Drive device and liquid discharge device

Abstract

To provide a drive device and a liquid discharge device that can suppress influx of current.SOLUTION: A drive device according to an embodiment includes a drive circuit that outputs a drive waveform to drive an actuator of a liquid discharge unit that discharges liquid. The drive waveform transitions from a first potential which is higher than an intermediate potential excluding the lowest voltage and the highest voltage to a second potential which is lower than the intermediate potential and transitions from the second potential to the intermediate potential within a time equal to or shorter than the time constant of charging / discharging of the actuator.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] An embodiment of the present invention relates to a drive device and a liquid ejection device. [Background technology]

[0002] In liquid ejection devices such as inkjet heads, a multi-drop drive is known as a drive waveform for ejection control, which continuously supplies voltage to an actuator at an AL pulse period to eject multiple ink droplets in succession to form one pixel. In such a drive waveform, if the balance between the amount of current flowing in and out of the intermediate potential is poor, a current flowing in to the intermediate potential may occur.

[0003] In such liquid ejection devices, there is a demand for technology that can suppress the inflow of current. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2006-256094 A Summary of the Invention [Problem to be solved by the invention]

[0005] An object of the present invention is to provide a drive device and a liquid ejection device that can suppress the inflow of current. [Means for solving the problem]

[0006] A driving device according to an embodiment includes a driving circuit that outputs a driving waveform for driving an actuator of a liquid ejection unit that ejects liquid. The driving waveform transitions from a first potential higher than an intermediate potential excluding a minimum voltage and a maximum voltage to a second potential lower than the intermediate potential, and transitions from the second potential to the intermediate potential in a time equal to or shorter than a time constant for charging and discharging the actuator. [Brief description of the drawings]

[0007] [Figure 1] FIG. 1 is an explanatory diagram illustrating a configuration of a liquid ejection device according to a first embodiment. [Diagram 2] FIG. 1 is a perspective view showing a configuration of a liquid ejection head according to a first embodiment. [Diagram 3] FIG. 4 is an equivalent circuit diagram for a channel of the liquid ejection head according to the embodiment. [Figure 4] 6 is a graph showing the relationship between the release discharge waveform and the current consumption of a second power source according to the embodiment. [Diagram 5] 11 is a graph showing the relationship between a standard waveform as a comparative example and the current consumption of a second power supply. [Figure 6] 13 is a graph showing the relationship between a release discharge waveform having a step waveform according to another embodiment and the current consumption of a second power source. [Figure 7] 11 is a graph showing the relationship between a standard waveform having a step waveform as a comparative example and the current consumption of a second power supply. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] A liquid ejection head 1 according to the first embodiment and a liquid ejection device 2 using the liquid ejection head 1 will be described below with reference to FIG. 1 and FIG. 2. FIG. 1 is an explanatory diagram showing the configuration of the liquid ejection device 2 according to the first embodiment, and FIG. 2 is a perspective view showing the configuration of the liquid ejection head 1. FIG. 3 is an explanatory diagram showing a drive circuit. FIG. 4 is a graph showing a discharge waveform according to the embodiment and a current consumption of the second power source. FIG. 5 is a graph showing a reference waveform and a current consumption of the second power source as a comparative example. FIG. 6 is a graph showing a discharge waveform having a step waveform Pe according to another embodiment and a current consumption of the second power source. FIG. 7 is a graph showing a reference waveform having a step waveform Pe and a current consumption of the second power source as a comparative example. Note that in each figure, the configuration is enlarged, reduced, or omitted as appropriate for the purpose of explanation.

[0009] A liquid ejection device 2 having a liquid ejection head 1 will be described with reference to Fig. 1. The liquid ejection device 2 includes a housing 2111, a medium supply unit 2112, an image forming unit 2113, a medium ejection unit 2114, a conveying device 2115 which is a supporting device, and a control unit 2118.

[0010] The liquid ejection device 2 is an inkjet printer that performs an image formation process on paper P by ejecting liquid such as ink while transporting the paper P as a recording medium, which is the object of ejection, along a predetermined transport path 2001 from a medium supply section 2112 through an image forming section 2113 to a medium ejection section 2114.

[0011] The medium supply unit 2112 includes a plurality of paper feed cassettes 21121. The image forming unit 2113 includes a support unit 2120 that supports paper, and a plurality of head units 2130 that are disposed above and facing the support unit 2120. The medium discharge unit 2114 includes a paper discharge tray 21141.

[0012] The support section 2120 includes a conveyor belt 21201 provided in a loop shape in a predetermined area where image formation is performed, a support plate 21202 supporting the conveyor belt 21201 from the rear side, and a plurality of belt rollers 21203 provided on the rear side of the conveyor belt 21201.

[0013] The head unit 2130 includes liquid ejection heads 1 which are multiple inkjet heads, multiple supply tanks 2132 as liquid tanks mounted on each liquid ejection head 1, a pump 2134 which supplies ink, and a connection flow path 2135 which connects the liquid ejection heads 1 and the supply tanks 2132.

[0014] The liquid ejection head 1 is supplied with ink as liquid stored in a supply tank 2132. The liquid ejection head 1 may be a non-circulation type head that does not circulate ink, or may be a circulation type head that circulates ink.

[0015] In this embodiment, the liquid ejection heads 1 are provided with four colors, cyan, magenta, yellow, and black, and four supply tanks 2132 for storing ink of each color. The supply tanks 2132 are connected to the liquid ejection heads 1 by connection flow paths 2135.

[0016] As shown in FIG. 2, the liquid ejection head 1 is an inkjet head, and includes a nozzle plate 21 having a plurality of nozzles 211, an actuator substrate 22, a manifold 23 joined to the actuator substrate 22, and a drive circuit 24 as a drive waveform generating means.

[0017] The actuator substrate 22 is disposed opposite the nozzle 211 and includes an actuator section 25 as a liquid ejection section having a plurality of pressure chambers 26 communicating with the nozzle 211, and a driving element 27 as an actuator that changes the volume of the pressure chambers 26. The actuator substrate 22 is configured in a predetermined shape that forms a predetermined flow path including the plurality of pressure chambers 26 between it and the nozzle plate 21.

[0018] An electrode connected to the drive circuit 24 is formed on the drive element 27 adjacent to the pressure chamber 26 of the actuator section 25. The electrode is connected to the control section 2118 via a driver of the drive circuit 24 (described later) by wiring connected to the drive circuit 24, for example, and is configured to be drive-controllable by control by a processor.

[0019] The drive circuit 24 includes a driver IC 241 and various wiring boards 242. The drive circuit 24 drives the actuator section 25 by applying a drive voltage to the wiring pattern of the actuator section 25 by the driver IC 241, thereby increasing or decreasing the volume of the pressure chamber 26 and causing droplets to be ejected from the nozzles 211 arranged opposite to each other.

[0020] The liquid ejection head 1 defines a predetermined flow path having a pressure chamber 26 therein by a nozzle plate 21, an actuator substrate 22, and a manifold 23. The flow path of the liquid ejection head 1 is connected to a connection flow path 2135 of the liquid ejection device.

[0021] The pump 2134 is a liquid-sending pump constituted by, for example, a piezoelectric pump. The pump 2134 is connected to the control unit 2118, and is drive-controlled by the control unit 2118.

[0022] The connection flow path 2135 includes a supply flow path that is connected to an ink supply pipe of the liquid ejection head 1. The connection flow path 2135 also includes a recovery flow path that is connected to an ink discharge pipe of the liquid ejection head 1. For example, if the liquid ejection head 1 is of a non-circulation type, the recovery flow path is connected to a maintenance device, and if the liquid ejection head 1 is of a circulation type, the recovery flow path is connected to a supply tank 2132.

[0023] The transport device 2115 transports the paper P along a transport path 2001 that runs from a paper feed cassette 21121 of the medium supply unit 2112 through the image forming unit 2113 to a paper discharge tray 21141 of the medium discharge unit 2114. The transport device 2115 includes a plurality of guide plate pairs 21211-21218 and a plurality of transport rollers 21221-21228 that are arranged along the transport path 2001. The transport device 2115 supports the paper P so that it can move relative to the liquid ejection head 1.

[0024] The control unit 2118 is, for example, a control board, and includes a processor, a read only memory (ROM), a random access memory (RAM), an I / O port which is an input / output port, and an image memory.

[0025] The processor is a processing circuit such as a CPU (Central Processing Unit) that is a controller. The processor controls the head unit 2130, the drive motor, the operation unit, various sensors, and the like provided in the liquid ejection device 2 through an I / O port. The processor transmits the print data stored in the image memory to the drive circuit 24 in the drawing order.

[0026] The control unit 2118 also determines a drive waveform, for example, by selecting a waveform to be applied from waveforms that can be set in a plurality of stages.

[0027] The ROM stores various programs, etc. The RAM temporarily stores various variable data, image data, etc. The I / O port is an interface unit that inputs data from the outside and outputs data to the outside. Print data from an externally connected device is sent to the control unit 2118 through the I / O port and saved in the image memory.

[0028] The print data is data that is converted from image data including color and density image information for each area, and is input to the head in order to eject liquid. The liquid ejection head 1 inputs a drive signal corresponding to the input print data to a drive circuit 24, and applies a drive waveform to each drive element 27 of the actuator section 25 via the drive circuit 24.

[0029] The characteristics of the liquid ejection head 1 used in the liquid ejection device 2 according to the embodiment and the drive waveform of the drive signal generated by the drive circuit 24 of the liquid ejection head 1 will be described below. For example, the liquid ejection head 1 is driven by a multi-drop drive in which a drive waveform is continuously supplied to the drive element 27 of the actuator section 25 at a certain pulse period of AL to continuously eject a plurality of ink droplets to form one pixel, and is driven at multiple gradations by combining multiple drop waveforms. That is, the drive circuit 24 drives with a multi-gradation drive waveform by multiple patterns (multiple types) of multi-drop signals. For example, in the drive waveform according to this embodiment, the width from the expansion element Pa to the contraction element Pb is set to AL (Acoustic Length), which is half the time of the natural vibration period of the pressure chamber 26 of the liquid ejection head 1.

[0030] Fig. 3 is an equivalent circuit diagram of the drive circuit 24 according to this embodiment. The drive circuit 24 can switch between three or more voltages, and serves as a drive waveform generating means that outputs a predetermined drive waveform by switching between three or more voltages. As an example, as shown in Fig. 3, the drive circuit 24 includes three switches 243 connected to the drive element 27 and two power sources 244 and 245, and outputs a drive waveform including three or more voltage values ​​by switching the connection of each switch 243 to switch the voltage applied to the drive element 27.

[0031] Based on the print data, the control unit 2118 sets the drive waveform to be applied to each drive element 27. For example, the control unit 2118 switches the connection state between the power supplies 244, 245 and GND by switching the switch 243 in the drive circuit 24, thereby switching between three or more types of voltage to be applied to the target drive element 27. That is, the drive circuit 24 functions as a drive waveform generating means that generates and outputs a predetermined drive waveform by switching the switch 243.

[0032] As an example, the voltage is switched between three potentials: a first potential connected to the first power supply 244, an intermediate potential connected to the second power supply 245, and a second potential connected to the ground.

[0033] Here, the intermediate potential Vb is set to a potential excluding the minimum potential and the maximum potential. Also, as an example, the second potential Va, which is the discharge potential, is set to the ground potential by grounding. That is, for example, in this embodiment, the first potential Vc is set to the maximum potential, the second potential Va, which is the ground potential, is set to the minimum potential, and the intermediate potential is set to a potential between them.

[0034] For example, the control unit 2118 outputs to at least any of the driving elements 27 an ejection waveform WA that temporarily lowers the voltage to a second potential Va that is even lower than the intermediate potential Vb when lowering the voltage from a first potential Vc that is higher than the intermediate potential Vb to the intermediate potential Vb.

[0035] 4 is a graph showing the ejection waveform WA according to this embodiment, with the vertical axis showing voltage [V] and the horizontal axis showing time [μs]. For example, the ejection waveform WA according to this embodiment is an ejection waveform that ejects liquid once from the nozzle 211 by expanding and contracting. For example, the ejection waveform WA shows a drop waveform for one drop in multi-drop driving. In other words, the ejection waveform WA is one drop waveform in a multi-drop waveform that has multiple drop waveforms in succession.

[0036] 4, the ejection waveform WA first transitions from an intermediate potential Vb excluding the minimum and maximum voltages to a second potential Va lower than the intermediate potential Vb, then transitions from the second potential Va to a first potential Vc higher than the intermediate potential Vb, then transitions from the first potential Vc to a second potential Va lower than the intermediate potential Vb, and transitions from the second potential Va to the intermediate potential Vb in a time equal to or shorter than the time constant of charging and discharging the actuator.

[0037] In other words, the ejection waveform WA in this embodiment is a drive waveform that has an expansion element Pa that first lowers the voltage from an intermediate potential Vb to a second potential Va to expand the pressure chamber, a contraction element Pb that increases the voltage from the second potential Va to the first potential Vc after a certain time has elapsed to contract the pressure chamber, a release element Pc that lowers the voltage from the first potential Vc to a second potential Va lower than the intermediate potential Vb at a predetermined timing after the contraction to release the current, and a return element Pd that, after lowering to the second potential Va, returns the voltage from the second potential Va to the intermediate potential Vb within a time equal to or less than the charge / discharge time constant.

[0038] Here, the time required for decreasing the potential to the second potential is set to be equal to or less than the time constant of charging and discharging the driving element 27 (actuator) to which the potential is applied.

[0039] Specifically, when switching from the first power supply 244 to the second power supply 245 in the drive circuit 24, the control unit 2118 temporarily switches to a second potential Va (GND) lower than the second power supply 245, and temporarily releases the current flowing into the second power supply 245 to GND. Then, within a time period equal to or shorter than the charge / discharge time constant, the power supply is switched back to the second power supply 245, thereby returning to the intermediate potential Vb.

[0040] The lower diagram in Fig. 4 is a graph showing the current consumption I of the second power supply 245 when driving the ejection waveform WA. According to Fig. 4, the current consumption I does not drop even when the ejection waveform WA returns to the intermediate potential after contraction, but shows a straight line that maintains a constant current value. In other words, this shows that no charge flows in.

[0041] According to this embodiment, it is possible to provide a driving device and a liquid ejection device capable of suppressing current flow in. That is, after the contraction element Pb, when the voltage is lowered from the first potential to the intermediate potential, the voltage is temporarily lowered to a second potential lower than the intermediate potential to discharge the voltage, thereby suppressing the electric charge stored in the driving element 27 from flowing into the second power source 245.

[0042] 5 is an explanatory diagram showing the correspondence between the standard waveform WB and the current consumption I of the second power source as a comparative example. The standard waveform WB includes an expansion element Pa that lowers the voltage from the intermediate potential Vb to the second potential Va, a contraction element Pb that increases the voltage from the second potential Va to the first potential Vc after a certain time has elapsed to contract the pressure chamber, and a return element Pf that returns the voltage from the first potential Vc to the intermediate potential Vb again at a predetermined timing thereafter. The current consumption I of the second power source 245 in driving the standard waveform WB maintains a reference current value until the timing of returning to the intermediate potential after contraction, drops once at the timing of returning to the intermediate potential, and presents a curved line from the drop point back to the reference current value. In other words, the current consumption of the power source drops at the timing of returning to the intermediate potential Vb, and at the timing of switching from the first power source to the second power source, the electric charge charged in the driving element 27 flows into the second power source 245.

[0043] In contrast to this, in the ejection waveform WA in the present embodiment, as shown in FIG. 4, discharge is performed at a primarily low potential, which makes it possible to suppress the outflow of charge from the driving element 27, which is an actuator.

[0044] In addition, by setting the time for the discharge waveform WA to the second potential to less than the time constant of charging and discharging the actuator, it is possible to prevent an increase in power consumption and an effect on the drive waveform. That is, for example, the discharge time is influenced by the voltage and the capacitance of the PZT (lead zirconate titanate) drive element 27, and if it is too short, some current will flow into the second power source, while if it is too long, current will flow out of the second power source, which will increase the current consumption of the second power source, so it is necessary to set it to an appropriate time. Therefore, by adjusting it to be short, for example, less than the time constant of charging and discharging, it is possible to prevent current flow from the power source and suppress the effect on print quality.

[0045] The embodiment of the present invention is not limited to the above-mentioned configuration, and can be modified as appropriate.

[0046] For example, the drive waveform is not limited to the example in the above embodiment, and can be changed as appropriate. Fig. 6 is a graph showing a discharge waveform WC having a step waveform Pe and a relief element Pc.

[0047] As shown in FIG. 6, the ejection waveform WC in this embodiment includes an expansion element Pa that expands the pressure chamber by lowering the voltage from the intermediate potential Vb to a second potential Va, a contraction element Pb having a step waveform Pe that returns the voltage from the second potential Va to the intermediate potential Vb after a certain time has elapsed, and then raises the voltage from the intermediate potential Vb to a first voltage Vc higher than the intermediate potential Vb, thereby contracting the pressure chamber 26, a release element Pc that temporarily lowers the voltage from the first voltage Vc to a second voltage Va lower than the intermediate potential Vb, and a return element Pd that returns the voltage from the second voltage Va to the intermediate potential Vb again.

[0048] In driving this ejection waveform WC, the consumption current I of the second power source 245 maintains a reference current value until the timing of returning to the intermediate potential during expansion, rises once at the timing of returning to the intermediate potential after expansion, and presents a curved line returning to the reference current value from the rising point. Thereafter, the consumption current I of the second power source 245 maintains a reference current value until the timing of returning to the intermediate potential after contraction, falls once at the timing of returning to the intermediate potential, and presents a curved line returning to the reference current value from the falling point. In the ejection waveform WC, the amount of increase in the consumption current that rises once at the timing of returning to the intermediate potential after expansion and the amount of decrease at the timing of returning to the intermediate potential are approximately the same. That is, in this embodiment, the escape element Pc is set to a condition that can cancel the inflow of charge in the previous step element. For example, the condition of the escape element Pc is set to a condition where the sum of the inflow current of charge becomes zero as a whole of the ejection waveform WC.

[0049] That is, the waveform WC according to this embodiment is a waveform that transitions from the intermediate potential Vb to the second potential Va, then transitions to the first potential Vc via a step waveform Pe that keeps the second potential Va at the intermediate potential Vb for a predetermined time. Since the charge flows out in this step waveform Pe, the discharge element Pc discharges the charge to the second potential Va in a time less than the time constant of the charge and discharge of the actuator, and the discharge amount and the charge amount in the step waveform Pe are adjusted to be close to each other or the same, so that they cancel each other out. That is, the waveform WC according to this embodiment generates an inflow of charge by discharging on the premise that the charge flows out once by the release ejection waveform, so that the inflow and outflow of charge can be offset by the step waveform Pe and the release ejection waveform.

[0050] According to this embodiment, after the contraction element Pb, when lowering the first potential Vc to the intermediate potential Vb, the voltage is temporarily lowered to the second potential Va which is even lower than the intermediate potential Vb, and then discharged, thereby preventing the electric charge stored in the driving element 27 from flowing into the second power source 245.

[0051] 7 shows a standard ejection waveform WD having a step waveform Pe as a comparative example. The ejection waveform WD includes an expansion element Pa that decreases the potential from the intermediate potential Vb to the second potential Va, a contraction element Pb that returns the voltage from the second potential Va to the intermediate potential Vb after a certain time has elapsed and then increases the voltage from the intermediate potential Vb to the first potential Vc at a predetermined timing to contract the pressure chamber, and a return element Pf that returns the voltage from the first potential Vc to the intermediate potential Vb again at the predetermined timing.

[0052] That is, during contraction, the standard waveform WB has a step waveform Pe that temporarily maintains the voltage at the intermediate potential Vb and gradually increases the voltage. During expansion, the current consumption of the second power supply 245 in driving the standard waveform WB having this step waveform maintains the reference current value until the timing of returning to the intermediate potential Vb, rises once at the timing of returning to the intermediate potential Vb after expansion, and presents a curved line returning to the reference current value from the rising point. Thereafter, the current consumption of the second power supply 245 maintains the reference current value until the timing of returning to the intermediate potential after contraction, falls once at the timing of returning to the intermediate potential, and presents a curved line returning to the reference current value from the falling point. That is, in the ejection waveform WD having a step waveform, the current consumption of the power supply falls at the timing of returning to the intermediate potential Vb, indicating that charge is flowing from the driving element 27 to the second power supply 245. In the ejection waveform WD, when the potential is increased from the second potential Va to the first potential Vc, the potential is increased stepwise to the intermediate potential Vb and then to the first potential Vc, which prevents the inflow of the second power source, but if the step time is not sufficient, the discharge cannot be sufficient. Also, if the step time is too long, it affects the print quality.

[0053] Here, the drop in current consumption at the timing of returning to the intermediate potential is suppressed in the ejection waveform WC compared to the ejection waveform WD having the step waveform Pe. Also, the drop is about the same as the increase in the step waveform Pe, and it can be seen that the charging by the step waveform Pe and the discharging by the release element Pc are able to cancel each other out.

[0054] Also, in the ejection waveform WC having the step waveform Pe, the time for the second potential can be set to be equal to or less than the time constant for charging and discharging the actuator, thereby preventing an increase in power consumption and an effect on the drive waveform. In other words, if the discharge time is too long, a current inflow from the power supply occurs, so by setting the time constant or less, the current inflow from the power supply can be prevented.

[0055] For example, in the above embodiment, the driving circuit 24 having the driver IC 241 provided in the liquid ejection head 1 is exemplified as an example of the driving device, but the present invention is not limited to this. For example, various control devices, such as a control device connected to the liquid ejection head 1 and provided outside the liquid ejection head 1, may be used as the driving device.

[0056] The waveform may be a combination of multiple types of waveforms rather than one type. For example, it is sufficient that the drive waveform applied to any one of the multiple drive elements 27 at any timing has an escape element, and it is also possible to drive the drive element 27 in combination with a different waveform. For example, the ejection waveform having an escape element may be part of a multi-drop waveform that ejects droplets using multiple ejection waveforms, or may be a single waveform that ejects droplets using a single ejection waveform.

[0057] The voltages are not limited to those in the above embodiment. For example, the discharge potential as the second potential is not limited to GND.

[0058] Moreover, the first potential and the second potential are set to the maximum voltage and the minimum voltage, respectively, in the above example, but are not limited to this and may be set to other voltage values.

[0059] Furthermore, the present invention is not limited to the example in which switching is performed at three potentials, and a configuration in which switching is performed at four or more potentials may be used.

[0060] Furthermore, at least one of the non-ejection waveforms may be included, which does not eject any liquid.

[0061] For example, the configuration of the liquid ejection head 1 is not limited to the above example, and may be used for other types of heads. For example, the liquid ejection head may be configured to drive the liquid ejection unit by vibrating a vibration plate provided between the pressure chamber and the drive element by deformation of the drive element.

[0062] According to at least one of the embodiments described above, it is possible to provide a drive device and a liquid ejection device capable of suppressing current inflow.

[0063] Although some embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included in the scope and spirit of the invention, and are included in the scope of the invention and its equivalents described in the claims. [Explanation of symbols]

[0064] 1...liquid ejection head, 2...liquid ejection device, 21...nozzle plate, 22...actuator substrate, 23...manifold, 24...driving circuit, 25...actuator section, 26...pressure chamber, 27...driving element (actuator), 211...nozzle, 241...driver IC, 242...wiring substrate, 243...switch, 244...first power source, 245...second power source, 2001...transport path, 2111...housing, 2112...medium supply section, 2113...image forming section, 2114...medium discharge section, 2115...transport device, 2 118...control unit, 2120...support unit, 2130...head unit, 2132...supply tank, 2134...pump, 2135...connecting flow path, 21121...paper feed cassette, 21141...output tray, 21201...conveyor belt, 21202...support plate, 21203...belt roller, 21211-21218...guide plate pair, 21221-21228...conveyor rollers, Pa...expansion element, Pb...contraction element, Pc...relief element, Pd...return element, Pe...step waveform, Pf...return element.

Claims

1. A drive circuit outputs a drive waveform for driving an actuator of a liquid ejection unit that ejects liquid, A drive device in which the drive waveform transitions from a first potential higher than an intermediate potential excluding a minimum voltage and a maximum voltage to a second potential lower than the intermediate potential, and transitions from the second potential to the intermediate potential in a time equal to or shorter than a time constant for charging and discharging the actuator.

2. The drive circuit outputs the drive waveform by switching three or more types of voltages, Before the drive waveform transitions from the first potential to the second potential, The drive device according to claim 1 , wherein the potential first changes from an intermediate potential to the second potential, and then changes from the second potential to the first potential.

3. 3. The drive device according to claim 2, wherein after the potential has transitioned from the intermediate potential to the second potential, the potential is transitioned to the first potential via a step waveform that keeps the potential at the intermediate potential from the second potential for a predetermined period of time.

4. Discharging the actuator by transitioning from the second potential to the intermediate potential in a time period equal to or less than a time constant of charging and discharging the actuator, 4. The drive device according to claim 3, wherein after the potential changes from the intermediate potential to the second potential, at least a part of the amount of charge caused by the step waveform that changes from the second potential to the intermediate potential for a predetermined period of time is offset.

5. A drive device according to any one of claims 1 to 4, a liquid ejection head that is driven by the drive device to eject liquid, Liquid discharge device.

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