Liquid ejecting device, drive waveform generating device, and head driving method

Abstract

To provide a device for discharging a liquid, a head driving device and a head driving method which achieve both suppression of satellite and fine drive.SOLUTION: A driving waveform Va continuously includes a first driving pulse P1 for discharging a liquid, a second driving pulse P2 for not discharging the liquid and a third driving pulse P3 for discharging the liquid in time series, wherein the second driving pulse P2 is singly usable as a fine drive waveform for oscillating a meniscus in such a degree as not to discharge the liquid; an interval between the first driving pulse P1 and the second driving pulse P2 and an interval between the second driving pulse P2 and the third driving pulse P3 have a relation of resonance; and a wave height value Vp2 of the second driving pulse P2 is a voltage that is within a range of -10% to +10% of a wave height value Vpp2 in which droplet speed when the first driving pulse P1 is applied and then the second driving pulse P2 is applied, and further the third driving pulse P3 is applied, and the liquid is discharged becomes a minimal value.SELECTED DRAWING: Figure 6

Description

Technical Field

[0001] The present invention relates to a liquid discharging device, a drive waveform generating device, and a head driving method.

Background Art

[0002] When discharging liquid from a liquid discharge head, it is required to suppress satellite droplets caused by trailing that occur with the discharge of main droplets.

[0003] Conventionally, when including a non-discharge pulse for not discharging liquid and a discharge pulse for discharging liquid in series in time series, when the peak value of the non-discharge pulse is Vp1, the time interval between the non-discharge pulse and the discharge pulse is Td, and the natural vibration period is Tc, the time interval Td is within the range of Tc - 0.2Tc to Tc + 0.45Tc, and the peak value Vp1 of the non-discharge pulse is within the range of -10% to +10% of the peak value Vpp1 when the droplet velocity of the liquid discharged by the discharge pulse becomes the minimum value. There is a known drive waveform (Patent Document 1).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in the configuration disclosed in Patent Document 1, it has been found that there are cases where it is difficult to use the non-discharge pulse as a micro drive waveform that vibrates the meniscus to such an extent that liquid is not discharged in order to suppress drying of the meniscus of the head. In this case, there is a problem that it is necessary to include a non-discharge pulse (non-discharge drive pulse) for satellite suppression and a micro drive waveform (micro drive pulse) for preventing meniscus drying in the drive waveform.

[0006] The present invention has been made in view of the above problems, and an object thereof is to achieve compatibility between a satellite suppression waveform and a fine drive waveform.

Means for Solving the Problems

[0007] In order to solve the above problems, the liquid ejecting apparatus according to claim 1 of the present invention includes: drive waveform generating means for generating a drive waveform including a plurality of drive pulses applied to a liquid ejecting head; the drive waveform successively includes, in time series, a first drive pulse for ejecting liquid, a second drive pulse for not ejecting the liquid, and a third drive pulse for ejecting the liquid; the second drive pulse can be used alone as a fine drive waveform for vibrating a meniscus so as not to eject the liquid; the intervals between the first drive pulse and the second drive pulse, and between the second drive pulse and the third drive pulse are respectively in a resonance relationship; the peak value Vp2 of the second drive pulse is a voltage within a range of -10% to +10% of the peak value Vpp2 at which the droplet velocity becomes a minimum value when the liquid is ejected by applying the first drive pulse, then applying the second drive pulse, and further applying the third drive pulse; configured as such.

[0008] According to the present invention, compatibility between a satellite suppression waveform and a fine drive waveform can be achieved.

Brief Description of the Drawings

[0009]

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Embodiments for Carrying Out the Invention

[0010] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. A printing apparatus as a device for discharging a liquid according to the first embodiment of the present invention will be described with reference to FIGS. 1 and 2. FIG. 1 is a schematic explanatory diagram of the printing apparatus, and FIG. 2 is a plan explanatory diagram of the discharge unit of the printing apparatus.

[0011] The printing apparatus 1 is a device for discharging a liquid, and includes a carrying-in unit 10 for carrying in a sheet material P, a pre-treatment unit 20, a printing unit 30, a drying unit 40, and a carrying-out unit 50. The printing apparatus 1 applies a pre-treatment liquid (coats) to the sheet material P carried in (supplied) from the carrying-in unit 10 as needed by the pre-treatment unit 20 which is a pre-treatment means, applies a liquid in the printing unit 30 to perform required printing, dries the liquid adhering to the sheet material P in the drying unit 40, and then discharges the sheet material P to the carrying-out unit 50.

[0012] The carrying-in unit 10 includes a carrying-in tray 11 (lower carrying-in tray 11A, upper carrying-in tray 11B) for accommodating a plurality of sheet materials P, and a feeding device 12 (12A, 12B) for separating and feeding out the sheet materials P one by one from the carrying-in tray 11, and supplies the sheet material P to the pre-treatment unit 20.

[0013] The pre-treatment unit 20 includes, for example, an application unit 21 which is a treatment liquid application means for applying a treatment liquid having an effect of aggregating ink and preventing back printing to the printing surface of the sheet material P.

[0014] The printing unit 30 includes a drum 31 which is a carrying member (rotating member) that carries and rotates the sheet material P on its circumferential surface, and a liquid discharge unit 32 that discharges liquid toward the sheet material P carried on the drum 31.

[0015] Further, the printing unit 30 includes a transfer cylinder 34 that receives the sheet material P fed from the pre-treatment unit 20 and transfers the sheet material P between it and the drum 31, and a delivery cylinder 35 that receives the sheet material P conveyed by the drum 31 and transfers it to the drying unit 40.

[0016] The sheet material P conveyed from the pre-treatment unit 20 to the printing unit 30 has its tip held by gripping means (sheet gripper) provided on the transfer cylinder 34 and is conveyed as the transfer cylinder 34 rotates. The sheet material P conveyed by the transfer cylinder 34 is delivered to the drum 31 at the position facing the drum 31.

[0017] Gripping means (sheet gripper) is also provided on the surface of the drum 31, and the tip of the sheet material P is held by the gripping means (sheet gripper). A plurality of suction holes are dispersedly formed on the surface of the drum 31, and a suction airflow directed inward is generated from the required suction holes of the drum 31 by suction means.

[0018] Then, the sheet material P delivered from the transfer cylinder 34 to the drum 31 has its tip held by the sheet gripper and is adsorbed and carried on the drum 31 by the suction airflow by the suction means, and is conveyed as the drum 31 rotates.

[0019] The liquid ejection unit 32 includes ejection units 33 (33A to 33D) which are liquid ejection means. For example, the ejection unit 33A ejects cyan (C) liquid, the ejection unit 33B ejects magenta (M) liquid, the ejection unit 33C ejects yellow (Y) liquid, and the ejection unit 33D ejects black (K) liquid, respectively. In addition, ejection units for ejecting special liquids such as white, gold (silver), etc. can also be used.

[0020] The ejection unit 33 is, for example, as shown in FIG. 2, a full-line type head in which a plurality of liquid ejection heads (hereinafter simply referred to as "heads") 100 each having a plurality of nozzle rows in which a plurality of nozzles 104 are arranged are arranged in a staggered manner on a base member 331.

[0021] Each ejection unit 33 of the liquid ejection unit 32 has its ejection operation controlled by a drive signal according to printing information. When the sheet material P carried on the drum 31 passes through the facing area with the liquid ejection unit 32, liquids of each color are ejected from the ejection unit 33, and an image according to the printing information is printed.

[0022] The drying unit 40 dries the liquid adhering to the sheet material P in the printing unit 30. Thereby, liquid components such as moisture in the liquid evaporate, the colorant contained in the liquid is fixed on the sheet material P, and curling of the sheet material P is suppressed.

[0023] The inversion mechanism unit 60 is a mechanism that inverts the sheet material P in a switchback manner when performing double-sided printing on the sheet material P that has passed through the drying unit 40, and the inverted sheet material P is sent back upstream of the transfer cylinder 34 through the transport path 61 of the printing unit 30.

[0024] The unloading unit 50 includes an unloading tray 51 on which a plurality of sheet materials P are stacked. The sheet materials P conveyed from the drying unit 40 via the inversion mechanism unit 60 are sequentially stacked and held on the unloading tray 51.

[0025] Next, an example of the head 100 will be described with reference to FIGS. 3 and 4. FIG. 3 is a cross-sectional explanatory view in a direction orthogonal to the nozzle array direction of the head, and FIG. 4 is a cross-sectional explanatory view along the nozzle array direction.

[0026] The liquid ejection head 100 of the present embodiment laminates and joins a nozzle plate 101, a flow path plate 102 which is an individual flow path member, and a diaphragm member 103 as a wall surface member. And it includes a piezoelectric actuator 111 that displaces the vibration region (diaphragm) 130 of the diaphragm member 103, and a common flow path member 120 that also serves as a frame member of the head.

[0027] The nozzle plate 101 has a plurality of nozzle rows in which a plurality of nozzles 104 for ejecting liquid are arranged.

[0028] The flow path plate 102 forms a plurality of pressure chambers 106 communicating with the plurality of nozzles 104, individual supply flow paths 107 that also serve as fluid resistance portions respectively communicating with the pressure chambers 106, and an intermediate supply flow path 108 that serves as a liquid introduction portion communicating with two or more individual supply flow paths 107.

[0029] The diaphragm member 103 has a plurality of displaceable diaphragms (vibration regions) 130 that form the wall surfaces of the pressure chambers 106 of the flow path plate 102. Here, the diaphragm member 103 has a two-layer structure (not limited), and is composed of a first layer 103A that forms a thin portion from the side of the flow path plate 102 and a second layer 103B that forms a thick portion.

[0030] And a deformable vibration region 130 is formed in a portion corresponding to the pressure chamber 106 in the first layer 103A which is a thin portion. Inside the vibration region 130, a convex portion 130a which is a thick portion joined to the piezoelectric actuator 111 with the second layer 103B is formed.

[0031] And on the side opposite to the pressure chamber 106 of the diaphragm member 103, a piezoelectric actuator 111 including an electromechanical conversion element as a driving means (actuator means, pressure generating element) for deforming the vibration region 130 of the diaphragm member 103 is arranged.

[0032] This piezoelectric actuator 111 forms grooves in the piezoelectric member bonded onto the base member 113 by half-cut dicing, and forms a required number of columnar piezoelectric elements 112 at predetermined intervals in a comb-like shape in the nozzle array direction. And the piezoelectric elements 112 are bonded, every other one, to convex portions 130a which are thick portions formed in the vibration region 130 of the diaphragm member 103.

[0033] This piezoelectric element 112 is formed by alternately laminating a piezoelectric layer and internal electrodes, the internal electrodes are respectively drawn out to the end faces and connected to external electrodes (end face electrodes), and a flexible wiring member 115 is connected to the external electrodes.

[0034] The common flow path member 120 forms a common supply flow path 110. The common supply flow path 110 communicates with an intermediate supply flow path 108 which serves as a liquid introduction part through an opening 109 which also serves as a filter part provided in the diaphragm member 103, and leads to an individual supply flow path 107 through the intermediate supply flow path 108.

[0035] In this liquid ejection head 100, for example, when the voltage applied to the piezoelectric element 112 is lowered from the reference potential (intermediate potential), the piezoelectric element 112 contracts, the vibration region 130 of the diaphragm member 103 is pulled, and the volume of the pressure chamber 106 expands, so that liquid flows into the pressure chamber 106.

[0036] Thereafter, the voltage applied to the piezoelectric element 112 is increased to extend the piezoelectric element 112 in the lamination direction, the vibration region 130 of the diaphragm member 103 is deformed in the direction toward the nozzle 104 to contract the volume of the pressure chamber 106, whereby the liquid in the pressure chamber 106 is pressurized and the liquid is ejected from the nozzle 104.

[0037] Next, a part related to the head drive control device for driving the head will be described with reference to the block explanatory diagram of FIG. 5.

[0038] A head drive control device 400 that supplies a drive waveform to a head 100 includes a head control unit 401, a drive waveform generation unit 402 and a waveform data storage unit 403 that constitute drive waveform generation means as the drive waveform generation device according to the present invention, a head driver 410, and a discharge timing generation unit 404 for generating a discharge timing.

[0039] When the head control unit 401 receives a discharge timing pulse stb, it outputs a discharge synchronization signal LINE that serves as a trigger for generating a drive waveform to the drive waveform generation unit 402. Further, the head control unit 401 outputs a discharge timing signal CHANGE corresponding to the delay amount from the discharge synchronization signal LINE to the drive waveform generation unit 402.

[0040] The drive waveform generation unit 402 generates a common drive waveform Vcom at a timing based on the discharge synchronization signal LINE and the discharge timing signal CHANGE.

[0041] The head control unit 401 receives image data and generates a mask control signal MN for selecting a predetermined waveform of the common drive waveform signal Vcom according to the size of the liquid discharged from each nozzle 104 of the head 100 based on this image data. The mask control signal MN is a signal at a timing synchronized with the discharge timing signal CHANGE.

[0042] Then, the head control unit 401 transfers the image data SD, the synchronization clock signal SCK, the latch signal LT for instructing the latch of the image data, and the generated mask control signal MN to the head driver 410.

[0043] The head driver 410 includes a shift register 411, a latch circuit 412, a tone decoder 413, a level shifter 414, and an analog switch array 415.

[0044] The shift register 411 inputs the image data SD and the synchronous clock signal SCK transferred from the head control unit 401. The latch circuit 412 latches each register value of the shift register 411 with the latch signal LT transferred from the head control unit 401.

[0045] The gradation decoder 413 decodes the value (image data SD) latched by the latch circuit 412 and the mask control signal MN and outputs the result. The level shifter 414 converts the logic level voltage signal of the gradation decoder 413 to a level at which the analog switch AS of the analog switch array 415 can operate.

[0046] The analog switch AS of the analog switch array 415 is a switch that turns on / off with the output of the gradation decoder 413 provided via the level shifter 414. This analog switch AS is provided for each nozzle 104 included in the head 100 and is connected to the individual electrode of the piezoelectric element 112 corresponding to each nozzle 104. Further, a common drive waveform signal Vcom from the drive waveform generation unit 402 is input to the analog switch AS. Also, as described above, the timing of the mask control signal MN is synchronized with the timing of the common drive waveform Vcom.

[0047] Therefore, by switching the on / off of the analog switch AS at an appropriate timing according to the output of the gradation decoder 413 provided via the level shifter 414, the drive pulse applied to the piezoelectric element 112 corresponding to each nozzle 104 is selected from the drive pulses constituting the common drive waveform signal Vcom. As a result, the size of the droplets ejected from the nozzle 104 is controlled.

[0048] The ejection timing generation unit 404 generates and outputs an ejection timing pulse stb every time the sheet material P is moved by a predetermined amount based on the detection result of the rotary encoder 405 that detects the rotation amount of the drum 31. The rotary encoder 405 is composed of an encoder wheel that rotates together with the drum 31 and an encoder sensor that reads the slit of the encoder wheel.

[0049] Next, the drive waveform in the first embodiment of the present invention will be described with reference to FIG. 6. FIG. 6 is an explanatory diagram for this description.

[0050] The drive waveform Va in this embodiment includes, as a plurality of drive pulses, a first drive pulse P1, a second drive pulse P2, and a third drive pulse P3 continuously in time series.

[0051] The first drive pulse P1 is a first discharge pulse that pressurizes the liquid in the pressure chamber 106 to discharge the liquid. The first drive pulse P1 is composed of an expansion waveform element a1 that expands the pressure chamber 106, a holding waveform element b1 that holds the expanded state by the expansion waveform element a1, and a contraction waveform element c1 that contracts the pressure chamber 106 from the state held by the holding waveform element b1 to discharge the liquid.

[0052] The expansion waveform element a1 of the first drive pulse P1 is a waveform that falls from the intermediate potential (or reference potential) Vm to the potential V1, the holding waveform element b1 is a waveform that holds the potential V1, and the contraction waveform element c1 is a waveform that rises from the potential V1 to the intermediate potential Vm. The peak value of this first drive pulse P1 is defined as Vp1.

[0053] The second drive pulse P2 is a non-discharge pulse that can be used as a micro drive waveform that pressurizes the liquid in the pressure chamber 106 to such an extent that the liquid is not discharged and the meniscus is vibrated. The second drive pulse P2 is composed of an expansion waveform element a2 that expands the pressure chamber 106, a holding waveform element b2 that holds the expanded state by the expansion waveform element a2, and a contraction waveform element c2 that contracts the pressure chamber 106 from the state held by the holding waveform element b2 to vibrate the meniscus.

[0054] The expansion waveform element a2 of the second drive pulse P2 is a waveform that falls from the intermediate potential (or reference potential) Vm to the potential V2 (V2 < V1), the holding waveform element b2 is a waveform that holds the potential V2, and the contraction waveform element c2 is a waveform that rises from the potential V2 to the intermediate potential Vm. The peak value of this second drive pulse P2 is defined as Vp2.

[0055] The third driving pulse P3 is a second discharge pulse that pressurizes the liquid in the pressure chamber 106 to discharge the liquid. The third driving pulse P3 is composed of an expansion waveform element a3 that expands the pressure chamber 106, a holding waveform element b3 that holds the state expanded by the expansion waveform element a3, and a contraction waveform element c3 that contracts the pressure chamber 106 from the state held by the holding waveform element b3 to discharge the liquid.

[0056] The expansion waveform element a3 of the third driving pulse P3 is a waveform that falls from the intermediate potential (or reference potential) Vm to the potential V3 (V3 > V1), the holding waveform element b3 is a waveform that holds the potential V3, and the contraction waveform element c3 is a waveform that rises from the potential V3 to the intermediate potential Vm. The peak value of this third driving pulse P3 is defined as Vp3.

[0057] The waveform from the end point of the contraction waveform element c1 of the first driving pulse P1 to the start point of the expansion waveform element a2 of the second driving pulse P2 is defined as an inter-pulse holding waveform element d1, and the time of the inter-pulse holding waveform element d1 (the time interval between the first driving pulse P1 and the second driving pulse P2) is defined as Td1.

[0058] The waveform from the end point of the contraction waveform element c2 of the second driving pulse P2 to the start point of the expansion waveform element a3 of the third driving pulse P3 is defined as an inter-pulse holding waveform element d2, and the time of the inter-pulse holding waveform element d2 (the time interval between the second driving pulse P2 and the third driving pulse P3) is defined as Td2.

[0059] Here, the interval (time Td1) between the first driving pulse P1 and the second driving pulse P2 is in a resonance relationship. The resonance relationship here means that the pressure when the liquid in the pressure chamber 106 is pressurized by the second driving pulse P2 due to the residual vibration when the liquid in the pressure chamber 106 is pressurized by the first driving pulse P1 is amplified.

[0060] Similarly, the interval (time Td2) between the second drive pulse P2 and the third drive pulse P3 is in a resonance relationship. The resonance relationship here means that the pressure when the liquid in the pressure chamber 106 is pressurized by the third drive pulse P3 is amplified by the residual vibration when the liquid in the pressure chamber 106 is pressurized by the second drive pulse P2.

[0061] In this embodiment, when the resonance period (natural vibration period) of the pressure chamber 106 of the liquid discharge head 100 is Tc, the time interval Td2 between the second drive pulse P2 and the third drive pulse P3 is within the range of Tc - (1 / 4)Tc to Tc + (1 / 4)Tc.

[0062] Also, the peak value Vp2 of the second discharge pulse P2 is within the range of -10% to +10% of the peak value Vpp2 at which the droplet velocity Vj becomes the minimum value when the liquid is discharged by applying the first drive pulse P1, then the second drive pulse P2, and further the third drive pulse P3.

[0063] Thereby, the satellite of the droplets discharged by the third drive pulse P3 can be suppressed.

[0064] Hereinafter, the operation and effects of this embodiment will be specifically described with reference to FIGS. 7 and later.

[0065] First, FIG. 7 shows an example of the change in the droplet velocity Vj when the peak value Vp3 of the third drive pulse P3 is a fixed value and the peak value Vp1 of the first drive pulse P1 or the peak value Vp2 of the second drive pulse P2 is changed. Note that the first drive pulse P1 and the second drive pulse P2, and the second drive pulse P2 and the third drive pulse P3 are in a resonance timing relationship.

[0066] From the results of FIG. 7, it can be roughly divided into three ranges S1, S2, and S3 according to the values of the peak values Vp1 and Vp2.

[0067] That is, when the peak value Vp1 of the first drive pulse P1 or the peak value Vp2 of the second drive pulse P2 is within the range S1, the droplet velocity Vj increases as the peak value Vp1 increases.

[0068] When the peak value Vp1 of the first driving pulse P1 or the peak value Vp2 of the second driving pulse P2 is within the range S2, the boundary between the range S1 and the range S2 is taken as the maximum value, and the droplet velocity Vj is decreasing.

[0069] When the peak value Vp1 of the first driving pulse P1 or the peak value Vp2 of the second driving pulse P2 is within the range S3, the boundary between the range S2 and the range S3 is taken as the minimum value (at this time, the peak values Vp1 and Vp2 are taken as the peak wave heights Vpp1 and Vpp2), and the droplet velocity Vj is increasing.

[0070] At this time, when the peak value Vp1 of the first driving pulse P1 and the peak value Vp2 of the second driving pulse P2 are voltages within the range of -10% to +10% of the peak wave height value Vpp1 or the peak wave height value Vpp2 at which the droplet velocity Vj becomes the minimum value when the liquid is discharged by applying the second driving pulse P2 after applying the first driving pulse P1 and then applying the third driving pulse P3, the satellite droplet velocity increases significantly, and depending on the conditions, the satellite droplets disappear.

[0071] In other words, as can be seen from FIG. 7, in the present embodiment, instead of the second driving pulse P2, the peak value Vp1 of the first driving pulse is set to a voltage within the range of -10% to +10% of the peak wave height value Vpp1 at which the droplet velocity becomes the minimum value when the liquid is discharged by applying the second driving pulse after applying the first driving pulse and then applying the third driving pulse. Depending on the conditions, the satellite droplets disappear.

[0072] That is, as described above, it is considered that the significant increase in the satellite droplet velocity and the disappearance of the satellite droplets depending on the conditions are due to the discharge by the third driving pulse P3 receiving the discharge energy of the first driving pulse P1 and the second driving pulse P2. Therefore, either the second driving pulse P2 or the first driving pulse P1 may provide the discharge energy within the range of -10% to +10% of the peak wave height value at which the droplet velocity Vj becomes the minimum value.

[0073] Here, without using the first driving pulse P1, the suppression and disadvantages of satellites in the pulse group composed of the second driving pulse P2 and the third driving pulse P3 will be described with reference to FIG. 8. FIG. 8 shows an example of the relationship between the peak value Vp3 of the third driving pulse P3 and the droplet velocity of satellite droplets when the peak value Vp3 of the third driving pulse P3 is adjusted so that the droplet velocity Vj becomes constant with respect to the peak value Vp2 of the second driving pulse P2.

[0074] The satellite droplet velocity Vjs slightly increases as the peak value Vp2 of the second driving pulse P2 increases. However, there is a region S0 where the satellite droplet velocity Vjs becomes zero (satellite-free) around the peak value Vp2 of the second driving pulse P2 corresponding to the vicinity (near the boundary between ranges S2 and S3) where the peak value Vp3 of the third driving pulse P3 takes the maximum value.

[0075] Note that the above explanation for obtaining the satellite-free region is the case where the interval Td2 between the second driving pulse P2 and the third driving pulse P3 is the same as the resonance period Tc (Td = Tc).

[0076] By the way, the condition of the peak value Vp2 where the satellite-free region is observed needs to be the voltage value near the boundary between range S2 and range S3. That is, it is necessary to apply a voltage near the boundary between range S2 where the meniscus vibration becomes too large due to the second driving pulse P2 and the meniscus is on the verge of overflowing, and range S3 where droplets start to be ejected by the second driving pulse P2 itself beyond that.

[0077] However, under the condition that the meniscus vibration is too large, the second driving pulse P2 cannot be used as the micro-driving waveform that is usually used to vibrate the meniscus to prevent drying. In the second driving pulse P2 with such a peak value, the meniscus is violently shaken, affecting the next ejected droplet, resulting in ejection failure, or droplets are ejected by the second driving pulse P2 (micro-driving waveform) itself, and it can no longer play the role of micro-driving.

[0078] Therefore, in order to achieve both satellite-less and micro-driving to prevent meniscus drying, a dedicated non-ejection pulse for satellite-less is required. That is, it is necessary to set both a non-ejection pulse with a high wave height value (high driving voltage) and a non-ejection pulse with a low driving voltage as the micro-driving waveform in the driving waveform. As a result, there is a disadvantage that the driving waveform length becomes long and the driving frequency cannot be increased.

[0079] Next, with reference to FIG. 9, an example of the relationship between the wave height value Vp3 of the third driving pulse P3 and the satellite droplet velocity Vjs with respect to the interval Td1 between the first driving pulse P1 and the second driving pulse P2 in this embodiment will be described.

[0080] In this example, the first driving pulse P1 is a ejection pulse that ejects a slow droplet with the wave height value Vp1 set so that the droplet velocity is about 5 m / s, and the second driving pulse P2 is a non-ejection pulse with a low wave height value Vp2 that can be used as a micro-driving waveform for vibrating the meniscus. And the interval Td2 between the second driving pulse P2 and the third driving pulse P3 is the resonance timing. Note that the wave height value Vp2 is a voltage corresponding to the voltage within the range S1 described above.

[0081] Then, with the interval Td1 between the first driving pulse P1 and the second driving pulse P2 as a parameter, the wave height value Vp3 of the third driving pulse P3 was adjusted so that the droplet velocity of the merged droplets by the first driving pulse P1, the second driving pulse P2, and the third driving pulse P3 became 7 m / s.

[0082] The wave height value Vp3 and the satellite droplet velocity Vjs with respect to the interval Td1 at this time are shown in FIG. 9.

[0083] From FIG. 9, it can be seen that the wave height value Vp3 of the third driving pulse P3 changes periodically according to the residual vibration caused by the first driving pulse P1 and the second driving pulse P2. However, at the first resonance timing, that is, at the timing of the interval Td1 when the wave height value Vp3 should become small, it seems that the voltage of the wave height value Vp3 is slightly large.

[0084] The satellite droplet velocity Vjs also appears to change periodically according to the interval Td1. However, in the first resonance timing, that is, a region S0 where the satellite disappears was obtained when the voltage of the wave height value Vp3 was slightly increased.

[0085] As described above, when the first drive pulse P1 is not used, when the voltage is increased to the limit voltage for whether or not to discharge by the second drive pulse P2 which is a non-discharge pulse, a region where the satellite disappears or the satellite droplet velocity becomes significantly faster is obtained.

[0086] On the other hand, in the present embodiment, the first drive pulse P1 is arranged before the second drive pulse P2. Therefore, when pressurizing by the second drive pulse P2, the meniscus vibration by the second drive pulse P2 is affected by the residual vibration of the first drive pulse P1.

[0087] As a result, even if the wave height value Vp2 of the second drive pulse P2 is a low voltage at which the satellite does not disappear or the satellite droplet velocity does not become significantly faster, the meniscus vibration by the second drive pulse P2 is amplified to the limit vibration for whether or not to discharge the liquid. As a result, a region where the satellite disappears or the satellite droplet velocity becomes significantly faster is obtained.

[0088] In this way, since the wave height value Vp2 of the second drive pulse P2 can be set to a low voltage at which the liquid is not discharged, the second drive pulse P2 can be used as a fine drive waveform capable of vibrating the meniscus without discharging the liquid.

[0089] That is, by arranging the drive pulse for discharging before the fine drive pulse for vibrating the meniscus, the vibration by the fine drive pulse is amplified by the residual vibration of the drive pulse, and the fine drive pulse can have the same waveform strength (wave height value) as the pulse for satellite suppression.

[0090] As a result, even with multiple droplets such as large droplets and medium droplets, satellite-free operation can be achieved, or the satellite droplet velocity can be significantly increased, eliminating the need for a dedicated non-ejection pulse for satellite-free operation, shortening the drive waveform length, and enabling high-frequency driving.

[0091] Next, the peak value of the second drive pulse will be described with reference to FIG. 10. FIG. 10 is an explanatory diagram showing an example of the change in the droplet velocity Vj when the peak value Vp3 of the third drive pulse P3 is fixed and the peak value Vp2 of the second drive pulse P2 is changed in the case of two pulses of the second drive pulse P2 and the third drive pulse P3.

[0092] Also in this case, the change in the droplet velocity Vj can be largely divided into three ranges S1, S2, and S3 depending on the value of the peak value Vp2.

[0093] At this time, the peak value Vp2 in the range S3 is the voltage at which droplets are about to be ejected by the second drive pulse P2 and is no longer a non-ejection pulse. Therefore, the second drive pulse P2 cannot be used as a fine drive waveform.

[0094] Further, the peak value Vp2 in the range S2 is the voltage at which the meniscus swells due to the second drive pulse P2 and is not a simple vibration but a voltage that is tending to swell. Therefore, it has been found that if the drive is continued, the control of the meniscus becomes impossible and non-ejection occurs.

[0095] Therefore, when the second drive pulse P2 is used as a fine drive waveform (fine drive pulse), it is preferable that the voltage of the peak value Vp2 in the range S1 is used. That is, when the second drive pulse P2 is used as a fine drive waveform (fine drive pulse), the peak value Vp2 is preferably a voltage at which the droplet velocity is slower than the maximum value of the droplet velocity.

[0096] Next, the relationship between the interval Td2 between the second drive pulse P2 and the third drive pulse P3 and the suppression of satellites will be described with reference to FIGS. 11 to 14.

[0097] Here, the interval Td2 between the second drive pulse P2 and the third drive pulse P3 was made different from the resonance period Tc, the peak value Vp3 of the third drive pulse P3 was adjusted so that the droplet velocity became constant, and the change in satellite droplets with respect to the change in the second drive pulse P2 was evaluated.

[0098] First, FIG. 11 shows the case where the interval Td2 between the second drive pulse P2 and the third drive pulse P3 is made shorter than the resonance period Tc by (2 / 5)Tc (Td2 = Tc - (2 / 5)Tc).

[0099] Under this condition, no condition for the peak value Vp2 of the second drive pulse P2 that results in satellite droplet - free is seen.

[0100] Next, FIG. 12 shows the case where the interval Td2 between the second drive pulse P2 and the third drive pulse P3 is made shorter than the resonance period Tc by (1 / 4)Tc (Td2 = Tc - (1 / 4)Tc).

[0101] Under this condition, the range of the peak value Vp2 of the second drive pulse P2 is narrower than that in the case of Td2 = Tc, but a satellite - droplet - free region S0 was confirmed.

[0102] Next, FIG. 13 shows the case where the interval Td2 between the second drive pulse P2 and the third drive pulse P3 is made longer than the resonance period Tc by (1 / 3)Tc (Td2 = Tc + (1 / 3)Tc).

[0103] Under this condition, the range of the peak value Vp2 of the second drive pulse P2 is narrower than that in the case of Td2 = Tc, but a satellite - droplet - free region S0 was confirmed.

[0104] Next, FIG. 14 shows the case where the interval Td2 between the second drive pulse P2 and the third drive pulse P3 is made longer than the resonance period Tc by (1 / 2)Tc (Td2 = Tc + 1 / 2Tc).

[0105] Under these conditions, no condition for the peak value Vp2 of the second drive pulse P2 to become satellite-free was observed. Also, even when the interval Td2 was made longer than (Tc + (1 / 2)Tc), no condition for becoming satellite-free could be confirmed.

[0106] Next, based on the above results, the relationship between the interval Td2 between the second drive pulse P2 and the third drive pulse P3 that can be made satellite-free and the resonance period Tc, and the peak value Vp2 of the second drive pulse P2 will be described with reference to FIGS. 15 to 19.

[0107] FIG. 14 shows the relationship between the maximum value and the minimum value of the peak value Vp2 of the second drive pulse P2 where the satellite-free region S0 occurs, and the voltage ratio thereof.

[0108] The horizontal axis of FIG. 15 represents the Tc ratio difference (Tc ratio conversion) from the resonance period Tc (resonance timing) of the interval Td2 between the second drive pulse P2 and the third drive pulse P3. For example, the Tc ratio difference of "0.1" indicates that it is the evaluation result at an interval Td2 (Td2 = Tc + 0.1Tc) that is longer by (0.1 × Tc) than the interval Td2 that is the same as the resonance period Tc.

[0109] FIG. 16 shows the maximum value and the minimum value of the peak value Vp2 of the second drive pulse P2 that becomes satellite-free, and the peak value Vp2 (this is referred to as the "peak peak value Vpp2") when the peak value Vp3 of the third drive pulse P3 is taken (when the droplet velocity of the liquid ejected by the third drive pulse P3 becomes the minimum value).

[0110] The horizontal axis of FIG. 16, similar to FIG. 15, represents the Tc ratio difference (Tc ratio conversion) from the resonance period Tc (resonance timing) of the interval Td2 between the second drive pulse P2 and the third drive pulse P3. For example, the Tc ratio difference of "0.1" indicates that it is the evaluation result at an interval Td2 (Td2 = Tc + 0.1Tc) that is longer by (0.1 × Tc) than the interval Td2 that is the same as the resonance period Tc.

[0111] Figures 17 to 19 show the voltage ranges of the maximum value (maximum Vp2) and the minimum value (minimum Vp2) of the peak value Vp2 of the second drive pulse P2, represented by the ratio of the voltage difference from the peak peak value Vpp2.

[0112] The horizontal axis of FIGS. 17 to 19 represents, as in FIG. 16, the Tc ratio difference (Tc ratio conversion) from the resonance period Tc (resonance timing) of the interval Td2 between the second drive pulse P2 and the third drive pulse P3. For example, the Tc ratio difference of "0.1" indicates that it is the evaluation result at an interval Td2 ((0.1 × Tc) longer than the interval Td2 equal to the resonance period Tc (Td2 = Tc + 0.1Tc)).

[0113] From these, it can be seen that when the interval Td2 between the second drive pulse P2 and the third drive pulse P3 deviates around the resonance period Tc, the voltage range of the peak value Vp2 of the second drive pulse P2 that can achieve satellite-less becomes narrower.

[0114] Here, the interval Td2 between the second drive pulse P2 and the third drive pulse P3 that can achieve satellite-less is within the range of ±1 / 3Tc (Tc - (1 / 3)Tc to Tc + (1 / 3)Tc) around the resonance period Tc.

[0115] Also, it can be seen that the second drive pulse P2 is within the range of "-10% to +10%" of the peak peak value Vpp2, which is the peak value Vp2 when the droplet velocity Vj of the liquid ejected by the third drive pulse P3 becomes the minimum value, that is, when the peak value Vp3 of the second drive pulse P3 takes a peak.

[0116] Here, in order to ensure a voltage margin Δ10% (±5%: -5% to +5%) or more, it is preferable that the interval Td2 between the second drive pulse P2 and the third drive pulse P3 is within the range of (Tc - (1 / 4)Tc to Tc + (1 / 4)Tc).

[0117] In addition, in order to ensure a voltage margin Δ of 15% or more (±7.5%: -7.5% to +7.5%), the interval Td2 between the second drive pulse P2 and the third drive pulse P3 is preferably within the range of (Tc - (1 / 6)Tc to Tc + (1 / 6)Tc).

[0118] Also, by setting the interval Td2 between the second drive pulse P2 and the third drive pulse P3 to the resonance period Tc (Td2 = Tc), a voltage margin Δ of 20% or more (±10.0%: -10.0% to +10.0%) can be ensured.

[0119] Next, a second embodiment of the present invention will be described with reference to FIGS. 20 to 22. FIGS. 20 to 22 are explanatory diagrams for explaining the relationship between the interval Td2 between the second drive pulse P2 and the third drive pulse P3 that can achieve satellite-less and the resonance period Tc, and the peak value Vp2 of the second drive pulse P2.

[0120] FIGS. 20 to 22 show the voltage ranges of the maximum value (maximum Vp2) and the minimum value (minimum Vp2) of the peak value Vp2 of the second drive pulse P2 represented by the ratio of the voltage difference from the peak-to-peak value Vpp2.

[0121] The horizontal axis in FIGS. 20 to 22 represents the Tc ratio difference (Tc ratio conversion) from the resonance period Tc (resonance timing) of the interval Td2 between the second drive pulse P2 and the third drive pulse P3. For example, the Tc ratio difference of "0.1" indicates that it is the evaluation result at a time interval Td2 (Td2 = Tc + 0.1Tc) that is longer by (0.1 × Tc) than the interval Td2 that is the same as the resonance period Tc.

[0122] In this embodiment, the interval Td2 between the second drive pulse P2 and the third drive pulse P3 that can achieve satellite-less is within the range of Tc - 0.2Tc to Tc + 0.45Tc, in other words, Tc - (1 / 5)Tc to Tc + (9 / 20)Tc.

[0123] Also, the second drive pulse P2 is within the range of "-5% to +10%" of the peak wave height value Vpp2, which is the wave height value Vp2 when the droplet velocity Vj of the liquid ejected by the third drive pulse P3 reaches the minimum value, that is, when the peak value Vp3 of the third drive pulse P3 peaks.

[0124] Here, in order to ensure a voltage margin of ±5% (-5% to +5%) or more, from FIG. 21, the interval Td2 between the second drive pulse P2 and the third drive pulse P3 is preferably in the range of Tc - 0.1Tc to Tc + 0.25Tc, in other words, Tc - (1 / 10)Tc to Tc + (1 / 4)Tc.

[0125] Also, in order to ensure a voltage margin of ±7.5% (-7.5% to +7.5%) or more, from FIG. 22, the interval Td2 between the second drive pulse P2 and the third drive pulse P3 is preferably in the range of Tc - 0.07Tc to Tc + 0.2Tc, in other words, Tc - (1 / 14)Tc to Tc + (1 / 5)Tc.

[0126] As described above, the drive waveform generation device in each embodiment successively includes in time series a first drive pulse P1 for ejecting liquid, a second drive pulse P2 for not ejecting liquid, and a third drive pulse P3 for ejecting liquid. The second drive pulse P2 can be used alone as a micro drive waveform for vibrating the meniscus to such an extent that it does not eject liquid. The intervals Td1 between the first drive pulse P1 and the second drive pulse P2 and Td2 between the second drive pulse P2 and the third drive pulse P3 are in a resonance relationship respectively. The wave height value Vp2 of the second drive pulse P2 is a voltage within the range of -10% to +10% of the wave height value Vpp2 at which the droplet velocity Vj becomes the minimum value when the first drive pulse P1 is applied, then the second drive pulse P2 is applied, and further the third drive pulse P3 is applied to eject the liquid, and a drive waveform Va is generated.

[0127] Also, in the drive waveform generation device according to each embodiment, a first drive pulse P1 for discharging liquid, a second drive pulse P2 for not discharging liquid, and a third drive pulse P3 for discharging liquid are continuously included in time series. The second drive pulse P2 can be used alone as a micro drive waveform for vibrating the meniscus to such an extent that liquid is not discharged. The intervals Td1 between the first drive pulse P1 and the second drive pulse P2 and Td2 between the second drive pulse P2 and the third drive pulse P3 are each in a resonance relationship. The peak value Vp1 of the first drive pulse P1 can be a voltage within the range of -10% to +10% of the peak value Vpp1 of the voltage at which the droplet velocity Vj becomes a minimum value when the first drive pulse P1 is applied, then the second drive pulse P2 is applied, and further the third drive pulse P3 is applied to discharge the liquid.

[0128] Also, the head drive method according to each embodiment includes, in time series, a first drive pulse P1 for discharging liquid, a second drive pulse P2 for not discharging liquid, and a third drive pulse P3 for discharging liquid. The second drive pulse P2 can be used alone as a micro drive waveform for vibrating the meniscus to such an extent that liquid is not discharged. The intervals Td1 between the first drive pulse P1 and the second drive pulse P2 and Td2 between the second drive pulse P2 and the third drive pulse P3 are each in a resonance relationship. The peak value Vp2 of the second drive pulse P2 is a voltage within the range of -10% to +10% of the peak value Vpp2 of the voltage at which the droplet velocity Vj becomes a minimum value when the first drive pulse P1 is applied, then the second drive pulse P2 is applied, and further the third drive pulse P3 is applied to discharge the liquid, and a drive waveform Va is generated and the drive waveform Va is applied to the liquid discharge head to discharge the liquid.

[0129] Also, in the head driving method in each embodiment, a first driving pulse P1 for discharging liquid, a second driving pulse P2 for not discharging liquid, and a third driving pulse P3 for discharging liquid are continuously included in time series. The second driving pulse P2 can be used alone as a micro driving waveform for vibrating the meniscus to such an extent that no liquid is discharged. The intervals Td1 between the first driving pulse P1 and the second driving pulse P2 and Td2 between the second driving pulse P2 and the third driving pulse P3 are in a resonance relationship respectively. The peak value Vp1 of the first driving pulse P1 is a voltage within the range of -10% to +10% of the peak value Vpp1 at which the droplet velocity Vj becomes a minimum value when the liquid is discharged by applying the first driving pulse P1, then the second driving pulse P2, and further the third driving pulse P3. A driving waveform Va is generated, and by applying the driving waveform Va to the liquid discharge head, the liquid can be discharged.

[0130] In the present application, the liquid to be discharged may be any liquid having a viscosity and surface tension that can be discharged from the head, and is not particularly limited. However, it is preferably a liquid whose viscosity becomes 30 mPa·s or less at normal temperature and normal pressure, or by heating or cooling. More specifically, it includes solutions, suspensions, emulsions, etc. containing solvents such as water and organic solvents, colorants such as dyes and pigments, polymerizable compounds, resins, functional imparting materials such as surfactants, biocompatible materials such as DNA, amino acids, proteins, calcium, and edible materials such as natural pigments. These can be used, for example, in applications such as inkjet inks, surface treatment liquids, components of electronic elements and light-emitting elements, liquids for forming electronic circuit resist patterns, and material liquids for three-dimensional shaping.

[0131] As an energy generation source for discharging liquid, those using a piezoelectric actuator (a laminated piezoelectric element and a thin film piezoelectric element), a thermal actuator using an electrothermal conversion element such as a heating resistor, an electrostatic actuator composed of a diaphragm and a counter electrode, etc. are included.

[0132] Also, the "device for discharging liquid" includes not only a device capable of discharging liquid onto an object to which the liquid can adhere, but also a device for discharging liquid into the air or into a liquid.

[0133] This "liquid discharging device" can include means related to the feeding, conveying, and paper discharging of objects to which liquid can adhere, as well as other pre-treatment devices, post-treatment devices, and the like.

[0134] For example, as the "liquid discharging device", there are an image forming device that discharges ink to form an image on a sheet of paper, and a three-dimensional modeling device (3D modeling device) that discharges a modeling liquid onto a powder layer formed by layering powders in order to model a three-dimensional object (3D object).

[0135] Also, the "liquid discharging device" is not limited to those in which a significant image such as characters or figures is visualized by the discharged liquid. For example, those that form a pattern or the like that has no meaning by itself, and those that model a three-dimensional image are also included.

[0136] The above-mentioned "objects to which liquid can adhere" means objects to which liquid can adhere at least temporarily, and includes those that adhere and adhere firmly, those that adhere and penetrate, and the like. Specific examples include recording media such as paper, recording paper, recording sheets, films, and cloth, electronic components such as electronic substrates and piezoelectric elements, powder layers (powder layers), organ models, media such as test cells, and all objects to which liquid adheres are included unless otherwise particularly limited.

[0137] The material of the above-mentioned "objects to which liquid can adhere" may be paper, thread, fiber, fabric, leather, metal, plastic, glass, wood, ceramics, etc., as long as liquid can adhere even temporarily.

[0138] Also, among the "liquid discharging devices", there are devices in which the liquid discharge head and the objects to which liquid can adhere move relative to each other, but it is not limited to this. Specific examples include serial type devices that move the liquid discharge head and line type devices that do not move the liquid discharge head.

[0139] In addition, as the "liquid ejection device", there are also other devices such as a treatment liquid coating device that ejects a treatment liquid onto paper to coat the surface of the paper for the purpose of modifying the surface of the paper, and an injection granulation device that granulates fine particles of raw materials by injecting a composition liquid in which the raw materials are dispersed in a solution through a nozzle.

[0140] Note that in the terms of this application, image formation, recording, printing, imprinting, printing, shaping, etc. are all synonymous.

Explanation of Reference Numerals

[0141] 1 Printing device 10 Loading unit 20 Pretreatment unit 30 Printing unit 40 Drying unit 50 Unloading unit 21 Coating unit 33 Ejection unit 100 Liquid ejection head (head) 106 Pressure chamber 112 Piezoelectric element 400 Head drive control unit 401 Head control unit 402 Drive waveform generation unit 403 Waveform data storage unit 410 Head driver

Claims

1. A driving waveform generating means for generating a driving waveform including a plurality of driving pulses applied to a liquid ejection head, wherein the driving waveform successively includes, in time series, a first driving pulse for ejecting liquid, a second driving pulse for not ejecting the liquid, and a third driving pulse for ejecting the liquid, wherein the second driving pulse can be used alone as a micro driving waveform for vibrating the meniscus to such an extent that the liquid is not ejected, wherein the intervals between the first driving pulse and the second driving pulse and between the second driving pulse and the third driving pulse are each in a resonance relationship, wherein the peak value Vp2 of the second driving pulse is a voltage within a range of -10% to +10% of the peak value Vpp2 at which the droplet velocity becomes a minimum value when the liquid is ejected by applying the first driving pulse, then the second driving pulse, and further the third driving pulse, An apparatus for ejecting a liquid, characterized in that.

2. A driving waveform generating means for generating a driving waveform including a plurality of driving pulses applied to a liquid ejection head, wherein the driving waveform successively includes, in time series, a first driving pulse for ejecting liquid, a second driving pulse for not ejecting the liquid, and a third driving pulse for ejecting the liquid, wherein the second driving pulse can be used alone as a micro driving waveform for vibrating the meniscus to such an extent that the liquid is not ejected, wherein the intervals between the first driving pulse and the second driving pulse and between the second driving pulse and the third driving pulse are each in a resonance relationship, wherein the peak value Vp1 of the first driving pulse is a voltage within a range of -10% to +10% of the peak value Vpp1 at which the droplet velocity becomes a minimum value when the liquid is ejected by applying the first driving pulse, then the second driving pulse, and further the third driving pulse, An apparatus for ejecting a liquid, characterized in that.

3. The peak value Vp2 of the second driving pulse is lower than the peak value at which the droplet velocity of the liquid becomes a maximum value when the second driving pulse and the third driving pulse are applied. The apparatus for ejecting a liquid according to claim 1 or 2, characterized in that.

4. The peak value Vp2 of the second driving pulse is within a range of -7.5% to +7.5% of the peak value Vpp2 at which the droplet velocity of the liquid becomes a minimum value when the third driving pulse is applied. The apparatus for ejecting a liquid according to any one of claims 1 to 3, characterized in that.

5. The peak value Vp2 of the second driving pulse is within the range of -5.0% to +5.0% of the peak value Vpp2 when the droplet velocity of the liquid becomes the minimum value when the third driving pulse is applied. The apparatus for discharging a liquid according to any one of claims 1 to 3, characterized in that.

6. A driving waveform generation device that generates a driving waveform including a plurality of driving pulses applied to a liquid discharge head, The driving waveform successively includes, in time series, a first driving pulse for discharging the liquid, a second driving pulse for not discharging the liquid, and a third driving pulse for discharging the liquid. The second driving pulse can be used alone as a micro driving waveform for vibrating the meniscus to such an extent that the liquid is not discharged. The intervals between the first driving pulse and the second driving pulse, and between the second driving pulse and the third driving pulse are respectively in a resonance relationship. The peak value Vp2 of the second driving pulse is a voltage within the range of -10% to +10% of the peak value Vpp2 when the droplet velocity becomes the minimum value when the first driving pulse is applied, then the second driving pulse is applied, and further the third driving pulse is applied to discharge the liquid. A driving waveform generation device, characterized in that.

7. A driving waveform generation device that generates a driving waveform including a plurality of driving pulses applied to a liquid discharge head, The driving waveform successively includes, in time series, a first driving pulse for discharging the liquid, a second driving pulse for not discharging the liquid, and a third driving pulse for discharging the liquid. The second driving pulse can be used alone as a micro driving waveform for vibrating the meniscus to such an extent that the liquid is not discharged. The intervals between the first driving pulse and the second driving pulse, and between the second driving pulse and the third driving pulse are respectively in a resonance relationship. The peak value Vp1 of the first driving pulse is a voltage within the range of -10% to +10% of the peak value Vpp1 when the droplet velocity becomes the minimum value when the first driving pulse is applied, then the second driving pulse is applied, and further the third driving pulse is applied to discharge the liquid. A driving waveform generation device, characterized in that.

8. A head driving method that generates a driving waveform including a plurality of driving pulses applied to a liquid discharge head, and applies the driving waveform to the liquid discharge head to discharge the liquid. The drive waveform sequentially and continuously includes a first drive pulse for ejecting the liquid, a second drive pulse for not ejecting the liquid, and a third drive pulse for ejecting the liquid. The second drive pulse can be used alone as a fine drive waveform that vibrates the meniscus to such an extent that the liquid is not ejected. The intervals between the first drive pulse and the second drive pulse, and between the second drive pulse and the third drive pulse are each in a resonance relationship. The peak value Vp2 of the second drive pulse is a voltage within the range of -10% to +10% of the peak value Vpp2 at which the droplet velocity becomes a minimum value when the first drive pulse is applied, then the second drive pulse is applied, and further the third drive pulse is applied to eject the liquid. A head drive method characterized by the above.

9. A head drive method for generating a drive waveform including a plurality of drive pulses applied to a liquid ejection head, and applying the drive waveform to the liquid ejection head to eject the liquid, The drive waveform sequentially and continuously includes a first drive pulse for ejecting the liquid, a second drive pulse for not ejecting the liquid, and a third drive pulse for ejecting the liquid. The second drive pulse can be used alone as a fine drive waveform that vibrates the meniscus to such an extent that the liquid is not ejected. The intervals between the first drive pulse and the second drive pulse, and between the second drive pulse and the third drive pulse are each in a resonance relationship. The peak value Vp1 of the first drive pulse is a voltage within the range of -10% to +10% of the peak value Vpp1 at which the droplet velocity becomes a minimum value when the first drive pulse is applied, then the second drive pulse is applied, and further the third drive pulse is applied to eject the liquid. A head drive method characterized by the above.

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