Driving device and liquid ejecting apparatus

Abstract

The invention provides a driving device and a liquid ejecting apparatus, which can suppress current inflow. A drive device according to an embodiment includes a drive circuit that outputs a drive waveform for driving an actuator of a liquid ejection unit that ejects a liquid. The drive waveform is shifted from a first potential higher than an intermediate potential, which is an intermediate potential other than a minimum voltage and a maximum voltage, to a second potential lower than the intermediate potential, and is shifted from the second potential to the intermediate potential for a time equal to or less than a time constant for charging and discharging the actuator.

Description

Technical Field

[0001] Embodiments of the present invention relate to a driving device and a liquid ejecting device. Background Art

[0002] In a liquid ejection device such as an inkjet head, a multi-drop drive is known, in which a voltage is continuously supplied to an actuator within a pulse period of AL as a drive waveform for ejection control, so that a plurality of inks are ejected continuously to form one pixel. In such a drive waveform, if the balance between the outflow and inflow of the current at the intermediate potential deteriorates, the current may flow into the intermediate potential.

[0003] In such a liquid ejection device, a technology capable of suppressing the inflow of electric current is required. Summary of the invention

[0004] Technical problem to be solved by the invention

[0005] The technical problem to be solved by the present invention is to provide a driving device and a liquid ejecting device capable of suppressing the inflow of current.

[0006] Solutions for solving technical problems

[0007] The driving device according to the embodiment includes a driving circuit that outputs a driving waveform for driving an actuator of a liquid ejection portion that ejects liquid. The driving waveform shifts from a first potential higher than an intermediate potential to a second potential lower than the intermediate potential, and shifts from the second potential to the intermediate potential within a time that is less than a time constant of charging and discharging of the actuator, wherein the intermediate potential is an intermediate potential other than a minimum voltage and a maximum voltage.

[0008] A liquid ejection device according to an embodiment includes the above-described driving device and a liquid ejection head that is driven by the driving device to eject liquid. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 It is an explanatory diagram showing the structure of the liquid ejecting device according to the first embodiment.

[0010] Figure 2 It is a perspective view showing the structure of the liquid ejecting head according to the first embodiment.

[0011] Figure 3 It is an equivalent circuit diagram of a channel of a liquid ejection head according to the same embodiment.

[0012] Figure 4 : is a graph showing the relationship between the release discharge waveform and the current consumption of the second power supply according to the same embodiment.

[0013] Figure 5 : is a graph showing the relationship between a standard waveform and the current consumption of the second power supply as a comparative example.

[0014] Figure 6 This is a graph showing the relationship between a discharge waveform having a step waveform and the current consumption of the second power supply according to another embodiment.

[0015] Figure 7 : is a graph showing the relationship between a standard waveform having a step waveform and the current consumption of the second power supply as a comparative example.

[0016] Description of Reference Numerals

[0017] 1: liquid ejection head; 2: liquid ejection device; 21: nozzle plate; 22: actuator substrate; 23: manifold; 24: drive circuit; 25: actuator unit; 26: pressure chamber; 27: drive element (actuator); 211: nozzle; 241: driver IC; 242: wiring substrate; 243: switch; 244: first power source; 245: second power source; 2001: conveying path; 2111: housing; 2112: medium supply unit; 2113: image forming unit; 2114: medium discharge unit; 2115: conveying device ; 2118: control unit; 2120: support unit; 2130: head unit; 2132: supply tank; 2134: pump; 2135: connecting flow path; 21121: paper supply box; 21141: paper discharge tray; 21201: conveyor belt; 21202: support plate; 21203: belt roller; 21211~21218: guide plate pair; 21221~21228: conveying roller; Pa: expansion element; Pb: contraction element; Pc: release element; Pd: return element; Pe: step waveform; Pf: return element. DETAILED DESCRIPTION

[0018] The following reference Figure 1 and Figure 2 A liquid ejecting head 1 according to a first embodiment and a liquid ejecting apparatus 2 using the liquid ejecting head 1 will be described. Figure 1 2 is an explanatory diagram showing the structure of the liquid ejecting device 2 according to the first embodiment. Figure 2 It is a perspective view showing the structure of the liquid ejection head 1. Figure 3 2 is an explanatory diagram showing a driving circuit. Figure 4 Graphs showing the discharge waveform and the current consumption of the second power supply according to the embodiment. Figure 5 : is a graph showing a reference waveform and a current consumption of the second power supply as a comparative example. Figure 6 Graphs showing a discharge waveform having a step waveform Pe and a current consumption of a second power supply according to another embodiment. Figure 7Graphs showing a reference waveform having a step waveform Pe and a current consumption of the second power supply as a comparative example. It should be noted that, in each of the drawings, the configuration is appropriately shown in an enlarged, reduced, or omitted manner for the sake of convenience of explanation.

[0019] Reference Figure 1 The liquid ejection device 2 having the liquid ejection head 1 will be described. The liquid ejection device 2 includes a housing 2111 , a medium supply unit 2112 , an image forming unit 2113 , a medium discharge unit 2114 , a transport device 2115 as a support device, and a control unit 2118 .

[0020] The liquid ejection device 2 is an inkjet printer, which performs image formation processing on paper P by ejecting liquid such as ink while transporting a ejection object such as paper P as a recording medium along a predetermined conveying path 2001 from a medium supply unit 2112 through an image forming unit 2113 to a medium discharge unit 2114.

[0021] The medium supply unit 2112 includes a plurality of paper supply cassettes 21121. The image forming unit 2113 includes a support unit 2120 for supporting paper, and a plurality of head units 2130 disposed above the support unit 2120 to face each other. The medium discharge unit 2114 includes a paper discharge tray 21141.

[0022] The support portion 2120 includes: a conveyor belt 21201 provided in an annular shape in a predetermined area where image formation is performed; a support plate 21202 supporting the conveyor belt 21201 from the back; and a plurality of belt rollers 21203 provided on the back side of the conveyor belt 21201 .

[0023] The head unit 2130 includes a plurality of liquid ejection heads 1 as inkjet heads, a plurality of supply tanks 2132 as liquid tanks respectively mounted on the liquid ejection heads 1 , a pump 2134 for supplying ink, and a connecting flow path 2135 connecting the liquid ejection heads 1 and the supply tanks 2132 .

[0024] The liquid ejecting head 1 is supplied with ink as liquid stored in the supply tank 2132. The liquid ejecting head 1 may be a non-circulating head that does not circulate ink, or a circulating head that circulates ink.

[0025] In this embodiment, the liquid ejection heads 1 include four colors of cyan, magenta, yellow, and black, and four color supply tanks 2132 for storing inks of these colors, respectively. The supply tanks 2132 are connected to the liquid ejection heads 1 via connection channels 2135 .

[0026] like Figure 2As shown, 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 mechanism.

[0027] The actuator substrate 22 includes an actuator section 25 as a liquid ejection section, and the actuator section 25 includes: a plurality of pressure chambers 26 arranged opposite to the nozzle 211 and communicating with the nozzle 211; and a driving element 27 as an actuator that changes the volume of the pressure chamber 26. The actuator substrate 22 is configured to have a predetermined shape in which a predetermined flow path including the plurality of pressure chambers 26 is formed between the actuator substrate 22 and the nozzle plate 21.

[0028] The electrode connected to the drive circuit 24 is formed on the drive element 27 adjacent to the pressure chamber 26 of the actuator unit 25. The electrode is configured to be connected to the control unit 2118 via a driver described later of the drive circuit 24, for example, through a wiring connected to the drive circuit 24, and can be driven and controlled by the control of the processor.

[0029] The drive circuit 24 includes a driver IC 241 and various wiring substrates 242. The drive circuit 24 drives the actuator 25 by applying a drive voltage to the wiring pattern of the actuator 25 through the driver IC 241, thereby increasing or decreasing the volume of the pressure chamber 26 to eject droplets from the nozzles 211 disposed opposite to each other.

[0030] The liquid ejection head 1 forms a predetermined flow path having a pressure chamber 26 therein by means of the nozzle plate 21, the actuator substrate 22 and the manifold 23. The flow path of the liquid ejection head 1 is connected to a connection flow path 2135 of the liquid ejection device.

[0031] The pump 2134 is a liquid delivery pump composed of, for example, a piezoelectric pump, and is connected to the control unit 2118 and driven and controlled by the control unit 2118 .

[0032] The connection flow path 2135 includes a supply flow path connected to the ink supply tube of the liquid ejection head 1. In addition, the connection flow path 2135 includes a recovery flow path connected to the ink discharge tube of the liquid ejection head 1. For example, when the liquid ejection head 1 is a non-circulation type, the recovery flow path is connected to the maintenance device, and when the liquid ejection head 1 is a circulation type, the recovery flow path is connected to the supply tank 2132.

[0033] The conveying device 2115 conveys the paper P along the conveying path 2001 from the paper supply cassette 21121 of the medium supply unit 2112 through the image forming unit 2113 to the paper discharge tray 21141 of the medium discharge unit 2114. The conveying device 2115 includes a plurality of guide plate pairs 21211 to 21218 and a plurality of conveying rollers 21221 to 21228 arranged along the conveying path 2001. The conveying device 2115 supports the paper P so as to be relatively movable with respect to the liquid ejection head 1.

[0034] The control unit 2118 is, for example, a control substrate and is equipped with a processor, a ROM (Read Only Memory), a RAM (Random Access Memory), an I / O port as an input / output port, and an image memory.

[0035] The processor is a processing circuit such as a CPU (Central Processing Unit) as a controller. The processor controls the head unit 2130, the drive motor, the operation unit, and various sensors provided in the liquid ejection device 2 through the I / O port. The processor sends the print data stored in the image memory to the drive circuit 24 in the drawing order.

[0036] In addition, the control unit 2118 determines the driving waveform. The control unit 2118 selects a waveform to be applied from waveforms that can be set in multiple stages, for example.

[0037] ROM stores various programs, etc. RAM temporarily stores various variable data, image data, etc. The I / O port is an interface for inputting data from the outside and outputting data to the outside. Print data from an externally connected machine is sent to the control unit 2118 through the I / O port and stored in the image memory.

[0038] Print data is data converted from image data including information on the color and density of each area and 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 the drive circuit 24, and applies a drive waveform to each drive element 27 of the actuator unit 25 through the drive circuit 24.

[0039] The following describes the characteristics of the liquid ejection head 1 of the liquid ejection device 2 involved in the embodiment, and the driving waveform based on the driving signal generated by the driving circuit 24 of the liquid ejection head 1. For example, the liquid ejection head 1 is a multi-drop drive that continuously supplies a driving waveform to the driving element 27 of the actuator part 25 within a certain pulse period of AL and continuously ejects multiple inks to form a pixel, and is driven with multiple grayscales by combining multiple drop waveforms. That is, the driving circuit 24 drives with a multi-grayscale driving waveform according to multiple patterns (multiple types) of multi-drop signals. For example, in the driving waveform involved in the present embodiment, the width from the expansion element Pa to the contraction element Pb is set to half the time of the natural vibration period of the pressure chamber 26 of the liquid ejection head 1, that is, AL (Acoustic Length).

[0040] Figure 3 2 is an equivalent circuit diagram of the drive circuit 24 involved in this embodiment. The drive circuit 24 is a drive waveform generating mechanism, wherein the drive waveform generating mechanism can switch three or more voltages and output a predetermined drive waveform by switching three or more voltages. Figure 3 As shown, the drive circuit 24 includes three switches 243 and two power supplies 244 and 245 connected to the drive element 27, and switches the voltage applied to the drive element 27 by switching the connection of each switch 243, thereby outputting a drive waveform including three or more voltage values.

[0041] The control unit 2118 sets the drive waveform applied to each drive element 27 based on the print data. For example, the control unit 2118 switches the voltage value applied to the target drive element 27 according to three or more voltages by switching the connection state between the power supply 244, 245 and GND by switching the switch 243 in the drive circuit 24. That is, the drive circuit 24 functions as a drive waveform generation mechanism that generates and outputs a predetermined drive waveform by switching the switch 243.

[0042] As an example, an example is shown in which the voltage is switched according to 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.

[0043] Here, the intermediate potential Vb is set to a potential other than the lowest potential and the highest potential. In addition, as an example, the second potential Va, which is the discharge potential, is set to a ground potential realized by grounding. That is, for example, in this embodiment, the first potential Vc is set to the highest potential, the ground potential, which is the second potential Va, is set to the lowest potential, and the intermediate potential is set to a potential between them.

[0044] For example, the control unit 2118 outputs the discharge waveform WA to at least any driving element 27 , in which the voltage is temporarily reduced to the second potential Va lower than the intermediate potential Vb when the voltage is reduced from the first potential Vc higher than the intermediate potential Vb to the intermediate potential Vb.

[0045] Figure 4 The graph showing the discharge waveform WA according to the present embodiment shows voltage [V] on the vertical axis and time [μs] on the horizontal axis. For example, the discharge waveform WA according to the present embodiment is a discharge waveform in which liquid is discharged once from the nozzle 211 by expansion and contraction. For example, the discharge waveform WA shows a droplet waveform corresponding to one droplet in multi-droplet driving. That is, there is a discharge waveform WA as one droplet waveform in a multi-droplet waveform having a plurality of droplet waveforms continuously.

[0046] like Figure 4 As shown in FIG. 1 , the discharge waveform WA first shifts from the middle potential Vb excluding the lowest voltage and the highest voltage to the second potential Va lower than the middle potential Vb, and then shifts from the second potential Va to the first potential Vc higher than the middle potential Vb. Then, it shifts from the first potential Vc to the second potential Va lower than the middle potential Vb, and shifts from the second potential Va to the middle potential Vb within a time equal to or less than the time constant of the actuator charge and discharge.

[0047] That is, the ejection waveform WA involved in the present embodiment is a driving waveform having the following elements: an expansion element Pa, which first reduces the voltage from the intermediate potential Vb to the second potential Va to expand the pressure chamber; a contraction element Pb, which increases the voltage from the second potential Va to the first potential Vc to contract the pressure chamber after a fixed time; a release element Pc, which temporarily reduces the voltage from the first potential Vc to the second potential Va lower than the intermediate potential Vb at a predetermined timing after contraction to release current; and a return element Pd, which returns from the second potential Va to the intermediate potential Vb within a time less than the time constant of charging and discharging after the voltage is reduced to the second potential Va.

[0048] Here, the time for the potential to be reduced to the second potential is set to a time equal to or less than a time constant of charging and discharging of the driving element 27 (actuator) to which the potential is applied.

[0049] Specifically, the control unit 2118 temporarily switches to the second potential Va (GND) lower than the second power supply 245 when switching from the first power supply 244 to the second power supply 245 in the driving circuit 24, and temporarily releases the current to GND to flow into the second power supply 245. Then, within a time period less than the time constant of charge and discharge, the current is switched back to the second power supply 245 to return to the intermediate potential Vb.

[0050] Figure 4The following figure is a graph showing the current consumption I of the second power supply 245 during the driving of the ejection waveform WA. Figure 4 In the discharge waveform WA, even when the current consumption I returns to the intermediate potential after contraction, it does not decrease, and a straight line is shown with a constant current value. That is, it shows that no charge inflow occurs.

[0051] According to this embodiment, a driving device and a liquid ejecting device capable of suppressing the inflow of current can be provided. That is, after the contraction element PB, by temporarily reducing the voltage to a second potential lower than the intermediate potential when reducing the voltage from the first potential to the intermediate potential for discharge, the charge charged to the driving element 27 can be suppressed from flowing into the second power supply 245.

[0052] Figure 5 This is an explanatory diagram showing the correspondence between the standard waveform WB as a comparative example and the current consumption I of the second power supply. The standard waveform WB includes an expansion element Pa that decreases 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 to contract the pressure chamber after a fixed time, and a return element Pf that returns from the first potential Vc to the intermediate potential Vb again at a predetermined timing. The current consumption I of the second power supply 245 driven by the standard waveform WB shows a curve that maintains the reference current value until the timing of returning to the intermediate potential after contraction, temporarily decreases at the timing of returning to the intermediate potential, and returns to the reference current value in a curve from the decreasing point. That is, it is shown that the current consumption of the power supply decreases at the timing of returning to the intermediate potential Vb, and the charge charged to the driving element 27 flows into the second power supply 245 at the timing of switching from the first power supply to the second power supply.

[0053] In contrast, in the ejection waveform WA in the present embodiment described above, Figure 4 As shown, it can be seen that by temporarily setting the potential to a low level to discharge, it is possible to suppress the outflow of charge from the drive element 27 as an actuator.

[0054] In addition, by setting the time for setting the second potential in the ejection waveform WA to be less than the time constant of the actuator charging and discharging, it is possible to prevent the increase in power consumption and the influence on the drive waveform. That is, for example, since the discharge time is also affected by the voltage, the electrostatic capacitance of PZT (lead zirconate titanate) as the driving element 27, etc., if it is too short, the current will flow into the second power supply to some extent, and if it is too long, the current will flow out from the second power supply, which will become the main reason for the increase in the current consumption of the second power supply, so it is necessary to set it to an appropriate time. Therefore, as an example, by setting it to be less than the time constant of charging and discharging and adjusting it to be shorter, it is possible to prevent the inflow from the power supply and suppress the influence on the printing quality.

[0055] It should be noted that the embodiments of the present invention are not limited to the above-described configurations, and can be implemented in various modified forms as appropriate.

[0056] For example, the driving waveform is not limited to the example in the above-mentioned embodiment, and can be changed as appropriate. Figure 6 3 is a graph showing a discharge waveform WC having a step waveform Pe and a release element Pc.

[0057] like Figure 6 As shown, the ejection waveform WC involved in this embodiment includes: an expansion element Pa, which is reduced from the intermediate potential Vb to the second potential Va to expand the pressure chamber; a contraction element Pb, which has a step waveform Pe that returns the voltage from the second potential Va to the intermediate potential Vb after a fixed time and further increases from the intermediate potential Vb to the first potential Vc higher than the intermediate potential Vb to shrink the pressure chamber 26; a release element Pc, which temporarily reduces the voltage from the first potential Vc to the second potential Va lower than the intermediate potential Vb; and a return element Pd, which returns from the second potential Va to the intermediate potential Vb again.

[0058] The current consumption I of the second power supply 245 in the driving of the ejection waveform WC shows the following line: the reference current value is maintained until the timing of returning to the intermediate potential during expansion, and the current value temporarily rises at the timing of returning to the intermediate potential after expansion, and returns to the reference current value in a curve from the rising point. Then, the current consumption I of the second power supply 245 shows the following line: the reference current value is maintained until the timing of returning to the intermediate potential after contraction, and the current value temporarily falls at the timing of returning to the intermediate potential, and returns to the reference current value in a curve from the falling point. In the ejection waveform WC, the rising amount of the current consumption temporarily rising at the timing of returning to the intermediate potential after expansion is the same as the falling amount at the timing of returning to the intermediate potential. That is, in this embodiment, the release element Pc is set to a condition that can offset the inflow of charge in the previous step element. For example, for the entire ejection waveform WC, the condition of the release element PC is set under the condition that the sum of the inflow current of the charge is zero.

[0059] That is, the waveform WC involved in the present embodiment is a waveform that moves from the intermediate potential Vb to the second potential Va, and then moves to the first potential Vc through the step waveform Pe that is temporarily set from the second potential Va to the intermediate potential Vb for a predetermined time. In the step waveform Pe, since the charge flows out, the discharge is performed by the release element Pc set to the second potential Va within a time period less than the time constant of the subsequent actuator charge and discharge, and the discharge amount and the charge amount in the step waveform Pe are adjusted to be close to or the same, thereby canceling each other. That is, the waveform WC involved in the present embodiment can cancel the inflow and outflow of charge by the step waveform Pe and the release ejection waveform, by causing the charge to flow in under the premise that the charge temporarily flows out, by the release ejection waveform.

[0060] According to this embodiment, when the voltage drops from the first potential Vc to the intermediate potential Vb after the contraction element PB, the voltage is temporarily dropped to the second potential Va lower than the intermediate potential Vb for discharge, thereby suppressing the charge charged in the driving element 27 from flowing into the second power supply 245 .

[0061] Figure 7 : is a standard discharge waveform WD having a step waveform Pe as a comparative example. The discharge waveform WD includes an expansion element Pa that decreases from the intermediate potential Vb to the second potential Va, a contraction element Pb that temporarily returns from the second potential Va to the intermediate potential Vb after a fixed time has passed, 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 from the first potential Vc to the intermediate potential Vb again at a predetermined timing thereafter.

[0062] That is, it has a step waveform Pe that temporarily maintains the intermediate potential Vb and increases the voltage in stages during contraction. The current consumption of the second power supply 245 in the drive of the standard waveform WB having the step waveform shows the following line: during expansion, the reference current value is maintained until the timing of returning to the intermediate potential Vb, and after expansion, it temporarily rises at the timing of returning to the intermediate potential Vb, and returns to the reference current value in a curve from the rising point. Then, the current consumption of the second power supply 245 shows the following line: after contraction, the reference current value is maintained until the timing of returning to the intermediate potential, and it temporarily decreases at the timing of returning to the intermediate potential, and returns to the reference current value in a curve from the falling point. That is, it is shown that in the ejection waveform WD having the step waveform, the current consumption of the power supply decreases at the timing of returning to the intermediate potential Vb, and the charge flows from the driving element 27 to the second power supply 245. In the discharge waveform WD, when the second potential Va is raised to the first potential Vc, the second power supply can be prevented from flowing in by setting the step waveform to rise to the intermediate potential Vb temporarily in stages and then rise to the first potential Vc. However, if the stage time is insufficient, the discharge cannot be sufficient. In addition, if the stage time is excessively extended, the printing quality will be affected.

[0063] Here, in the discharge waveform WC, the consumption current is suppressed from decreasing at the timing of returning to the intermediate potential compared to the discharge waveform WD having the step waveform Pe. Moreover, it can be seen that the decrease is the same as the increase in the step waveform Pe, and the charge of the step waveform Pe and the discharge of the release element Pc can be offset.

[0064] In addition, even in the ejection waveform WC having the step waveform Pe, by setting the time for setting the second potential to be less than the time constant of the actuator charge and discharge, it is possible to prevent the increase in power consumption and the influence on the drive waveform. That is, contrary to the excessively long discharge time, since the inflow from the power supply occurs, by setting it to be less than the time constant, the inflow from the power supply can be prevented.

[0065] For example, in the above embodiment, as an example of a driving device, a driving circuit 24 having a driver IC 241 provided in the liquid ejection head 1 is illustrated, but the present invention is not limited thereto. 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.

[0066] The waveform may not be one type, but may be a combination of more than one waveform. For example, the driving waveform applied to any driving element 27 at any timing may have a release element, and may be combined with other different waveforms for driving. For example, the ejection waveform having the release element may be a part of a multi-droplet waveform for ejecting droplets through a plurality of ejection waveforms, or may be a single waveform for ejecting droplets through a single ejection waveform.

[0067] Each voltage is not limited to the above-described embodiment. For example, the discharge potential as the second potential is not limited to GND.

[0068] In addition, although an example in which the first potential and the second potential are set to the highest voltage and the lowest voltage, respectively, is shown, the present invention is not limited thereto and may be set to other voltage values.

[0069] Furthermore, the present invention is not limited to the example of converting in three potentials, and may be configured to be capable of converting in four or more potentials.

[0070] In addition, it may include at least a non-discharge waveform in which no liquid is discharged.

[0071] For example, the structure of the liquid ejection head 1 is not limited to the above example, and can also be used for other types of heads. For example, the liquid ejection head can also be a structure that drives the liquid ejection part by vibrating a vibration plate disposed between the pressure chamber and the driving element by utilizing deformation of the driving element.

[0072] According to at least one of the embodiments described above, it is possible to provide a driving device and a liquid ejecting device that can suppress the inflow of electric current.

[0073] Although several embodiments of the present invention have been described, these embodiments are only presented as examples and are not intended to limit the scope of the invention. These new embodiments can be implemented in various other ways, and various omissions, substitutions, and changes can be made without departing from the scope of the purpose of the invention. These embodiments and their variations are included in the scope and purpose of the invention, and are also included in the invention described in the claims and their equivalents.

Claims

1. A driving device, characterized in that: The driving device includes a driving circuit that outputs a driving waveform for driving an actuator of a liquid ejection portion that ejects liquid. The drive waveform shifts from a first potential higher than an intermediate potential to a second potential lower than the intermediate potential, and shifts from the second potential to the intermediate potential within a time equal to or less than a time constant of charging and discharging of the actuator, wherein the intermediate potential is an intermediate potential excluding a minimum voltage and a maximum voltage.

2. The driving device according to claim 1, characterized in that: The driving circuit outputs the driving waveform by converting three or more voltages, and Before the driving waveform shifts from the first potential to the second potential, First, the potential is shifted from the intermediate potential to the second potential, and then the potential is shifted from the second potential to the first potential.

3. The driving device according to claim 2, characterized in that: After the transition from the intermediate potential to the second potential, the potential is transitioned from the second potential to the first potential after passing through a step waveform of the intermediate potential for a predetermined time.

4. The driving device according to claim 3, characterized in that: The discharge is performed by shifting from the second potential to the intermediate potential within a time period equal to or less than a time constant of charging and discharging of the actuator, Thus, after the transition from the intermediate potential to the second potential, at least a part of the charge amount of the step waveform that has passed through the intermediate potential set to a predetermined time from the second potential is canceled.

5. A liquid ejection device, characterized in that: have: The driving device according to any one of claims 1 to 4; and The liquid ejection head is driven by the driving device and ejects liquid.

6. The liquid ejection device according to claim 5, characterized in that: The driving waveform has the following elements: An expansion element first reduces the voltage from the intermediate potential to the second potential; a contraction element, which increases the voltage from the second potential to the first potential after a fixed time has passed; a release element that temporarily reduces the voltage from the first potential to the second potential lower than the intermediate potential at a predetermined timing after contraction to release the current; as well as The return element returns from the second potential to the intermediate potential within a time equal to or shorter than a time constant of charge and discharge after the potential is lowered to the second potential.

7. The liquid ejection device according to claim 5, characterized in that: The driving waveform has the following elements: an expansion element, which decreases from the intermediate potential to the second potential; a contraction element having a step waveform that returns the voltage from the second potential to the intermediate potential after a fixed time has passed and further increases the voltage from the intermediate potential to the first potential higher than the intermediate potential; a release element temporarily lowering the first potential from the first potential to the second potential lower than the intermediate potential; as well as The return element returns from the second potential to the intermediate potential again.

8. The liquid ejection device according to claim 6 or 7, characterized in that: The driving waveform is a part of a multi-drop waveform for ejecting liquid droplets using a plurality of ejection waveforms.

9. The liquid ejection device according to claim 6 or 7, characterized in that: The driving waveform is a single waveform for discharging droplets using a single discharge waveform.

10. The liquid ejection device according to claim 6 or 7, characterized in that: The second potential is connected to ground potential.

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