Liquid discharge head, driving method of liquid discharge head, liquid discharge unit, and liquid discharge device

Abstract

To provide a liquid discharge head, a driving method of the liquid discharge head, a liquid discharge unit, and a liquid discharge device, which enable preventing printing quality deterioration.SOLUTION: Provided is a liquid discharge head comprising: a plurality of nozzles; a piezoelectric element that is disposed in each of the nozzles, to which a drive signal is applied, and which has droplets discharged from the nozzles; a first switching element that is connected to an electrode of the piezoelectric element, and which is on / off controlled; a second switching element that is connected in parallel to the first switching element, and which is on / off controlled; a drive signal source that is connected to the first switching element, and which has the drive signal applied to the electrode; a voltage source that is connected to the second switching element, and which has a voltage at the completion of one cycle of the drive signal applied to the electrode; and a control part that turns the first switching element on and turns the second switching element off when the drive signal is applied to the piezoelectric element, and that turns the first switching element off and turns the second switching element on when the drive signal is not applied to the piezoelectric element.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a liquid ejection head, a driving method for a liquid ejection head, a liquid ejection unit, and a liquid ejection apparatus. [Background technology]

[0002] Inkjet printers and other droplet ejection devices have a method of generating one type of drive waveform, and turning on only the portion of the drive waveform used to eject ink (an example of droplets) by switching on an analog switch, supplying it to the piezo (piezoelectric element) of the liquid ejection head, and ejecting ink from the nozzles of the liquid ejection head. There are a large number of analog switches, the number of which is equal to the number of nozzles in the inkjet head, so switching all of them at the same time generates a large amount of noise and causes malfunctions. Therefore, a circuit is used that shifts the switching timing for each channel to reduce the number of simultaneous switches. Because this circuit shifts the switching timing, it takes, for example, several hundred nanoseconds to turn on or off the analog switches of all channels.

[0003] The drive waveform generated by the droplet ejection device has a waveform rounding of several μs at the rising part of the voltage due to the influence of the electrostatic capacitance of the piezoelectric element, etc., and it takes time for it to stabilize at the intermediate potential. If the timing of turning the analog switch on and off was extended until it stabilized at the intermediate potential, the drive waveform would become longer, the drive frequency could not be increased, and the printing speed would decrease, so the analog switch is turned off before the drive waveform reaches the intermediate potential. The voltage applied to the piezoelectric element when the analog switch is turned off differs for each drive channel due to variations in the timing of turning the analog switch off, causing variations in the ejection characteristics between channels and reducing print quality.

[0004] For example, Patent Document 1 discloses a configuration in which the intermediate voltage of each drive waveform is independently corrected for each drive element in accordance with the characteristics of each liquid chamber and nozzle, in order to suppress variations in ejection volume between multiple nozzles resulting from the characteristics of the liquid chamber and the nozzle. Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the technology described in Patent Document 1, variations in the voltage applied to the piezo when the analog switch is turned off cause variations in the ejection characteristics between channels, resulting in a decrease in print quality.

[0006] The present invention has been made in view of the above, and has an object to provide a liquid ejection head, a driving method for a liquid ejection head, a liquid ejection unit, and a liquid ejection apparatus that are capable of preventing a decrease in print quality. [Means for solving the problem]

[0007] In order to solve the above-mentioned problems and achieve the object, the present invention provides a piezoelectric element provided for each nozzle, which ejects droplets from the nozzle when a drive signal is applied to it, a first switching element connected to an electrode of the piezoelectric element and controlled to be turned on and off, a second switching element connected in parallel to the first switching element and controlled to be turned on and off, a drive signal source connected to the first switching element and applying the drive signal to the electrode, a voltage source connected to the second switching element and applying a voltage at the end of one cycle of the drive signal to the electrode, and a control unit that turns on the first switching element and turns off the second switching element when the drive signal is applied to the piezoelectric element, and turns off the first switching element and turns on the second switching element when the drive signal is not applied to the piezoelectric element. Effect of the Invention

[0008] According to the present invention, it is possible to prevent a decrease in print quality. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a diagram illustrating an example of the overall configuration of an inkjet printer according to the present embodiment. [Diagram 2] FIG. 2 is a diagram illustrating an example of the overall configuration of the inkjet printer according to the present embodiment. [Diagram 3] FIG. 3 is a diagram showing an example of a driving waveform generated in the inkjet printer according to the present embodiment. [Figure 4] FIG. 4 is a diagram showing an example of a driving voltage applied to a piezo in the inkjet printer according to the present embodiment. [Diagram 5] FIG. 5 is a diagram showing an example of a driving waveform switching circuit in the inkjet printer according to the present embodiment. [Figure 6] FIG. 6 is a diagram showing an example of a timing chart for turning on and off the ASW in the inkjet printer according to this embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of a liquid ejection head, a method for driving the liquid ejection head, a liquid ejection unit, and a liquid ejection apparatus will be described in detail with reference to the accompanying drawings.

[0011] 1 and 2 are diagrams that show an example of the overall configuration of an inkjet printer according to the present embodiment. Specifically, Fig. 1 is a perspective view of the inkjet printer 1, and Fig. 2 is a side view of the inkjet printer 1.

[0012] 1 and 2, an inkjet printer 1 (an example of a liquid ejection device) according to this embodiment includes a print mechanism section and the like, which is made up of a carriage 101 movable in the main scanning direction inside the device body, a recording head 102 mounted on the carriage 101, and an ink cartridge 103 that supplies ink to the recording head 102. A paper feed cassette (or a paper feed tray) 104 capable of loading a large number of recording media such as paper P can be removably attached from the front side to the lower part of the device body of the inkjet printer 1. Also, in the inkjet printer 1, a manual feed tray 105 for manually feeding paper P can be opened and closed.

[0013] The inkjet printer 1 takes in paper P fed from a paper feed cassette 104 or a manual feed tray 105, records a required image on it using the printing mechanism described above, and then discharges the paper to a paper discharge tray 106 attached to the rear side. Note that, in the following description, the recording medium will be described as paper P, but the recording medium can be any sheet-like material such as paper, film, plastic, or the like, as long as it is an object for forming and outputting an image.

[0014] The printing mechanism also holds the carriage 101 slidably in the main scanning direction (perpendicular to the paper surface) by a main guide rod 107 and a sub guide rod 108, which are guide members that are horizontally mounted on the left and right side panels. The carriage 101 is equipped with a liquid ejection unit 440 that integrates a recording head 102 and a head tank 441. The recording head 102 mounted on the liquid ejection unit 440 ejects ink droplets of the colors yellow, cyan, magenta, and black. A plurality of ink ejection ports that eject ink of each color are arranged in a direction (sub-scanning direction) that intersects with the main scanning direction, and the ink ejection ports face downward.

[0015] Each ink cartridge 103 for supplying ink of each color to the recording head 102 is replaceably mounted on the carriage 101. The ink cartridge 103 has an air port communicating with the standby port at the top, a supply port for supplying ink to the recording head 102 at the bottom, and a porous body filled with ink inside. The ink supplied to the recording head 102 is maintained at a slight negative pressure by the capillary force of this porous body. Note that, although the present embodiment shows an example in which a recording head 102 is provided for each color, a single head having nozzles for ejecting ink of each color may also be used.

[0016] The rear side (downstream side in the paper transport direction) of the carriage 101 is slidably attached to a main guide rod 107, and the front side (upstream side in the paper transport direction) is slidably attached to a slave guide rod 108. In order to move the carriage 101 in the main scanning direction, a timing belt 112 is stretched between a drive pulley 110 and a driven pulley 111, which are rotated by a main scanning motor 109. The timing belt 112 and the carriage 101 are fixed, and the carriage 101 is driven to reciprocate by the forward and reverse rotation of the main scanning motor 109.

[0017] On the other hand, in order to transport the paper set in the paper feed cassette 104 to the lower side of the recording head 102, there are provided a paper feed roller 113, a friction pad 114, a guide member 115, a transport roller 116, a transport roller 117, and a tip roller 118. The paper feed roller 113 and the friction pad 114 separate and feed the paper P from the paper feed cassette 104, and the guide member 115 guides the paper P that has been separated and fed.

[0018] The conveying roller 116 reverses and conveys the fed paper P. The conveying roller 117 is pressed against the circumferential surface of the conveying roller 116, and the tip roller 118 determines the angle at which the paper P is sent out from the conveying roller. The conveying roller 116 is rotated by a sub-scanning motor via a gear train.

[0019] An image receiving member 119 is provided as a paper guide member that guides the paper P sent out from the transport roller 116 below the recording head 102 in accordance with the range of movement of the carriage 101 in the main scanning direction. On the downstream side of the image receiving member 119 in the paper transport direction, a transport roller 120 and a spur 121 that are driven to rotate are provided to send the paper P in the paper discharge direction. In addition, a paper discharge roller 122 and a spur 123 that send the paper P to the paper discharge tray 106, and guide members 124 and 125 that form a paper discharge path are also provided.

[0020] When recording an image on paper P, the controller of the inkjet printer 1 drives the recording head 102 in response to an image signal while moving the carriage 101, thereby ejecting ink onto the stationary paper P to record one scan. Then, the controller of the inkjet printer 1 records the next line after transporting the paper P a predetermined distance. Furthermore, when the controller of the inkjet printer 1 receives a recording end signal or a signal indicating that the rear end of the paper P has reached the recording area, it ends the recording operation and ejects the paper P.

[0021] As described above, the recording head 102 includes a piezoelectric element as a drive element for driving each of the multiple nozzles. That is, in the inkjet printer 1 according to this embodiment, a piezoelectric element is used as an actuator element that generates a discharge force for discharging ink (an example of a liquid droplet) from each of the multiple nozzles. By applying a predetermined drive waveform to this piezoelectric element, ink is discharged from each nozzle. That is, the recording head 102 (an example of a liquid discharge head) has multiple nozzles and a piezoelectric element (piezo) that is provided for each nozzle and to which a drive signal (drive waveform) is applied to cause ink to be discharged from the nozzle.

[0022] A maintenance and recovery device 126 for recovering ejection defects of the print head 102 is disposed at a position outside the printing area on the right end side in the moving direction of the carriage 101. The maintenance and recovery device 126 has a capping means, a suction means, and a cleaning means. When the carriage 101 is on standby for printing, it is moved to the side of the maintenance and recovery device 126 and the print head 102 is capped by the capping means. This keeps the ejection port moist and prevents ejection defects due to dried ink.

[0023] In addition, the print head 102 discharges (idle discharges) ink not related to printing into the maintenance and recovery device 126 during printing, etc., to keep the ink viscosity at all the ejection ports constant and maintain stable ejection performance. In detail, if an ejection failure occurs, the capping means seals the ejection ports (nozzles) of the print head 102, and the suction means sucks out air bubbles and the like together with the ink from the ejection ports through a tube. Then, the ink and dust adhering to the ejection port surface are removed by the cleaning means, and the ejection failure is restored. The sucked ink is discharged into a waste ink tank installed at the bottom of the main body, and is absorbed and held by an ink absorber inside the waste ink tank.

[0024] Furthermore, the pressure generating means used in the liquid ejection head such as the recording head 102 is not limited. For example, in addition to the piezoelectric actuator (which may use a laminated piezoelectric element) as described in the above embodiment, a thermal actuator using an electrothermal conversion element such as a heating resistor, or an electrostatic actuator consisting of a vibration plate and an opposing electrode may be used.

[0025] In addition, in the present application, the terms image formation, recording, printing, imprinting, printing, modeling, and the like are all synonymous.

[0026] In this embodiment, the liquid ejection unit is a liquid ejection head integrated with functional parts and mechanisms, and is a collection of parts related to ejecting liquid. For example, the liquid ejection unit 440 includes a combination of at least one of the components of a head tank such as an ink cartridge 103, a carriage 101, a supply mechanism, a maintenance and recovery device 126, and a main scanning movement mechanism with the recording head 102.

[0027] Here, integration includes, for example, a liquid ejection head, a functional part, and a mechanism that are fixed to each other by fastening, bonding, engaging, etc., and one is held movably relative to the other. Also, the liquid ejection head, the functional part, and the mechanism may be configured to be detachable from each other.

[0028] For example, there are liquid ejection units in which the liquid ejection head and the head tank are integrated together, and there are also liquid ejection units in which the liquid ejection head and the head tank are integrated together by being connected to each other by a tube, etc. Here, a unit including a filter can be added between the head tank and the liquid ejection head of these liquid ejection units.

[0029] Furthermore, there is a liquid ejection unit in which the liquid ejection head and the carriage 101 are integrated.

[0030] In some liquid ejection units, the liquid ejection head is movably supported by a guide member that constitutes a part of the main scanning movement mechanism, and the liquid ejection head and the main scanning movement mechanism are integrated together. In other liquid ejection units, the liquid ejection head, the carriage 101, and the main scanning movement mechanism are integrated together.

[0031] In addition, there is a liquid ejection unit in which a cap member, which is part of a maintenance and recovery device 126, is fixed to a carriage 101 on which a liquid ejection head is attached, thereby integrating the liquid ejection head, carriage 101, and maintenance and recovery device 126.

[0032] In addition, some liquid ejection units have a head tank or a liquid ejection head to which a flow path component is attached, and a tube is connected to the liquid ejection head, integrating the liquid ejection head with a supply mechanism. Liquid is supplied from a liquid storage source to the liquid ejection head via this tube.

[0033] The main scanning movement mechanism includes the guide member alone, and the supply mechanism includes the tube alone and the loading unit alone.

[0034] In the present application, a liquid ejection device such as the inkjet printer 1 is a device that includes a liquid ejection head or a liquid ejection unit and ejects liquid by driving the liquid ejection head. Liquid ejection devices include not only devices that can eject liquid onto objects to which the liquid can adhere, but also devices that eject liquid into air or liquid.

[0035] This liquid ejection device can also include means for feeding, transporting, and discharging objects onto which liquid can be attached, as well as pre-processing devices and post-processing devices.

[0036] For example, liquid ejection devices include image forming devices that eject ink to form an image on paper, and three-dimensional modeling devices that eject modeling liquid onto a powder layer formed by layering powder in order to create a three-dimensional object (a three-dimensional model).

[0037] Furthermore, the liquid ejection device is not limited to one that visualizes meaningful images such as characters and figures by ejecting liquid. For example, it also includes one that forms patterns that have no meaning in themselves and one that forms three-dimensional images.

[0038] The above-mentioned object to which liquid can adhere means an object to which liquid can adhere at least temporarily, and to which the liquid adheres and sticks, or to which the liquid adheres and penetrates, etc. Specific examples include media such as paper, recording paper, film, cloth, and other recording media, electronic boards, electronic components such as piezoelectric elements, powder layers, organ models, and test cells, and unless otherwise specified, includes all objects to which liquid can adhere.

[0039] The materials to which the liquid can be attached include paper, thread, fiber, cloth, leather, metal, plastic, glass, wood, ceramics, and the like, so long as the liquid can be attached even temporarily.

[0040] The liquid may have a viscosity or surface tension that allows it to be discharged from a liquid discharge head, and is not particularly limited, but is preferably one whose viscosity becomes 30 mPa·s or less at room temperature and pressure, or by heating or cooling. More specifically, the liquid may be a solution, suspension, emulsion, etc., containing a solvent such as water or an organic solvent, a colorant such as a dye or pigment, a functionalizing material such as a polymerizable compound, a resin, or a surfactant, a biocompatible material such as DNA, amino acids, proteins, calcium, or an edible material such as a natural colorant, and these can be used for applications such as inkjet ink, surface treatment liquid, a liquid for forming a component of an electronic element or a light-emitting element, an electronic circuit resist pattern, a material liquid for three-dimensional modeling, etc.

[0041] In addition, the liquid ejection device may be a device in which the liquid ejection head and the object to which the liquid can be attached move relatively, but is not limited to this. Specific examples include a serial type device in which the liquid ejection head moves, a line type device in which the liquid ejection head does not move, etc.

[0042] Other examples of liquid ejection devices include a treatment liquid application device that ejects a treatment liquid onto paper to apply the treatment liquid to the surface of the paper for purposes such as modifying the surface of the paper, and an injection granulation device that ejects a composition liquid in which raw materials are dispersed through a nozzle to granulate fine particles of the raw materials.

[0043] FIG. 3 is a diagram showing an example of a drive waveform generated in the inkjet printer according to this embodiment. In FIG. 3, the vertical axis represents the drive voltage of the drive waveform (drive signal), and the horizontal axis represents time. In this embodiment, the inkjet printer 1 generates one type of drive waveform, and applies it to the piezo (piezoelectric element of the recording head 102) by turning on an analog switch. In the example of FIG. 3, the second and third pulses are applied to the piezo. The drive waveform shown in FIG. 3 is an example of an ideal waveform that is not distorted due to the electrostatic capacitance of the piezo, etc.

[0044] Fig. 4 is a diagram showing an example of a drive voltage applied to a piezo in an inkjet printer according to this embodiment. In Fig. 4, the vertical axis represents the drive voltage of the drive waveform, and the horizontal axis represents time. Specifically, Fig. 4 shows an example of a drive voltage actually applied to a piezo in the portion indicated by the symbol A in the drive waveform shown in Fig. 3.

[0045] As shown in Figure 4, the drive waveform applied to the piezo has a dull rise due to the influence of the piezo's capacitance, etc. To reduce the number of simultaneous switches, the analog switch shifts the OFF timing for each channel (i.e., for each nozzle), so it turns OFF somewhere between B and C in Figure 4 ("time when all channels are turned OFF"). Variations in piezo voltage caused by changes in the OFF timing of this analog switch cause variations in the ejection characteristics between channels, reducing print quality.

[0046] 5 is a diagram showing an example of a drive waveform switching circuit in an inkjet printer according to this embodiment. In inkjet printer 1 according to this embodiment, a drive waveform is generated by drive waveform generating circuit 501, an intermediate potential is generated by intermediate potential generating circuit 502, and either the drive waveform or the intermediate potential is selected by analog switches (ASW) N×2-1, N×2. Specifically, inkjet printer 1 (e.g., recording head 102, liquid ejection unit) has drive waveform generating circuit 501, intermediate potential generating circuit 502, analog switches (ASW) 1, 2...N×2-1, N×2, and a waveform selection control circuit 503.

[0047] The analog switch (ASW) N×2-1 is an example of a second switching element that is connected to a piezoelectric electrode and is on / off controlled, where N is an integer equal to or greater than 1. The analog switch (ASW) N×2 is an example of a first switching element that is connected to a piezoelectric electrode, connected in parallel to the analog switch (ASW) N×2-1, and is on / off controlled.

[0048] The drive waveform generating circuit 501 is connected to an analog switch (ASW) N×2 and is an example of a drive signal source that applies a drive waveform to the piezoelectric electrodes. The intermediate potential generating circuit 502 is connected to an analog switch (ASW) N×2-1 and is an example of a voltage source that applies a voltage (e.g., intermediate potential) at the end of one cycle of the drive signal to the piezoelectric electrodes.

[0049] The waveform selection control circuit 503 selects a drive waveform when applying a drive waveform to the piezo (for example, selects ASW2 in the case of ch1 shown in FIG. 5), and selects an intermediate potential otherwise (for example, selects ASW1 in the case of ch1 shown in FIG. 5). That is, the waveform selection control circuit 503 (an example of a control unit) turns on the analog switch (ASW) N×2 and turns off the analog switch (ASW) N×2-1 when applying a drive waveform to the piezo. Also, the waveform selection control circuit 503 turns off the analog switch (ASW) N×2 and turns on the analog switch (ASW) N×2-1 when not applying a drive waveform to the piezo.

[0050] This method allows the intermediate potential to be applied for a sufficiently long time even after the required drive waveform has been applied to the piezo, suppressing the variation in intermediate potential for each channel, reducing the variation in ejection characteristics and improving print quality. This configuration allows the intermediate potential generation circuit 502 to be realized with a fixed voltage power supply, and the analog switches (ASW) N×2-1, N×2 and waveform selection control circuit 503 to be realized with a small additional circuit, with only a slight increase in cost.

[0051] Furthermore, the waveform selection control circuit 503 may shift the timing of turning off the N×2 analog switches for each nozzle (each channel). This reduces the number of simultaneous switches, making it possible to prevent malfunctions caused by large noise.

[0052] 6 is a diagram showing an example of a timing chart of ASW on / off in the inkjet printer according to this embodiment. For the nozzles to be printed, ASW1 is turned off and ASW2 is turned on at the timing when the drive waveform is applied, and the drive waveform is applied to the piezo. At other times, ASW1 is turned on and ASW2 is turned off, and an intermediate potential is applied.

[0053] For nozzles that are not printing, ASW1 is turned on and ASW2 is turned off when not printing, and even in areas where a drive waveform is present, no waveform is applied to the piezo, so the on and off states of ASW1 and ASW2 do not change and an intermediate potential continues to be applied.

[0054] In this way, according to the inkjet printer 1 of this embodiment, since the intermediate potential can be applied for a sufficiently long time even after the necessary drive waveform has been applied to the piezo, the variation in the intermediate potential for each channel can be suppressed, the variation in the ejection characteristics can be reduced, and the print quality can be improved. In this configuration, the intermediate potential generating circuit 502 can be realized with a fixed voltage power supply, and the analog switches (ASW) N×2-1, N×2 and the waveform selection control circuit 503 can be realized by adding small circuits, with only a slight increase in cost.

[0055] In the above embodiment, an example is given in which an image forming apparatus such as a liquid ejection apparatus of the present invention is applied to a multifunction machine having at least two of a copy function, a printer function, a scanner function, and a facsimile function, but the present invention can be applied to any image forming apparatus such as a copier, printer, scanner device, or facsimile device. [Explanation of symbols]

[0056] 1. Inkjet printer 102 Recording head 501 Drive waveform generation circuit 502 Intermediate potential generation circuit 503 Waveform selection control circuit N×2-1, N×2 analog switch [Prior art documents] [Patent documents]

[0057] [Patent Document 1] Patent No. 6766390

Claims

1. A plurality of nozzles; a piezoelectric element provided for each of the nozzles, the piezoelectric element causing droplets to be ejected from the nozzle when a drive signal is applied thereto; a first switching element connected to an electrode of the piezoelectric element and controlled to be turned on and off; a second switching element connected in parallel to the first switching element and controlled to be turned on and off; a drive signal source connected to the first switching element and configured to apply the drive signal to the electrode; a voltage source connected to the second switching element and configured to apply a voltage to the electrode at the end of one cycle of the drive signal; a control unit that turns on the first switching element and turns off the second switching element when the drive signal is applied to the piezoelectric element, and turns off the first switching element and turns on the second switching element when the drive signal is not applied to the piezoelectric element; A liquid ejection head comprising:

2. The liquid ejection head according to claim 1 , wherein the voltage applied by the voltage source is an intermediate potential.

3. The liquid ejection head according to claim 1 , wherein the control unit shifts the timing for turning off the first switching element for each of the nozzles.

4. a piezoelectric element provided for each of the nozzles, the piezoelectric element configured to eject droplets from the nozzle when a drive signal is applied to the piezoelectric element; a first switching element connected to an electrode of the piezoelectric element and controlled to be turned on and off; a second switching element connected in parallel to the first switching element and controlled to be turned on and off; a drive signal source connected to the first switching element and applying the drive signal to the electrode; and a voltage source connected to the second switching element and applying a voltage at the end of one cycle of the drive signal to the electrode, turning on the first switching element and turning off the second switching element when applying the drive signal to the piezoelectric element; turning off the first switching element and turning on the second switching element when the drive signal is not applied to the piezoelectric element; A method for driving a liquid ejection head, comprising:

5. A plurality of nozzles; a piezoelectric element provided for each of the nozzles, the piezoelectric element causing droplets to be ejected from the nozzle when a drive signal is applied thereto; a first switching element connected to an electrode of the piezoelectric element and controlled to be turned on and off; a second switching element connected in parallel to the first switching element and controlled to be turned on and off; a drive signal source connected to the first switching element and configured to apply the drive signal to the electrode; a voltage source connected to the second switching element and configured to apply a voltage to the electrode at the end of one cycle of the drive signal; a control unit that turns on the first switching element and turns off the second switching element when the drive signal is applied to the piezoelectric element, and turns off the first switching element and turns on the second switching element when the drive signal is not applied to the piezoelectric element; A liquid ejection unit comprising:

6. A plurality of nozzles; a piezoelectric element provided for each of the nozzles, the piezoelectric element causing droplets to be ejected from the nozzle when a drive signal is applied thereto; a first switching element connected to an electrode of the piezoelectric element and controlled to be turned on and off; a second switching element connected in parallel to the first switching element and controlled to be turned on and off; a drive signal source connected to the first switching element and configured to apply the drive signal to the electrode; a voltage source connected to the second switching element and configured to apply a voltage to the electrode at the end of one cycle of the drive signal; a control unit that turns on the first switching element and turns off the second switching element when the drive signal is applied to the piezoelectric element, and turns off the first switching element and turns on the second switching element when the drive signal is not applied to the piezoelectric element; A liquid ejection device comprising:

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