving signal including a first ejection pulse that causes liquid to be ejected from the nozzle, the first ejection pulse having: a first decompression potential change element, driving the driving element to reduce the pressure of the liquid within the pressure chamber; and a first... A pressure-increasing potential change element drives the driving element after the first pressure-reducing potential change element to increase the pressure of the liquid in the pressure chamber so that the liquid surface protrudes from the nozzle. The potential change amplitude of the first pressure-reducing potential change element is more than 40% of the potential change amplitude of the first pressure-increasing potential change element, and the potential change rate of the first pressure-reducing potential change element is more than 1V / µs and less than 2V / µs. The driving method performs the following steps: a first step of supplying the first pressure-reducing potential change element to the driving element of the ejection section; and a second step of supplying the first pressure-increasing potential change element to the driving element of the ejection section. Attached Figure Description

[0007] Figure 1 This is a schematic diagram illustrating a configuration example of the liquid ejection device 100 according to the first embodiment.

[0008] Figure 2 This is a diagram showing the electrical configuration of the liquid ejection device 100 according to the first embodiment.

[0009] Figure 3 This is a cross-sectional view showing an example of head chip 51.

[0010] Figure 4 This is a diagram used to illustrate the switching circuit 52.

[0011] Figure 5 This diagram is used to explain the reason for ink mist generation in the small dot ejection pulse in the comparison mode.

[0012] Figure 6 This is a diagram used to illustrate the drive signal Com used to generate the supply signal Vin supplied to the head chip 51.

[0013] Figure 7 This is a diagram used to illustrate the various elements of the small-point ejection pulse WS.

[0014] Figure 8 This is a flowchart illustrating the operation of the liquid ejection device 100 in the first embodiment.

[0015] Figure 9 This is a diagram used to illustrate the small-point ejection pulse WSb in the first modified example.

[0016] Figure 10 This is a diagram used to illustrate the small-point ejection pulse WSc in the second variation.

[0017] Figure 11 This is a diagram used to illustrate the large-point ejection pulse WLd in the third variation.

[0018] Figure 12 This is a diagram used to illustrate the large-point ejection pulse WLe in the fourth variation.

[0019] Figure 13 This is a diagram used to illustrate the large-point ejection pulse WLf in the fifth variation.

[0020] Explanation of reference numerals in the attached figures

[0021] 10…Liquid container; 20…Control unit; 21…Control circuit; 22…Storage circuit; 23…Power supply circuit; 24…Drive signal generation circuit; 30…Conveying mechanism; 40…Moving mechanism; 41…Carriage; 42…Conveyor belt; 50…Liquid nozzle; 51…Head chip; 51a…Flow path substrate; 51b…Pressure chamber substrate; 51c…Nozzle plate; 51d…Vibration absorber; 51e…Vibrating plate; 51f…Driver element; 51g…Protective plate; 51h…Housing; 51i…Wiring substrate; 52…Switching circuit; 52a…Connection status specification circuit; 100…Liquid ejection device; 200…External device; C…Pressure chamber, CH…Change signal; CHP, CHPa, CHPb, CHPc…Pressure Force characteristics; CI…waveform information; CLK…clock signal; Com…drive signal; D…ejection section; DR…ink droplet; EHA…highest potential; ELA…lowest potential; E0…reference potential; E1, E1a, E2, E2a, E3, E3a, E4, E4a…potential; FN…nozzle face; IH…inlet; Img…image data; L1…first column; L2…second column; LAT…latch signal; LC…liquid column; LHa, LHd…wiring; MN…curved surface; N…nozzle; Na…connecting flow path; PP…medium; Plc1, Plc1d, Plc1e, Plc1f, Plc2f…ejection elements; Pld1, Pld1d, Pld1e, Pld1f…filling Elements; Pld2, Pld2d, Pld2f… Vibration damping expansion elements; Pld1, Pld1d, Pld1e, Pld1f… Potential maintenance elements; Pld2, Pld2d, Pld2f… Vibration damping maintenance elements; Pld3f… Potential maintenance elements; PldsC, PldsL… Pulse; Pwc… Pressure change elements; Pwc1, Pwc1a… First pressure change elements; Pwc2, Pwc2a… Second pressure change elements; Pwca… Pressure change elements; Pwd… Pressure reduction change elements; Pwd1, Pwd1a, Pwd1c… First pressure reduction change elements; Pwd2, Pwd2a… Second pressure reduction change elements; Pwd3, Pw… d3a, Pwd3b…Third pressure reduction potential change element; Pwda…Pressure reduction potential change element; Pwh…Potential maintenance element; Pwh1, Pwh1a…First potential maintenance element; Pwh2, Pwh2a, Pwh2b…Second potential maintenance element; Pwh3, Pwh3a…Third potential maintenance element; Pwh4, Pwh4a…Fourth potential maintenance element; Pwha…Potential maintenance element; R…Reservoir; R1, R2…Space; Ra…Supply path; S2, S4, S6, S8…Step; SI…Printing data signal; SLa, SLb, SLc…Connection status specification signal; SWA…Switch; Sd…Individual specification signal; Sk1, Sk2…Control signal; TL…Wire drawing;Tc…natural vibration period; Tc1c2, Tc2d3, Tld1d, Tld1e, Tld1f, Tlh1d, Tlh1e, Tlh1f…period; Tu…unit period; Tu1, Tu2…control period; Twc1, Twc2, Twd1, Twd1c, Twd2, Twd3, Twh1, Twh2, Twh2b, Twh3, Twh4…period; V1, V1d, V1e, V1f, V2, V2 d, V2e, V2f, V3, V4… Potential change amplitude; VBS… Bias potential; VHV… Power supply potential; Vin… Supply signal; WL, WLd, WLe, WLf… Large point ejection pulse; WS, WSa, WSb, WSc… Small point ejection pulse; Zd, Zu… Electrode; ae… End potential maintenance element; ai… Connection element; as… Start potential maintenance element; dCom… Waveform specification signal; g1, g2, g3, g4… Chart. Detailed Implementation

[0022] Hereinafter, the embodiments for implementing this disclosure will be described with reference to the accompanying drawings. In the drawings, the dimensions and scales of the various parts are sometimes appropriately different from the actual dimensions and scales. Furthermore, since the embodiments described below are preferred examples of this disclosure, various technically preferred limitations are imposed; however, unless otherwise stated in the following description, the scope of this disclosure is not limited to these embodiments.

[0023] It should be noted that the following explanation appropriately uses the intersecting X-axis, Y-axis, and Z-axis. Furthermore, in the following description, the direction along the X-axis is the X1 direction, and the direction opposite to the X1 direction is the X2 direction. Similarly, the opposite directions along the Y-axis are the Y1 and Y2 directions. The opposite directions along the Z-axis are the Z1 and Z2 directions.

[0024] Here, typically, the Z-axis is a vertical axis, and the Z2 direction corresponds to the downward direction in the vertical direction. However, the Z-axis may not be a vertical axis. In addition, the X-axis, Y-axis, and Z-axis are typically orthogonal to each other, but are not limited to this; for example, they can intersect at an angle between 80° and 100°.

[0025] A: First Implementation Method

[0026] A1: Overall Composition of the Liquid Ejection Device

[0027] Figure 1This is a schematic diagram illustrating an example configuration of the liquid ejection apparatus 100 according to the first embodiment. The liquid ejection apparatus 100 is an inkjet printing apparatus that ejects ink, an example of a liquid, as droplets onto a medium PP. The medium PP is, for example, printing paper. It should be noted that the medium PP is not limited to printing paper, and may be any printing material such as resin film or fabric.

[0028] like Figure 1 As shown, the liquid ejection device 100 includes a liquid container 10, a control unit 20, a conveying mechanism 30, a moving mechanism 40, and a liquid ejection head 50.

[0029] Liquid container 10 stores ink. Specific examples of liquid container 10 include a box that can be detached from the liquid dispensing device 100, a bag-shaped ink pouch made of a flexible film, and an ink canister that can be refilled with ink. It should be noted that the type of ink stored in liquid container 10 is arbitrary.

[0030] The control unit 20 controls the operation of various elements of the liquid dispensing device 100. The control unit 20 may include, for example, one or more processing circuits such as a CPU (Central Processing Unit) or FPGA (Field Programmable Gate Array), and one or more storage circuits such as semiconductor memory. This will be discussed later based on... Figure 2 The detailed configuration of the control unit 20 will be explained.

[0031] Under the control of the control unit 20, the conveying mechanism 30 conveys the medium PP along the Y1 direction. Under the control of the control unit 20, the moving mechanism 40 causes the liquid nozzle 50 to reciprocate along the X-axis. The moving mechanism 40 has a generally box-shaped carriage 41 that houses the liquid nozzle 50, and an annular conveyor belt 42 that fixes the carriage 41. It should be noted that the number of liquid nozzles 50 mounted on the carriage 41 is not limited to one, and can be multiple. Alternatively, in addition to mounting the liquid nozzle 50, the aforementioned liquid container 10 may also be mounted on the carriage 41.

[0032] Under the control of the control unit 20, the liquid ejector head 50 ejects ink supplied from the liquid container 10 from each of the plurality of nozzles N onto the medium PP. This ejection, in parallel with the transport of the medium PP based on the transport mechanism 30 and the reciprocating movement of the liquid ejector head 50 based on the moving mechanism 40, forms an ink-based image on the surface of the medium PP.

[0033] A2: Electrical configuration of the liquid ejection device 100

[0034] Figure 2This is a diagram showing the electrical configuration of the liquid ejection device 100 according to the first embodiment. (See diagram below.) Figure 2 As shown, the liquid ejector head 50 has one head chip 51. However, the liquid ejector head 50 may also have multiple head chips 51.

[0035] The head chip 51 has a switching circuit 52 and M ejection sections D. Hereinafter, when the number of ejection sections D in the head chip 51 is set to M, in order to distinguish each of the M ejection sections D, the ejection section D is sometimes referred to as ejection section D[m] using the subscript [m]. Here, M is an integer of 2 or more, and m is an integer of 1 or more but less than or equal to M. Furthermore, in the liquid ejection device 100, the subscript [m] is sometimes used to describe the elements included in the ejection section D.

[0036] Under the control of the control unit 20, the switching circuit 52 switches whether to supply the drive signal Com output from the control unit 20 as the supply signal Vin to each of the M ejector sections D. It should be noted that, in this embodiment, although the switching circuit 52 is included in the head chip 51, it is also possible for the switching circuit 52 not to be included in the head chip 51.

[0037] The control unit 20 includes a control circuit 21, a storage circuit 22, a power supply circuit 23, and a drive signal generation circuit 24.

[0038] The control circuit 21 has the function of controlling the operation of various parts of the liquid dispensing device 100 and processing various data. The control circuit 21 includes, for example, one or more processors such as CPUs. It should be noted that the control circuit 21 may also replace the CPU or include programmable logic devices such as FPGAs in addition to CPUs. In addition, when the control circuit 21 is composed of multiple processors, the multiple processors may be mounted on different substrates.

[0039] In addition, the control circuit 21 generates control signals Sk1, Sk2, printing data signal SI, waveform specification signal dCom, latch signal LAT, change signal CH, and clock signal CLK through the execution of the program as signals for controlling the operation of each part of the liquid ejection device 100.

[0040] Control signal Sk1 is used to control the drive of the conveying mechanism 30. Control signal Sk2 is used to control the drive of the moving mechanism 40. Printing data signal SI is a digital signal used to specify the operating state of the drive element 51f. Latch signal LAT and change signal CH are timing signals used in conjunction with printing data signal SI to specify the timing of ink ejection from each nozzle N of the head chip 51.

[0041] In addition, the control circuit 21 executes the driving method in this embodiment by reading the program stored in the storage circuit 22 and executing the read program.

[0042] The storage 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 used to generate the waveform specification signal dCom. The storage circuit 22 may be a semiconductor memory comprising, for example, one or both of the following: volatile memory such as RAM (Random Access Memory), non-volatile memory such as ROM (Read Only Memory), EEPROM (Electrically Erasable Programmable Read-Only Memory), or PROM (Programmable Read-Only Memory). The image data Img is supplied from an external device 200 such as a personal computer or digital camera. It should be noted that the storage circuit 22 may also be configured as part of the control circuit 21.

[0043] The power supply circuit 23 receives power from a commercial power supply not shown in the figure and generates various predetermined potentials. These potentials are appropriately supplied to various parts of the liquid dispensing device 100. For example, the power supply circuit 23 generates a power supply potential VHV and a bias potential VBS. The bias potential VBS is supplied to the liquid nozzle 50. Additionally, the power supply potential VHV is supplied to the drive signal generation circuit 24.

[0044] The drive signal generation circuit 24 is a circuit that repeatedly generates drive signals Com for driving each drive element 51f included in each ejector section D. Specifically, the drive signal generation circuit 24 includes, for example, a DA conversion circuit and an amplification circuit. In the drive signal generation circuit 24, the DA conversion circuit converts the waveform specification signal dCom from the control circuit 21 from a digital signal to an analog signal. The amplification circuit generates the drive signal Com by amplifying the analog signal using the power supply potential VHV from the power supply circuit 23. The signal of the waveform actually supplied to the drive element 51f in the waveform included in the drive signal Com is the aforementioned supply signal Vin. The waveform specification signal dCom is a digital signal used to specify the waveform of the drive signal Com. The control circuit 21 generates the waveform specification signal dCom based on the waveform information CI. Figure 5 The details of waveform information CI will be discussed later.

[0045] A3: The specific structure of the head chip 51

[0046] Figure 3 This is a cross-sectional view showing an example of head chip 51. For example... Figure 3 As shown, the head chip 51 has M nozzles N arranged along the Y-axis. The M nozzles N are divided into a first column L1 and a second column L2 arranged side by side with intervals between them along the X-axis. The first column L1 and the second column L2 are each a set of 0.5 × M nozzles N arranged in a straight line along the Y-axis.

[0047] The head chip 51 is configured to be approximately symmetrical to each other along the X-axis. However, the positions of the plurality of nozzles N in the first column L1 and the plurality of nozzles N in the second column L2 along the Y-axis can be either the same or different. Figure 3 In the example, it is shown that the multiple nozzles N in the first column L1 and the multiple nozzles N in the second column L2 are positioned in the same direction along the Y-axis.

[0048] like Figure 3 As shown, 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, multiple driving elements 51f, a protection plate 51g, a housing 51h, and a wiring substrate 51i.

[0049] The flow path substrate 51a and the pressure chamber substrate 51b are sequentially stacked along the Z1 direction to form a flow path for supplying ink to M nozzles N. A vibrating plate 51e, M driving elements 51f, a protective plate 51g, a housing 51h, and a wiring substrate 51i are provided in a region located further along the Z1 direction than the stack formed by 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 provided in a region located further along the Z2 direction than the stack. The elements of the head chip 51 are generally plate-shaped components that are elongated in the Y direction and are joined together, for example, by adhesive. The elements of the head chip 51 will be described in detail below.

[0050] The nozzle plate 51c is a plate-shaped component having M nozzles N for each of the first column L1 and the second column L2. Each of the M nozzles N is a through-hole through which ink passes. These nozzles N are disposed on the nozzle surface FN facing the Z2 direction of the nozzle plate 51c. The nozzle plate 51c is manufactured, for example, 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 also be appropriately used in the manufacture of the nozzle plate 51c. In addition, the cross-sectional shape of the nozzles N is typically circular, but is not limited to this; for example, it may also be a non-circular shape such as a polygon or an ellipse.

[0051] On the flow path substrate 51a, a space R1, M supply flow paths Ra, and M connecting flow paths Na are provided for each of the first column L1 and the second column L2. In a top view along the Z-axis, the space R1 is an elongated opening extending along the Y-axis. Each supply flow path Ra and each connecting flow path Na is a through-hole formed for each nozzle N. Each supply flow path Ra communicates with the space R1.

[0052] The pressure chamber substrate 51b is a plate-shaped component having M pressure chambers C, referred to as cavities, for each of the first column L1 and the second column L2. The M pressure chambers C are arranged along the Y-axis. Each pressure chamber C is formed for each nozzle N and is an elongated space extending along the X-axis when viewed from above. The flow path substrate 51a and the pressure chamber substrate 51b are manufactured in the same manner as the aforementioned nozzle plate 51c, for example, by processing a silicon single crystal substrate using semiconductor manufacturing technology. However, other known methods and materials may be appropriately used in the manufacturing of the flow path substrate 51a and the pressure chamber substrate 51b.

[0053] The pressure chamber C is the space located between the flow path substrate 51a and the vibrating plate 51e. M pressure chambers C are arranged along the Y-axis for each of the first column L1 and the second column L2. Furthermore, the pressure chamber C is connected to both the connecting flow path Na and the supply flow path Ra. Therefore, the pressure chamber C is connected to the nozzle N via the connecting flow path Na and to the space R1 via the supply flow path Ra.

[0054] A vibrating plate 51e is disposed on the Z1-oriented surface of the pressure chamber substrate 51b. The vibrating plate 51e is a plate-shaped component capable of elastic vibration. The vibrating plate 51e has, for example, a first layer and a second layer, which are stacked sequentially along the Z1 direction. The first layer is, for example, an elastic film made of silicon oxide (SiO2). This elastic film is formed, for example, by thermal oxidation of one side of a silicon single crystal substrate. The second layer is, for example, an insulating film made of zirconium oxide (ZrO2). This insulating film is formed, for example, by sputtering a zirconium layer and then thermally oxidizing that layer. It should be noted that the vibrating plate 51e is not limited to the aforementioned stacking of the first and second layers; for example, it can be composed of a single layer or three or more layers.

[0055] On the Z1-oriented surface of the vibrating plate 51e, M drive elements 51f, corresponding to nozzles N, are arranged for each of the first column L1 and the second column L2. Each drive element 51f is a passive element that deforms upon the supply of a drive signal Com. Viewed from above, each drive element 51f appears as an elongated strip extending along the X-axis. The M drive elements 51f are arranged along the Y-axis in a manner corresponding to the M pressure chambers C. Viewed from above, the drive elements 51f overlap with the pressure chambers C.

[0056] Each drive element 51f is a piezoelectric element, and although not shown, it has a first electrode, a piezoelectric layer, and a second electrode, which are stacked sequentially along the Z1 direction. One of the first and second electrodes is a separate electrode arranged separately for each drive element 51f, and a supply signal Vin is applied to this electrode. The other electrode is a strip-shaped common electrode extending along the Y-axis in a continuous manner across 0.5 × M drive elements 51f, and a bias potential VBS is supplied to this other electrode. Examples of metal materials used for these electrodes include platinum (Pt), aluminum (Al), nickel (Ni), gold (Au), and copper (Cu), and one of them can be used alone or in combination of two or more in an alloy or stacked manner. The piezoelectric layer is made of a piezoelectric material such as lead zirconate titanate (Pb(Zr,Ti)O3), and for example, it is a strip-shaped material extending along the Y-axis in a continuous manner across 0.5 × M drive elements 51f. However, the piezoelectric layer can also be a single unit encompassing 0.5 × M driving elements 51f. In this case, through holes extending through the piezoelectric layer are provided in the region corresponding to the gaps between adjacent pressure chambers C when viewed from above, extending in the direction along the X-axis. If the vibrating plate 51e vibrates in conjunction with the deformation of the driving elements 51f, the pressure in the pressure chamber C changes, and ink is ejected from the nozzle N.

[0057] The protective plate 51g is a plate-shaped component disposed on the Z1-oriented surface of the vibrating plate 51e, protecting the M drive elements 51f and strengthening the mechanical strength of the vibrating plate 51e. Here, the M drive elements 51f are accommodated between the protective plate 51g and the vibrating plate 51e. The protective plate 51g is, for example, made of resin material.

[0058] The housing 51h is a component for storing ink supplied to the M pressure chambers C. The housing 51h is, for example, made of resin material. Within the housing 51h, spaces R2 are provided for each of the first column L1 and the second column L2. Spaces R2 communicate with the aforementioned space R1 and, together with space R1, function as reservoirs R for storing the ink supplied to the M pressure chambers C. The housing 51h is provided with inlets IH for supplying ink to each reservoir R. The ink in each reservoir R is supplied to the pressure chambers C via respective supply flow paths Ra.

[0059] The vibration absorber 51d, also known as a flexible circuit board, is a flexible resin film that forms the wall of the reservoir R, absorbing pressure fluctuations of the ink within the reservoir R. It should be noted that the vibration absorber 51d can also be a flexible sheet of metal. The Z1-oriented surface of the vibration absorber 51d is bonded to the flow path substrate 51a using an adhesive or the like.

[0060] The wiring substrate 51i is mounted on the Z1-oriented surface of the vibrating plate 51e and is a mounting component for electrically connecting the control unit 20 and the head chip 51. The wiring substrate 51i is, for example, a flexible wiring substrate such as COF (Chip On Film), FPC (Flexible Printed Circuit), or FFC (Flexible Flat Cable). In this embodiment, a switching circuit 52 for supplying drive voltage to each drive element 51f is mounted on the wiring substrate 51i.

[0061] like Figure 3 As illustrated, a jet section D includes a drive element 51f, a pressure chamber C, and a nozzle N. That is, M drive elements 51f correspond one-to-one with M pressure chambers C. As per... Figure 3 As can be understood, the drive element 51f corresponding to the pressure chamber C refers to the drive element 51f that partially or completely overlaps with the pressure chamber C when viewed from above in the Z2 direction. When a drive signal Com is supplied to the drive element 51f based on the printing data signal SI, the drive element 51f is driven by the drive signal Com, thereby causing the ejection section D to eject the ink in the pressure chamber C from the nozzle N.

[0062] A4: Driving element 51f

[0063] Figure 4 This is a diagram used to illustrate the switching circuit 52. The driving element 51f is driven by the supply signal Vin from the switching circuit 52. The following is based on... Figure 4 The switching circuit 52 will be described.

[0064] like Figure 4 As shown, wiring LHa is connected to the switching circuit 52. Wiring LHa is the signal line that transmits the drive signal Com. It should be noted that in Figure 4 In this context, for each integer m from 1 to M, one of the first electrode and the second electrode of the aforementioned driving element 51f is denoted as electrode Zd[m], and the other is denoted as electrode Zu[m]. A wiring LHd is connected to electrode Zd[m]. Wiring LHd is a power supply line that supplies the bias potential VBS.

[0065] The switching circuit 52 has M switches SWa, namely switches SWa[1] to SWa[M], and a connection state specifying circuit 52a that specifies the connection state of these switches.

[0066] For each integer m from 1 to M, switch SWA[m] is a switch that toggles the conduction and non-conduction between wiring LHa, used for transmitting the drive signal Com, and the electrode Zu[m] of the drive element 51f[m]. Each of these switches is, for example, a transmission gate.

[0067] The connection status specifying circuit 52a generates connection status specifying signals SLa[1] to SLa[M] for the on / off state of specified switches SWa[1] to SWa[M] based on the clock signal CLK, printed data signal SI, latch signal LAT and change signal CH supplied from the control circuit 21.

[0068] For example, although not shown, the connection state designation circuit 52a has multiple transmission circuits, multiple latching circuits, and multiple decoders in a one-to-one correspondence with the drive elements 51f[1] to 51f[M]. Among them, a print data signal SI is supplied to the transmission circuit. Here, in the print data signal SI, each drive element 51f includes... Figure 6 The individual specified signal Sd is represented in the figure. The individual specified signal Sd is supplied serially, for example, the individual specified signal Sd is transmitted sequentially to multiple transmission circuits in sync with the clock signal CLK. In addition, the latch circuit latches the individual specified signal Sd supplied to the transmission circuit based on the latch signal LAT. In addition, the decoder generates connection state specified signals SLa[m], SLb[m], and SLc[m] for each integer m from 1 to M based on the individual specified signal Sd and the latch signal LAT.

[0069] The switching circuit 52 switches the switch SWA[m] on and off based on the connection state specification signal SLa[m] generated as described above for each integer m from 1 to M. For example, the switch SWA[m] is in the on state when the connection state specification signal SLa[m] is high and in the off state when it is low. As described above, the switching circuit 52 supplies a portion or all of the waveform included in the drive signal Com as the supply signal Vin to the drive element 51f of one or more ejector sections D selected from the M ejector sections D.

[0070] A5: About Ink Mist

[0071] To improve either or both of the ink ejection volume and ejection speed (i.e., ejection performance) from nozzle N, a drive signal Com with an ejection pulse having an inherent vibration period Tc based on the ejector section D is considered. The ejection pulse causes ink to be ejected from nozzle N.

[0072] In addition, during ink ejection, fine, misty ink droplets, known as ink mist, may sometimes be generated due to the stringing of the ejected ink. If ink mist is generated, it may cause deterioration of ejection performance and poor ejection because it adheres to the area around nozzle N.

[0073] Furthermore, the drive signal Com can have large-dot ejection pulses that eject ink equivalent to a large dot amount, and small-dot ejection pulses that eject ink equivalent to a small dot amount. Hereinafter, large-dot ejection pulses and small-dot ejection pulses will sometimes be referred to simply as ejection pulses without distinguishing between them. Through the inventors' experiments, it has been found that if an attempt is made to ensure the ejection speed of the ejection pulse is at the level desired by the manufacturer of the liquid ejector head 50, ink mist may sometimes be generated in the ejection pulse. Hereinafter, this ejection pulse will sometimes be referred to as the ejection pulse in a comparative mode. Furthermore, the two types of ejection pulses in the comparative mode will sometimes be referred to as the large-dot ejection pulse in the comparative mode and the small-dot ejection pulse in the comparative mode. Additionally, the manufacturer of the liquid ejector head 50 will sometimes be referred to as a head manufacturer. Figure 5 The reason for the generation of ink mist in the small dot ejection pulse in the comparison method is explained.

[0074] Figure 5 This diagram is used to explain the reason for ink mist generation in the small dot ejection pulse in the comparison mode. Figure 5 Graph g1 shows the potential of the small-dot ejection pulse WSa and the pressure of the ink in ejection section D in the comparison method. The pressure characteristic CHPa shown in Graph g1 represents the pressure characteristic of the ink in ejection section D when the small-dot ejection pulse WSa in the comparison method is supplied to ejection section D. The horizontal axis of Graph g1 represents time, the vertical axis of Graph g1 represents potential with respect to the small-dot ejection pulse WSa, and the vertical axis of Graph g1 represents pressure with respect to the pressure in the ink. In Graph g1, [μs] means the unit of time, i.e., microsecond, [V] means the unit of potential, i.e., volt, and [kPa] means the unit of pressure, i.e., kilopascal.

[0075] The small-point ejected pulse WSa in the comparison method has a first depressurization potential change element Pwd1a, a first potential maintenance element Pwh1a, a first applied pressure potential change element Pwc1a, a third potential maintenance element Pwh3a, a second depressurization potential change element Pwd2a, a fourth potential maintenance element Pwh4a, a second applied pressure potential change element Pwc2a, a second potential maintenance element Pwh2a, and a third depressurization potential change element Pwd3a. Hereinafter, the first depressurization potential change element Pwd1a, the second depressurization potential change element Pwd2a, and the third depressurization potential change element Pwd3a are sometimes referred to as the depressurization potential change element Pwda without distinguishing between them. Sometimes, the first applied pressure potential change element Pwc1a and the second applied pressure potential change element Pwc2a are sometimes referred to as the applied pressure potential change element Pwca without distinguishing between them. Sometimes, the first potential maintenance element Pwh1a, the third potential maintenance element Pwh3a, the fourth potential maintenance element Pwh4a, and the second potential maintenance element Pwh2a are not distinguished and are simply recorded as the potential maintenance element Pwha.

[0076] The depressurization potential change element Pwda drives the drive element 51f to reduce the pressure of the ink in the pressure chamber C. The pressurization potential change element Pwca drives the drive element 51f to increase the pressure of the ink in the pressure chamber C. The potential maintenance element Pwha maintains the potential from its beginning to its end.

[0077] The beginning of the first decompression potential change element Pwd1a coincides with the beginning of the small-point ejection pulse WSa. The first decompression potential change element Pwd1a changes the initial potential (reference potential E0) of the small-point ejection pulse WSa to potential E1a, thereby generating negative pressure within pressure chamber C. The reference potential E0 is approximately 9.6 [V]. Potential E1a is approximately 0 [V]. The potential change rate of the first decompression potential change element Pwd1a is greater than 2 V / microsecond. The potential change rate is obtained by dividing the potential change amplitude by the length of the period during which the potential changes. The potential change amplitude is the potential difference between the potential at the beginning and the end of the period during which the potential changes. In this specification, the potential difference between two potentials is the absolute value of the difference between the values ​​of one potential and the other.

[0078] The first potential maintenance element Pwh1a is connected to the terminal of the first depressurization potential change element Pwd1a, and maintains the potential E1a. The first pressurization potential change element Pwc1a is connected to the terminal of the first potential maintenance element Pwh1a, and changes from potential E1a to potential E2a, thereby generating positive pressure in pressure chamber C. Potential E2a is approximately 16 [V]. The third potential maintenance element Pwh3a is connected to the terminal of the first pressurization potential change element Pwc1a, and maintains the potential E2a. The second depressurization potential change element Pwd2a changes from potential E2a to potential E3a, thereby generating negative pressure in pressure chamber C. Potential E3a is approximately 10.3 [V]. The fourth potential maintenance element Pwh4a is connected to the terminal of the second depressurization potential change element Pwd2a, and maintains the potential E3a. The second pressurization potential change element Pwc2a is connected to the terminal of the fourth potential maintenance element Pwh4a, and changes from potential E3a to potential E4a, thereby generating positive pressure in pressure chamber C. The potential E4a is approximately 20 [V]. The second potential maintenance element Pwh2a is connected to the terminal of the second pressurization potential change element Pwc2a and maintains the potential E4a. The third depressurization potential change element Pwd3a is connected to the terminal of the second potential maintenance element Pwh2a, and changes from potential E4a to the reference potential E0, thereby generating negative pressure in the pressure chamber C.

[0079] Furthermore, in Figure 5 The image shows the state of ink droplets DR being ejected from nozzle N. More specifically, a liquid column (not shown) is formed along the Z-axis at the liquid surface (curved surface MN) of nozzle N. Ink droplets DR are ejected by the splitting of this liquid column. By cutting the liquid column, stringing (TL) is formed on the ink droplets DR. Furthermore, according to… Figure 5 As can be understood, by supplying the third depressurization potential change element Pwd3a to the drive element 51f, the meniscus MN is introduced in the Z1 direction. Therefore, a force in the Z1 direction acts on the liquid column at its Z1 position, i.e., the base portion of the liquid column, while a force in the Z2 direction acts on the Z2 front portion of the liquid column. Thus, the inventors' experiments have shown that because two forces in opposite directions act on the liquid column, a large amount of ink mist is generated if an attempt is made to ensure the ejection speed desired by the head manufacturer.

[0080] Therefore, in this embodiment, the amount of ink mist generated is suppressed by adjusting the timing of the liquid column splitting. Figure 6 as well as Figure 7 The driving signal Com, which includes the small-point ejection pulse WS, will be explained in this embodiment.

[0081] A6: Drive signal Com

[0082] Figure 6This diagram illustrates the drive signal Com used to generate the supply signal Vin supplied to the head chip 51. In this embodiment, the operation period of the liquid ejection device 100 includes one or more unit periods Tu. It should be noted that, generally, the liquid ejection device 100 forms the image shown in the image data Img by ejecting liquid from each ejection section D over multiple unit periods Tu, either continuously or intermittently.

[0083] like Figure 6 As shown, control circuit 21 outputs a latch signal LAT with a pulse PlsL and a change signal CH with a pulse PlsC. Thus, control circuit 21 defines the unit period Tu as the period from the rising edge of pulse PlsL to the rising edge of the next pulse PlsL. The specific length or period of the unit period Tu is not specifically limited. Furthermore, control circuit 21 divides the unit period Tu into two control periods, Tu1 and Tu2, using pulse PlsC.

[0084] The printing data signal SI includes individual designation signals Sd[1] to Sd[M] that specify the driving mode of the ejector parts D[1] to D[M] in each unit period Tu. As mentioned 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 integer m from 1 to M in that unit period Tu.

[0085] The individually specified signal Sd[m] is a signal that specifies any one of the three driving modes for the ejector section D[m] during each unit period Tu: ejection of ink equivalent to a large amount of ink, ejection of ink equivalent to a small amount of ink, and no ejection.

[0086] like Figure 6 As shown, the drive signal generation circuit 24 outputs a drive signal Com, which sequentially includes a start potential maintenance element as, a small-point ejection pulse WS, a connection element ai, a large-point ejection pulse WL, and an end potential maintenance element ae within a unit period Tu. The start potential maintenance element as, the small-point ejection pulse WS, and a portion of the start time including the connection element ai are set within the control period Tu1. A portion of the end time including the connection element ai, the large-point ejection pulse WL, and the end potential maintenance element ae are set within the control period Tu2.

[0087] The start potential maintenance element *as* maintains the reference potential *E0* from the beginning of a unit period *Tu* to the beginning of the small-point ejection pulse *WS*. The connection element *ai* maintains the reference potential *E0* from the end of the small-point ejection pulse *WS* to the beginning of the large-point ejection pulse *WL*. The end potential maintenance element *ae* maintains the reference potential *E0* from the end of the large-point ejection pulse *WL* to the end of a unit period *Tu*.

[0088] use Figure 7 The elements of the small-dot ejection pulse WS are explained. The large-dot ejection pulse WL sequentially includes a filling element Pld1, a potential maintenance element Plh1, an ejection element Plc1, a vibration damping maintenance element Plh2, and a vibration damping expansion element Pld2. The filling element Pld1 changes from the reference potential E0 to the lowest potential ELA, creating a negative pressure in the pressure chamber C. The lowest potential ELA is the lowest potential within the large-dot ejection pulse WL. The terminal of the filling element Pld1 is connected to the beginning of the potential maintenance element Plh1. The potential maintenance element Plh1 maintains the lowest potential ELA. The terminal of the potential maintenance element Plh1 is connected to the ejection element Plc1. The ejection element Plc1 changes from the lowest potential ELA to the highest potential EHA, creating a positive pressure in the pressure chamber C. The highest potential EHA is the highest potential within the large-dot ejection pulse WL. If the drive element 51f receives a supply from the ejection element Plc1, it causes ink droplets to be ejected from the nozzle N. The vibration damping maintenance element Plh2 maintains the highest potential EHA from the end of the ejection element Plc1. The vibration damping expansion element Pld2 begins to change potential from the end of the vibration damping maintenance element Plh2, causing the pressure chamber C to expand. The vibration damping expansion element Pld2 changes potential from the highest potential EHA to the reference potential E0.

[0089] When a signal Sd[m] is individually assigned to each integer from 1 to M to specify the amount of ink to be ejected from the ejector section D[m] in the form of a small dot, the connection state specifying circuit 52a is set to a high level during control period Tu1 and a low level during control period Tu2. In this case, the ejector section D[m] is driven by the small dot ejection pulse WS during control period Tu1, ejecting an amount of ink in the form of a small dot.

[0090] When a signal Sd[m] is individually assigned to the ejector section D[m] for each integer m from 1 to M, specifying an ink ejection amount equivalent to a large dot, the connection state specifying circuit 52a is set to a low level during control period Tu1 and a high level during control period Tu2. In this case, the ejector section D[m] is driven by the large dot ejection pulse WL during control period Tu2 and ejects ink.

[0091] It should be pointed out that, in Figure 6In this context, the unit period Tu is divided into two control periods, Tu1 and Tu2. The drive signal Com has one ejection pulse for each of the control periods Tu1 and Tu2, but this is not a limitation. For example, the drive signal Com could have two systems of signals, drive signal Com-A and drive signal Com-B, with a small ejection pulse WS in one signal and a large ejection pulse WL in the other.

[0092] Figure 7 This is a diagram used to illustrate the various elements of the small-point ejection pulse (WS). Furthermore, Figure 7 The graph g2 shown represents the potential of the dot ejection pulse WS and the pressure of the ink in the ejection section D. The pressure characteristic CHP shown in graph g2 represents the pressure characteristic of the ink in the ejection section D when the dot ejection pulse WS is supplied to the ejection section D.

[0093] The small-point ejected pulse WS sequentially comprises a first depressurization potential change element Pwd1, a first potential maintenance element Pwh1, a first applied pressure potential change element Pwc1, a third potential maintenance element Pwh3, a second depressurization potential change element Pwd2, a fourth potential maintenance element Pwh4, a second applied pressure potential change element Pwc2, a second potential maintenance element Pwh2, and a third depressurization potential change element Pwd3. Hereinafter, the first depressurization potential change element Pwd1, the second depressurization potential change element Pwd2, and the third depressurization potential change element Pwd3 are sometimes referred to as the depressurization potential change element Pwd without distinguishing between them. The first applied pressure potential change element Pwc1 and the second applied pressure potential change element Pwc2 are sometimes referred to as the applied pressure potential change element Pwc without distinguishing between them. The first potential maintenance element Pwh1, the third potential maintenance element Pwh3, the fourth potential maintenance element Pwh4, and the second potential maintenance element Pwh2 are sometimes referred to as the potential maintenance element Pwh. It should be noted that the small-point ejection pulse WS is an example of the "first ejection pulse".

[0094] The pressure reduction potential change element Pwd drives the drive element 51f to reduce the pressure of the ink in the pressure chamber C. The pressure increase potential change element Pwc drives the drive element 51f to increase the pressure of the ink in the pressure chamber C. The potential maintenance element Pwh maintains the potential from its beginning to its end. The potential E1 maintained by the first potential maintenance element Pwh1 is approximately the same as potential E1a. The potential E2 maintained by the third potential maintenance element Pwh3 is approximately the same as potential E2a. The potential E3 maintained by the fourth potential maintenance element Pwh4 is approximately the same as potential E3a. The potential E4 maintained by the second potential maintenance element Pwh2 is approximately the same as potential E4a.

[0095] Figure 2The waveform information CI shown specifies the small-point ejection pulse WS and large-point ejection pulse WL of the drive signal Com. Specifically, the waveform information CI has termination information, which includes information indicating the time of termination of each element of the drive signal Com and information indicating the potential of the termination. For example, the waveform information CI has termination information for the start potential maintenance element as, the small-point ejection pulse WS, the connection element ai, the large-point ejection pulse WL, and the end potential maintenance element ae. The termination information of the small-point ejection pulse WS includes termination information for the first depressurization potential change element Pwd1, the first potential maintenance element Pwh1, the first pressurization potential change element Pwc1, the third potential maintenance element Pwh3, the second depressurization potential change element Pwd2, the fourth potential maintenance element Pwh4, the second pressurization potential change element Pwc2, the second potential maintenance element Pwh2, and the third depressurization potential change element Pwd3. The terminal information of the large-point ejection pulse WL includes the terminal information of the filling element Pld1, the terminal information of the potential maintenance element Plh1, the terminal information of the ejection element Plc1, the terminal information of the vibration damping maintenance element Plh2, and the terminal information of the vibration damping expansion element Pld2. The terminal information of the end potential maintenance element ae includes a signal indicating the time of the terminal, representing one unit period Tu.

[0096] The durations of each element in the small-point ejection pulse WS are explained. For example, the duration Twd1 of the first depressurization potential change element Pwd1 is 0.63 times the length of Tc. The duration Twh1 of the first potential maintenance element Pwh1 is 0.15 times the length of Tc. The duration Twc1 of the first pressurization potential change element Pwc1 is 0.26 times the length of Tc. The duration Twh3 of the third potential maintenance element Pwh3 is 0.16 times the length of Tc. The duration Twd2 of the second depressurization potential change element Pwd2 is 0.14 times the length of Tc. The duration Twh4 of the fourth potential maintenance element Pwh4 is 0.10 times the length of Tc. The duration Twc2 of the second pressurization potential change element Pwc2 is 0.20 times the length of Tc. The duration Twh2 of the second potential maintenance element Pwh2 is 0.76 times the length of Tc. The duration Twd3 of the third decompression potential change element Pwd3 is 0.63 times the length of Tc. The differences between the elements in the comparison method and those of the small-point ejection pulse WSa are described below.

[0097] The potential change amplitude V1 of the first depressurization potential change element Pwd1 is more than 40% of the potential change amplitude V2 of the first pressurization potential change element Pwc1. The potential change amplitude V1 is the potential difference between the reference potential E0 and the potential E1. The potential change amplitude V2 is the potential difference between the potential E1 and the potential E2. For example, the potential change amplitude V1 is 60% of the potential change amplitude V2.

[0098] Furthermore, the potential change rate of the first depressurization potential change element Pwd1 is greater than or equal to 1 V / µs and less than or equal to 2 V / µs. The potential change rate of the first depressurization potential change element Pwd1 is obtained by dividing the potential change amplitude V1 by the length of the period Twd1 of the first depressurization potential change element Pwd1. The potential change rate of the first depressurization potential change element Pwd1 is 1.92 V / µs.

[0099] Furthermore, the duration Twh1 of the first potential maintenance element Pwh1 and the duration Twh3 of the third potential maintenance element Pwh3 are 0.1 times or more and 0.25 times or less of Tc. For example, the duration Twh1 is 0.15 times Tc as described above, and the duration Twh3 is 0.16 times Tc as described above.

[0100] Furthermore, the potential change rate of the first applied voltage potential change element Pwc1 is 4 V / µs or more. For example, the potential change rate of the first applied voltage potential change element Pwc1 is 7.62 V / µs. Additionally, the potential change rates of both the second applied voltage potential change element Pwd2 and the second applied voltage potential change element Pwc2 are preferably 4 V / µs or more. For example, the potential change rate of the second applied voltage potential change element Pwd2 is 5.45 V / µs, and the potential change rate of the second applied voltage potential change element Pwc2 is 6.25 V / µs. On the other hand, the potential change rate of the third applied voltage potential change element Pwd3 is 2.08 V / µs, which is less than 4 V / µs.

[0101] Furthermore, the period Twd1 of the first decompression potential change element Pwd1 is less than or equal to Tc. For example, the period Twd1 is 0.63 times Tc as described above.

[0102] Furthermore, the period Tc2d3 from the beginning of the second applied pressure potential change element Pwc2 to the beginning of the third depressurized pressure potential change element Pwd3 is more than 0.75 times Tc. For example, the period Tc2d3 is 0.96 times Tc.

[0103] Furthermore, the period Tc1c2 from the start of the first applied voltage change element Pwc1 to the start of the second applied voltage change element Pwc2 is a period that is 0.5 times or more and 0.75 times Tc. For example, the period Tc1c2 is 0.66 times Tc.

[0104] Furthermore, the potential change amplitude V4 of the second applied pressure potential change element Pwc2 is more than 50% and less than 70% of the potential change amplitude V2 of the first applied pressure potential change element Pwc1. The potential change amplitude V4 is the potential difference between potential E3 and potential E4. For example, the potential change amplitude V4 is 63% of the potential change amplitude V2.

[0105] Furthermore, the duration Twh2 of the second potential maintenance element Pwh2 is more than 0.5 times Tc. For example, the duration Twh2 is 0.76 times Tc.

[0106] The potential change amplitude V3 of the second pressure reduction potential change element Pwd2 is more than 20% and less than 50% of the potential change amplitude V2. The potential change amplitude V3 is the potential difference between potential E2 and potential E3. For example, the potential change amplitude V3 is 38% of the potential change amplitude V2.

[0107] The pressure characteristic CHP is explained by comparing it with the pressure characteristic CHPa. In the comparison method, the potential change rate of the first decompression potential change element Pwd1a is greater than 2V / µs. Therefore, as shown in the pressure characteristic CHPa, the pressure vibration generated in the ink within the ejection section D increases. Specifically, as shown in the pressure characteristic CHPa, from the start time of the first decompression potential change element Pwd1a to the end time of the first pressurization potential change element Pwc1a, the ink pressure drops to approximately -200 kPa and then rises to approximately 650 kPa. On the other hand, in this embodiment, the potential change rate of the first decompression potential change element Pwd1 is more than 1V / µs and less than 2V / µs. Therefore, as shown in the pressure characteristic CHP, the magnitude of the pressure vibration generated in the ink within the ejection section D is more suppressed compared to the comparison method. Specifically, as shown in the pressure characteristic CHP, from the start time of the first decompression potential change element Pwd1 to the end time of the first pressurization potential change element Pwc1, the pressure of the ink drops to about 0 kPa and then rises to about 450 kPa. However, the amplitude of the pressure vibration of the ink in the pressure characteristic CHP is smaller than the amplitude of the pressure vibration of the ink in the pressure characteristic CHPa.

[0108] Furthermore, in Figure 7The diagram illustrates the meniscus MN within the nozzle N when all elements of the small-point ejection pulse WS are supplied to the drive element 51f. At the start of the first decompression potential change element Pwd1, the meniscus MN is positioned approximately parallel to the XY plane. At the start of the first potential maintenance element Pwh1, the meniscus MN is introduced in the Z1 direction due to the first decompression potential change element Pwd1, and the leading edge of the central portion of the meniscus MN is positioned further in the Z1 direction than the nozzle surface FN. Although the leading edge of the central portion of the meniscus MN gradually moves in the Z2 direction during the first potential maintenance element Pwh1, even at the start of the first pressurization potential change element Pwc1, the leading edge of the meniscus MN is positioned further in the Z1 direction than the nozzle surface FN.

[0109] The meniscus MN is squeezed out in the Z2 direction due to the first pressure change element Pwc1. At the start of the third potential maintenance element Pwh3, the meniscus MN is located near the opening of the nozzle N. At the start of the second pressure reduction change element Pwd2, the meniscus MN squeezed out in the Z2 direction due to the first pressure change element Pwc1 forms a liquid column LC protruding in the Z2 direction.

[0110] At the beginning of the fourth potential maintenance element Pwh4, due to the second decompression potential change element Pwd2, a force in the Z1 direction acts on the base portion of the liquid column LC, while a force in the Z2 direction acts on the front portion of the liquid column LC. Therefore, two forces in opposite directions act on the liquid column LC, and the liquid column LC grows along the Z-axis.

[0111] Following this, the ink within nozzle N is again extruded in the Z2 direction due to the second pressure potential change element Pwc2. At the start of the second potential maintenance element Pwh2, the leading edge of the liquid column LC continues to move in the Z2 direction and grows along the Z-axis. During the second potential maintenance element Pwh2, the ink is extruded from nozzle N towards the base of the liquid column LC due to the second pressure potential change element Pwc2. Furthermore, at the start of the third pressure reduction potential change element Pwd3, the ink extruded from the base of the liquid column LC due to the second pressure potential change element Pwc2 moves towards the leading edge of the liquid column LC, and the leading edge of the liquid column LC also moves in the Z2 direction, causing the liquid column LC to grow elongated along the Z-axis.

[0112] During the period when the ink in the nozzle N is introduced in the Z1 direction while being supplied with the third depressurization potential change element Pwd3, the liquid column LC splits between the ink extruded due to the second pressure change element Pwc2 and the leading edge portion, and ink droplets DR are ejected. At the time of the splitting of the liquid column LC, although the base portion of the liquid column LC moves in the Z1 direction, the splitting of the liquid column LC mainly occurs due to the action of surface tension, and occurs in the portion between the ink extruded due to the second pressure change element Pwc2 and the leading edge portion where two forces acting in opposite directions do not act on each other. After the second pressure potential change element Pwc2, the duration Twh2 of the second potential maintenance element Pwh2 is set to a length of 0.5 times or more of Tc. Therefore, during the movement of the leading edge of the liquid column LC along the Z2 direction, the force introduced in the Z1 direction will not act on the liquid column LC due to the displacement of the driving element 51f. Instead, the velocity distribution of the leading edge, central portion, and base of the liquid column LC causes the liquid column LC to neck at a splitting point, and the leading edge of the liquid column LC splits into ink droplets DR primarily due to surface tension. Therefore, compared to the comparative method, the generation of ink mist can be suppressed in this embodiment.

[0113] At the end of the third decompression potential change element Pwd3, the ink droplet DR moves along the Z2 direction, and the leading edge of the liquid column LC after splitting into ink droplets DR moves along the Z1 direction.

[0114] A7: Actions of the First Implementation Method

[0115] Figure 8 This is a flowchart illustrating the operation of the liquid ejection device 100 in the first embodiment. Figure 8The series of processes shown is executed upon receiving image data Img from external device 200. In step S2, control circuit 21 acquires waveform information CI from storage circuit 22. Next, in step S4, control circuit 21 generates a waveform specification signal dCom based on the waveform information CI. Then, in step S6, control circuit 21 outputs the waveform specification signal dCom to drive signal generation circuit 24. By executing step S6, drive signal generation circuit 24 outputs drive signal Com to liquid ejector head 50. By outputting the waveform specification signal dCom to drive signal generation circuit 24, control circuit 21 causes drive signal generation circuit 24 to supply drive signal Com to ejection section D. After the processing in step S6 is completed, in step S8, control circuit 21 outputs the printing data signal SI generated based on image data Img to liquid ejector head 50 per unit period Tu. Imagine that for any m from 1 to M, the individual specification signal Sd[m] included in the printing data signal SI is a signal specifying the amount of ink ejected, corresponding to a small dot. In this design, the drive signal generation circuit 24 supplying the first depressurization potential change element Pwd1 included in the small dot ejection pulse WS to the drive element 51f of the ejection section D [m] is an example of the "first step," and the drive signal generation circuit 24 supplying the first pressurization potential change element Pwc1 included in the small dot ejection pulse WS to the drive element 51f of the ejection section D [m] is an example of the "second step." When step S8 is executed multiple times and an image is formed on the medium PP, the control circuit 21 terminates. Figure 8 The series of processes shown.

[0116] A8: Summary of the First Implementation Method

[0117] The liquid ejection device 100 includes an ejection section D and a drive signal generation circuit 24 for generating a drive signal Com. The ejection section D includes: a nozzle N for ejecting ink; a pressure chamber C connected to the nozzle N; and a drive element 51f that is driven according to the supplied drive signal Com to cause pressure fluctuations in the ink within the pressure chamber C. The drive signal Com includes a small-dot ejection pulse WS that causes ink to be ejected from the nozzle N. The small-dot ejection pulse WS includes: a first depressurization potential change element Pwd1 that drives the drive element 51f to reduce the pressure of the ink within the pressure chamber C; and a first pressurization potential change element Pwc1 that drives the drive element 51f after the first depressurization potential change element Pwd1 to increase the pressure of the ink within the pressure chamber C, so that the liquid surface protrudes from the nozzle N. The potential change amplitude V1 of the first depressurization potential change element Pwd1 is 40% or more of the potential change amplitude V2 of the first pressurization potential change element Pwc1, and the potential change rate of the first depressurization potential change element Pwd1 is 1V / µs or more and 2V / µs or less.

[0118] Alternatively, in the first embodiment, a driving method for a liquid ejection device 100 having an ejection section D and a drive signal generation circuit 24 can also be specified. The drive signal generation circuit 24 performs the steps of supplying a first depressurization potential change element Pwd1 to the drive element 51f of the ejection section D and supplying a first pressurization potential change element Pwc1 to the drive element 51f of the ejection section D.

[0119] In the case where the potential change rate of the first depressurization potential change element Pwd1 is greater than 2V / µs, as shown in the comparison method, the amplitude of the pressure vibration generated in the ink within the ejection section D increases, making stringing more likely. On the other hand, in the case where the potential change rate of the first depressurization potential change element Pwd1 is less than 1V / µs, in addition to the time consumed until the ink is fully filled into the pressure chamber C, the amplitude of the pressure vibration generated in the ink within the ejection section D is also too small. If the amplitude of the pressure vibration generated in the ink within the ejection section D is too small, it becomes difficult to ensure the speed of the ink droplet DR separated from the meniscus MN in the first pressurization potential change element Pwc1 after the first depressurization potential change element Pwd1. As described above, according to the first embodiment, since the ink is fully filled into the pressure chamber C before the meniscus MN protrudes, and the amplitude of the pressure vibration generated in the ink within the ejection section D is not excessively increased, it is possible to reduce stringing TL while ensuring the ejection speed of the ink droplet DR after separation from the meniscus MN.

[0120] In addition, the small-point ejection pulse WS also has a first potential maintenance element Pwh1, which connects the terminal of the first depressurization potential change element Pwd1 and the beginning of the first pressurization potential change element Pwc1, and maintains the potential E1 at a predetermined potential. The first potential maintenance element Pwh1 is for a period of more than 0.1 times and less than 0.25 times Tc.

[0121] In the mode where the first potential maintenance element Pwh1 is longer than 0.25 times Tc, the timing of pressurizing the ink in the ejection section D by supplying the first pressure change element Pwc1 overlaps with the timing of the decrease in ink pressure in the ejection section D, and the pressure vibration of the ink in the ejection section D is attenuated. On the other hand, in the first embodiment, compared with the mode where the first potential maintenance element Pwh1 is longer than 0.25 times Tc, the timing of pressurizing the ink in the ejection section D by supplying the first pressure change element Pwc1 overlaps with the timing of the increase in ink pressure in the ejection section D due to pressure vibration. Therefore, according to the first embodiment, since the increase in ink pressure in the ejection section D can be multiplied, the ejection speed of the ink droplet DR based on the small dot ejection pulse WS can be ensured.

[0122] In addition, the potential change rate of the first applied voltage potential change element Pwc1 is above 4V / microsecond.

[0123] According to the first embodiment, compared with the first pressure potential change element Pwc1 having a potential change rate of less than 4V / microsecond, the ejection speed of ink droplets DR based on small dot ejection pulses WS can be ensured.

[0124] In addition, the first decompression potential change element Pwd1 is the period below Tc.

[0125] In a configuration where the duration of the first depressurization potential change element Pwd1 is longer than Tc, the amplitude of the pressure vibration generated in the ink within the ejection section D becomes too small, making it difficult to ensure the velocity of the ink droplet DR after separation from the meniscus MN in the first pressurization potential change element Pwc1 following the first depressurization potential change element Pwd1. Therefore, according to the first embodiment, compared to a configuration where the duration of the first depressurization potential change element Pwd1 is longer than Tc, it is possible to ensure the velocity of the ink droplet DR after separation from the meniscus MN in the first pressurization potential change element Pwc1.

[0126] In addition, the small-dot ejection pulse WS also includes: a second depressurization potential change element Pwd2, which drives the drive element 51f after the first pressurization potential change element Pwc1 to reduce the pressure of the ink in the pressure chamber C; a second pressurization potential change element Pwc2, which drives the drive element 51f after the second depressurization potential change element Pwd2 to increase the pressure of the ink in the pressure chamber C; a second potential maintenance element Pwh2, which maintains the potential from the end of the second pressurization potential change element Pwc2; and a third depressurization potential change element Pwd3, which is connected to the end of the second potential maintenance element Pwh2 and drives the drive element 51f to reduce the pressure of the ink in the pressure chamber C. The period Tc2d3 from the beginning of the second pressurization potential change element Pwc2 to the beginning of the third depressurization potential change element Pwd3 is more than 0.75 times Tc.

[0127] The small-dot ejection pulse WS is used to adjust the weight of the ink droplets DR by repeatedly changing the pressure potential change element Pwc and the depressurization potential change element Pwd. According to the first embodiment, compared with a method where the period Tc2d3 is less than 0.75 times Tc, the fiber drawing TL can be reduced.

[0128] Furthermore, during the period from the start of the first applied voltage change element Pwc1 to the start of the second applied voltage change element Pwc2, when Tc1c2 is more than 0.5 times and less than 0.75 times Tc, the potential change amplitude V4 of the second applied voltage change element Pwc2 is more than 50% and less than 70% of the potential change amplitude V2 of the first applied voltage change element Pwc1.

[0129] According to the first embodiment, when a portion of the liquid column LC separates from the ink in the nozzle N, it can be made to follow the leading edge of the liquid column LC in a manner that does not reduce the speed of the trailing edge of the liquid column LC. By making it follow the leading edge of the liquid column LC in a manner that does not reduce the speed of the trailing edge of the liquid column LC, stringing TL can be reduced.

[0130] In addition, the duration of the second potential maintenance element Pwh2, Twh2, is more than 0.5 times that of Tc.

[0131] In the first embodiment, compared to a method where the period Twh2 is less than 0.5 times Tc, after the second pressure potential change element Pwc2, pressure fluctuations generated in the ink within the pressure chamber C can be suppressed by driving the drive element 51f. As described above, according to the first embodiment, by suppressing the pressure vibration of the ink, stringing TL can be reduced.

[0132] The small-point ejection pulse WS also has a third potential maintenance element Pwh3, which maintains the terminal potential from the first pressurization potential change element Pwc1. The period Twh3 of the third potential maintenance element is more than 0.1 times and less than 0.25 times Tc. Furthermore, the potential change amplitude V3 of the second depressurization potential change element Pwd2 is more than 20% and less than 50% of the potential change amplitude V2 of the first pressurization potential change element Pwc1.

[0133] According to the first embodiment, the weight of the ink droplet DR can be adjusted to the desired amount without making the meniscus MN unstable.

[0134] 2. Variations

[0135] The methods illustrated above can be varied in many ways. The following examples illustrate specific variations that can be applied to the aforementioned methods. Two or more methods chosen arbitrarily from the following examples can be appropriately combined without contradiction.

[0136] 2-1. First variation example

[0137] In the first embodiment, the period Tc2d3 is more than 0.75 times Tc, but it can also be less than 0.75 times Tc.

[0138] Figure 9 This diagram is used to illustrate the small-dot ejection pulse WSb in the first modified example. Furthermore, Figure 9 The graph g3 shown represents the potential of the dot ejection pulse WSb and the pressure of the ink in the ejection section D. The pressure characteristic CHPb shown in graph g3 represents the pressure characteristic of the ink in the ejection section D when the dot ejection pulse WSb is supplied to the ejection section D.

[0139] The small-point ejection pulse WSb has a second potential maintenance element Pwh2b instead of the second potential maintenance element Pwh2, and a third decompression potential change element Pwd3b instead of the third decompression potential change element Pwd3, which is different from the small-point ejection pulse WS.

[0140] The second potential maintenance element Pwh2b differs from the second potential maintenance element Pwh2 in that its duration Twh2b is less than 0.5 times Tc. Furthermore, the third depressurization potential change element Pwd3b differs from the third depressurization potential change element Pwd3 in that its potential change rate is 4V / µs or higher.

[0141] Even in the first modified example, the potential change amplitude V1 of the first depressurization potential change element Pwd1 is more than 40% of the potential change amplitude V2 of the first pressurization potential change element Pwc1, and the potential change rate of the first depressurization potential change element Pwd1 is more than 1V / µs and less than 2V / µs. Therefore, similar to the first embodiment, before the meniscus MN protrudes, the ink is fully filled into the pressure chamber C, and the amplitude of the pressure vibration generated in the ink in the ejection section D is not excessively increased. Thus, while reducing stringing TL, the ejection speed of the ink droplets DR after separating from the meniscus MN can be ensured.

[0142] 2-2. Second variation

[0143] In the first embodiment, the potential change rate of the first decompression potential change element Pwd1 is greater than 1V / microsecond and less than 2V / microsecond, but is not limited to this, for example, it may be greater than 2V / microsecond.

[0144] Figure 10 This diagram is used to illustrate the small-dot ejection pulse WSc in the second variation. Furthermore, Figure 10 The graph g4 shown represents the potential of the dot ejection pulse WSc and the pressure of the ink in the ejection section D. The pressure characteristic CHPc shown in graph g4 represents the pressure characteristic of the ink in the ejection section D when the dot ejection pulse WSc is supplied to the ejection section D.

[0145] The small-point ejection pulse WSc differs from the small-point ejection pulse WS in that it has a first decompression potential change element Pwd1c instead of the first decompression potential change element Pwd1.

[0146] The first depressurization potential change element Pwd1c differs from the first depressurization potential change element Pwd1 in that the potential change rate of the first depressurization potential change element Pwd1c is greater than 2V / microsecond. It should be noted that although the period Twd1c of the first depressurization potential change element Pwd1c is less than or equal to Tc, it can also be longer than Tc.

[0147] Even in the second variation, the period Tc2d3 from the beginning of the second applied voltage change element Pwc2 to the beginning of the third depressurized voltage change element Pwd3 is more than 0.75 times Tc. Therefore, similarly to the first embodiment, compared to the method where it is less than 0.75 times Tc, the wire drawing TL can be reduced.

[0148] 2-3. Third variation example

[0149] In the above methods, the small-point ejection pulse WS is an example of the "first ejection pulse", but the large-point ejection pulse WL can also be an example of the "first ejection pulse".

[0150] Figure 11 This diagram illustrates the large-point ejection pulse WLd in the third variation. The large-point ejection pulse WLd sequentially comprises a filling element Pld1d, a potential maintenance element Pld1d, an ejection element Plc1d, a vibration damping maintenance element Pld2d, and a vibration damping expansion element Pld2d. The large-point ejection pulse WLd is a so-called pull-push-pull waveform. It should be noted that in the third variation, the large-point ejection pulse WLd is an example of the "first ejection pulse," the filling element Pld1d is an example of the "first depressurization potential change element," the potential maintenance element Pld1d is an example of the "first potential maintenance element," and the ejection element Plc1d is an example of the "first pressurization potential change element."

[0151] The potential change amplitude V1d of the filling element Pld1d is more than 40% of the potential change amplitude V2d of the ejection element Plc1d. Furthermore, the potential change rate of the filling element Pld1d is more than 1 V / µs and less than 2 V / µs. According to the third variation, in the large-dot ejection pulse WL, since, similarly to the small-dot ejection pulse WS in the first embodiment, the ink is fully filled into the pressure chamber C before the meniscus MN protrudes, and the amplitude of the pressure vibration generated in the ink within the ejection section D is not excessively increased, it is possible to reduce stringing TL while ensuring the ejection speed of the ink droplets DR after separation from the meniscus MN.

[0152] Furthermore, the duration Tlh1d of the potential maintenance element Plh1d is 0.1 times or more and 0.25 times or less of Tc. According to the third modified example, since the increase in ink pressure within the ejection section D can be multiplied, the ejection speed of the ink droplets DR based on the small dot ejection pulse WS can be ensured.

[0153] Furthermore, the potential change rate of the ejection element Plc1d is 4V / µs or more. According to the third variation, compared with the method where the potential change rate of the ejection element Plc1d is less than 4V / µs, the ejection speed of ink droplets DR based on the large-dot ejection pulse WLd can be ensured.

[0154] Furthermore, the period Tld1d of the filling element Pld1d is less than or equal to Tc. In the third variation, compared to the case where the period of the first depressurization potential change element Pwd1 is longer than Tc, the speed of the ink droplet DR after separation from the meniscus MN can be ensured in the first pressurization potential change element Pwc1.

[0155] 2-4. Fourth variation example

[0156] In the third variation, the pull-push-pull waveform, i.e., the large-point ejection pulse WLd, is an example of the "first ejection pulse," but it is not limited to this. For example, the so-called pull-push waveform can also be an example of the "first ejection pulse."

[0157] Figure 12 This diagram illustrates the large-point ejection pulse WLe in the fourth variation. The large-point ejection pulse WLe sequentially comprises a filling element Pld1e, a potential maintenance element Plh1e, and an ejection element Plc1e. The large-point ejection pulse WLe is a so-called pull-push waveform. It should be noted that in the fourth variation, the large-point ejection pulse WLe is an example of the "first ejection pulse," the filling element Pld1e is an example of the "first depressurization potential change element," the potential maintenance element Plh1e is an example of the "first potential maintenance element," and the ejection element Plc1e is an example of the "first pressurization potential change element."

[0158] The potential change amplitude V1e of the filling element Pld1e is approximately the same as the potential change amplitude V2e of the ejection element Plc1e. Therefore, even in the fourth variation, the condition that the potential change amplitude V1e is more than 40% of the potential change amplitude V2e is satisfied. That is, the potential change amplitude V1e can also be more than the potential change amplitude V2e.

[0159] The potential change rate of the filling element Pld1e is greater than or equal to 1 V / µs and less than or equal to 2 V / µs. The duration Tlh1e of the potential maintenance element Plh1e is greater than or equal to 0.1 times and less than 0.25 times Tc. The potential change rate of the ejection element Plc1e is greater than or equal to 4 V / µs. The duration Tld1e of the filling element Pld1e is less than or equal to Tc.

[0160] 2-5. Fifth variation

[0161] In the fourth variation, the pull-push waveform, i.e., the large-point ejection pulse WLe, is an example of the "first ejection pulse," but it is not limited to this. For example, the so-called pull-push waveform can also be an example of the "first ejection pulse."

[0162] Figure 13 This diagram illustrates the large-point ejection pulse WLf in the fifth variation. The large-point ejection pulse WLf sequentially comprises a filling element Pld1f, a potential maintenance element Pld1f, an ejection element Plc1f, a potential maintenance element Pld3f, an ejection element Plc2f, a vibration damping maintenance element Pld2f, and a vibration damping expansion element Pld2f. The large-point ejection pulse WLf is a so-called pull-push waveform. It should be noted that in the fifth variation, the large-point ejection pulse WLf is an example of the "first ejection pulse," the filling element Pld1f is an example of the "first depressurization potential change element," the potential maintenance element Pld1f is an example of the "first potential maintenance element," and the ejection element Plc1f is an example of the "first pressurization potential change element."

[0163] The potential change amplitude V1f of the filling element Pld1f is greater than the potential change amplitude V2f of the ejection element Plc1f. Therefore, in the fifth variation, the condition that the potential change amplitude V1f is more than 40% of the potential change amplitude V2f is also satisfied.

[0164] The potential change rate of the filling element Pld1f is greater than or equal to 1 V / µs and less than or equal to 2 V / µs. The duration Tlh1f of the potential maintenance element Plh1f is greater than or equal to 0.1 times and less than 0.25 times Tc. The potential change rate of the ejection element Plc1f is greater than or equal to 4 V / µs. The duration Tld1f of the filling element Pld1f is less than or equal to Tc.

[0165] 2-6. Sixth Variation

[0166] In the first embodiment, the first modification, and the second modification, the period Twh1 of the first potential maintenance element Pwh1 is 0.1 times or more and 0.25 times or less of Tc, but is not limited to this. For example, the period Twh1 may be less than 0.1 times Tc or longer than 0.25 times Tc. Similarly, in the third to fifth modifications, the period Tlh1d of the potential maintenance element Plh1 may be less than 0.1 times Tc or longer than 0.25 times Tc.

[0167] 2-7. Seventh Variation

[0168] In the first embodiment, the first modified example, the second modified example, and the sixth modified example based on one of the first embodiment, the first modified example, and the second modified example, the potential change rate of the first pressurized potential change element Pwc1 is 4V / µs or more, but it is not limited to this. For example, the potential change rate of the first pressurized potential change element Pwc1 may be less than 4V / µs. Similarly, in the third to fifth modified examples and the sixth modified example based on any one of the third to fifth modified examples, the potential change rate of the ejection element Plc1 may be less than 4V / µs.

[0169] 2-8. Eighth Variation

[0170] In the first embodiment, the first modification, the second modification, and the sixth or seventh modification based on one of the first embodiment, the first modification, and the second modification, the first decompression potential change element Pwd1 is a period of Tc or less, but is not limited thereto. The first decompression potential change element Pwd1 may also be a period longer than Tc. Similarly, in the third to fifth modifications and the sixth or seventh modification based on any one of the third to fifth modifications, the filling element Pld1 may also be a period longer than Tc.

[0171] 2-9. Ninth Variation

[0172] In the first embodiment, the first modification, the second modification, and the sixth to eighth modifications based on one of the first embodiment, the first modification, and the second modification, the period Tc1c2 from the start of the first applied voltage potential change element Pwc1 to the start of the second applied voltage potential change element Pwc2 is a period that is 0.5 times or more and 0.75 times Tc, but may be less than 0.5 times Tc or longer than 0.75 times Tc. Alternatively, the potential change amplitude V4 of the second applied voltage potential change element Pwc2 may be less than 50% of the potential change amplitude V2 of the first applied voltage potential change element Pwc1 or greater than 70%.

[0173] 2-10. Tenth Variation

[0174] In the first embodiment, the first modified example, the second modified example, and the sixth to ninth modified examples based on one of the first embodiment, the first modified example, and the second modified example, the duration Twh2 of the second potential maintenance element Pwh2 is more than 0.5 times Tc, but may be less than 0.5 times.

[0175] 2-11. Eleventh Variation Example

[0176] In the first embodiment, the first modification, the second modification, and the sixth to tenth modifications based on one of the first embodiment, the first modification, and the second modification, the period Twh3 of the third potential maintenance element Pwh3 is a period that is 0.1 times or more and 0.25 times or less of Tc, and the potential change amplitude V3 of the second depressurization potential change element Pwd2 is 20% or more and 50% or less of the potential change amplitude V2 of the first pressurization potential change element Pwc1, but is not limited thereto. For example, the period Twh3 may be less than 0.1 times Tc or longer than 0.25 times Tc. In addition, the potential change amplitude V3 may be less than 20% of the potential change amplitude V2 or longer than 50%.

[0177] 2-12. Twelfth Variation

[0178] Of the above-described methods, an example is a method for manufacturing a liquid ejection device 100 in a serial manner in which the liquid ejection head 50 reciprocates along the X-axis direction; however, this disclosure is not limited to this method. The liquid ejection device 100 may also be a row-type liquid ejection device in which multiple nozzles N are distributed across the full width of the medium PP.

[0179] 2-13. Other variations

[0180] The liquid ejection device 100 described above can be used not only in printing equipment but also in various other devices such as fax machines and copiers. However, the application of the recording device of the present invention is not limited to printing. For example, the recording device that ejects a solution of color material can be used as a manufacturing apparatus for color filters in liquid crystal display devices. In addition, the recording device that ejects a solution of conductive material can be used as a manufacturing apparatus for wiring and electrodes in wiring substrates.

Claims

1. A liquid ejection device, characterized in that, have: The ejection section has a nozzle, a pressure chamber, and a drive element. The nozzle ejects liquid, the pressure chamber is connected to the nozzle, and the drive element is driven according to a supplied drive signal to cause pressure changes in the liquid inside the pressure chamber. as well as A drive signal generation circuit generates the drive signal; The drive signal includes a first ejection pulse that causes liquid to be ejected from the nozzle. The first ejection pulse has: The first pressure reduction potential change element drives the driving element to reduce the pressure of the liquid in the pressure chamber; as well as A first pressurization potential change element, following a first depressurization potential change element, drives the drive element to increase the pressure of the liquid in the pressure chamber, causing the liquid level to protrude from the nozzle. The potential change amplitude of the first decompression potential change element is more than 40% of the potential change amplitude of the first pressurization potential change element. The potential change rate of the first decompression potential change element is greater than 1V / microsecond and less than 2V / microsecond.

2. The liquid ejection device according to claim 1, characterized in that, The first ejection pulse also has a first potential maintenance element. The first potential maintenance element connects the terminal of the first depressurization potential change element and the beginning of the first pressurization potential change element, and maintains a predetermined potential. The first potential maintenance element is during a period that is more than 0.1 times and less than 0.25 times Tc. Tc is the inherent vibration period within the ejection section.

3. The liquid ejection device according to claim 1, characterized in that, The potential change rate of the first applied potential change element is above 4V / microsecond.

4. The liquid ejection device according to claim 1, characterized in that, The first decompression potential change element is the period below Tc. Tc is the inherent vibration period within the ejection section.

5. The liquid ejection device according to claim 1, characterized in that, The first ejection pulse also has: The second depressurization potential change element drives the driving element after the first pressurization potential change element to reduce the pressure of the liquid in the pressure chamber. The second pressurization potential change element drives the drive element after the second depressurization potential change element to increase the pressure of the liquid in the pressure chamber. The second potential maintenance element is the terminal maintenance potential of the second applied potential change element; as well as The third pressure reduction potential change element is connected to the terminal of the second potential maintenance element and drives the driving element to reduce the pressure of the liquid in the pressure chamber. The period from the beginning of the second applied pressure potential change element to the beginning of the third depressurization potential change element is more than 0.75 times Tc. Tc is the inherent vibration period within the ejection section.

6. The liquid ejection device according to claim 5, characterized in that, The period from the start of the first applied voltage potential change element to the start of the second applied voltage potential change element is a period that is more than 0.5 times and less than 0.75 times Tc. The potential change amplitude of the second applied pressure potential change element is more than 50% and less than 70% of the potential change amplitude of the first applied pressure potential change element.

7. The liquid ejection device according to claim 5, characterized in that, The duration of the second potential maintenance element is more than 0.5 times Tc.

8. The liquid ejection device according to claim 5, characterized in that, The first ejection pulse also has a third potential maintenance element. The third potential maintenance element maintains the potential from the terminal potential of the first applied potential change element. The period of the third potential maintenance element is a period of more than 0.1 times and less than 0.25 times Tc. The potential change amplitude of the second decompression potential change element is more than 20% and less than 50% of the potential change amplitude of the first pressurization potential change element.

9. A driving method, characterized in that, This is a method for driving a liquid ejection device, the liquid ejection device comprising: The ejection section has a nozzle, a pressure chamber, and a drive element. The nozzle ejects liquid, the pressure chamber is connected to the nozzle, and the drive element is driven according to a supplied drive signal to cause pressure changes in the liquid inside the pressure chamber. as well as The drive signal generation circuit generates the drive signal. The drive signal includes a first ejection pulse that causes liquid to be ejected from the nozzle. The first ejection pulse has: The first pressure reduction potential change element drives the driving element to reduce the pressure of the liquid in the pressure chamber; as well as A first pressurization potential change element, following a first depressurization potential change element, drives the drive element to increase the pressure of the liquid in the pressure chamber, causing the liquid level to protrude from the nozzle. The potential change amplitude of the first decompression potential change element is more than 40% of the potential change amplitude of the first pressurization potential change element. The potential change rate of the first decompression potential change element is greater than 1 V / µs and less than 2 V / µs. The driving method is executed as follows: The first step is to supply the first pressure reduction potential change element to the driving element of the ejection section; as well as The second step is to supply the first pressure potential change element to the drive element of the ejection section.

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