Liquid discharge head and liquid discharge device

Abstract

To reduce a voltage of a signal that is supplied from a liquid discharge device to a liquid discharge head requiring a high voltage.SOLUTION: A liquid discharge device is provided with: a discharge unit configured to discharge liquid inside a pressure chamber; a supply passage through which liquid to be supplied to the pressure chamber flows; a recovery passage, connected to the supply passage through the pressure chamber, through which liquid recovered from the pressure chamber flows; a circulation pump that can supply liquid to the pressure chamber through the supply passage, on the basis of an AC pump driving signal, recover liquid from the pressure chamber through the recovery passage and reflux the recovered liquid to the supply passage; and a pump driving circuit that generates a pump driving signal, by boosting a DC reference voltage signal whose voltage is smaller than a peak-to-peak voltage of the pump driving signal to convert the signal to an AC voltage signal.SELECTED DRAWING: Figure 6

Description

Technical Field

[0001] The present disclosure relates to a liquid ejection head and a liquid ejection device.

Background Art

[0002] In the field of inkjet printers in recent years, in a liquid ejection device of a liquid ejection head scanning type, an ink circulation type liquid ejection device that can handle special ink according to a recording medium for outputting high-quality printed matter has been demanded. A configuration has been proposed in which an ink supply channel and an ink recovery channel are provided for ink circulation, and a circulation flow is obtained by generating a differential pressure between the ink supply channel and the ink recovery channel. The liquid ejection head disclosed in Patent Document 1 includes a discharge unit for discharging ink, a supply-side reservoir for supplying ink to the discharge unit, and a recovery-side reservoir for recovering ink from the discharge unit. Further, the liquid ejection head also includes a circulation pump for refluxing ink from the recovery-side reservoir to the supply-side reservoir, two pressure sensors provided in the two reservoirs respectively, and a drive circuit for driving the circulation pump according to the outputs of the two pressure sensors.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Here, in the above-described configuration, the voltage for driving the circulation pump is initially 200V and varies in the range of 120V to 300V. A configuration in which such a high voltage is supplied from the main body of the liquid ejection device to the liquid ejection head may have an unfavorable effect on the handling by the user and the peripheral components at the electrical connection portion between the liquid ejection device and the liquid ejection head. Here, in a configuration in which the liquid ejection head equipped with the circulation pump moves in the main scanning direction, it is preferable to miniaturize the circulation pump for weight reduction and volume reduction. In order to ensure the necessary circulation flow rate with the miniaturized circulation pump, it is necessary to further increase the voltage for driving the circulation pump.

[0005] The present disclosure has been made in view of the above points, and an object thereof is to reduce the voltage of the signal supplied from the liquid ejection device to the liquid ejection head that requires a high voltage.

Means for Solving the Problems

[0006] One embodiment of the present disclosure includes a discharge unit configured to discharge the liquid inside the pressure chamber, a supply flow path through which the liquid supplied to the pressure chamber flows, a recovery flow path connected to the supply flow path via the pressure chamber and through which the liquid recovered from the pressure chamber flows, a circulation pump that can supply liquid to the pressure chamber via the supply flow path, recover the liquid from the pressure chamber via the recovery flow path, and reflux the recovered liquid to the supply flow path based on an alternating current pump drive signal, and a pump drive circuit that generates the pump drive signal by boosting and converting an alternating current a DC reference voltage signal having a voltage smaller than the peak-to-peak voltage of the pump drive signal.

Effects of the Invention

[0007] According to the present disclosure, it is possible to reduce the voltage of the signal supplied from the liquid ejection device to the liquid ejection head that requires a high voltage.

Brief Description of the Drawings

[0008]

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Embodiments for Carrying Out the Invention

[0009] Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. Note that the following embodiments do not limit the invention according to the claims. Although a plurality of features are described in the embodiments, not all of these plurality of features are essential to the invention, and the plurality of features may be arbitrarily combined. Further, in the accompanying drawings, the same or similar configurations may be given the same reference numerals, and redundant descriptions may be omitted in some cases.

[0010] FIG. 1(a) is a schematic perspective view showing an overview of the liquid discharge device of the present disclosure, and FIG. 1(b) is a functional block diagram of the liquid discharge device of the present disclosure.

[0011] The liquid ejection device according to this embodiment is an inkjet liquid ejection device (hereinafter simply referred to as "liquid ejection device") 101 of a serial scan type that ejects ink from a liquid ejection head 201 to record an image on a recording medium P. The liquid ejection head 201 as an inkjet liquid ejection head is mounted on a carriage 121. The carriage 121 reciprocates along a guide shaft 132 extending in the main scanning direction as shown by the two-way arrow X. The recording medium P is conveyed in the sub-scanning direction intersecting (orthogonal in this example) the main scanning direction by conveyance rollers 133, 134, 135, and 136 as shown by the arrow Y.

[0012] The liquid ejection head 201 includes a plurality of liquid circulation units 204 and a ejection unit 206. The plurality of liquid circulation units 204 circulate the ink flowing through the ejection unit 206. A plurality of ejection elements for ejecting ink are formed in an ejection module 209 provided in the ejection unit 206. The element drive signal generated by the head driver 123 drives the plurality of ejection elements for ink ejection, and is supplied to the plurality of ejection elements formed in the ejection module 209 via an electric circuit board 205 and an electric wiring tape 208.

[0013] A guide 131 is connected to the carriage 121. Electric wiring and supply tubes are disposed on the guide 131. Such electric wiring and supply tubes supply the electric signals and ink necessary for ink ejection by the plurality of ejection elements formed in the ejection module 209 to the carriage 121.

[0014] A processor 142 such as a CPU controls the liquid ejection device 101 by reading and executing a program stored in a ROM 143. A RAM 144 is used as a work area or the like when the processor 142 reads and executes a program. The processor 142 controls a head driver 123 based on image data supplied from a host device 111 connected to the liquid ejection device 101. Further, the processor 142 controls a carriage motor 146 for moving a carriage 121 via a motor driver 145. Still further, the processor 142 controls a conveyance motor 148 for conveying a recording medium P by conveyance rollers 133, 134, 135, and 136 via a motor driver 147.

[0015] The liquid ejection head 201 is capable of full-color printing using CMYK (cyan, magenta, yellow, black) ink. A cap portion (not shown) is disposed at a position adjacent to the conveyance path of the recording medium P. The cap portion relatively moves to a position covering the ejection surface of the liquid ejection head 201 during a period when the liquid ejection device 101 does not perform a recording operation. Then, the cap portion performs capping for preventing drying of ejection ports formed in the ejection surface, suction operations for filling ink into the head, and recovery of the head function.

[0016] [Configuration of Liquid Ejection Head] FIG. 2 shows an exploded perspective view of the liquid ejection head 201 of the present embodiment. As shown in FIG. 2, the liquid ejection head 201 has a plurality of liquid circulation units 204 as described above. The plurality of liquid circulation units 204 include liquid circulation units 204m, 204y, 204k, and 204c corresponding to inks of respective colors, and these are housed inside the flow path member 202. The liquid circulation unit 204 is provided with a flow path, and the flow path member 202 is also provided with a flow path. As a connection method for these flow paths, a screw tightening method in which a seal member is sandwiched between both, or a connection method by welding can be used. In the ejection head 201 according to the present embodiment, the number of ink types is 4, and accordingly, the number of liquid circulation units 204 is also 4, but the present disclosure is not limited thereto. Hereinafter, the description will proceed on the assumption that the number of ink types is 4, but this does not limit the number of ink types in the present disclosure to 4.

[0017] As shown in FIG. 2, the flow path member 202 is provided with four joints 203 for receiving the ink supplied from the supply tube disposed on the guide 131 from the main body of the liquid ejection device 101. The four joints 203 are connected to the liquid circulation units 204m, 204y, 204k, and 204c in a one-to-one relationship. When the liquid ejection head 201 is attached to the main body of the liquid ejection device 101, each supply tube connected to each ink tank 151 (see FIG. 1) of each color is connected to each joint 203. The inks of respective colors supplied from each supply tube pass through each joint 203 and are supplied to the liquid circulation units 204m, 204y, 204k, and 204c. A discharge unit 206 is connected to the bottom surface of the flow path member 202. The inks of respective colors supplied to the liquid circulation units 204m, 204y, 204k, and 204c pass through the flow path member 202 and are supplied to the discharge unit 206.

[0018] As shown in FIG. 2, the ejection unit 206 includes an ejection module 209 in which a plurality of ejection elements for ejecting ink are arranged, and a support member 207. Further, the ejection unit 206 further includes an electrical wiring tape 208 for sending an electrical signal to the ejection module 209, and a cover member 210 that covers the electrical wiring tape 208. The ejection module 209 and the electrical wiring tape 208 are adhesively fixed to the support member 207, and further, the cover member 210 is adhesively joined to them so as to cover their surfaces. The ejection module 209 and the electrical wiring tape 208 are electrically connected by wire bonding. Here, as the electrical connection method, a method such as flying lead bonding can be used. A portion of the cover member 210 corresponding to the ejection module 209 is open. As a connection method between the ejection unit 206 and the flow path member 202, an adhesion method using an adhesive or a fixing method by screwing with a seal member sandwiched therebetween can be used.

[0019] The surface on the opposite side of the surface where the joint 203 of the flow path member 202 is disposed is a contact surface. An electric circuit board 205 is disposed on the contact surface. The electric circuit board 205 may be fixed to the flow path member 202 by caulking or an adhesive, or may be fixed by a double-sided tape.

[0020] As shown in FIG. 1, the electric circuit board 205 relays an electrical signal transmitted between the carriage board 122 and the ejection unit 206. Further, the electric circuit board 205 also relays an electrical signal transmitted between the carriage board 122 and the liquid circulation unit 204.

[0021] The electrical wiring tape 208 included in the ejection unit 206 is connected to the electric circuit board 205 by ACF crimping, wire bonding, flying lead bonding, or the like. The electrical wiring tape 208 relays an electrical signal transmitted between the electric circuit board 205 and the ejection module 209 included in the ejection unit 206.

[0022] [Description of the circulation flow path] FIG. 3 is a schematic external view of the liquid circulation unit 204 applied to the liquid ejecting apparatus 101. One liquid circulation unit 204 is arranged for each color on the flow path member 202. The liquid circulation unit 204 is provided with a first pressure regulating mechanism 302, a second pressure regulating mechanism 304, a filter 301, and a circulation pump 303.

[0023] FIG. 4 is a schematic diagram showing a liquid circulation flow path for one color applied to the liquid ejecting apparatus 101. Ink is pressurized and supplied from the ink tank 151 to the liquid ejecting head 201 by an external pump 152. After the ink is filtered by the filter 301 to remove dust, it is supplied to the first valve chamber 401 of the first pressure regulating mechanism 302. Then, when the ink flows into the first pressure control chamber 402 communicating with the first valve chamber 401 via the first valve (not shown), the pressure is adjusted to the supply side pressure.

[0024] The circulation pump 303 is a piezoelectric diaphragm pump in which the volume in the pump chamber is changed by an input of a drive voltage signal having alternately applied pump drive voltages supplied to two piezoelectric elements attached to the diaphragm, and two check valves alternately move due to pressure fluctuations to send the liquid. The circulation pump 303 is driven to send the ink from the pump inlet flow path 407 on the downstream side to the pump outlet flow path 408 on the upstream side.

[0025] By driving the circulation pump 303, the ink with the pressure adjusted in the first pressure control chamber 402 is supplied to the supply flow path 405 and the bypass flow path 409. The supply flow path 405 is a flow path formed in the flow path member 202 and is connected to the ejection unit 206. The recovery flow path 406 is also a flow path formed in the flow path member 202 and is connected to the ejection unit 206.

[0026] The ejection unit 206 includes an ejection module 209, and a plurality of ejection elements are formed in the ejection module 209. Each ejection element includes a pressure chamber, an ejection port, and an energy conversion element. The pressure chamber and the ejection port are in communication. The ejection ports are arranged as openings on the ejection surface. The ink supplied to the supply channel 405 is supplied to a plurality of pressure chambers formed in the ejection module 209 of the ejection unit 206. The ink in the pressure chamber is ejected from the ejection port by the energy output by the energy conversion element. The ink that has not been ejected from the ejection port is discharged from the pressure chamber to the recovery channel 406, and then recovered into the second pressure control chamber 404 of the second pressure adjustment mechanism 304.

[0027] Also, the ink supplied to the second valve chamber 403 of the second pressure adjustment mechanism 304 is supplied to the second pressure control chamber 404 that communicates with the second valve chamber 403 via a second valve (not shown). Note that the pressure in the second pressure control chamber 404 is adjusted to the recovery-side pressure. During recording, the recovery-side pressure is lower than the supply-side pressure.

[0028] The ink supplied to the second pressure control chamber 404 is supplied to the pump inlet channel 407, passes through the circulation pump 303, is then supplied to the pump outlet channel 408, and is further refluxed to the first pressure control chamber 402. However, at least a part of the ink supplied to the second pressure control chamber 404 may be supplied to the flow path member 202 via the recovery channel 406. By configuring the ink to pass through and circulate through the ejection elements formed in the ejection module 209 by the circulation pump 303 in this way, it is possible to suppress the thickening of the ink in the ejection module 209.

[0029] The circulation channel is not limited to a configuration that passes through the ejection module 209, and it may be configured to circulate the ink in the ejection unit 206 within a range that has an effect of suppressing the thickening of the ink in the ejection module 209.

[0030] [Explanation of the Circulation Pump Driving Mechanism] FIG. 5 is a schematic diagram showing a configuration for electrical connection for driving the circulation pump 303. Various drive signals are sent from the processor 142 mounted on the main board 141 in the liquid ejection device 101 to the carriage board 122 mounted on the carriage 121 via the main board 141 and the flexible flat cable (FFC) 501. The various drive signals include signals related to the circulation pump 303 included in the liquid circulation unit 204 and signals related to the ejection unit 206.

[0031] Also, various drive signals are sent from the carriage board 122 to the electric circuit board 205 via the electrical connection portion 504 by contact connection. Here, the electrical connection portion 504 includes a plurality of pins 505 on the carriage 121 side as shown in FIG. 5 and a plurality of pads (not shown) disposed on the pad surface 502 of the electric circuit board 205, and electrical connection is established by contact between each pin and the corresponding pad.

[0032] As will be described later with reference to FIG. 6 and the like, a booster circuit 606 is disposed on the electric circuit board 205 as a boosting means for boosting the reference voltage of the reference voltage signal 654 based on the boost control signal 656. The booster circuit 606 boosts the reference voltage to the voltage specified by the boost control signal 656 to generate a drive voltage signal 657 having a pump drive voltage. The drive voltage signal 657 is converted into an alternating pump drive signal 658 by an output switching circuit 607 (see FIG. 6 and the like), and then supplied to a connector terminal (not shown) disposed on the electric circuit board 205. The pump drive signal 658 is supplied to the four circulation pumps 303 via the harness wiring 506 connected to the connector terminal. The four circulation pumps 303 are driven for ink circulation by the pump drive signal 658 having the pump drive voltage as the peak-to-peak voltage. Note that the peak-to-peak voltage is a voltage obtained by subtracting the minimum voltage from the maximum voltage of a signal whose voltage is not constant.

[0033] It is preferable to provide the wire path from the boost circuit 606 to the circulation pump 303 in a place where it is difficult for the user to touch. For example, the boost circuit 606 is provided on the surface of the electric circuit board 205 on the side of the flow path member 202, and it is preferable that the wire path from the boost circuit 606 to the circulation pump 303 is covered by the flow path member 202.

[0034] Also, a configuration in which the carriage substrate 122 and the electric circuit substrate 205 are integrated may be adopted. A configuration in which the user cannot remove the electric circuit substrate 205 from the carriage substrate 122 may be adopted. In such a configuration, the boost circuit 606 may be provided on the carriage substrate 122.

[0035] [First Embodiment] FIG. 6 is a schematic configuration diagram of the liquid ejection device 101 according to the first embodiment.

[0036] A printing signal 651 is supplied from the host device 111 to the processor 142 provided in the liquid ejection device 101. Power 652 is supplied from the external power source 601 to the power supply unit 602 provided in the liquid ejection device 101. When the printing signal 651 is supplied, the processor 142 activates the power control signal 653 to the power supply unit 602. In this embodiment, the power control signal 653 is high-active, and the signal is activated by setting the signal voltage from 0V to 3.3V. Note that the signal voltage is equal to the signal potential with respect to the ground potential. Hereinafter, when referring to "~ voltage", it means the potential with respect to the ground potential. When the active power control signal 653 is supplied, the power supply unit 602 supplies a reference voltage signal 654 to the first terminal group 603. In this embodiment, the reference voltage signal 654 has a DC 24V. Note that 24V is merely an example, and the reference voltage signal 654 may be a DC signal having a constant voltage lower than the peak-to-peak voltage of the pump drive signal. The reference voltage is preferably equal to or lower than the voltage of the power supply for the circuit on the electric circuit board 205 to operate, but this is not limiting. Also, since the reference voltage is preferably stable, for example, it is preferably a voltage generated by a regulator on the main board 141. Further, the voltage of the reference voltage signal is preferably a voltage that does not damage the user when the user touches the wiring for the reference voltage signal. Therefore, the reference voltage signal 654 may have, for example, DC 12V or DC 5V. When the printing signal 651 is supplied, the processor 142 supplies an AC conversion control signal 655 and a boost control signal 656 to the first terminal group 603. The AC conversion control signal 655 is composed of signals 655a and 655b corresponding to the opposing electrode terminals provided in the circulation pump 303, respectively. In this embodiment, the power control signal 653 is high-active, and the signal is activated by setting the signal voltage from 0V to 3.3V. Also, the boost control signal 656 is a signal that drives the boost circuit 606 by transitioning between 0V and 24V. The first terminal group 603 is a terminal group provided in the liquid ejection device 101. The first terminal group 603 supplies signals and voltages to the second terminal group 604 provided on the electric circuit board 205 mounted on the liquid ejection head 201.According to this embodiment, the highest voltage among the voltages of the signals output from the first terminal group 603 is 24V, which is a relatively low voltage.

[0037] The second terminal group 604 supplies the reference voltage signal 654 and the boost control signal 656 supplied from the first terminal group 603 to the boost circuit 606. The boost circuit 606 generates a drive voltage signal 657 having a DC 72V based on the reference voltage signal 654 having a DC 24V in accordance with the boost control signal 656, and supplies the signal 657 to the output switching circuit 607. The specific configuration of the boost circuit 606 will be described later. The output switching circuit 607 generates an AC pump drive signal 658 based on the drive voltage signal 657 and the AC conversion control signal 655 of AC supplied from the second terminal group 604, and supplies the signal 658 to the third terminal group 608. Therefore, it can be said that the output switching circuit 607 generates the pump drive signal 658 by converting the DC drive voltage signal 657 into AC (that is, converting from DC to AC) based on the AC conversion control signal 655. As shown in FIG. 6, the boost circuit 606 and the output switching circuit 607 are included in the pump drive circuit 605. The third terminal group 608 includes two terminals corresponding to the opposed electrode terminals provided on the circulation pump 303, and the pump drive signal 658 includes two signals. The two signals included in the pump drive signal 658 are supplied to the two terminals corresponding to the opposed electrode terminals provided on the circulation pump 303 in a one-to-one correspondence. The pump drive signal 658 transitions between 0V and 72V which is the pump drive voltage at a frequency corresponding to the drive frequency of the pump. Here, the reference voltage signal 654 is a DC signal of 24V. Therefore, the voltage of the reference voltage signal 654 is smaller than the peak-to-peak voltage of the pump drive signal 658. The third terminal group 608 is provided on the electric circuit board 205. The pump drive signal 658 is supplied from the third terminal group 608 to the fourth terminal group 609 provided in the liquid circulation unit 204 via the harness wiring 506. The fourth terminal group 609 supplies the supplied pump drive signal 658 to the circulation pump 303. The circulation pump 303 is driven in accordance with the supplied pump drive signal 658.

[0038] Note that the boost control signal 656 is, for example, a PWM signal, and by adjusting the duty cycle, the voltage of the drive voltage signal 657 output by the boost circuit 606 can be adjusted.

[0039] FIG. 7 is a circuit schematic diagram of the boost circuit 606 according to the first embodiment. The boost circuit 606 shown in FIG. 7 is a boost chopper type circuit. A reference voltage signal 654 having 24V is supplied to the first terminal of the inductor 701 and the first terminal of the bypass capacitor 705. In this embodiment, a chip inductor is used as the inductor 701. The second terminal of the inductor 701 is connected to the drain of the switching element 702 and the anode of the diode 703. The switching element 702 is supplied with the boost control signal 656 at the gate, and the source is grounded to the ground. In this embodiment, an n-channel FET is used as the switching element 702. The cathode of the diode 703 is connected to the first terminal of the capacitor 704, and the drive voltage signal 657 is output from these connection points. The second terminal of the capacitor 704 and the second terminal of the bypass capacitor 705 are grounded to the ground.

[0040] When the boost control signal 656 is at the active voltage of 24V, the switching element 702 becomes active, so current flows from the input terminal of the reference voltage signal 654, through the inductor 701 and the switching element 702, to ground. Note that the active voltage is equal to the active potential with respect to the ground potential. Here, when the boost control signal 656 transitions from the active voltage to the ground voltage of 0V, the switching element 702 turns off. However, since there is an inductor 701 between the input terminal of the reference voltage signal 654 and the drain of the switching element 702, charge flows into the capacitor 704 through the diode 703 due to the back electromotive force generated during the transition. Here, the charge that has flowed into and accumulated in the capacitor 704 cannot return to the anode side of the diode 703 because of the presence of the diode 703. Therefore, every time the boost control signal 656 drives the switching element 702, charge flows into and accumulates in the capacitor 704, so the drive voltage signal 657 is boosted to a voltage higher than the reference voltage signal 654. In this embodiment, the boost control signal 656 is supplied to the switching element 702 such that the drive voltage signal 657 becomes 72V.

[0041] Figure 8 is a circuit schematic diagram of the output switching circuit 607 according to the first embodiment. The drive voltage signal 657 having 72V is supplied to the first terminal of the resistor 801a, the first terminal of the resistor 801b, the collector of the transistor 802a, and the collector of the transistor 802b. In this embodiment, NPN transistors are used as the transistors 802a and 802b. The emitters of the transistor 802a and the transistor 802b are respectively connected to the emitters of the transistor 803a and the transistor 803b. In this embodiment, PNP transistors are used as the transistors 803a and 803b. The pump drive signal 658a is output from the connection point between the emitters of the transistor 802a and the transistor 803a. Similarly, the pump drive signal 658b is output from the connection point between the emitters of the transistor 802b and the transistor 803b.

[0042] The collectors of transistors 803a and 803b are grounded. The second terminal of resistor 801a is connected to the base of transistor 802a, the base of transistor 803a, the collector of transistor 805a, and the first terminal of capacitor 806a. Similarly, the second terminal of resistor 801b is connected to the base of transistor 802b, the base of transistor 803b, the collector of transistor 805b, and the first terminal of capacitor 806b.

[0043] In this embodiment, NPN transistors are used as transistors 805a and 805b. The AC conversion control signals 655a and 655b are respectively supplied to the bases of transistors 805a and 805b. The emitters of transistors 805a and 805b and the second terminals of capacitors 806a and 806b are grounded.

[0044] Note that a and b attached to reference numerals 655, 801 to 803, 805, and 806 respectively correspond to the opposing electrode terminals a and b provided on the circulation pump 303.

[0045] Next, the operation of the output switching circuit 607 shown in FIG. 8 will be described. Since the operation is common to the a series and the b series, a and b described above are omitted in the description.

[0046] When the AC conversion control signal 655 is at the ground voltage of 0V, transistor 805 is open. In such a state, the drive voltage signal 657 is supplied to the bases of transistors 802 and 803 via resistor 801. Then, a base current flows from the base to the emitter of transistor 802. Therefore, since transistor 802 becomes active, the voltage of the pump drive signal 658 becomes 72V, which is equal to the voltage of the drive voltage signal 657. On the other hand, since the emitter and the base of transistor 803 have the same voltage, transistor 803 is open.

[0047] When the AC conversion control signal 655 is at the active voltage of 3.3V, a base current flows from the base to the emitter of the transistor 805. Thus, since the transistor 805 becomes active, the bases of the transistors 802 and 803 are grounded. When the pump drive signal 658 has a voltage of 72V for driving the pump, a base current flows from the emitter to the base of the transistor 803. Thus, since the transistor 803 becomes active, the voltage of the pump drive signal 658 becomes the ground voltage of 0V, which is the collector voltage of the transistor 803. On the other hand, since the base and emitter of the transistor 802 have the same voltage, it becomes open.

[0048] As described above, when the AC conversion control signal 655 has a ground voltage of 0V, the voltage of the pump drive signal 658 becomes equal to the voltage of the drive voltage signal 657. On the other hand, when the AC conversion control signal 655 has an active voltage of 3.3V, the voltage of the pump drive signal 658 becomes the ground voltage of 0V. Here, since the voltages of the AC conversion control signals 655a and 655b alternately repeat the ground voltage and the active voltage of 3.3V, the voltages of the pump drive signals 658a and 658b alternately repeat the ground voltage and the voltage of the drive voltage signal 657, which is 72V.

[0049] FIG. 9 is a timing chart showing the operation of the pump drive circuit 605 according to the first embodiment. First, the reference voltage signal 654 transitions from 0V, which is the ground voltage, to 24V. Thereafter, the boost control signal 656 alternately repeats the ground voltage of 0V and the active voltage of 24V according to a specified rule. Based on the boost control signal 656, the drive voltage signal 657 is boosted from the ground voltage of 0V to 72V, which is the voltage required for pump drive. Thereafter, by alternately repeating the voltages of the AC conversion control signals 655a and 655b between 0V and 3.3V, the voltages of the pump drive signals 658a and 658b alternately repeat between 0V and 72V.

[0050] As described above, as the output switching circuit 607, a so-called class-B amplifier type circuit can be used. Further, in the present embodiment, it is possible to avoid the presence of a signal having a high voltage necessary for driving the circulation pump 303 in the path from the first terminal group 603 to the second terminal group 604. Therefore, it is possible to avoid the presence of a signal having a high voltage in the flexible flat cable (FFC) 501, the carriage substrate 122, and the electrical connection portion 504. Thus, it is possible to reduce the unfavorable effects on the handling by the user and the peripheral components due to the electrical connection.

[0051] [Second Embodiment] FIG. 10 is a circuit schematic diagram of the booster circuit 606 according to the second embodiment. The booster circuit 606 shown in FIG. 10 is a charge pump type circuit. A reference voltage signal 654c having 24V is supplied to the anode of the diode 1011 and the first terminal of the bypass capacitor 1010. The cathode of the diode 1011 is connected to the first terminal of the capacitor 1013 and the anode of the diode 1014. The second terminal of the capacitor 1013 is connected to the drain of the switching element 1012 and the second terminal of the capacitor 1017. A reference voltage signal 654d is supplied to these three mutually connected terminals. A boost control signal 656 is supplied to the gate of the switching element 1012, and the source of the switching element 1012 is grounded. In the present embodiment, an n-channel FET is used as the switching element 1012. The cathode of the diode 1014 is connected to the first terminal of the capacitor 1015 and the anode of the diode 1016.

[0052] The cathode of the diode 1016 is connected to the first terminal of the capacitor 1017 and the anode of the diode 1018. The cathode of the diode 1018 is connected to the first terminal of the capacitor 1019, and the drive voltage signal 657 is output therefrom. The second terminals of the capacitors 1015 and 1019 are grounded.

[0053] When the boost control signal 656 is at the active potential of 24V, the switching element 1012 becomes active, so the second terminals of the capacitor 1013 and the capacitor 1017 are grounded. In this state, charges flow into the four capacitors through the four diodes so that the voltage of the first terminals of the four capacitors becomes the same as the voltage of the reference voltage signal 654c. The four capacitors mentioned here are the capacitors 1013, 1015, 1017, and 1019, and the four diodes are the diodes 1011, 1014, 1016, and 1018. Next, when the voltage of the boost control signal 656 transitions from the active voltage to the ground voltage, the switching element 1012 turns off. Then, the voltage of the second terminal of the capacitor 1013 becomes 24V, which is the same as the voltage of the reference voltage signal 654d. On the other hand, there is a potential difference of 24V between both terminals of the capacitor 1013. Therefore, charges flow into the capacitor 1013 from the terminal of the reference voltage signal 654c through the diode 1011 so that a potential difference of 24V is generated between both terminals with the voltage of the second terminal of the capacitor 1013, which is 24V, as a reference. As a result, the voltage of the first terminal of the capacitor 1013 becomes 48V with the ground voltage of 0V as a reference. Then, since the anode side of the diode 1014 is 48V and the cathode side is 24V, charges flow into the capacitor 1015 through the diode 1014 so that the cathode side becomes 48V. Similarly, charges flow into the capacitors 1017 and 1019 so that the cathode sides of the diodes 1016 and 1018 become 48V.

[0054] Next, when the boost control signal 656 transitions from the ground voltage to the active voltage, the switching element 1012 becomes active. Then, the second terminals of the capacitor 1013 and the capacitor 1017 are grounded. Further, when the boost control signal 656 transitions from the active voltage to the ground voltage, the switching element 1012 turns off. Then, the voltage at the second terminal of the capacitor 1017 becomes 24V, which is the same as the voltage of the reference voltage signal 654d. On the other hand, there is a potential difference of 48V between both terminals of the capacitor 1017. Therefore, with the voltage at the first terminal of the capacitor 1013 being based on the voltage of 24V at the second terminal, a potential difference of 48V is generated between both terminals, and charge flows into the capacitor 1017 from the terminal of the reference voltage signal 654c through the diode 1016. That is, charge flows into the capacitor 1017 through the diode 1016 so that the potential at the first terminal of the capacitor 1017 becomes 72V with reference to the ground voltage of 0V. Then, since the anode side of the diode 1018 is 72V and the cathode side is 48V, charge flows into the capacitor 1019 through the diode 1018 so that the cathode side becomes 72V.

[0055] As described above, as the boost circuit 606, a so-called charge pump type circuit can be used.

[0056] [Third Embodiment] FIG. 11 is a circuit schematic diagram of the output switching circuit 607 in the third embodiment. A drive voltage signal 657 having 72V is supplied to the sources of the switching elements 1111a and 1111b via a resistor 1110. The drains of the switching elements 1111a and 1111b are respectively connected to the drains of the switching elements 1112a and 1112b. A pump drive signal 658a is output from the connection point between the drain of the switching element 1111a and the drain of the switching element 1112a. Similarly, a pump drive signal 658b is output from the connection point between the drain of the switching element 1111b and the drain of the switching element 1112b. The sources of the switching elements 1112a and 1112b are grounded. An AC conversion control signal 655a is supplied to the gates of the switching elements 1111a and 1112a. Similarly, an AC conversion control signal 655b is supplied to the gates of the switching elements 1111b and 1112b. In this embodiment, p-channel FETs are used as the switching elements 1111a and 1111b, and n-channel FETs are used as the switching elements 1112a and 1112b.

[0057] Note that a and b attached to the reference numerals 655, 658, 1111, and 1112 respectively correspond to the opposing electrode terminals a and b provided on the circulation pump 303.

[0058] Next, the operation of the output switching circuit 607 shown in FIG. 11 will be described. Since the operation is common to the a series and the b series, a and b described above will be omitted in the description.

[0059] When the voltage of the AC conversion control signal 655 is the ground voltage of 0V, the switching element 1111 is active and the switching element 1112 is open. In such a state, the drive voltage signal 657 is output as the pump drive signal 658 through the resistor 1110 and the switching element 1111. When the AC conversion control signal 655 is the active voltage of 3.3V, the switching element 1112 is active and the switching element 1111 is open. In such a state, the pump drive signal 658 is grounded through the switching element 1112. Here, since the voltages of the AC conversion control signals 655a and 655b alternately repeat the ground voltage and the active voltage of 3.3V, the voltages of the pump drive signals 658a and 658b alternately repeat the ground voltage and the voltage of the drive voltage signal 657, which is 72V.

[0060] As described above, a so-called full-bridge type circuit can be used as the output switching circuit 607.

[0061] [Fourth Embodiment] FIG. 12 is a circuit schematic diagram of the output switching circuit 607 in the fourth embodiment. A drive voltage signal 657 having 72V is supplied to the collectors of transistors 1221a and 1221b through a resistor 1223. In this embodiment, NPN type transistors are used as the transistors 1221a and 1221b. The AC conversion control signal 655a is input to the base of the transistor 1221a. Similarly, the AC conversion control signal 655b is input to the base of the transistor 1221b. The emitter of the transistor 1221a is connected to a constant current source 1222a. Similarly, the emitter of the transistor 1221b is connected to a constant current source 1222b. The pump drive signal 658a is output from the emitter of the transistor 1221a. Similarly, the pump drive signal 658b is output from the emitter of the transistor 1221b.

[0062] Note that a and b attached to the reference numerals 1221 and 1222 respectively correspond to the opposing electrode terminals a and b provided on the circulation pump 303.

[0063] Next, the operation of the output switching circuit 607 shown in FIG. 12 will be described. Since the operation is common to the a series and the b series, the above a and b will be omitted in the description.

[0064] When the voltage of the AC conversion control signal 655 is the ground voltage 0V, the transistor 1221 is open. In such a state, since the constant current source 1222 draws current from the signal line of the pump drive signal 658, the pump drive signal 658 drops to the ground voltage. When the AC conversion control signal 655 is the active voltage 3.3V, the transistor 1221 becomes active. In such a state, since current flows from the signal line of the drive voltage signal 657 through the resistor 1223 and the transistor 1221 to the signal lines of the constant current source 1222 and the pump drive signal 658, the drive voltage signal 657 is output as the pump drive signal 658. In this way, since the voltages of the AC conversion control signals 655a and 655b alternately repeat the ground voltage and the active voltage 3.3V complementarily, the voltages of the pump drive signals 658a and 658b alternately repeat the ground voltage and the voltage of the drive voltage signal 657, which is 72V, complementarily.

[0065] As described above, a so-called class A amplifier type circuit can be used as the output switching circuit 607.

[0066] [Fifth Embodiment] FIG. 13 is a schematic configuration diagram of the liquid ejection device 101 according to the fifth embodiment. In the present embodiment, a reference voltage signal and a composite control signal 1351 are input to the boosting / AC conversion circuit 1301. A pump drive signal 658 is output from the boosting / AC conversion circuit 1301 to the third terminal group 608. The composite control signal 1351 has 1351a and 1351b corresponding to the counter electrode terminals provided in the circulation pump 303, respectively. Other configurations are the same as those in the first embodiment.

[0067] FIG. 14 is a circuit schematic diagram of the boost / AC conversion circuit 1301 according to the fifth embodiment. The boost / AC conversion circuit 1301 shown in FIG. 14 has a configuration combining a boost chopper circuit on the positive side and a boost chopper circuit on the negative side. A reference voltage signal 654 having 24V is supplied to the drain of the switching element 1421b and the first terminal of the bypass capacitor 1420. In this embodiment, n-channel FETs are used as the switching elements 1421a and 1421b. The source of the switching element 1421b is connected to the first terminal of the inductor 1422 and the cathode of the diode 1423b. The source of the switching element 1421a is grounded, and the drain is connected to the second terminal of the inductor 1422 and the anode of the diode 1423a. Composite control signals 1351a and 13516b are supplied to the gates of the switching elements 1421a and 1421b, respectively. The cathode of the diode 1423a is connected to the first terminal of the capacitor 1424a, the first terminal of the resistor 1426a, and the emitter of the transistor 1427a. The anode of the diode 1423b is connected to the first terminal of the capacitor 1424b, the first terminal of the resistor 1426b, and the emitter of the transistor 1427b. The collectors of the transistors 1427a and 1427b are connected to each other, and a pump drive signal 658 is output from the connection point. In this embodiment, a PNP-type transistor is used as the transistor 1427a, and an NPN-type transistor is used as the transistor 1427b.

[0068] The second terminals of the capacitors 1424a and 1424b are grounded. The second terminal of the resistor 1426a is connected to the first terminal of the resistor 1425a and the gate of the transistor 1427a. Similarly, the second terminal of the resistor 1426b is connected to the first terminal of the resistor 1425b and the gate of the transistor 1427b. The second terminals of the resistors 1425a and 1425b are grounded.

[0069] When the voltages of the composite control signals 13516a and 1351b are active voltages of 24V, the switching elements 1421a and 1421b become active. Therefore, current flows from the input terminal of the reference voltage signal 654 through the switching element 1421b, the inductor 1422, and the switching element 1421a to the ground voltage.

[0070] Here, when the voltage of the composite control signal 1351a transitions from the active voltage to the ground voltage, the switching element 1421a turns off. However, since there is an inductor 1422 between the terminal of the reference voltage signal 654 and the ground voltage, charge flows into the capacitor 1424a through the diode 1423a due to the back electromotive force generated during the transition. Here, the charge flowing into and accumulated in the capacitor 1424a cannot return to the anode side of the diode 1423a due to the presence of the diode 1423a. Therefore, every time the composite control signal 1351a drives the switching element 1421a, charge flows into and accumulates in the capacitor 1424a, so the voltage of the terminal of the capacitor 1424a on the diode 1423a side is boosted to a voltage higher than the reference voltage signal 654. Such a voltage is divided by the resistors 1426a and 1425a and input to the gate of the transistor 1427a. When the voltage of the pump drive signal 658 is the ground voltage, current flows from the gate to the collector of the transistor 1427a due to the voltage difference between the divided voltage and the ground voltage. Therefore, since the transistor 1427a becomes active, the boosted voltage is output from the output terminal of the pump drive signal 658. The composite control signal 1351a is driven so that the voltage of the pump drive signal 658 becomes the pump drive voltage of 72V.

[0071] Next, when the voltage of the composite control signals 1351a and 1351b transitions from the active voltage to the ground voltage for the composite control signal 1351b, the switching element 1421b turns off. However, since there is an inductor 1422 between the switching element 1421b and the ground voltage, due to the back electromotive force generated during the transition, charge flows out from the capacitor 1424b via the diode 1423b. Here, since there is a diode 1423b for the charge flowing out and accumulating in the capacitor 1424b, it cannot return to the cathode side of the diode 1423b. Therefore, every time the composite control signal 1351b drives the switching element 1421b, charge flows out and accumulates in the capacitor 1424b. Thus, the terminal of the capacitor 1424b on the diode 1423b side is stepped down to a voltage lower than the reference voltage signal 654. Such a voltage is divided by the resistors 1426b and 1425b and input to the gate of the transistor 1427b. When the output terminal of the pump drive signal 658 is at a voltage higher than the ground voltage, due to the voltage difference between the divided voltage and the collector voltage, current flows from the collector to the gate of the transistor 1427b. Therefore, since the transistor 1427b becomes active, the stepped-down voltage is output to the output terminal of the pump drive signal 658. The composite control signal 1351b is driven so that the voltage of the pump drive signal 658 becomes -72V.

[0072] Figure 15 is a timing chart showing the operation of the pump drive circuit according to the fifth embodiment. First, the voltage of the reference voltage signal 654 transitions from 0V, which is the ground voltage, to 24V.

[0073] Thereafter, the voltage of the composite control signal 1351b becomes the active voltage of 24V, and the voltage of the composite control signal 1351a transitions between the ground voltage of 0V and the active voltage of 24V according to a specified rule. Due to the transition of the composite control signal 1351a, the voltage of the pump drive signal 658 is boosted from the ground voltage of 0V to 72V, which is the voltage required for pump drive.

[0074] Thereafter, the voltage of the composite control signal 1351a becomes the active voltage of 24V, and the voltage of the composite control signal 1351b transitions between the ground voltage of 0V and the active voltage of 24V according to the specified rules. Due to the transition of the composite control signal 1351b, the voltage of the pump drive signal 658 is stepped down from the ground voltage of 0V to -72V, which is the voltage required for pump drive.

[0075] By alternately switching the signal transitions of the composite control signals 1351a and 1351b in this way, +72V, which is the positive voltage required for pump drive, and -72V, which is the negative voltage, are alternately output to the output terminal of the pump drive signal 658.

[0076] As described above, by fixing the AC conversion control signal 655b to active and repeating the transition of 655a between the active voltage and the ground voltage, +72V is output to the output terminal of the pump drive signal 658. Also, by reversing the AC conversion control signals 655a and 655b, -72V is output to the output terminal of the pump drive signal 658. By connecting one of the opposing electrode terminals provided on the circulation pump 303 to the ground and supplying the pump drive signal 658 to the other, the same pump drive ability as in the first embodiment can be obtained.

[0077] [Sixth Embodiment] FIG. 16 is a schematic configuration diagram of a liquid ejection device 101 according to the sixth embodiment. In this embodiment, a pump drive circuit control signal 1651 is supplied from a processor 142 to a pump drive circuit control unit (also referred to as "control means") 1601 provided in a liquid ejection head 201. In response to the supply of the pump drive circuit control signal 1651, the pump drive circuit control unit 1601 supplies a boost control signal 656 to a boost circuit 606 and an AC conversion control signal 655 to an output switching circuit 607. Note that the pump drive circuit control unit 1601 also receives a reference voltage signal 654, which is for electrical matching at the interface between the boost circuit 606 and the output switching circuit 607. The pump drive circuit control unit 1601 does not adjust the drive voltage specified by the boost control signal 656 according to the voltage of the reference voltage signal 654. Therefore, the pump drive circuit control unit 1601 specifies the same drive voltage as the drive voltage specified by the pump drive circuit control signal 1651 to the boost circuit 606 by the boost control signal 656. Also, the pump drive circuit control unit 1601 gives the AC conversion control signal 655 the same switching period as the switching period specified by the pump drive circuit control signal 1651.

[0078] Note that the boost control signal 656 is, for example, a PWM signal, and the voltage of a drive voltage signal 657 output from the boost circuit 606 can be adjusted by adjusting the duty of the boost control signal 656 according to the pump drive circuit control signal 1651.

[0079] In this embodiment, an FPGA (Field Programable Gate Array) is used as the pump drive circuit control unit 1601. However, the pump drive circuit control unit 1601 may be configured in any way as long as it realizes the above functions. The pump drive circuit control unit 1601 may be configured by, for example, a circuit formed of discrete elements, or may be configured by a PLD (Programable Logic Device), a microcomputer, an ASIC, or the like. Other configurations are the same as those in the first embodiment.

[0080] By providing the pump drive circuit control unit 1601 separately from the processor 142 in this way, it becomes possible to control the pump drive circuit corresponding to signals in a frequency band not supported by the output port of the processor 142. For example, the boost circuit 606 can be controlled by a signal in a frequency band not supported by the output port of the processor 142. Also, the output switching circuit 607 can be controlled by a signal in a frequency band not supported by the output port of the processor 142. That is, a configuration can be realized in which at least one of the boost control signal 656 and the AC conversion control signal 655 has a frequency band exceeding the frequency band of the pump drive circuit control signal 1651 output by the processor 142.

[0081] [Embodiment 7] FIG. 17 is a schematic configuration diagram of the liquid ejection device 101 according to the seventh embodiment. In this embodiment, the pump drive circuit control signal 1651 is supplied from the processor 142 to the pump drive circuit control unit 1601 provided on the main board 141. The pump drive circuit control unit 1601 outputs a boost control signal 656 to the boost circuit 606 and an AC conversion control signal 655 to the output switching circuit 607 in response to the supply of the pump drive circuit control signal 1651 via the first terminal group 603 and the second terminal group 604. In this embodiment, the pump drive circuit control unit 1601 uses an FPGA. Other configurations are the same as those in the sixth embodiment.

[0082] By providing the pump drive circuit control unit 1601 on the main board 141 in this way, the number of components of the liquid ejection head 201 can be reduced.

[0083] [Embodiment 8] FIG. 18 is a schematic configuration diagram of a liquid ejection device 101 according to the eighth embodiment. A head information storage unit 1801 is provided in the liquid ejection head 201. In this embodiment, an EEPROM (Electrically Erasable Programable Read Only Memory) is used as the head information storage unit 1801, and an FPGA is used as the pump drive circuit control unit 1601. However, the head information storage unit 1801 may be configured in any manner as long as it realizes the function as a storage means. For example, a mask ROM, a fuse ROM, or the like may be used. The processor 142 supplies a head element control signal 1851 to the pump drive circuit control unit 1601 and the head information storage unit 1801. In this embodiment, the head element control signal conforms to the I2C (Inter Integrated Circuit) standard and is composed of a data line and a clock line. In this embodiment, an IC conforming to the I2C standard is used as the head information storage unit 1801 and the pump drive circuit control unit 1601. By adopting such a configuration, the signal lines for controlling the head information storage unit 1801 and the pump drive circuit control unit 1601 can be shared, so that an increase in the number of control signals can be suppressed. However, the head element control signal 1851 may include signals for the head information storage unit 1801 and signals for the pump drive circuit control unit 1601 as independent signals. Also, in this embodiment, the pump drive circuit control unit 1601 reads the pump drive condition information written in the head information storage unit 1801 and outputs an AC conversion control signal 655 and a boost control signal 656 according to the information. For example, information specifying the voltage of the drive voltage signal and information specifying the frequency of the pump drive signal may be included in the pump drive condition information. Also, for example, information specifying the voltage of the drive voltage signal and a plurality of sets of indexes may be included in the pump drive condition signal. And the pump drive circuit control unit 1601 may be configured to read from the head information storage unit 1801 information specifying the voltage of the drive voltage signal corresponding to the index transmitted from the processor 142. Similarly, for example, information specifying the frequency of the pump drive signal and a plurality of sets of indexes may be included in the pump drive condition signal.Then, the pump drive circuit control unit 1601 may read from the head information storage unit 1801 information specifying the frequency of the pump drive signal corresponding to the index transmitted from the processor 142.

[0084] By adopting such a configuration, the processor 142 does not need to supply information on pump drive conditions to the pump drive circuit control unit 1601 for each pump drive, so the transmission and reception efficiency of the control signal can be improved. However, the pump drive circuit control unit 1601 may directly obtain information on pump drive conditions from the head element control signal 1851 supplied from the processor 142.

[0085] [Embodiment 9] FIG. 19 is a schematic configuration diagram of the liquid ejection device 101 according to the ninth embodiment. In this embodiment, a booster circuit 606 and an output switching circuit 607 are provided in the liquid circulation unit 204. Other configurations are the same as those in the first embodiment.

[0086] By adopting such a configuration, the wiring lengths of the drive voltage signal 657 and the pump drive signal 658, which are high voltages, can be suppressed. Also, even if the output switching circuit 607 is provided in the liquid circulation unit 204 and the booster circuit 606 is provided in a portion other than the liquid circulation unit 204 of the liquid ejection head 201, the same effect can be achieved.

[0087] [Embodiment 10] FIG. 20 is a schematic configuration diagram of the liquid ejection device 101 according to the tenth embodiment. In this embodiment, the pump drive circuit control unit 1601, the booster circuit 606, and the output switching circuit 607 are included in one package IC 2001 mounted on the electric circuit board 205. Other configurations are the same as those in the sixth embodiment.

[0088] By adopting such a configuration, the area of the pump drive circuit can be reduced. Even if only a part of the pump drive circuit control unit 1601, the booster circuit 606, and the output switching circuit 607, rather than all of them, are included in one package IC 2001, the same effect can be achieved.

[0089] [Embodiment 11] When the booster circuit 606 mounted on the liquid ejection head 201 fails, excessive boosting may occur, which may adversely affect peripheral components due to abnormal operation or the like. This embodiment proposes a configuration for preventing abnormal boosting due to a booster circuit failure.

[0090] FIG. 21 is a circuit schematic diagram of the booster circuit and the voltage dividing circuit. The booster circuit 606 shown in FIG. 21 is the same as that shown in FIG. 7, and an explanation thereof has been given in the first embodiment, so duplicate explanations are omitted. The voltage dividing circuit 2101 divides the voltage of the drive voltage signal 657 by the voltage dividing resistors 2102 and 2103 connected in series, and outputs a voltage dividing signal (also referred to as a "voltage detection signal") 2151 having the voltage after voltage division.

[0091] In this embodiment, the boost control signal 656 is input to the switching element 702 so that the drive voltage signal 657 having a voltage of 72V is generated based on the reference voltage signal 654 having a voltage of 24V. The voltage dividing circuit 2101 outputs a voltage dividing signal 2151 having a voltage approximately 1 / 20 of the voltage of the drive voltage signal 657.

[0092] (Explanation of the operation at the time of over-boost detection) FIG. 22 is a schematic configuration diagram of a liquid ejection apparatus 101 according to the eleventh embodiment. A voltage dividing circuit 2101 is included in a pump drive circuit 605. The voltage dividing circuit 2101 divides the drive voltage signal 657 output from a boosting circuit 606 and outputs a voltage dividing signal 2151 having a voltage after voltage division. A pump drive circuit control unit 1601 performs control described later based on the voltage dividing signal 2151. Since other configurations are the same as those in the sixth embodiment, redundant descriptions are omitted. Note that, as the boosting circuit 606, a circuit as shown in FIG. 7 or FIG. 10 can be used. The boosting circuit 606 and an output switching circuit 607 may be replaced with a boosting / AC conversion circuit 1301 shown in FIG. 14.

[0093] When the pump drive circuit control unit 1601 detects that the voltage of the drive voltage signal 657 exceeds the maximum allowable voltage (for example, 80 V), the pump drive circuit control unit 1601 performs control to lower the voltage of the drive voltage signal 657. This control is, for example, stopping the boosting control signal 656, or reducing or setting to 0 V the pump drive voltage specified by the boosting control signal 656. Thereby, the switching element included in the boosting circuit 606 or the boosting / AC conversion circuit 1301 can be stopped, or the voltage of the drive voltage signal 656 or the pump drive signal 658 output from the boosting circuit 606 or the boosting / AC conversion circuit 1301 can be reduced.

[0094] Alternatively, this control may include controlling the processor 142 by the processor control signal 2252 to adjust the pump drive circuit control signal 1651 or the power supply control signal 653. This adjustment may include, for example, changing the pump drive voltage specified by the pump drive circuit control signal 1651 to a low voltage or 0V. Also, this adjustment includes deactivating the power supply control signal 653. As a result, the voltage of the reference voltage signal 654 output by the power supply unit 602 becomes 0V. Therefore, the pump drive circuit control unit 1601 can stop the booster circuit 606 by intervening in the specification of the voltage of the pump drive signal 658 by the processor 142 of the liquid ejecting apparatus 101. Also, the pump drive circuit control unit 1601 can lower the voltage of the drive voltage signal 657 output by the booster circuit 657 or set it to 0V by intervening in the specification of the voltage of the pump drive signal 658 by the processor 142 of the liquid ejecting apparatus 101.

[0095] In addition, the voltage division signal 2151 can also be used to feedback-control the voltage of the drive voltage signal 657 during normal operation. That is, based on the difference between the actual voltage of the drive voltage signal 657 indicated by the voltage division signal 2151 and the voltage indicated by the pump drive circuit control signal 1651, the voltage indicated by the boost control signal 656 may be changed. The boost control signal 656 is, for example, a PWM signal, and according to this difference, by adjusting the duty of the boost control signal 656, the voltage of the drive voltage signal 657 output by the boost circuit 606 can be adjusted. Specifically, if the actual voltage of the drive voltage signal 657 indicated by the voltage division signal 2151 is higher than the voltage indicated by the pump drive circuit control signal 1651, the voltage indicated by the boost control signal 656 is decreased. For example, the duty of the boost control signal 656 is lowered. And if the actual voltage of the drive voltage signal 657 indicated by the voltage division signal 2151 is lower than the voltage indicated by the pump drive circuit control signal 1651, the voltage indicated by the boost control signal 656 is increased. For example, the duty of the boost control signal 656 is raised. Also, in this feedback control, a dead voltage range may be provided. That is, when the voltage of the drive voltage signal 657 is within a predetermined voltage range, feedback control may not be performed, and when the voltage of the drive voltage signal 657 deviates from the predetermined voltage range, feedback control may be performed. The target voltage in this case can be appropriately selected from the predetermined voltage range. For example, the center voltage of the predetermined voltage range may be used as the target voltage. Through feedback control, a more stable pump drive signal 658 can be supplied to the fluid pump 303.

[0096] [Embodiment 12] FIG. 23 is a schematic configuration diagram of the liquid ejection device 101 according to the 12th embodiment. This embodiment is different from the 11th embodiment in that the location where the pump drive circuit control unit 1601 is arranged is changed from the electric circuit board 205 to the carriage board 122, but there are no other changes. Therefore, in this embodiment, the boost circuit 606 and the voltage division circuit 2101 are mounted on the electric circuit board 205, and the pump drive circuit control unit 1601 is mounted on the carriage board 122.

[0097] According to the present embodiment, the circuit included in the electric circuit board 205 is simplified. When performing an electrical inspection in the manufacturing process of the liquid ejection head 201, since the circuit included in the electric circuit board 205 is simplified, the defect occurrence rate due to the electric circuit board 205 is reduced, and as a result, it can be expected that the productivity of the liquid ejection head 201 is improved. In particular, in a system where the liquid ejection head 201 is a replacement part, the improvement in productivity is significant.

[0098] Note that the voltage division signal 2251 is returned from the electric circuit board 205 to the carriage board 122, and the output signal of the pump drive circuit control unit 1601 is supplied from the carriage board 122 to the electric circuit board 205. Since the carriage board 122 and the electric circuit board 205 are connected by contacts at the electrical connection portion 504 as shown in FIG. 5, the signal quality of the signal across both boards 122 and 205 is ensured.

[0099] [13th Embodiment] FIG. 24 is a schematic configuration diagram of the liquid ejection apparatus 101 according to the 13th embodiment. This embodiment is different from the 11th embodiment in that the mounting location of the pump drive circuit control unit 1601 is changed from the electric circuit board 205 to the main board 141, but there are no other changes. Therefore, in this embodiment, the booster circuit 606 and the voltage division circuit 2101 are mounted on the electric circuit board 205, and the pump drive circuit control unit 1601 is mounted on the main board 141.

[0100] In the case of a scanning type liquid ejection head, the sizes of the liquid ejection head 201 and the carriage 121 are likely to affect the apparatus size, and there are often space constraints. According to the configuration of this embodiment, since the pump drive circuit control unit 1601 is not arranged on either the liquid ejection head 201 or the carriage 121, the liquid ejection head 201 and the carriage 121 can be miniaturized. Also, similar to the 12th embodiment, the productivity of the liquid ejection head 201 can be improved.

[0101] [14th Embodiment] FIG. 25 is a configuration diagram of a main part of the liquid ejection device 101 according to the 14th embodiment, and FIG. 26 is a schematic configuration diagram of the liquid ejection device 101 according to the 14th embodiment.

[0102] In this embodiment, a relay board 2501 is inserted between the carriage board 122 mounted on the carriage 121 and the main board 141. In a liquid ejection device assumed to be used by individuals or in an office, it is common for the carriage board 122 and the main board 141 to be directly connected via an FFC. On the other hand, in a device for large-format output such as a poster, the scanning range of the liquid ejection head is wide, and in the configuration as described above, the FFC becomes long, and there is a possibility that the signal quality deteriorates. As a countermeasure against this, by inserting a relay board 2501 between the carriage board 122 and the main board 141, deterioration of the signal quality can be prevented. In this embodiment, as shown in FIG. 26, a pump drive circuit control unit 1601 is mounted on the relay board 2501.

[0103] According to this configuration, similar to the 13th embodiment, miniaturization design is possible, and productivity of the liquid ejection head 201 can be improved.

[0104] [15th Embodiment] Similar to deriving the 6th embodiment shown in FIG. 16 based on the configuration of the 1st embodiment shown in FIG. 6, a 15th embodiment as shown in FIG. 27 may be derived based on the configuration of the 5th embodiment shown in FIG. 13. In this case, the pump drive circuit control unit 1601 does not generate a boost control signal 656 and an AC conversion control signal 655, but generates a composite control signal 1351. That is, the pump drive circuit control unit 1601 according to the 15th embodiment generates a composite control signal 1351 based on a pump drive circuit control signal, and supplies this to the boost / AC conversion circuit 1301.

[0105] [16th Embodiment] Similar to deriving the seventh embodiment shown in FIG. 17 based on the configuration of the first embodiment shown in FIG. 6, a sixteenth embodiment as shown in FIG. 28 may be derived based on the configuration of the fifth embodiment shown in FIG. 13. In this case, the pump drive circuit control unit 1601 does not generate the boost control signal 656 and the AC conversion control signal 655, but generates a composite control signal 1351. That is, the pump drive circuit control unit 1601 according to the fifteenth embodiment generates the composite control signal 1351 based on the pump drive circuit control signal, and supplies this to the boost / AC conversion circuit 1301 via the first terminal group 603 and the second terminal group 604.

[0106] [Seventh Embodiment] Similar to deriving the eighth embodiment shown in FIG. 18 based on the configuration of the first embodiment shown in FIG. 6, a seventeenth embodiment as shown in FIG. 29 may be derived based on the configuration of the fifth embodiment shown in FIG. 13. In this case, the pump drive circuit control unit 1601 does not generate the boost control signal 656 and the AC conversion control signal 655, but generates a composite control signal 1351. That is, the pump drive circuit control unit 1601 according to the fifteenth embodiment generates the composite control signal 1351 based on the pump drive circuit control signal, and supplies this to the boost / AC conversion circuit 1301.

[0107] [Eighth Embodiment] Similar to deriving the tenth embodiment shown in FIG. 20 based on the configuration of the first embodiment shown in FIG. 6, an eighteenth embodiment as shown in FIG. 30 may be derived based on the configuration of the fifth embodiment shown in FIG. 13. In this case, the pump drive circuit control unit 1601 does not generate the boost control signal 656 and the AC conversion control signal 655, but generates a composite control signal 1351. That is, the pump drive circuit control unit 1601 according to the fifteenth embodiment generates the composite control signal 1351 based on the pump drive circuit control signal, and supplies this to the boost / AC conversion circuit 1301.

[0108] [Nineteenth Embodiment] Similar to deriving the 11th embodiment shown in FIG. 22 based on the configuration of the first embodiment shown in FIG. 6, a 19th embodiment as shown in FIG. 31 may be derived based on the configuration of the fifth embodiment shown in FIG. 13. In this case, the pump drive circuit control unit 1601 does not generate the boost control signal 656 and the AC conversion control signal 655, but generates a composite control signal 1351. That is, the pump drive circuit control unit 1601 according to the 15th embodiment generates the composite control signal 1351 based on the pump drive circuit control signal and supplies this to the boost / AC conversion circuit 1301. The signal 657 input to the voltage division circuit 2101 is a signal indicating the voltage of the pump drive signal. This can be obtained, for example, by dividing the peak-to-peak voltage of the pump drive signal. This is the same for the 20th to 22nd embodiments described later.

[0109] [20th Embodiment] Similar to deriving the 12th embodiment shown in FIG. 23 based on the configuration of the first embodiment shown in FIG. 6, a 20th embodiment as shown in FIG. 32 may be derived based on the configuration of the fifth embodiment shown in FIG. 13. In this case, the pump drive circuit control unit 1601 does not generate the boost control signal 656 and the AC conversion control signal 655, but generates a composite control signal 1351. That is, the pump drive circuit control unit 1601 according to the 15th embodiment generates the composite control signal 1351 based on the pump drive circuit control signal and supplies this to the boost / AC conversion circuit 1301 via the first terminal group 603 and the second terminal group 604.

[0110] [21st Embodiment] Similar to deriving the 13th embodiment shown in FIG. 24 based on the configuration of the first embodiment shown in FIG. 6, a 21st embodiment as shown in FIG. 33 may be derived based on the configuration of the fifth embodiment shown in FIG. 13. In this case, the pump drive circuit control unit 1601 does not generate the boost control signal 656 and the AC conversion control signal 655, but generates a composite control signal 1351. That is, the pump drive circuit control unit 1601 according to the 15th embodiment generates the composite control signal 1351 based on the pump drive circuit control signal and supplies this to the boost / AC conversion circuit 1301.

[0111] [22nd Embodiment] Similar to deriving the 14th embodiment shown in FIG. 26 based on the configuration of the 1st embodiment shown in FIG. 6, a 22nd embodiment as shown in FIG. 34 may be derived based on the configuration of the 5th embodiment shown in FIG. 13. In this case, the pump drive circuit control unit 1601 does not generate the boost control signal 656 and the AC conversion control signal 655, but generates the composite control signal 1351. That is, the pump drive circuit control unit 1601 according to the 15th embodiment generates the composite control signal 1351 based on the pump drive circuit control signal, and supplies this to the boost / AC conversion circuit 1301 via the first terminal group 603 and the second terminal group 604.

[0112] [Technical Features of the Present Disclosure] The present disclosure includes the following configurations.

[0113] [Configuration 1] A discharge unit configured to discharge the liquid inside the pressure chamber, A supply flow path through which the liquid supplied to the pressure chamber flows, A recovery flow path connected to the supply flow path via the pressure chamber and through which the liquid recovered from the pressure chamber flows, A circulation pump capable of supplying liquid to the pressure chamber via the supply flow path based on an AC pump drive signal, recovering the liquid from the pressure chamber via the recovery flow path, and refluxing the recovered liquid to the supply flow path, A pump drive circuit that generates the pump drive signal by boosting and converting to AC a DC reference voltage signal having a voltage smaller than the peak-to-peak voltage of the pump drive signal, Comprising A liquid discharge head.

[0114] [Configuration 2] The pump drive circuit A boost circuit that boosts the reference voltage signal to generate a DC drive voltage signal, An AC conversion circuit that converts the drive voltage signal to AC to generate the pump drive signal, Comprising The liquid ejection head according to Configuration 1.

[0115] [Configuration 3] The booster circuit boosts the reference voltage signal based on a booster control signal for controlling the booster circuit to generate the drive voltage signal. The liquid ejection head according to Configuration 2.

[0116] [Configuration 4] The AC conversion circuit converts the drive voltage signal into an AC signal based on an AC conversion control signal for controlling the AC conversion circuit to generate the pump drive signal. The liquid ejection head according to Configuration 2 or 3.

[0117] [Configuration 5] The booster circuit boosts the reference voltage signal based on a booster control signal for controlling the booster circuit to generate the drive voltage signal. The AC conversion circuit converts the drive voltage signal into an AC signal based on an AC conversion control signal for controlling the AC conversion circuit to generate the pump drive signal. The liquid ejection head further includes control means for generating the booster control signal and the AC conversion control signal based on a pump drive circuit control signal. The liquid ejection head according to Configuration 2.

[0118] [Configuration 6] The pump drive circuit control signal includes information specifying the voltage of the drive voltage signal. The control means adjusts the booster control signal so that the drive voltage signal has the voltage specified by the pump drive circuit control signal. The liquid ejection head according to Configuration 5.

[0119] [Configuration 7] The pump drive circuit control signal includes information specifying the voltage of the drive voltage signal. The liquid ejection head further includes a circuit for generating a voltage detection signal indicating the voltage of the drive voltage signal. The control means adjusts the boost control signal so that the voltage of the drive voltage signal indicated by the voltage detection signal becomes the same as the voltage specified by the pump drive circuit control signal. The liquid ejection head according to Configuration 5.

[0120] [Configuration 8] The pump drive circuit control signal includes information specifying the period of the AC conversion control signal. The control means causes the AC conversion control signal to have a period according to the specification by the pump drive circuit control signal. The liquid ejection head according to any one of Configurations 5 to 7.

[0121] [Configuration 9] The liquid ejection head further includes a circuit that generates a voltage detection signal indicating the voltage of the drive voltage signal. When the voltage of the drive voltage signal indicated by the voltage detection signal exceeds the maximum allowable voltage, the control means adjusts the boost control signal to lower the voltage of the drive voltage signal generated by the boost circuit below the maximum allowable voltage or to 0V. The liquid ejection head according to any one of Configurations 5 to 8.

[0122] [Configuration 10] The liquid ejection head further includes a circuit that generates a voltage detection signal indicating the voltage of the drive voltage signal. The voltage of the drive voltage signal is specified by a liquid ejection device on which the liquid ejection head is mounted. When the voltage of the drive voltage signal indicated by the voltage detection signal exceeds the maximum allowable voltage, the control means intervenes in the specification of the voltage of the drive voltage signal by the liquid ejection device to lower the voltage of the drive voltage signal generated by the boost circuit below the maximum allowable voltage or to 0V. The liquid ejection head according to any one of Configurations 5 to 8.

[0123] [Configuration 11] The liquid ejection head further includes storage means for storing pump drive condition information. The control means refers to the pump drive condition information stored in the storage means. The liquid discharge head according to any one of Configurations 5 to 10.

[0124] [Configuration 12] At least one of the boost control signal and the AC conversion control signal has a frequency band exceeding the frequency band of the pump drive circuit control signal. The liquid discharge head according to any one of Configurations 5 to 11.

[0125] [Configuration 13] The pump drive circuit generates the pump drive signal by boosting and converting the reference voltage signal into AC based on a composite control signal for controlling the pump drive circuit. The liquid discharge head according to Configuration 1.

[0126] [Configuration 14] The liquid discharge head further includes control means for generating the composite control signal based on a pump drive circuit control signal. The liquid discharge head according to Configuration 13.

[0127] [Configuration 15] The composite control signal includes information specifying the voltage of the pump drive signal. The control means adjusts the composite control signal so that the pump drive signal has a voltage specified by the pump drive circuit control signal. The liquid discharge head according to Configuration 14.

[0128] [Configuration 16] The composite control signal includes information specifying the voltage of the pump drive signal. The liquid discharge head further includes a circuit for generating a voltage detection signal indicating the voltage of the pump drive signal. The control means adjusts the composite control signal so that the voltage of the pump drive signal indicated by the voltage detection signal is the same as the voltage specified by the pump drive circuit control signal. The liquid discharge head according to Configuration 14.

[0129] [Configuration 17] The pump drive circuit control signal includes information specifying the period of the composite control signal, The control means causes the composite control signal to have a period according to the specification by the pump drive circuit control signal. The liquid ejection head according to Configuration 14.

[0130] [Configuration 18] The liquid ejection head further includes a circuit that generates a voltage detection signal indicating the voltage of the pump drive signal, When the voltage of the pump drive signal indicated by the voltage detection signal exceeds the maximum allowable voltage, the control means adjusts the composite control signal to reduce the voltage of the pump drive signal generated by the pump drive circuit below the maximum allowable voltage or to 0V. The liquid ejection head according to any one of Configurations 14 to 17.

[0131] [Configuration 19] The liquid ejection head further includes a circuit that generates a voltage detection signal indicating the voltage of the pump drive signal, The voltage of the pump drive signal is specified by a liquid ejection apparatus on which the liquid ejection head is mounted, When the voltage of the pump drive signal indicated by the voltage detection signal exceeds the maximum allowable voltage, the control means intervenes in the specification of the voltage of the pump drive signal by the liquid ejection apparatus to reduce the voltage of the pump drive signal generated by the pump drive circuit below the maximum allowable voltage or to 0V. The liquid ejection head according to any one of Configurations 14 to 17.

[0132] [Configuration 20] The liquid ejection head further includes storage means for storing pump drive condition information, The control means refers to the pump drive condition information stored in the storage means. The liquid ejection head according to any one of Configurations 14 to 19.

[0133] [Configuration 21] The composite control signal has a frequency band that exceeds the frequency band of the pump drive circuit control signal. The liquid ejection head according to any one of Configurations 14 to 20.

[0134] [Configuration 22] A circuit that generates a voltage detection signal indicating the voltage of the pump drive signal, A control unit that controls the pump drive circuit based on the voltage detection signal, further comprising The liquid ejection head according to Configuration 1.

[0135] [Configuration 23] When the voltage of the pump drive signal indicated by the voltage detection signal exceeds the maximum allowable voltage, the control unit stops the pump drive circuit. The liquid ejection head according to Configuration 22.

[0136] [Configuration 24] First pressure adjusting means disposed between the outlet of the circulation pump and the inlet of the supply flow path, for adjusting the pressure of the liquid at the inlet of the supply flow path, Second pressure adjusting means disposed between the inlet of the circulation pump and the outlet of the recovery flow path, for adjusting the pressure at the outlet of the recovery flow path, further comprising The liquid ejection head according to any one of Configurations 1 to 13.

[0137] [Configuration 25] A discharge unit configured to discharge the liquid inside the pressure chamber, A supply flow path through which the liquid supplied to the pressure chamber flows, A recovery flow path connected to the supply flow path via the pressure chamber, through which the liquid recovered from the pressure chamber flows, A circulation pump that can supply liquid to the pressure chamber via the supply flow path based on an alternating current pump drive signal, recover the liquid from the pressure chamber via the recovery flow path, and reflux the recovered liquid to the supply flow path, Based on a boost control signal for controlling a boost circuit, a boost circuit boosts a reference voltage signal having a voltage lower than the peak-to-peak voltage of the pump drive signal to generate a DC drive voltage signal. Based on an AC conversion control signal for controlling an AC conversion circuit, an AC conversion circuit converts the drive voltage signal into an AC signal to generate the pump drive signal. A liquid discharge head comprising: Control means for generating the AC conversion control signal and the boost control signal based on a pump drive circuit control signal. Comprising: A liquid discharge device.

[0138] [Configuration 26] The pump drive circuit control signal includes information specifying the voltage of the drive voltage signal. The control means adjusts the boost control signal so that the drive voltage signal has the voltage specified by the pump drive circuit control signal. The liquid discharge device according to Configuration 25.

[0139] [Configuration 27] The pump drive circuit control signal includes information specifying the voltage of the drive voltage signal. The liquid discharge head further includes a circuit for generating a voltage detection signal indicating the voltage of the drive voltage signal. The control means adjusts the boost control signal so that the voltage of the drive voltage signal indicated by the voltage detection signal is the same as the voltage specified by the pump drive circuit control signal. The liquid discharge device according to Configuration 25.

[0140] [Configuration 28] The pump drive circuit control signal includes information specifying the period of the AC conversion control signal. The control means causes the AC conversion control signal to have a period according to the specification by the pump drive circuit control signal. The liquid discharge device according to any one of Configurations 25 to 27.

[0141] [Configuration 29] The liquid ejection head further includes a circuit that generates a voltage detection signal indicating the voltage of the drive voltage signal. When the voltage of the drive voltage signal indicated by the voltage detection signal exceeds the maximum allowable voltage, the control means adjusts the boost control signal to reduce the voltage of the drive voltage signal generated by the boost circuit below the maximum allowable voltage or to 0V. The liquid ejection device according to any one of Configurations 25 to 28.

[0142] [Configuration 30] The liquid ejection head further includes a circuit that generates a voltage detection signal indicating the voltage of the drive voltage signal. The voltage of the drive voltage signal is specified by the liquid ejection device. When the voltage of the drive voltage signal indicated by the voltage detection signal exceeds the maximum allowable voltage, the control means intervenes in the specification of the voltage of the drive voltage signal by the liquid ejection device to reduce the voltage of the drive voltage signal generated by the boost circuit below the maximum allowable voltage or to 0V. The liquid ejection device according to any one of Configurations 25 to 28.

[0143] [Configuration 31] The control means is provided on any one of a carriage substrate provided on a carriage on which the liquid ejection head is mounted, a main substrate provided on the main body of the liquid ejection device, and a relay substrate inserted between the main substrate and the carriage substrate. The liquid ejection device according to any one of Configurations 25 to 30.

[0144] [Configuration 32] The liquid ejection head is further provided with a first pressure adjustment means that is arranged between the outlet of the circulation pump and the inlet of the supply flow path and adjusts the pressure of the liquid at the inlet of the supply flow path. and a second pressure adjustment means that is arranged between the inlet of the circulation pump and the outlet of the recovery flow path and adjusts the pressure at the outlet of the recovery flow path. The liquid ejection device according to any one of Configurations 25 to 31.

[0145] [Configuration 33] A discharge unit configured to discharge the liquid inside the pressure chamber, A supply flow path through which the liquid supplied to the pressure chamber flows, A recovery flow path that is connected to the supply flow path via the pressure chamber and through which the liquid recovered from the pressure chamber flows, A circulation pump capable of supplying liquid to the pressure chamber through the supply flow path, recovering the liquid from the pressure chamber through the recovery flow path, and refluxing the recovered liquid to the supply flow path based on an alternating current pump drive signal, A pump drive circuit that generates the pump drive signal by boosting and converting a DC reference voltage signal having a voltage smaller than the peak-to-peak voltage of the pump drive signal into an alternating current based on a composite control signal, A liquid ejection head including: Control means for generating the composite control signal based on a pump drive circuit control signal, Comprising: Liquid ejection device.

[0146] [Configuration 34] The pump drive circuit control signal includes information specifying the voltage of the pump drive signal, The control means adjusts the composite control signal so that the pump drive signal has the voltage specified by the pump drive circuit control signal. The liquid ejection device according to Configuration 33.

[0147] [Configuration 35] The pump drive circuit control signal includes information specifying the voltage of the pump drive signal, The liquid ejection head further includes a circuit that generates a voltage detection signal indicating the voltage of the pump drive signal, The control means adjusts the composite control signal so that the voltage of the pump drive signal indicated by the voltage detection signal is the same as the voltage specified by the pump drive circuit control signal. The liquid ejection device according to Configuration 33.

[0148] [Configuration 36] The pump drive circuit control signal includes information specifying the period of the composite control signal. The control means causes the composite control signal to have a period according to the specification by the pump drive circuit control signal. The liquid ejection device according to any one of Configurations 33 to 35.

[0149] [Configuration 37] The liquid ejection head further includes a circuit that generates a voltage detection signal indicating the voltage of the pump drive signal. When the voltage of the pump drive signal indicated by the voltage detection signal exceeds the maximum allowable voltage, the control means adjusts the composite control signal to lower the voltage of the pump drive signal generated by the pump drive circuit below the maximum allowable voltage or to 0V. The liquid ejection device according to any one of Configurations 33 to 36.

[0150] [Configuration 38] The liquid ejection head further includes a circuit that generates a voltage detection signal indicating the voltage of the pump drive signal. The voltage of the pump drive signal is specified by the liquid ejection device. When the voltage of the pump drive signal indicated by the voltage detection signal exceeds the maximum allowable voltage, the control means intervenes in the specification of the voltage of the pump drive signal by the liquid ejection device to lower the voltage of the pump drive signal generated by the pump drive circuit below the maximum allowable voltage or to 0V. The liquid ejection device according to any one of Configurations 33 to 36.

[0151] [Configuration 39] The control means is provided on any one of a carriage board provided on a carriage on which the liquid ejection head is mounted, a main board provided on the main body of the liquid ejection device, and a relay board inserted between the main board and the carriage board. The liquid ejection device according to any one of Configurations 33 to 38.

[0152] [Configuration 40] The liquid ejection head is disposed between the outlet of the circulation pump and the inlet of the supply flow path, and is a first pressure adjustment means for adjusting the pressure of the liquid at the inlet of the supply flow path, is disposed between the inlet of the circulation pump and the outlet of the recovery flow path, and is a second pressure adjustment means for adjusting the pressure at the outlet of the recovery flow path, and further includes The liquid ejection device according to any one of Configurations 33 to 39.

Explanation of Signs

[0153] 201 Liquid ejection head 303 Circulation pump 606 Boost circuit 607 Output switching circuit 1601 Pump drive circuit control unit

Claims

1. A discharge unit configured to discharge a liquid inside a pressure chamber; A supply flow path through which the liquid supplied to the pressure chamber flows; A recovery flow path connected to the supply flow path via the pressure chamber and through which the liquid recovered from the pressure chamber flows; A circulation pump capable of supplying a liquid to the pressure chamber via the supply flow path, recovering the liquid from the pressure chamber via the recovery flow path, and refluxing the recovered liquid to the supply flow path based on an alternating current pump drive signal; A pump drive circuit that generates the pump drive signal by boosting a DC reference voltage signal having a voltage lower than the peak-to-peak voltage of the pump drive signal and converting it to an alternating current; Comprising: A liquid discharge head.

2. The pump drive circuit: A boosting circuit that boosts the reference voltage signal to generate a DC drive voltage signal; An alternating current conversion circuit that converts the drive voltage signal to an alternating current to generate the pump drive signal; Comprising: The liquid discharge head according to Claim 1.

3. The boosting circuit generates the drive voltage signal by boosting the reference voltage signal based on a boosting control signal for controlling the boosting circuit. The liquid discharge head according to Claim 2.

4. The alternating current conversion circuit generates the pump drive signal by converting the drive voltage signal to an alternating current based on an alternating current conversion control signal for controlling the alternating current conversion circuit. The liquid discharge head according to Claim 2.

5. The boosting circuit generates the drive voltage signal by boosting the reference voltage signal based on a boosting control signal for controlling the boosting circuit. The alternating current conversion circuit generates the pump drive signal by converting the drive voltage signal to an alternating current based on an alternating current conversion control signal for controlling the alternating current conversion circuit. The liquid discharge head further comprises control means for generating the boosting control signal and the alternating current conversion control signal based on a pump drive circuit control signal. The liquid discharge head according to Claim 2.

6. The pump drive circuit control signal includes information specifying the voltage of the drive voltage signal. The control means adjusts the boosting control signal so that the drive voltage signal has the voltage specified by the pump drive circuit control signal. The liquid discharge head according to Claim 5.

7. The pump drive circuit control signal includes information specifying the voltage of the drive voltage signal. Further comprising a circuit that generates a voltage detection signal indicating the voltage of the drive voltage signal. The control means adjusts the boost control signal so that the voltage of the drive voltage signal indicated by the voltage detection signal becomes the same as the voltage specified by the pump drive circuit control signal. The liquid discharge head according to claim 5.

8. The pump drive circuit control signal includes information specifying the period of the AC conversion control signal. The control means causes the AC conversion control signal to have a period according to the specification by the pump drive circuit control signal. The liquid discharge head according to claim 5.

9. The apparatus further includes a circuit that generates a voltage detection signal indicating the voltage of the drive voltage signal. When the voltage of the drive voltage signal indicated by the voltage detection signal exceeds the maximum allowable voltage, the control means adjusts the boost control signal to lower the voltage of the drive voltage signal generated by the boost circuit below the maximum allowable voltage or to 0V. The liquid discharge head according to claim 5.

10. The apparatus further includes a circuit that generates a voltage detection signal indicating the voltage of the drive voltage signal. The voltage of the drive voltage signal is specified by a liquid discharge apparatus on which the liquid discharge head is mounted. When the voltage of the drive voltage signal indicated by the voltage detection signal exceeds the maximum allowable voltage, the control means intervenes in the specification of the voltage of the drive voltage signal by the liquid discharge apparatus to lower the voltage of the drive voltage signal generated by the boost circuit below the maximum allowable voltage or to 0V. The liquid discharge head according to claim 5.

11. The apparatus further includes storage means for storing pump drive condition information. The control means refers to the pump drive condition information stored in the storage means. The liquid discharge head according to claim 5.

12. At least one of the boost control signal and the AC conversion control signal has a frequency band exceeding the frequency band of the pump drive circuit control signal. The liquid discharge head according to claim 5.

13. The pump drive circuit generates the pump drive signal by boosting and AC-converting the reference voltage signal based on a composite control signal for controlling the pump drive circuit. The liquid discharge head according to claim 1.

14. The liquid discharge head further includes control means for generating the composite control signal based on a pump drive circuit control signal. The liquid discharge head according to claim 13.

15. The composite control signal includes information specifying the voltage of the pump drive signal. The control means adjusts the composite control signal so that the pump drive signal has a voltage specified by the pump drive circuit control signal. The liquid ejection head according to claim 14.

16. The composite control signal includes information specifying the voltage of the pump drive signal. The apparatus further includes a circuit that generates a voltage detection signal indicating the voltage of the pump drive signal. The control means adjusts the composite control signal so that the voltage of the pump drive signal indicated by the voltage detection signal is the same as the voltage specified by the pump drive circuit control signal. The liquid ejection head according to claim 14.

17. The pump drive circuit control signal includes information specifying the period of the composite control signal. The control means causes the composite control signal to have a period according to the specification by the pump drive circuit control signal. The liquid ejection head according to claim 14.

18. The apparatus further includes a circuit that generates a voltage detection signal indicating the voltage of the pump drive signal. When the voltage of the pump drive signal indicated by the voltage detection signal exceeds the maximum allowable voltage, the control means adjusts the composite control signal to reduce the voltage of the pump drive signal generated by the pump drive circuit below the maximum allowable voltage or to 0V. The liquid ejection head according to claim 14.

19. The apparatus further includes a circuit that generates a voltage detection signal indicating the voltage of the pump drive signal. The voltage of the pump drive signal is specified by a liquid ejection apparatus on which the liquid ejection head is mounted. When the voltage of the pump drive signal indicated by the voltage detection signal exceeds the maximum allowable voltage, the control means intervenes in the specification of the voltage of the pump drive signal by the liquid ejection apparatus to reduce the voltage of the pump drive signal generated by the pump drive circuit below the maximum allowable voltage or to 0V. The liquid ejection head according to claim 14.

20. The apparatus further includes storage means for storing pump drive condition information. The control means refers to the pump drive condition information stored in the storage means. The liquid ejection head according to claim 14.

21. The composite control signal has a frequency band exceeding the frequency band of the pump drive circuit control signal. The liquid ejection head according to claim 14.

22. A circuit that generates a voltage detection signal indicating the voltage of the pump drive signal; A control unit that controls the pump drive circuit based on the voltage detection signal; further comprising; The liquid ejection head according to claim 1.

23. When the voltage of the pump drive signal indicated by the voltage detection signal exceeds the maximum allowable voltage, the control unit stops the pump drive circuit. The liquid ejection head according to claim 22.

24. A first pressure adjustment means arranged between the outlet of the circulation pump and the inlet of the supply flow path, for adjusting the pressure of the liquid at the inlet of the supply flow path; A second pressure adjustment means arranged between the inlet of the circulation pump and the outlet of the recovery flow path, for adjusting the pressure at the outlet of the recovery flow path; further comprising; The liquid ejection head according to claim 1.

25. A discharge unit configured to discharge the liquid inside the pressure chamber; A supply flow path through which the liquid supplied to the pressure chamber flows; A recovery flow path connected to the supply flow path via the pressure chamber, through which the liquid recovered from the pressure chamber flows; A circulation pump capable of supplying liquid to the pressure chamber through the supply flow path based on an alternating current pump drive signal, recovering liquid from the pressure chamber through the recovery flow path, and refluxing the recovered liquid to the supply flow path; A boost circuit that boosts a reference voltage signal having a voltage smaller than the peak-to-peak voltage of the pump drive signal based on a boost control signal for controlling the boost circuit, to generate a direct current drive voltage signal; An AC conversion circuit that converts the drive voltage signal into an alternating current based on an AC conversion control signal for controlling the AC conversion circuit, to generate the pump drive signal; A liquid ejection head comprising; Control means for generating the AC conversion control signal and the boost control signal based on a pump drive circuit control signal; comprising; A liquid ejection device.

26. The pump drive circuit control signal includes information specifying the voltage of the drive voltage signal; The control means adjusts the boost control signal so that the drive voltage signal has the voltage specified by the pump drive circuit control signal. The liquid ejection device according to claim 25.

27. The pump drive circuit control signal includes information specifying the voltage of the drive voltage signal; The liquid ejection head further comprises a circuit that generates a voltage detection signal indicating the voltage of the drive voltage signal. The control means adjusts the boost control signal so that the voltage of the drive voltage signal indicated by the voltage detection signal becomes the same as the voltage specified by the pump drive circuit control signal. The liquid discharge device according to claim 25.

28. The pump drive circuit control signal includes information specifying the period of the AC conversion control signal. The control means causes the AC conversion control signal to have a period according to the specification by the pump drive circuit control signal. The liquid discharge device according to claim 25.

29. The liquid discharge head further includes a circuit that generates a voltage detection signal indicating the voltage of the drive voltage signal. When the voltage of the drive voltage signal indicated by the voltage detection signal exceeds the maximum allowable voltage, the control means adjusts the boost control signal to reduce the voltage of the drive voltage signal generated by the boost circuit below the maximum allowable voltage or set it to 0V. The liquid discharge device according to claim 25.

30. The liquid discharge head further includes a circuit that generates a voltage detection signal indicating the voltage of the drive voltage signal. The voltage of the drive voltage signal is specified by the liquid discharge device. When the voltage of the drive voltage signal indicated by the voltage detection signal exceeds the maximum allowable voltage, the control means intervenes in the specification of the voltage of the drive voltage signal by the liquid discharge device to reduce the voltage of the drive voltage signal generated by the boost circuit below the maximum allowable voltage or set it to 0V. The liquid discharge device according to claim 25.

31. The control means is provided on any one of a carriage substrate provided on a carriage on which the liquid discharge head is mounted, a main substrate provided on the main body of the liquid discharge device, and a relay substrate inserted between the main substrate and the carriage substrate. The liquid discharge device according to claim 25.

32. The liquid discharge head A first pressure adjusting means arranged between the outlet of the circulation pump and the inlet of the supply flow path to adjust the pressure of the liquid at the inlet of the supply flow path; A second pressure adjusting means arranged between the inlet of the circulation pump and the outlet of the recovery flow path to adjust the pressure at the outlet of the recovery flow path; further includes. The liquid discharge device according to claim 25.

33. A discharge unit configured to discharge the liquid inside the pressure chamber; A supply flow path through which the liquid supplied to the pressure chamber flows; A recovery flow path that is connected to the supply flow path via the pressure chamber and through which the liquid recovered from the pressure chamber flows; A circulation pump that can supply liquid to the pressure chamber via the supply flow path based on an alternating current pump drive signal, recover liquid from the pressure chamber via the recovery flow path, and reflux the recovered liquid to the supply flow path; A pump drive circuit that generates the pump drive signal by boosting and converting a DC reference voltage signal having a voltage lower than the peak-to-peak voltage of the pump drive signal into an alternating current based on a composite control signal; A liquid discharge head comprising:; Control means for generating the composite control signal based on a pump drive circuit control signal; Comprising; A liquid discharge device.

34. The pump drive circuit control signal includes information specifying the voltage of the pump drive signal, The control means adjusts the composite control signal so that the pump drive signal has a voltage specified by the pump drive circuit control signal. The liquid discharge device according to claim 33.

35. The pump drive circuit control signal includes information specifying the voltage of the pump drive signal, The liquid discharge head further includes a circuit that generates a voltage detection signal indicating the voltage of the pump drive signal, The control means adjusts the composite control signal so that the voltage of the pump drive signal indicated by the voltage detection signal is the same as the voltage specified by the pump drive circuit control signal. The liquid discharge device according to claim 33.

36. The pump drive circuit control signal includes information specifying the period of the composite control signal, The control means causes the composite control signal to have a period according to the specification by the pump drive circuit control signal. The liquid discharge device according to claim 33.

37. The liquid discharge head further includes a circuit that generates a voltage detection signal indicating the voltage of the pump drive signal, When the voltage of the pump drive signal indicated by the voltage detection signal exceeds the maximum allowable voltage, the control means adjusts the composite control signal to lower the voltage of the pump drive signal generated by the pump drive circuit below the maximum allowable voltage or to 0V. The liquid discharge device according to claim 33.

38. The liquid discharge head further includes a circuit that generates a voltage detection signal indicating the voltage of the pump drive signal, The voltage of the pump drive signal is specified by the liquid discharge device. When the voltage of the pump drive signal indicated by the voltage detection signal exceeds the maximum allowable voltage, the control means intervenes in the specification of the voltage of the pump drive signal by the liquid discharge device, so that the voltage of the pump drive signal generated by the pump drive circuit is reduced below the maximum allowable voltage or set to 0 V. The liquid discharge device according to claim 33.

39. The control means is provided on any one of a carriage substrate provided on a carriage on which the liquid discharge head is mounted, a main substrate provided on the main body of the liquid discharge device, and a relay substrate inserted between the main substrate and the carriage substrate. The liquid discharge device according to claim 33.

40. The liquid discharge head is disposed between the outlet of the circulation pump and the inlet of the supply flow path, and includes first pressure adjusting means for adjusting the pressure of the liquid at the inlet of the supply flow path; is disposed between the inlet of the circulation pump and the outlet of the recovery flow path, and includes second pressure adjusting means for adjusting the pressure at the outlet of the recovery flow path; and further includes. The liquid discharge device according to claim 33.

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