Liquid ejecting head

Abstract

Provided is a liquid ejection head capable of suppressing the influence of high-frequency vibration generated by a resonance point on the higher-frequency side than the main resonance frequency dependent on a piezoelectric actuator and a liquid. According to one embodiment, a liquid ejection head includes a piezoelectric actuator and a drive circuit. The drive circuit connects a plurality of switching elements in parallel to one terminal of the power supply, the switching elements connecting the power supply and the piezoelectric actuator. The on-resistance of a first switching element among the plurality of switching elements is greater than the on-resistance of a second switching element. The drive circuit turns off the second switching element and turns on the first switching element for a period of time equal to or less than a first time constant based on the on resistance of the first switching element and the capacitance of the piezoelectric actuator, and turns off the second switching element and turns on the first switching element after the elapse of the period of time. The second switching element is turned on for a time longer than a second time constant based on the on resistance of the second switching element and the capacitance of the piezoelectric actuator, and the piezoelectric actuator is charged or discharged.

Description

Technical Field

[0001] An embodiment of the present invention relates to a liquid ejection head. Background Art

[0002] There is known a liquid ejection head that supplies a predetermined amount of liquid to a predetermined position. The liquid ejection head is mounted on, for example, an inkjet printer, a 3D printer, a dispensing device, etc. An inkjet printer ejects droplets of ink from an inkjet head to form an image on the surface of a recording medium. A 3D printer ejects droplets of a modeling material from a modeling material ejection head and solidifies the droplets to form a three-dimensional modeling object. A dispensing device ejects droplets of a sample to supply a predetermined amount to a plurality of containers, etc.

[0003] The liquid ejection head has a plurality of channels for ejecting liquid. Each channel has a nozzle for ejecting liquid, a pressure chamber connected to the nozzle, and a piezoelectric actuator for changing the volume of the pressure chamber. The liquid ejection head selects a channel for ejecting liquid from the plurality of channels, applies a driving voltage to the piezoelectric actuator of the selected channel, and ejects the liquid. However, if the rise / fall of the voltage of the piezoelectric actuator when the driving voltage is applied is too rapid, there is the following problem: the resonance of the parasitic vibration generated on the higher frequency side than the main resonant frequency determined by the piezoelectric actuator and the liquid causes unnecessary high-frequency vibration that has an adverse effect on the ejection action of the liquid. As a countermeasure, if a free waveform generating device for controlling the rise / fall waveform of the voltage is provided, the circuit scale becomes larger.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Publication No. 2010-18028

[0007] Patent Document 2: Japanese Patent Application Publication No. 2006-255977

[0008] Patent Document 3: Japanese Patent Application Publication No. 2009-196266 Summary of the invention

[0009] Technical problem to be solved by the invention

[0010] The technical problem to be solved by the present invention is to provide a liquid ejection head capable of suppressing the influence of high-frequency vibration generated by a resonance point on the higher-frequency side than a main resonance frequency determined by a piezoelectric actuator and liquid.

[0011] Technical solutions to solve problems

[0012] The liquid ejection head of an embodiment of the present invention includes a piezoelectric actuator and a driving circuit. The driving circuit connects a plurality of switching elements in parallel to one terminal of a power supply, and the switching elements connect the power supply to the piezoelectric actuator. The on-resistance of a first switching element among the plurality of switching elements is greater than the on-resistance of a second switching element. The driving circuit disconnects the second switching element and turns on the first switching element within a time period less than a first time constant based on the on-resistance of the first switching element and the electrostatic capacitance of the piezoelectric actuator, and after the time period has passed, turns on the second switching element within a time period longer than a second time constant based on the on-resistance of the second switching element and the electrostatic capacitance of the piezoelectric actuator, thereby charging or discharging the piezoelectric actuator. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a diagram showing the overall structure of an inkjet printer including the inkjet head according to the first embodiment.

[0014] Figure 2 It is a perspective view of the above-mentioned inkjet head.

[0015] Figure 3 This is a cross-sectional view of a partially enlarged portion of the head portion of the inkjet head.

[0016] Figure 4 This is a cross-sectional view of a part of the head of the inkjet head.

[0017] Figure 5 It is a top view which enlarges a part of the head part of the said inkjet head.

[0018] Figure 6 It is a driving circuit of the above-mentioned inkjet head.

[0019] Figure 7 is a circuit diagram of the output section of the above-mentioned drive circuit.

[0020] Figure 8 is a circuit diagram of a switching portion of the above-mentioned drive circuit.

[0021] Fig. 9 It is the state of the drive waveform generated by the above-mentioned drive circuit and the setting value of the timer.

[0022] Fig.10 is a waveform diagram of the above driving waveform.

[0023] Fig.11 It is a diagram for explaining the operation of the piezoelectric actuator to which the above-mentioned driving waveform is applied.

[0024] Fig.12 1 is a circuit diagram of an output section of a driving circuit according to a second embodiment.

[0025] Fig.13is a waveform diagram of the drive waveform generated by the above-mentioned drive circuit.

[0026] Fig.14 1 is a circuit diagram of an output section of a driving circuit according to a third embodiment.

[0027] Fig.15 It is the simulation result (ON / OFF of the switching element) of the inkjet head of the third embodiment.

[0028] Fig.16 It is the simulation result (driving waveform) of the inkjet head of the third embodiment.

[0029] Fig.17 : is a circuit diagram of the output section of the driving circuit of the comparative example.

[0030] Fig.18 It is the simulation result (driving waveform) of 3rd Embodiment and comparative example.

[0031] Fig.19 It is the simulation result (charge and discharge current) of the third embodiment and the comparative example.

[0032] Fig. 20 These are the frequency components of the driving waveforms of the third embodiment and the comparative example.

[0033] Description of Reference Numerals

[0034] 10: inkjet printer; 100~103: inkjet head; 2: head; 24: nozzle; 3: driver IC; 42: pressure chamber; 6: actuator; 60: support; 7: driver; 71: output unit; 72: selection unit; Q1~Q9: switching elements. DETAILED DESCRIPTION

[0035] Hereinafter, the liquid ejection head according to the embodiment will be described in detail with reference to the drawings. In addition, in each figure, the same reference numerals are attached to the same components.

[0036] (First embodiment)

[0037] As an example of an image forming apparatus equipped with the liquid ejection head according to the embodiment, an inkjet printer 10 that prints an image on a recording medium will be described. Figure 1 1 shows a schematic configuration of an inkjet printer 10. The inkjet printer 10 is provided inside a housing 11 with: a cassette 12 for storing a sheet S as an example of a recording medium, an upstream conveying path 13 for the sheet S, a conveyor belt 14 for conveying the sheet S taken out from the cassette 12, a plurality of inkjet heads 100 to 103 for ejecting ink droplets onto the sheet S on the conveyor belt 14, a downstream conveying path 15 for the sheet S, a discharge tray 16, and a control board 17. An operation unit 18 as a user interface is provided on the upper side of the housing 11.

[0038] Image data to be printed on the sheet S is generated by, for example, a computer 200 as an externally connected device. The image data generated by the computer 200 is sent to the control board 17 of the inkjet printer 10 via the cable 201 and the connectors 202 and 203 .

[0039] The pickup roller 204 supplies sheets S one by one from the cassette 12 to the upstream conveying path 13. The upstream conveying path 13 is composed of a feed roller pair 131, 132 and sheet guide plates 133, 134. The sheet S is conveyed to the upper surface of the conveyor belt 14 via the upstream conveying path 13. The arrow 104 in the figure indicates the conveying path of the sheet S from the cassette 12 to the conveyor belt 14.

[0040] The conveyor belt 14 is an endless belt with a mesh having a plurality of through holes formed on the surface. The three rollers of the driving roller 141, the driven rollers 142 and 143 support the conveyor belt 14 rotatably. The motor 205 rotates the conveyor belt 14 by rotating the driving roller 141. The motor 205 is an example of a driving device. 105 in the figure indicates the rotation direction of the conveyor belt 14. A negative pressure container 206 is arranged on the back side of the conveyor belt 14. The negative pressure container 206 is connected to a fan 207 for decompression. The fan 207 creates a negative pressure in the negative pressure container 206 through the airflow formed, thereby adsorbing and holding the sheet S on the upper surface of the conveyor belt 14. 106 in the figure indicates the flow direction of the airflow.

[0041] The inkjet heads 100 to 103, which are examples of liquid ejection heads, are arranged opposite to the sheet S held by adsorption on the conveyor belt 14 with a small gap of, for example, 1 mm. The inkjet heads 100 to 103 eject ink droplets toward the sheet S, respectively. The inkjet heads 100 to 103 print images when the sheet S passes thereunder. The inkjet heads 100 to 103 have the same structure except that the ink ejected has different colors. The colors of the inks are, for example, cyan, magenta, yellow, and black.

[0042] The inkjet heads 100 to 103 are connected to ink cartridges 315 to 318 and ink supply pressure adjustment devices 321 to 324 via ink flow paths 311 to 314, respectively. Each ink cartridge 315 to 318 is arranged above each inkjet head 100 to 103. When on standby, each ink supply pressure adjustment device 321 to 324 adjusts the pressure inside each inkjet head 100 to 103 to a negative pressure, for example -1.2 kPa, relative to the atmospheric pressure to prevent the ink from flowing out of the nozzles 24 (see Figure 2 When forming an image, the ink of each ink cartridge 315 to 318 is supplied to each inkjet head 100 to 103 through the ink supply pressure adjustment device 321 to 324.

[0043] After the image is formed, the sheet S is conveyed from the conveyor belt 14 toward the downstream conveying path 15. The downstream conveying path 15 is composed of feed roller pairs 151, 152, 153, 154 and sheet guide plates 155, 156 that define the conveying path of the sheet S. The sheet S is conveyed from the discharge port 157 to the discharge tray 16 via the downstream conveying path 15. The arrow 107 in the figure indicates the conveying path of the sheet S.

[0044] Next, the structure of the inkjet heads 100 to 103 will be described. Figures 2 to 5 The inkjet head 100 will be described. The structures of the inkjet heads 101 to 103 are also the same as that of the inkjet head 100 .

[0045] like Figure 2 As shown, the inkjet head 100 includes a head 2 as an example of a liquid ejection unit. The head 2 is connected to a flexible printed wiring board 21 as an example of a thin film wiring substrate. The flexible printed wiring board 21 is connected to a printed substrate 22 as an example of a relay substrate. The head 2 includes a nozzle plate 23 as an example of a nozzle unit.

[0046] The head 2 is connected to the ink flow path 311 via the ink flow path 311. Figure 1 The ink supply pressure regulating device 321 is connected.

[0047] The nozzles 24 of each channel ejecting ink are arranged along the first direction of the nozzle plate 23, for example, the X direction. The nozzle density is set within the range of 150 to 1200 dpi, for example. The nozzles 24 are not limited to one row, but may be multiple rows. The detailed structure of the head 2 will be described later.

[0048] The flexible printed wiring board 21 is a flexible printed wiring board using a synthetic resin film such as polyimide. The flexible printed wiring board 21 is equipped with a driving IC (Integrated Circuit) 3 (hereinafter referred to as a driving IC) as a driving chip. The printed substrate 22 is a hard through-hole substrate formed by stacking epoxy resin layers containing glass fibers and copper wiring layers. The driving IC 3, which is the control unit of the inkjet head 100, temporarily stores data sent from the control substrate 17 via the printed substrate 22, and applies a driving signal to each channel at a predetermined timing to eject ink, wherein the control substrate 17 has a CPU as the control unit of the inkjet printer 10.

[0049] Figures 3 to 5 It is a partial cross-sectional view of the head 2. Figure 4 yes Figure 3 The AA cross-sectional view, Figure 5 yes Figure 3BB cross-sectional view. The nozzle plate 23 is bonded to one side of the pressure chamber substrate 4. The nozzle plate 23 is, for example, a rectangular plate formed of a resin such as polyimide or a metal such as stainless steel. The vibration plate 5 is bonded to one side of the pressure chamber substrate 4 on the opposite side of the nozzle plate 23. The vibration plate 5 has flexibility to deform when an external force is applied. The vibration plate 5 is, for example, a thin plate formed of a metal such as nickel or stainless steel. The material of the vibration plate 5 may also be a material other than metal such as a polyimide film.

[0050] The pressure chamber 42 is formed on the pressure chamber substrate 4. A plurality of pressure chambers 42 are arranged at the positions of the nozzles 24 and are respectively connected to the nozzles 24. The pressure chamber substrate 4 is formed of a metal such as stainless steel. As an example, the pressure chamber 42 is formed by forming a rectangular opening penetrating along the second direction, such as the Z direction, on the pressure chamber substrate 4, and blocking the openings on both sides with the nozzle plate 23 and the vibration plate 5.

[0051] The pressure chamber 42 is connected to a guide flow path 43 having a narrow portion, and further connected to an ink supply manifold 45 via an ink supply port 44 which is an opening hole penetrating the vibration plate 5. The guide flow path 43 is formed in a groove shape along a third direction, for example, the Y direction, on one surface of the pressure chamber substrate 4 on the vibration plate 5 side for each pressure chamber 42. The ink supply manifold 45 is formed in a frame 46 joined to one surface of the vibration plate 5. The ink supply manifold 45 extends in the X direction and is connected to the pressure chamber 42 of each channel via the ink supply port 44 and the guide flow path 43 of each channel. The ink supply manifold 45, which is a common ink chamber, is connected to the ink flow path 311 (see Figure 1 , Figure 2 ).

[0052] The actuator 6 of each channel is arranged at a position facing the pressure chamber 42 via the vibration plate 5. Each actuator 6 is fixed by bonding a surface on the opposite side of the vibration plate 5 in the Z direction to the support member 47.

[0053] The actuator 6 as an example of a piezoelectric actuator is a stacked piezoelectric actuator (see in particular) in which a piezoelectric body 61 such as a piezoelectric element, a first internal electrode 62, and a second internal electrode 63 are alternately stacked in layers. Figure 3). Each piezoelectric body 61 is configured so that the polarization directions are opposite to each other, for example, in the Z direction, and deform in the d33 mode. The first internal electrode 62 and the second internal electrode 63 are conductive films respectively formed on the main surface of the piezoelectric body 61. The first internal electrode 62 respectively forms an end surface of the actuator 6 in the Y direction, and is connected to the first external electrode 64 formed on the end surface. The second internal electrode 63 respectively forms another end surface of the actuator 6 in the Y direction, and is connected to the second external electrode 65 formed on the end surface. The virtual layer 68 is made of the same material as the piezoelectric body 61. However, the virtual layer 68 is not provided with an internal electrode, is not applied with an electric field, and therefore does not deform. The virtual layer 68 becomes the basis for fixing the actuator 6 to the support member 47 (especially refer to Figure 4 ), or as a grinding allowance for grinding to improve the accuracy during or after assembly.

[0054] As an example, an actuator 6 formed by stacking a plurality of piezoelectric bodies 61 has a first internal electrode 62 and a second internal electrode 63 formed on the main surface of each piezoelectric body 61 processed into a thin plate shape. Moreover, the piezoelectric bodies 61 are stacked and fired to form a whole. Then, a first external electrode 64 and a second external electrode 65 are formed. Then, the piezoelectric body 61 is polarized. The piezoelectric body 61 is formed of a lead-containing piezoelectric material such as lead zirconate titanate (PZT), or a lead-free piezoelectric material such as sodium potassium niobate. The first internal electrode 62 and the second internal electrode 63 are formed of a conductive material that can be fired, such as silver palladium. The first external electrode 64 and the second external electrode 65 are formed by known methods such as electroplating and sputtering, and using Ni, Cr, Au, etc.

[0055] The first external electrode 64 of each actuator 6 is Figure 3 The depth direction of the channel is separated into each channel, and each is connected to the discrete wiring 66 of the flexible printed wiring board 21 (refer to Figure 5 ). The flexible printed wiring board 21 is composed of a resin film 26 as a base material, discrete wiring 66, and an insulating film 27. The flexible printed wiring board 21 is formed by Figure 3 The discrete wirings 66 separated for each channel in the depth direction are arranged in contact with the first external electrodes 64 separated for each channel in the depth direction, and fixed by, for example, NCF (Non-Conductive Film). NCF is obtained by removing conductive particles from ACF (Anisotropic Conductive Film), and is an insulator itself, but the first external electrode 64 is connected to the discrete wiring 66 by contacting the first external electrode 64 and the discrete wiring 66 and thermally curing. Alternatively, it can also be fixed by solder or the like. On the other hand, the second external electrode 65 of each channel is connected to a common wiring (not shown) and is connected to a common potential via, for example, a flexible printed wiring board 21.

[0056] The support column 60 is arranged between the actuators 6 of each channel via the groove 69. The driving actuator 6 and the dummy actuator serving as the support column 60 are formed uniformly using a common piezoelectric body 61, a first internal electrode 62, and a second internal electrode 63, and the support column 60 is separated into each actuator 6 and the support column 60 by forming the groove 69. The support column 60 is arranged at a position corresponding to the partition wall 40 between adjacent pressure chambers 42 (see Figure 4 ). The support column 60 may be formed of other components instead of being formed of the piezoelectric body 61 or the like like the actuator 6. For example, the support column may be formed integrally with the support member 47.

[0057] Figure 6 is a driving circuit of the inkjet head 100. Figure 6 As shown, the actuator 6 (Cx1 to Cxn) of each channel is connected to the driver 7 of each channel of the driving IC 3 via a discrete wiring 66 connected to the first external electrode 64. The connection point between the first external electrode 64 and the discrete wiring 66 is a discrete terminal of the actuator 6. On the other hand, the second external electrode 65 of each actuator 6 (Cx1 to Cxn) is connected to a common potential via a common wiring 67. The connection point between the second external electrode 65 and the common wiring 67 is a common terminal of the actuator 6. The common potential is, for example, 0V.

[0058] The driver 7 of each channel is connected to a power source for applying potentials V1 and V0 as driving voltages to the actuator 6. The values ​​of potentials V1 and V0 can be determined, for example, according to the structure of the actuator 6 or the type of ink. For example, potential V1 is 10V and potential V0 is 0V.

[0059] The driver 7 of each channel includes an output unit 71 and a selection unit 72. The output unit 71 includes a plurality of switch elements Q1 to Q4 described later. The output unit 71 turns the switch elements Q1 to Q4 on / off and connects a power supply of a potential V1 or a potential V0 to a discrete terminal of the actuator 6. The selection unit 72 applies a signal to the output unit 71 for controlling the switch elements Q1 to Q4 to be on / off at a predetermined timing, depending on whether the channel ejects ink.

[0060] like Figure 7 As shown, the output unit 71 connects two switching elements Q1 and Q2 in parallel with the power supply terminal V0. In addition, two switching elements Q3 and Q4 are connected in parallel with the power supply terminal V1. That is, the output unit 71 connects two switching elements in parallel to each terminal of the power supply. Furthermore, there are two sets of power supply terminals (V0 / V1) and switching elements (Q1 and Q2 / Q3 and Q4).

[0061] The on-resistances of the switch element Q1 and the switch element Q2 connecting the power supply terminal V0 and the discrete terminal of the actuator 6 are different from each other. The on-resistance of the switch element Q1 as the first switch element is, for example, 1000Ω. The on-resistance of the switch element Q2 as the second switch element is, for example, 200Ω. In this case, the parallel on-resistance when both the switch element Q1 and the switch element Q2 are turned on is 167Ω, which is smaller than the on-resistance of the switch element Q1 as the first switch element. The switch elements Q1 and Q2 are, for example, transistors.

[0062] The on-resistances of the switch element Q3 and the switch element Q4 connecting the power supply terminal V1 and the discrete terminal of the actuator 6 are different from each other. The on-resistance of the switch element Q3 as the first switch element is, for example, 1000Ω. The on-resistance of the switch element Q4 as the second switch element is, for example, 200Ω. In this case, the parallel on-resistance when both the switch element Q3 and the switch element Q4 are turned on is 167Ω, which is smaller than the on-resistance of the switch element Q3 as the first switch element. The switch elements Q3 and Q4 are, for example, transistors.

[0063] The switching elements Q1 and Q2 connected to the power supply terminal V0 use, for example, N-channel transistors. The gates of the respective transistors are connected to the output terminals of the selection unit 72 via the buffers 73. The transistor as the switching element Q1 is controlled to be turned on in accordance with the signal N1g applied from the selection unit 72. The transistor as the switching element Q2 is controlled to be turned on in accordance with the signal N2g applied from the selection unit 72. The switching elements Q1 and Q2 connecting the power supply terminal V0 and the discrete terminals of the actuator 6 are controlled to be turned on when the actuator 6 is discharged.

[0064] The switching elements Q3 and Q4 connected to the power supply terminal V1 use, for example, P-channel transistors. The gates of the respective transistors are connected to the output terminals of the selection unit 72 via the NOT circuit 74. The transistor as the switching element Q3 is controlled to be turned on according to the signal P3g applied from the selection unit 72. The transistor as the switching element Q4 is controlled to be turned on according to the signal P4g applied from the selection unit 72. The switching elements Q3 and Q4 connecting the power supply terminal V1 and the discrete terminals of the actuator 6 are controlled to be turned on when the actuator 6 is charged.

[0065] The first switching elements Q1 and Q3 preferably have the same on-resistance, but may be different. Similarly, the second switching elements Q2 and Q4 preferably have the same on-resistance, but may be different.

[0066] Here, the electrostatic capacitance C of the actuator 6 is, for example, 1000 pF. When the on-resistances of the switch element Q1 and the switch element Q3 as the first switch element are 1000Ω, the time constant T1 of the time constant circuit formed by the on-resistances of the switch element Q1 and the switch element Q3 and the actuator 6 is 1μs (T1=1μs). When the on-resistances of the switch element Q2 and the switch element Q4 as the second switch element are 200Ω, the time constant T2 of the time constant circuit formed by the parallel on-resistances of the switch element Q1 and the switch element Q2, and the parallel on-resistances of the switch element Q3 and the switch element Q4 and the actuator 6 is 0.17μs (T2=0.17μs). That is, the first time constant T1 based on the on-resistance of the first switch element and the electrostatic capacitance of the actuator 6 is greater than the second time constant T2 based on the parallel on-resistances of the first and second switch elements and the electrostatic capacitance of the actuator 6 (T1>T2).

[0067] The selection unit 72 switches whether to drive the actuator 6 with a voltage waveform generated according to whether ink is ejected. Figure 8 As shown, the selection unit 72 is composed of a switching circuit that switches the output of the switch elements Q1 to Q4 to A / B according to whether the ink is ejected. Whether the ink is ejected is determined based on the print data to be printed. When the ink is ejected, the input and output of the B side are selected, and when the ink is not ejected, the input and output of the A side are selected.

[0068] Each input terminal on the B side of the selection unit 72 is connected to the state memory 75 (see Figure 6 ) is connected to the output terminal of the state memory 75. When ejecting ink, the selector 72 outputs the signals P3g, P4g, N1g, and N2g according to the signals P3c, P4c, N1c, and N2c applied from the state memory 75, and applies them to the switch elements Q1 to Q4 of the output unit 71. For example, the signal is applied "1" when turned on, and "0" is applied when turned off. The switch elements Q1 to Q4 to which the signal "1" is applied are turned on for the duration of the pulse width thereof.

[0069] Each input terminal on the A side of the selection unit 72 applies a signal of "1" to P3g to turn on the switch element Q3, and applies "0" to P4g, N1g, and N2g. As a result, a potential V1 is applied to the discrete terminals of the actuator 6 to put the actuator 6 into a standby state. The standby state is maintained, for example, until the drive cycle for ejecting ink is reached. In addition, if the switch element Q3 is turned on, the pressure chamber 42 contracts, but when only the switch element Q3 is turned on, it contracts slowly due to a large time constant T1, so that ink is not ejected from the nozzle 24.

[0070] return Figure 6For explanation, the driving circuit of the inkjet head 100 also includes a state memory 75, a timer value memory 76, a timer 77, and an address generation unit 78. The state memory 75 stores information on which state the switch elements Q1 to Q4 are turned on or off. For example, the state is set to "1" for on and "0" for off. The timer value memory 76 stores information on the time t0, t1, and t2 for maintaining the state. The timer 77 counts the time t0, t1, and t2 read from the timer value memory 76. When the time of the timer 77 ends, the address generation unit 78 advances to the next time and state. In the case of a multi-nozzle inkjet head 100 having multiple channels for ejecting ink, the state memory 75, the timer value memory 76, the timer 77, and the address generation unit 78 can be formed as a circuit shared by multiple channels. Figure 6 A circuit common to all channels is formed in the example, but is not limited to this.

[0071] The waveform information is set in advance in the state memory 75 and the timer value memory 76 , and the drive waveform applied to the actuator 6 of the channel for ejecting ink is generated while reading the information in the drive cycle for ejecting ink. Fig. 9 The table is an example of the status memory values ​​and the timer values ​​set in the status memory 75 and the timer value memory 76, respectively. Fig.10 is based on Fig. 9 The drive waveform generated by the setting value of Fig.10 , the time series on / off timings of the switching elements Q1 to Q4 are shown corresponding to the drive waveforms.

[0072] Fig. 9 and Fig.10 The time t1 shown is a time that is less than the time constant T1 as the first time constant and is greater than 1 / 5 (0.2T1) of the time constant T1. In addition, the time t1 is less than 1 / 2 (1 μs) of the half period (2 μs) of the main resonance of the ink in the pressure chamber 42 and is greater than 1 / 10 (0.2 μs) of the half period (2 μs) of the main resonance. As an example, when the time constant T1 is 1 μs and the half period of the main resonance is 2 μs, the time t1 is set to a time of 1 μs to 0.2 μs.

[0073] The time t2 as the second time constant is set to a time longer than the time constant T2. When the time constant T2 is 0.17μs, it is set to a time longer than 0.17μs. The time t0 is set, for example, so that both the potential V1 and the potential V0 are not connected to the discrete terminals of the actuator 6, and is set to a time shorter than the time t1 and the time t2. For the times t0, t1, and t2, if the total time t0+t1+t2 is equal to the half period of the main resonance of the pressure chamber 42, the pressure vibration can be applied to the ink in the pressure chamber 42 with the highest efficiency. In addition, if the total time t0+t1+t2 is shorter than the half period of the main resonance of the pressure chamber 42, the ejection volume is reduced, so this situation can also be used to adjust the ejection volume of the ink.

[0074] Next, refer to Fig.10 and Fig.11 The ink ejection operation of the inkjet head 100 will be described. Fig.11 Schematically showing the application of the actuator 6 Fig.10 The operation of actuator 6 when the driving waveform is .

[0075] The inkjet head 100 utilizes the pressure vibration of the ink in the pressure chamber 42 to eject the ink from the nozzle 24. If the pressure chamber 42 is relatively expanded and maintained for a time equal to the half cycle (AL) of the main resonance and then restored (relatively contracted), the pressure vibration can be applied to the ink most efficiently and the ink can be ejected from the nozzle 24.

[0076] First, for example, the input and output of the selection unit 72 are set to the A side, and "1" is applied to P3g as an initial value to turn on the switch element Q3. When the switch element Q3 is turned on, the potential V1 is applied to the actuator 6. At this time, an electric field is applied to the actuator 6 in the direction of the polarization axis of the piezoelectric body 61, such as Fig.11 As shown in (a), the actuator 6 is stretched in the stacking direction (Z direction) of the piezoelectric body 61, and the volume of the pressure chamber 42 is reduced. This is performed before the timing of ejecting the ink. And this standby state is maintained until the ink ejection operation starts according to the print data. As described above, when the switch element Q3 is turned on, the pressure chamber 42 is slowly contracted by the large time constant T1, so that the ink is not ejected from the nozzle 24.

[0077] When the ink ejection operation starts, the selection unit 72 switches to the input and output of the B side. In addition, the signals P3g, P4g, N1g, and N2g are applied to the output unit 71 at a predetermined timing according to the set values ​​of the state memory 75 and the timer value memory 76. More specifically, the switch element Q3 is turned off, and the switch element Q1 is turned on after a time t0. When the switch element Q1 is turned on, the potential V0 is applied to the actuator 6, and the drive waveform decreases along a curve with a time constant T1. That is, the actuator 6 is discharged.

[0078] If this state continues, Fig.10 The voltage slowly drops as shown by the dotted line, but the voltage is prevented from slowing down with the time constant T1 by turning on the switch element Q2 after the time t1. That is, during the time t1, the drive waveform drops along the curve of the time constant T1 before the middle, and after the time t1, the switch element Q2 is turned on, so that the drive waveform follows the curve of the time constant T2 before the potential V0. During the time t2, the switch element Q1 and the switch element Q2 are both turned on. At this time, as shown in FIG. Fig.11 As shown in (b), the actuator 6 returns to its original state from the extended state, i.e., contracts relatively, and the volume of the pressure chamber 42 expands relatively. An amount of ink corresponding to the expansion of the volume of the pressure chamber 42 flows into the pressure chamber 42 via the guide flow path 43, and the meniscus of the ink in the nozzle 24 retreats. Fig.11 (a) is the steady-state negative pressure (-1.2 kPa), relative to this, Fig.11 (b) is that the negative pressure increases after the volume of the pressure chamber 42 is reduced, so the suction of the meniscus is large.

[0079] If the driving waveform of the discharge is applied to the actuator 6 in this way, Fig.10 As shown in FIG. 1 , the voltage drops slowly at the beginning of the waveform drop. As a result, unnecessary high-frequency vibrations are not caused by parasitic vibrations during the waveform drop, and the current peak value is also reduced. Furthermore, after the switching element Q2 is turned on, the potential can be reduced to V0 in a short time, so even if the pulse width is shortened, the voltage of the actuator 6 can be sufficiently reduced to the potential V0.

[0080] Then, the switching elements Q1 and Q2 are turned off, and after time t0, the switching element Q3 is turned on. When the switching element Q3 is turned on, the potential V1 is applied to the actuator 6, and the drive waveform rises along a curve with a time constant T1. That is, the actuator 6 is charged.

[0081] If this state continues, Fig.10The voltage rises slowly as shown by the dotted line, but the voltage rises slowly with the time constant T1 by turning on the switch element Q4 after the time t1. That is, during the time t1, the drive waveform rises with the curve of the time constant T1 before the middle, and after the time t1, the switch element Q4 is turned on, so that the drive waveform follows the curve of the time constant T2 before the potential V1. As a result, Fig.11 As shown in (c) of FIG. 8 , the actuator 6 expands in the stacking direction (Z direction), and the volume of the pressure chamber 42 is relatively reduced, so that ink droplets R are ejected from the nozzle 24 .

[0082] When the ink is continuously ejected, the ink is ejected in the same manner in the next drive cycle. When the ink is not ejected in the next drive cycle, the input and output of the A side are selected in the selection unit 72, and the actuator 6 is restored to the standby state. When a series of liquid ejection operations are completed, the switching elements Q1 to Q4 may be turned off to make the potential of the actuator 6 zero.

[0083] If the driving waveform for charging is applied to the actuator 6 in this way, Fig.10 As shown in FIG. 1 , the voltage rises slowly at the initial stage of the waveform rise. As a result, unnecessary high-frequency vibrations are not caused by parasitic vibrations during the rise of the waveform, and the current peak value is also reduced. Furthermore, after the switching element Q4 is turned on, the potential can be raised to V1 in a short time, so even if the pulse width is shortened, the voltage of the actuator 6 can be sufficiently raised to the potential V1.

[0084] In the above embodiment, after time t1 has passed, both the switch element Q1 and the switch element Q2 are turned on, but the switch element Q1 may be turned off and only the switch element Q2 is turned on. Similarly, after time t1 has passed, both the switch element Q3 and the switch element Q4 are turned on, but the switch element Q3 may be turned off and only the switch element Q4 is turned on. When the on-resistance of the switch element Q2 and the switch element Q4 is, for example, 200Ω, the time constant T2 of the time constant circuit formed by the on-resistance of the switch element Q2 and the switch element Q4 and the actuator 6 is 0.20μs (T2=0.20μs). In this case, the time constant T1 is also greater than the time constant T2 (T1>T2).

[0085] (Second embodiment)

[0086] Furthermore, in the above-described embodiment, the drive waveform is generated with two potentials, namely, the potential V1 and the potential V0 , but the number of potentials may be two or more. Fig.12This is an example of an output unit 71 in which two switching elements are connected in parallel to three power supply terminals, namely, potential V1, potential V2, and potential V0. Potential V1 is, for example, 20V, potential V2 is, for example, 10V, and potential V0 is, for example, 0V (V1>V2>V0). Switching element Q5 and switching element Q6 are connected in parallel to the power supply terminal of potential V2. Potential V2, which is an intermediate potential, is used to charge and discharge actuator 6, so switching element Q5 and switching element Q6 are bidirectional switches.

[0087] Fig.13 This is an example of a driving waveform generated by the potential V1, the potential V2, and the potential V0. The driving waveform includes, for example, a waveform that attenuates residual vibration after the ink is ejected. Fig.13 As shown, the inkjet head 100 switches the switching elements Q1, Q2, Q5, and Q6 to expand and contract the pressure chamber 42, thereby ejecting ink from the nozzle 24. The waveform from the standby state to the ejection of ink is similar to Fig.10 same.

[0088] Then, when time t2 has passed, switch elements Q5 and Q6 are turned off. And, after time t0 has passed, switch element Q3 is turned on. When switch element Q3 is turned on, the drive waveform rises with a curve of time constant T1 before the middle during time t1, and after time t1 has passed, switch element Q4 is turned on so that the drive waveform follows a curve of time constant T2 before potential V1. That is, actuator 6 is charged. During time t2, both switch elements Q3 and switch element Q4 are kept turned on. When time t2 has passed, switch elements Q3 and Q4 are turned off.

[0089] Then, after time t0 has passed, the switch element Q5 is turned on. When the switch element Q5 is turned on, the drive waveform drops along a curve of time constant T1 before the middle of time t1, and after time t1 has passed, the switch element Q6 is turned on so that the drive waveform follows a curve of time constant T2 before the potential V2. That is, the actuator 6 is discharged. During time t2, the state in which both the switch element Q5 and the switch element Q6 are turned on is maintained. The actuator 6 is extended and restored by this charging and discharging, and the volume of the pressure chamber 42 is reduced and restored, and the residual vibration is attenuated by this action.

[0090] (Third Embodiment)

[0091] In the above embodiment, two switching elements are connected in parallel at one terminal of the power supply, but the number of switching elements connected in parallel may be more than 2. In addition, in the above embodiment, both of the multiple switches connected in parallel are turned on in the second half, but multiple switches with different on-resistances may be turned on exclusively. Fig.14This is an example of the output unit 71 in which three switching elements are connected in parallel to three power supply terminals, namely, the potential V1 , the potential V2 , and the potential V0 .

[0092] like Fig.14 As shown, the output unit 71 connects three switching elements Q1, Q2, and Q3 in parallel with the power terminal V0. The on-resistance of the switching element Q1 is, for example, 1000Ω. The on-resistance of the switching element Q2 is, for example, 500Ω. The on-resistance of the switching element Q3 is, for example, 200Ω. Three switching elements Q7, Q8, and Q9 are connected in parallel with respect to the power terminal V2. The on-resistance of the switching element Q7 is, for example, 1000Ω. The on-resistance of the switching element Q8 is, for example, 500Ω. The on-resistance of the switching element Q9 is, for example, 200Ω. Three switching elements Q4, Q5, and Q6 are connected in parallel with respect to the power terminal V1. The on-resistance of the switching element Q4 is, for example, 1000Ω. The on-resistance of the switching element Q5 is, for example, 500Ω. The on-resistance of the switching element Q6 is, for example, 200Ω.

[0093] Fig.15 and Fig.16 This is a simulation result of this embodiment. Fig.15 The on / off timing and on time of each switching element Q1 to Q9 are shown. Fig.16 The generated drive waveform is shown in FIG. 1. The PWL (Piece-wise Linear) of the control signal for turning on / off each of the switching elements Q1 to Q9 is as follows.

[0094] The gate of the switching element Q6; P6g is PWL (0 0 6μs 0 6.01μs 1 7μs 1 7.01μs 0) and the gate of the switching element Q5; P5g is PWL (0 0 5.7μs 0 5.71μs 1 6μs 1 6.01μs 0) and the gate of the switching element Q4; P4g is PWL (0 1 0.99μs 1 1μs 0 5.5μs 0 5.51μs 1 5.7μs 15.71μs 0) and the gate of the switching element Q9; P9g is PWL (0 0 2μs 0 2.01μs 1 2.3μs 1 2.31μs 0 4μs 0 4.01μsμs 1 5.2μs 1 5.21μs 0) and the gate of the switching element Q8; P8g is PWL (0 0 1.7μs 0 1.71μs 1 2μs 1 2.01μs 0 3.7μs 0 3.71μs1 4μs 1 4.01μs 0) and the gate of the switching element Q7; P7g is PWL (0 0 1.5μs 0 1.51μs 1 1.7μs 1 1.71μs 0 3.5μs 0 3.51μs 1 3.7μs 1 3.71μs 0) and the gate of the switching element Q3; N3g is PWL (0 0 2.7μs 02.71μs 1 3.4μs 1 3.41μs 0), the gate of the switching element Q2; N2g is PWL (0 0 2.5μs 0 2.51μs 1 2.7μs 1 2.71μs 0), the gate of the switching element Q1; N1g is PWL (0 0 2.4μs 0 2.41μs 1 2.5μs 1 2.51μs0).

[0095] That is, the switching elements Q1, Q2, and Q3 are exclusively turned on in the order of on-resistance from large to small when the actuator 6 is charged or discharged. In addition, the switching elements Q4, Q5, and Q6 are exclusively turned on in the order of on-resistance from large to small when the actuator 6 is charged or discharged. In addition, the switching elements Q7, Q8, and Q9 are exclusively turned on in the order of on-resistance from large to small when the actuator 6 is charged or discharged. If represented by a timing diagram, it is as follows Fig.15 shown.

[0096] The time constant T1 based on the on-resistance (e.g. 1000Ω) of the switching elements Q1, Q4, Q7 as the first switching elements and the electrostatic capacitance (e.g. 1000pF) of the actuator 6 is 1μs. The time constant T1 is equal to 1 / 2 of the half cycle (e.g. 2μs) of the main resonance determined by the actuator 6 and the ink. The time t1 during which only the switching elements Q1, Q4, Q7 are turned on is less than the time constant T1. The time t1 during which only the switching elements Q4 and Q7 are turned on is 1 / 5 (0.2μs) of the time constant T1 (except Q1). The time t1 during which only the switching elements Q4 and Q7 are turned on is 1 / 10 (0.2μs) of the half cycle of the main resonance (except Q1). In addition, the time constant T2 based on the on-resistance (e.g. 200Ω) of the switching elements Q3, Q6, Q9 as the second switching elements and the electrostatic capacitance (e.g. 1000pF) of the actuator 6 is 0.2μs. The time that the switching elements Q3, Q6, and Q9 are turned on is longer than the time constant T2. In addition, the time constant T3 based on the on-resistance (e.g., 500Ω) of the switching elements Q2, Q5, and Q8 and the electrostatic capacitance (e.g., 1000pF) of the actuator 6 is 0.5μs. The time that the switching elements Q2, Q5, and Q8 are turned on is shorter than the time constant T3.

[0097] like Fig.15 and Fig.16 As shown, before the timing of ejecting ink, the switch element Q4 is turned on, and the potential V1 is applied to the actuator 6 to enter the standby state. Moreover, after the switch element Q4 is turned off at the time 0.99μs, the switch element Q7 is turned on at the time 1.51μs. When the switch element Q7 as the first switch element is turned on, the actuator 6 is connected to the potential V2 via the on-resistance of the switch element Q7, and the drive waveform drops with the curve of the time constant T1. Moreover, the switch element Q7 is turned off at the time 1.71μs, and the switch element Q8 is turned on. As a result, the potential of the drive waveform drops with the curve of the time constant T3 (T1>T3). Furthermore, the switch element Q8 is turned off at the time 2.01μs, and the switch element Q9 is turned on. When the switch element Q9 as the second switch element is turned on, the drive waveform drops to the potential V2 with the curve of the time constant T2 (T3>T2). The switch element Q9 is turned on before the time 2.3μs and turned off at the time 2.31μs. Here, the switch element Q9 is turned on within 0.3 μs, but if Fig.16As shown, this step forms a step around the time 2.3 to 2.4 μs of the drive waveform. The existence of this step is related to the power reduction effect, but since the step of the drive waveform contains high-frequency components, even if the step is not preferred, it can be transformed to shorten the conduction time of the switch element Q9 to about 0.2 μs to 0.1 μs only in this part and enter the next step in advance. By turning on the switch elements Q7 to Q9 in sequence, the actuator 6 is discharged from the potential V1 to the potential V2.

[0098] Next, at time 2.41μs, the switch element Q1 is turned on. When the switch element Q1 as the first switch element is turned on, the actuator 6 is connected to the potential V0 via the on-resistance of the switch element Q1, and the drive waveform drops along a curve with a time constant T1. Furthermore, at time 2.51μs, the switch element Q1 is turned off, and the switch element Q2 is turned on. As a result, the potential of the drive waveform drops along a curve with a time constant T3 (T1>T3). Furthermore, at time 2.71μs, the switch element Q2 is turned off, and the switch element Q3 is turned on. When the switch element Q3 as the second switch element is turned on, the drive waveform drops to the potential V0 along a curve with a time constant T2 (T3>T2). The switch element Q3 is turned on until time 3.4μs. By turning on the switch elements Q1 to Q3 in sequence in this way, the actuator 6 is discharged from the potential V2 to the potential V0. As a result, the actuator 6 returns to its original state from the standby state, and the ink flows into the pressure chamber 42 by an amount corresponding to the expansion of the volume of the pressure chamber 42 , and the meniscus of the ink in the nozzle 24 is sucked.

[0099] Then, at time 3.51μs, the switch element Q7 is turned on. When the switch element Q7 as the first switch element is turned on, the actuator 6 is connected to the potential V2 via the on-resistance of the switch element Q7, and the drive waveform rises with a curve of the time constant T1. Moreover, at time 3.71μs, the switch element Q7 is turned off, and the switch element Q8 is turned on. As a result, the potential of the drive waveform rises with a curve of the time constant T3 (T1>T3). Furthermore, at time 4.01μs, the switch element Q8 is turned off, and the switch element Q9 is turned on. When the switch element Q9 as the second switch element is turned on, the drive waveform rises to the potential V2 with a curve of the time constant T2 (T3>T2). The switch element Q9 is turned on until time 5.2μs. By turning on the switch elements Q7 to Q9 in sequence in this way, the actuator 6 is charged from the potential V0 to the potential V2. As a result, the volume of the pressure chamber 42 is reduced and the droplets R of the ink are ejected from the nozzle 24.

[0100] Next, at time 5.51μs, the switch element Q4 is turned on. When the switch element Q4 as the first switch element is turned on, the actuator 6 is connected to the potential V1 via the on-resistance of the switch element Q4, and the drive waveform rises with a curve of the time constant T1. Moreover, at time 5.71μs, the switch element Q4 is turned off, and the switch element Q5 is turned on. As a result, the potential of the drive waveform rises with a curve of the time constant T3 (T1>T3). Furthermore, at time 6.01μs, the switch element Q5 is turned off, and the switch element Q6 is turned on. When the switch element Q6 as the second switch element is turned on, the drive waveform rises to the potential V1 with a curve of the time constant T2 (T3>T2). By turning on the switch elements Q4 to Q6 in sequence in this way, the actuator 6 is charged from the potential V2 to the potential V1. As a result, the volume of the pressure chamber 42 is further reduced, and the residual vibration is attenuated. In addition, the switching element Q6 is turned off at the time 7.01 μs, but may be in the standby state when it is turned on.

[0101] Fig.17 This is an output unit as a comparative example. This output unit connects one switching element Q1, Q4, Q7 to each power supply terminal V1, V2, V0. The on-resistance of the switching elements Q1, Q4, Q7 is, for example, 300Ω.

[0102] Fig.18 express Fig.16 The simulation results of the driving waveform of the present embodiment and the simulation results of the driving waveform of the comparative example are shown in FIG. Fig.18 It is clear that in this embodiment, the rising / falling curve of the driving waveform can be made gentle by the first switching element, and the potential can be changed to a predetermined potential before a predetermined time by the second switching element.

[0103] Fig.19 The simulation results of the charge and discharge current of the present embodiment and the simulation results of the charge and discharge current of the comparative example are shown. Fig.19 It is clear that this embodiment has the effect of reducing the maximum value of the charge and discharge current.

[0104] Fig. 20 : represents the frequency components of the driving waveform of the present embodiment and the frequency components of the driving waveform of the comparative example. Fig. 20 It is clear that in this embodiment, the 250 kHz (1 / (2×2 μs)=250 kHz) component of the main resonance frequency is unchanged, and the frequency components above 1 MHz can be reduced compared with the comparative example, so high-frequency parasitic vibration is less likely to occur.

[0105] As described above, according to the above embodiment, it is possible to provide the inkjet head 100 which can suppress the influence of high-frequency vibration generated by the resonance point on the higher-frequency side than the main resonance frequency determined by the actuator 6 and the ink.

[0106] In addition, the actuator 6 is not limited to a stacked type formed by stacking a plurality of piezoelectric bodies 61. The piezoelectric body 61 may also be a single-layer actuator. In addition, the action of the actuator when a driving voltage is applied is not limited to longitudinal vibration. Furthermore, it is not limited to the drop-on-demand piezoelectric method, and can also be applied to a continuous method.

[0107] In the above embodiment, the inkjet head 100 of the inkjet printer 10 is described as an example of the liquid ejection head, but the liquid ejection head may be a modeling material ejection head of a 3D printer or a sample ejection head of a dispensing device.

[0108] The embodiments of the present invention are presented as examples and are not intended to limit the scope of the invention. These new embodiments can be implemented in various other forms, and various omissions, substitutions, and changes can be made without departing from the scope of the main purpose of the invention. These embodiments and their variations are included in the scope or main purpose of the invention, and are included in the invention recorded in the claims and their equivalents.

Claims

1. A liquid ejection head, characterized in that: have: piezoelectric actuator; and A driving circuit, wherein a plurality of switching elements are connected in parallel to one terminal of a power supply, wherein the switching elements connect the power supply to the piezoelectric actuator, wherein an on-resistance of a first switching element is greater than an on-resistance of a second switching element, The driving circuit disconnects the second switching element and turns on the first switching element within a time period shorter than a first time constant based on the on-resistance of the first switching element and the electrostatic capacitance of the piezoelectric actuator. After the time period has elapsed, the driving circuit turns on the second switching element for a time period longer than a second time constant based on the on-resistance of the second switching element and the electrostatic capacitance of the piezoelectric actuator to charge or discharge the piezoelectric actuator.

2. A liquid ejection head, characterized in that: have: piezoelectric actuator; and A driving circuit is provided, wherein a plurality of switching elements are connected in parallel to one terminal of a power source, wherein the switching elements connect the power source to the piezoelectric actuator. The driving circuit disconnects the second switching element and turns on the first switching element within a time shorter than a first time constant based on the on-resistance of the first switching element and the electrostatic capacitance of the piezoelectric actuator. After the time has passed, the driving circuit turns on the first switching element and the second switching element simultaneously within a time longer than a second time constant based on the parallel on-resistance of the first switching element and the second switching element and the electrostatic capacitance of the piezoelectric actuator to charge or discharge the piezoelectric actuator.

3. The liquid ejection head according to claim 1 or 2, characterized in that: The power supply has two or more terminals with different potentials. The terminal of the power supply and the first switching element and the second switching element connected to the terminal are provided in two or more groups, and the first switching element and the second switching element of each group are on / off controlled by the driving circuit.

4. The liquid ejection head according to claim 1 or 2, characterized in that: The first time constant is greater than 1 / 10 of a half period of a main resonance of the piezoelectric actuator and the liquid.

5. The liquid ejection head according to claim 1 or 2, characterized in that: The piezoelectric actuator is a stacked piezoelectric actuator in which a piezoelectric body, a first internal electrode, and a second internal electrode are alternately stacked in layers.

6. The liquid ejection head according to claim 1 or 2, characterized in that: The liquid ejection head further includes a selection section including a switching circuit that switches an output for controlling conduction of the switching element according to whether or not ink is ejected.

7. A liquid ejection head, characterized in that: have: piezoelectric actuator; and A driving circuit, wherein a plurality of switching elements are connected in parallel to one terminal of a power supply, wherein the switching elements connect the power supply to the piezoelectric actuator, wherein an on-resistance of a first switching element is greater than an on-resistance of a second switching element, The driving circuit disconnects the second switching element and turns on the first switching element within a time shorter than 1 / 2 of a half period of a main resonance determined by the piezoelectric actuator and the liquid and longer than 1 / 10 of a half period of the main resonance, and turns on the second switching element within a time longer than a time constant based on an on-resistance of the second switching element and an electrostatic capacitance of the piezoelectric actuator to charge the piezoelectric actuator.

8. The liquid ejection head according to claim 7, wherein: The power supply has two or more terminals with different potentials. The terminal of the power supply and the first switching element and the second switching element connected to the terminal are provided in two or more groups, and the first switching element and the second switching element of each group are on / off controlled by the driving circuit.

9. The liquid ejection head according to claim 7, wherein: The piezoelectric actuator is a stacked piezoelectric actuator in which a piezoelectric body, a first internal electrode, and a second internal electrode are alternately stacked in layers.

10. The liquid ejection head according to claim 7, wherein: The liquid ejection head further includes a selection section including a switching circuit that switches an output for controlling conduction of the switching element according to whether or not ink is ejected.

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