Liquid discharge head and liquid discharge apparatus

Abstract

The invention relates to a liquid discharge head and a liquid discharge apparatus. A liquid discharge head or apparatus includes: a discharge unit configured to discharge liquid inside a pressure chamber; a supply flow path through which a liquid to be supplied to the pressure chamber flows; a collection flow path which is connected to the supply flow path through the pressure chamber and through which a liquid collected from the pressure chamber flows; a circulation pump capable of supplying the liquid to the pressure chamber through the supply flow path, collecting the liquid from the pressure chamber through the collection flow path, and recirculating the collected liquid to the supply flow path; and a pump driving circuit configured to generate the pump driving signal by boosting and converting a direct current reference voltage signal having a voltage lower than a peak-to-peak voltage of the pump driving signal into an alternating current.

Description

Technical Field

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

[0002] Recently, in the field of inkjet printers, as a liquid ejection head scanning type liquid ejection device, an ink circulation type liquid ejection device that can use special ink according to a print medium for outputting a print material with high image quality has been desired. In the disclosed configuration, an ink supply flow path and an ink collection flow path are provided for ink circulation, and a pressure difference is generated between the ink supply flow path and the ink collection flow path to obtain a circulation flow. The liquid ejection head disclosed in Japanese Patent Application Laid-Open No. 2018-030350 (hereinafter referred to as the literature) includes an ejection unit for ejecting ink, a supply side accumulation unit for supplying ink to the ejection unit, and a collection side accumulation unit for collecting ink from the ejection unit. The liquid ejection head further includes a circulation pump for recirculating ink from the collection side accumulation unit to the supply side accumulation unit, two pressure sensors provided at the two accumulation units respectively, and a drive circuit configured to drive the circulation pump according to the outputs from the two pressure sensors.

[0003] In the above configuration, the voltage for driving the circulation pump is initially 200V and varies in the range of 120V to 300V. Such a configuration of supplying a high voltage from the main body of the liquid ejection device to the liquid ejection head may have an undesirable effect on user manipulation at the electrical connection portion between the liquid ejection device and the liquid ejection head and on peripheral components. In a configuration in which the liquid ejection head in which the circulation pump is installed moves in the main scanning direction, preferably the circulation pump is miniaturized for weight reduction and volume reduction. In order to ensure a necessary circulation flow rate with the miniaturized circulation pump, it is necessary to further increase the voltage for driving the circulation pump. Summary of the Invention

[0004] According to some embodiments of the present disclosure, a liquid ejection head includes: an ejection unit configured to eject a liquid inside a pressure chamber; a supply flow path through which the liquid to be supplied to the pressure chamber flows; a collection flow path that is connected to the supply flow path through the pressure chamber and through which the liquid collected from the pressure chamber flows; a circulation pump that can supply the liquid to the pressure chamber through the supply flow path, collect the liquid from the pressure chamber through the collection flow path, and recirculate the collected liquid to the supply flow path based on an AC pump drive signal; and a pump drive circuit configured to generate 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 into AC.

[0005] Additional features of the present disclosure will become apparent from the following description of exemplary embodiments with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] Figure 1A is a schematic configuration diagram of a liquid discharge device of the present disclosure, and Figure 1B is a block diagram of a control system of the liquid discharge device.

[0007] Figure 2A is an exploded perspective view of a liquid discharge head of the present disclosure, and Figure 2B is a cross-sectional view of a discharge module.

[0008] Figure 3 is an external schematic view of a liquid circulation unit of the present disclosure.

[0009] Figure 4 is a schematic diagram of a liquid circulation path of the present disclosure.

[0010] Figure 5 is a schematic diagram of pump drive wiring connection.

[0011] Figure 6 is a schematic configuration diagram of a liquid discharge device according to the first embodiment.

[0012] Figure 7 is a circuit schematic diagram of a booster circuit according to the first embodiment.

[0013] Figure 8 is a circuit schematic diagram of an AC conversion circuit according to the first embodiment.

[0014] Figure 9 is a timing diagram illustrating the operation of a pump drive circuit according to the first embodiment.

[0015] Figure 10 is a circuit schematic diagram of a booster circuit according to the second embodiment.

[0016] Figure 11 is a circuit schematic diagram of an AC conversion circuit according to the third embodiment.

[0017] Figure 12 is a circuit schematic diagram of an AC conversion circuit according to the fourth embodiment.

[0018] Figure 13 is a schematic configuration diagram of a liquid discharge device according to the fifth embodiment.

[0019] Figure 14 is a circuit schematic diagram of a booster / AC conversion circuit according to the fifth embodiment.

[0020] Figure 15 is a timing diagram illustrating the operation of a pump drive circuit according to the fifth embodiment.

[0021] Figure 16 It is a schematic configuration diagram of a liquid discharge device according to the sixth embodiment.

[0022] Figure 17 It is a schematic configuration diagram of a liquid discharge device according to the seventh embodiment.

[0023] Figure 18 It is a schematic configuration diagram of a liquid discharge device according to the eighth embodiment.

[0024] Figure 19 It is a schematic configuration diagram of a liquid discharge device according to the ninth embodiment.

[0025] Figure 20 It is a schematic configuration diagram of a liquid discharge device according to the tenth embodiment.

[0026] Figure 21 It is a circuit schematic diagram of a booster circuit and a voltage divider circuit according to the eleventh embodiment.

[0027] Figure 22 It is a schematic configuration diagram of a liquid discharge device according to the eleventh embodiment.

[0028] Figure 23 It is a schematic configuration diagram of a liquid discharge device according to the twelfth embodiment.

[0029] Figure 24 It is a schematic configuration diagram of a liquid discharge device according to the thirteenth embodiment.

[0030] Figure 25 It is a schematic configuration diagram of the main part of a liquid discharge device according to the fourteenth embodiment.

[0031] Figure 26 It is a schematic configuration diagram of a liquid discharge device according to the fourteenth embodiment.

[0032] Figure 27 It is a schematic configuration diagram of a liquid discharge device according to the fifteenth embodiment.

[0033] Figure 28 It is a schematic configuration diagram of a liquid discharge device according to the sixteenth embodiment.

[0034] Figure 29 It is a schematic configuration diagram of a liquid discharge device according to the seventeenth embodiment.

[0035] Figure 30 It is a schematic configuration diagram of a liquid discharge device according to the eighteenth embodiment.

[0036] Figure 31It is a schematic configuration diagram of a liquid ejection device according to the nineteenth embodiment.

[0037] Figure 32 It is a schematic configuration diagram of a liquid ejection device according to the twentieth embodiment.

[0038] Figure 33 It is a schematic configuration diagram of a liquid ejection device according to the twenty - first embodiment.

[0039] Figure 34 It is a schematic configuration diagram of a liquid ejection device according to the twenty - second embodiment. Detailed Description of the Embodiments

[0040] Various exemplary embodiments, features, and aspects will be described in detail below with reference to the accompanying drawings. The following embodiments do not limit the disclosure according to the claims. Not all of the multiple features described in the embodiments are necessarily essential for the disclosure, and multiple features can be optionally combined. Also, components that are exactly the same or equivalent in the drawings are denoted by the same reference numerals, and in some cases, their repeated description is omitted.

[0041] Figure 1A It is a schematic perspective view schematically illustrating the liquid ejection device of the present disclosure, and Figure 1B It is a functional block diagram of the liquid ejection device of the present disclosure.

[0042] The liquid ejection device according to the present embodiment is a serial - scanning ink - jet liquid ejection device (hereinafter simply referred to as "liquid ejection device") 101, which is configured to print an image on a print medium P by ejecting ink from a liquid ejection head 201. The liquid ejection head 201 as an ink - jet liquid ejection head is mounted on a carriage 121. As shown by the bidirectional arrow X, the carriage 121 reciprocates along a guide shaft 132 extending in the main scanning direction. As shown by the arrow Y, the print 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.

[0043] The liquid ejection head 201 includes a plurality of liquid circulation units 204 and a discharge unit 206. The plurality of liquid circulation units 204 circulate the ink flowing through the discharge unit 206. A discharge module 209 provided at the discharge unit 206 is formed with a plurality of discharge elements 211 for discharging ink (refer to Figure 2B ). The element drive signal generated by the head driver 123 drives the plurality of discharge elements 211 to perform ink discharge, and is supplied to the plurality of discharge elements 211 formed in the discharge module 209 through a circuit board 205 and an electrical wiring tape 208.

[0044] The guide member 131 is connected to the carriage 121. Wires and supply tubes are deployed at the guide member 131. Through the wires and supply tubes, an electrical signal and ink for ink ejection for forming a plurality of ejection elements 211 in the ejection module 209 are supplied to the carriage 121.

[0045] A processor 142 such as a central processing unit (CPU) controls the liquid ejection device 101 by reading and executing a computer program stored in a read-only memory (ROM) 143. When the processor 142 reads and executes the computer program, a random access memory (RAM) 144 is used as a work area and the like. The processor 142 controls the head driver 123 based on image data supplied from a host device 111 connected to the liquid ejection device 101. The processor 142 also controls a carriage motor 146 for moving the carriage 121 through a motor driver 145. The processor 142 further controls a conveyance motor 148 for conveying a print medium P by using conveyance rollers 133, 134, 135, and 136 through a motor driver 147.

[0046] The liquid ejection head 201 can perform full-color printing using cyan, magenta, yellow, and black (CMYK) inks. A capping unit (not shown) is deployed at a position adjacent to the conveyance path of the print medium P. The capping unit relatively moves to a position for covering the ejection surface of the liquid ejection head 201 during a period in which the liquid ejection device 101 does not perform a printing operation. Then, the capping unit performs a capping operation for preventing drying through the ejection ports 213 (refer to Figure 2B ) formed in the ejection surface, and a suction operation for ink filling of the head and function recovery of the head.

[0047] [Configuration of Liquid Ejection Head]

[0048] Figure 2A An exploded perspective view of the liquid ejection head 201 is illustrated, and Figure 2B is a cross-sectional view of the ejection module 209 of the present embodiment. As Figure 2A shown, the liquid ejection head 201 includes 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, which are accommodated inside a flow path member 202. Each liquid circulation unit 204 is provided with a flow path, and the flow path member 202 is provided with a flow path. Schemes for connecting these flow paths include a screw fastening scheme in which a sealing member is sandwiched between the flow paths and a connection scheme by welding. Note that in the ejection head 201 according to the present embodiment, the number of ink types is four, and accordingly, for example, the number of liquid circulation units 204 is four, but the present disclosure is not limited thereto. In the following description, the number of ink types is four, but the number of ink types is not limited to four in the present disclosure.

[0049] As Figure 2A shown, four connectors 203 are deployed at the flow path member 202 for receiving ink supplied from the main body of the liquid discharging device 101 through a supply tube deployed at the guide member 131. The four connectors 203 are connected one-to-one to the liquid circulation units 204m, 204y, 204k, and 204c. When the liquid discharge head 201 is mounted on the main body of the liquid discharging device 101, the supply tubes connected to the ink tanks 151 of the respective colors (refer to Figure 1A and Figure 1B ) are connected to the connectors 203. The ink of the respective colors supplied from the respective supply tubes is supplied to the liquid circulation units 204m, 204y, 204k, and 204c through the connectors 203. The discharge unit 206 is connected to the bottom surface of the flow path member 202. The ink of the respective colors supplied to the liquid circulation units 204m, 204y, 204k, and 204c is supplied to the discharge unit 206 through the flow path member 202.

[0050] As Figure 2A shown, the discharge unit 206 includes a discharge module 209 in which a plurality of discharge elements 211 for ink discharge are arranged, and a support member 207. The discharge unit 206 further includes an electric wiring tape 208 for transmitting an electric signal to the discharge module 209, and a cover member 210 covering the electric wiring tape 208. The discharge module 209 and the electric wiring tape 208 are joined and fixed to the support member 207, and are also joined and bonded to the cover member 210 to cover their surfaces. The discharge module 209 and the electric wiring tape 208 are electrically connected to each other by wire bonding. A scheme such as flying lead bonding can be used for the electrical connection. In the cover member 210, an opening is provided at a place corresponding to the discharge module 209. A joining scheme using an adhesive or a fixing scheme of clamping a sealing member and fastening with screws can be used as the scheme for connecting the discharge unit 206 and the flow path member 202.

[0051] The surface opposite to the surface of the flow path member 202 where the connectors 203 are deployed is a contact surface. A circuit board 205 is deployed on the contact surface. The circuit board 205 can be fixed to the flow path member 202 by forging or using an adhesive, or can be fixed using a double-sided tape.

[0052] As Figure 1A and Figure 1B shown, the circuit board 205 relays the electric signals transmitted between the carriage plate 122 and the discharge unit 206. The circuit board 205 also relays the electric signals transmitted between the carriage plate 122 and each liquid circulation unit 204.

[0053] The electric wiring tape 208 included in the discharge unit 206 is connected to the circuit board 205 by anisotropic conductive film (ACF) crimping, wire bonding, flying lead bonding, etc. The electric wiring tape 208 relays the electrical signals transmitted between the circuit board 205 and the discharge module 209 included in the discharge unit 206.

[0054] [Description of the circulation flow path]

[0055] Figure 3 is a schematic external view of each liquid circulation unit 204 applied to the liquid discharge device 101. One liquid circulation unit 204 is deployed for each color in the flow path member 202. The first pressure adjustment mechanism 302, the second pressure adjustment mechanism 304, the filter 301, and the circulation pump 303 are deployed in each liquid circulation unit 204.

[0056] Figure 4 is a schematic diagram showing the liquid circulation flow path for one color applied to the liquid discharge device 101. Ink is pressurized and supplied from the corresponding ink tank 151 to the liquid discharge head 201 by an external pump 152. The ink is dust-removed by the filter 301 and then supplied to the first valve chamber 401 of the first pressure adjustment mechanism 302. Thereafter, when the ink flows into the first pressure control chamber 402 that communicates with the first valve chamber 401 through a first valve (not shown), the pressure of the ink is adjusted to the supply-side pressure.

[0057] The circulation pump 303 is a piezoelectric diaphragm pump configured to change the volume in the pump chamber by alternately inputting a pump drive voltage and a drive voltage signal supplied to two piezoelectric elements bonded to the diaphragm, such that two check valves alternately move due to the pressure change to convey the liquid. The circulation pump 303 is driven to convey the ink from the pump inlet flow path 407 on the downstream side to the pump outlet flow path 408 on the upstream side.

[0058] By driving the circulation pump 303, the pressure-adjusted ink 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 connected to the discharge unit 206. Similarly, the collection flow path 406 is a flow path formed in the flow path member 202 and connected to the discharge unit 206.

[0059] The discharge unit 206 includes a discharge module 209, and the discharge module 209 is formed with a plurality of discharge elements 211. Each discharge element 211 includes a pressure chamber 212, a discharge port 213, and an energy conversion element 214. The pressure chamber 212 and the discharge port 213 communicate with each other. The discharge port 213 is arranged as an opening on the discharge surface. The ink supplied to the supply flow path 405 is supplied to the plurality of pressure chambers 212 formed in the discharge module 209 of the discharge unit 206. The ink in each pressure chamber 212 is discharged from the discharge port 213 by using the energy output from the energy conversion element 214. The ink that is not discharged from the discharge port 213 is discharged from the pressure chamber 212 to the collection flow path 406 and is then collected by the second pressure control chamber 404 of the second pressure adjustment mechanism 304.

[0060] 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 through a second valve (not shown). It should be noted that the pressure in the second pressure control chamber 404 is adjusted to the collection side pressure. During printing, the collection side pressure is lower than the supply side pressure.

[0061] The ink supplied to the second pressure control chamber 404 is supplied to the pump inlet flow path 407 and passes through the circulation pump 303, and then is supplied to the pump outlet flow path 408 and is then recycled to the first pressure control chamber 402. However, in some cases, at least a part of the ink supplied to the second pressure control chamber 404 is supplied to the flow path member 202 through the collection flow path 406. With this configuration in which the circulation pump 303 circulates the ink through the discharge elements 211 formed at the discharge module 209, thickening of the ink in the discharge module 209 can be suppressed.

[0062] The circulation flow path is not limited to the configuration passing through the discharge module 209, but may have any configuration that circulates the ink in the discharge unit 206 as long as the effect of suppressing thickening of the ink in the discharge module 209 is obtained.

[0063] [Description of the circulation pump drive mechanism]

[0064] Figure 5 is a schematic diagram showing the configuration of the electrical connection for driving the circulation pump 303. Various drive signals are transmitted from the processor 142 mounted on the main board 141 in the liquid discharge device 101 to the carriage board 122 mounted on the carriage 121 through 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 each liquid circulation unit 204 and signals related to the discharge unit 206.

[0065] In addition, the various drive signals are transmitted from the carriage board 122 to the circuit board 205 through the electrical connection portion 504 by contact connection. AsFigure 5 As shown, the electrical connection portion 504 includes a plurality of pins 505 on the carriage 121 side and a plurality of pads (not shown) disposed on the pad surface 502 of the circuit board 205, and an electrical connection is established when each pin contacts the corresponding pad.

[0066] As will be described later with reference to, for example Figure 6 As described, a boost circuit 606 as a boost unit is disposed on the circuit board 205, and is configured to boost the reference voltage of the reference voltage signal 654 based on the boost control signal 656. The boost circuit 606 generates a drive voltage signal 657 having a pump drive voltage by boosting the reference voltage to the voltage specified by the boost control signal 656. The drive voltage signal 657 is converted into an AC pump drive signal 658 by an AC conversion circuit 607 (refer to, for example Figure 6 ), and then is supplied to a connector terminal (not shown) disposed on the circuit board 205. The pump drive signal 658 is supplied to the four circulation pumps 303 through a wire harness 506 connected to the connector terminal. The four circulation pumps 303 are driven by the pump drive signal 658 having the pump drive voltage as the peak-to-peak voltage to perform ink circulation. Note that the peak-to-peak voltage is the voltage obtained by subtracting the minimum voltage of a signal having a non-constant voltage from its maximum voltage.

[0067] The electrical path from the boost circuit 606 to each circulation pump 303 is preferably provided in a place where it is less likely to be touched by a user's hand. For example, it is preferable to provide the boost circuit 606 on the surface of the circuit board 205 on the side of the flow path member 202 and the electrical path from the boost circuit 606 to each circulation pump 303 is covered by the flow path member 202.

[0068] A configuration in which the carriage plate 122 and the circuit board 205 are integrated may be adopted. A configuration in which the user cannot remove the circuit board 205 from the carriage plate 122 may be adopted. In such a configuration, the boost circuit 606 may be provided on the carriage plate 122.

[0069] [First Embodiment]

[0070] Figure 6 is a schematic configuration diagram of the liquid discharge device 101 according to the first embodiment.

[0071] A print signal 651 is supplied from a host device 111 to a processor 142 provided in a liquid discharge device 101. Electric power 652 is supplied from an external power source 601 to a power supply unit 602 provided in the liquid discharge device 101. When the print signal 651 is supplied, the processor 142 activates a power control signal 653 to the power supply unit 602. In the present embodiment, the power control signal 653 is active high and is activated by changing its signal voltage from 0 volts (V) to 3.3 V. Note that the signal voltage is equal to the signal potential with respect to the ground potential. Hereinafter, "voltage" means the potential with respect to the ground potential. When the valid power control signal 653 is supplied, the power supply unit 602 supplies a reference voltage signal 654 to a first terminal group 603. In the present embodiment, the reference voltage signal 654 has a DC voltage of 24 V. Note that 24 V is merely exemplary, and the reference voltage signal 654 only needs to 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 for circuit operation on the supply circuit board 205, but the present disclosure is not limited thereto. Moreover, the reference voltage is preferably stable and is thus preferably a voltage generated by a regulator on the main board 141, for example. The voltage of the reference voltage signal is preferably a voltage at which a user is not harmed in the case where the user touches the wiring for the reference voltage signal. Therefore, the reference voltage signal 654 may have a DC voltage of 12 V or 5 V, for example. When the print 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 respective counter electrode terminals provided at the circulation pump 303. In the present embodiment, the power control signal 653 is active high and is activated by changing its signal voltage from 0 V to 3.3 V. The boost control signal 656 is a signal that drives a boost circuit 606 by changing between 0 V and 24 V. The first terminal group 603 is a terminal group provided in the liquid discharge device 101. The first terminal group 603 supplies signals and voltages to a second terminal group 604 provided at a circuit board 205 mounted on the liquid discharge head 201. According to the present embodiment, the highest voltage among the voltages of the signals output from the first terminal group 603 is relatively low at 24 V.

[0072] 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. According to the boost control signal 656, the boost circuit 606 generates a drive voltage signal 657 with a DC voltage of 72V based on the reference voltage signal 654 with a DC voltage of 24V, and supplies the signal 657 to the AC conversion circuit 607. The specific configuration of the boost circuit 606 will be described later. The AC conversion circuit 607 generates an AC pump drive signal 658 based on the drive voltage signal 657 and the AC conversion control signal 655 supplied from the second terminal group 604, and supplies the signal 658 to the third terminal group 608. In other words, the AC conversion circuit 607 generates the pump drive signal 658 by converting the DC drive voltage signal 657 into AC (from DC to AC) based on the AC conversion control signal 655. Note that the boost circuit 606 and the AC conversion circuit 607 constitute the pump drive circuit 605, as Figure 6 shown. The third terminal group 608 includes two terminals corresponding to the counter electrode terminals provided at 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 one-to-one to the two terminals corresponding to the counter electrode terminals provided at the circulation pump 303. 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. The reference voltage signal 654 is a DC signal of 24V. Therefore, the voltage of the reference voltage signal 654 is lower than the peak-to-peak voltage of the pump drive signal 658. The third terminal group 608 is provided on the circuit board 205. The pump drive signal 658 is supplied from the third terminal group 608 to the fourth terminal group 609 provided in each liquid circulation unit 204 through the wire harness 506. The fourth terminal group 609 supplies the supplied pump drive signal 658 to the circulation pump 303. The circulation pump 303 is driven according to the supplied pump drive signal 658.

[0073] Note that the boost control signal 656 is, for example, a pulse width modulation (PWM) signal, and the voltage of the drive voltage signal 657 output from the boost circuit 606 can be adjusted by adjusting the duty ratio of the PWM signal.

[0074] Figure 7 is a circuit schematic diagram of the boost circuit 606 according to the first embodiment. Figure 7The boost circuit 606 shown in [figure] is a boost chopper 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 the present 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 gate of the switching element 702 is supplied with a boost control signal 656 and its source is grounded. In the present 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 a drive voltage signal 657 is output from this connection point. The second terminal of the capacitor 704 and the second terminal of the bypass capacitor 705 are grounded.

[0075] In a state where the boost control signal 656 is at 24V which is an effective voltage, the switching element 702 is effective and thus current flows from the input terminal of the reference voltage signal 654 through the inductor 701 and the switching element 702 to the ground. Note that the effective voltage is equal to the effective potential with respect to the ground potential. When the boost control signal 656 changes from the effective voltage to 0V which is the ground voltage, the switching element 702 is turned off. However, since the inductor 701 is located between the input terminal of the reference voltage signal 654 and the drain of the switching element 702, charge flows through the diode 703 into the capacitor 704 due to the back electromotive force generated at the time of the transition. The charge that has flowed in and accumulated in the capacitor 704 cannot return to the anode side of the diode 703 due to the diode 703. In this way, each time the boost control signal 656 drives the switching element 702, charge flows and accumulates in the capacitor 704, and thus the drive voltage signal 657 is boosted to a voltage higher than the reference voltage signal 654. In the present embodiment, the boost control signal 656 is supplied to the switching element 702 such that the voltage of the drive voltage signal 657 becomes 72V.

[0076] Figure 8 is a circuit schematic diagram of the AC conversion circuit 607 according to the first embodiment. A 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 the present embodiment, NPN-type 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 the present embodiment, PNP-type transistors are used as the transistors 803a and 803b. A pump drive signal 658a is output from the connection point between the emitter of the transistor 802a and the emitter of the transistor 803a. Similarly, a pump drive signal 658b is output from the connection point between the emitter of the transistor 802b and the emitter of the transistor 803b.

[0077] 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.

[0078] In this embodiment, NPN-type transistors are used as transistors 805a and 805b. AC conversion control signals 655a and 655b are supplied to the bases of transistors 805a and 805b, respectively. The emitters of transistors 805a and 805b and the second terminals of capacitors 806a and 806b are grounded.

[0079] Note that the "a" and "b" attached to reference symbols 655, 801 to 803, 805, and 806 correspond to the counter electrode terminals "a" and "b" provided at the circulation pump 303, respectively.

[0080] The following description Figure 8 of the operation of the AC conversion circuit 607 shown. Since the operation is common to sequence "a" and sequence "b", the above "a" and "b" are omitted in the description.

[0081] When the AC conversion control signal 655 is at the ground voltage of 0V, transistor 805 is open. In this state, the drive voltage signal 657 is supplied to the bases of transistors 802 and 803 through resistor 801. Then, the base current flows from the base of transistor 802 to the emitter. Consequently, transistor 802 becomes effective, and thus the voltage of the pump drive signal 658 becomes equal to the voltage of the drive voltage signal 657, which is 72V. At the same time, the emitter and base of transistor 803 are at the same voltage, and thus transistor 803 is open.

[0082] When the AC conversion control signal 655 is at the effective voltage of 3.3V, the base current flows from the base of transistor 805 to the emitter. Consequently, transistor 805 becomes effective, and thus the bases of transistors 802 and 803 are grounded. In a state where the pump drive signal 658 has a voltage of 72V for driving the pump, the base current flows from the emitter of transistor 803 to the base. Consequently, transistor 803 becomes effective, and thus the voltage of the pump drive signal 658 becomes equal to the ground voltage of 0V, which is the collector voltage of transistor 803. At the same time, transistor 802 has the same voltage at the base and emitter, and thus is open.

[0083] As described above, when the AC conversion control signal 655 has a ground voltage of 0V, the voltage of the pump drive signal 658 is equal to the voltage of the drive voltage signal 657. When the AC conversion control signal 655 has an active voltage of 3.3V, the voltage of the pump drive signal 658 becomes equal to the ground voltage of 0V. The voltages of the AC conversion control signals 655a and 655b complementarily repeat the ground voltage and the active voltage of 3.3V, and thus the voltages of the pump drive signals 658a and 658b complementarily repeat the ground voltage and 72V which is the voltage of the drive voltage signal 657.

[0084] Figure 9 FIG. is a timing chart showing the operation of the pump drive circuit 605 according to the first embodiment. First, the reference voltage signal 654 changes from the ground voltage of 0V to 24V. Thereafter, the boost control signal 656 repeatedly changes to the ground voltage of 0V and the active voltage of 24V according to a defined 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 necessary for pump driving. Thereafter, the voltages of the AC conversion control signals 655a and 655b complementarily repeat 0V and 3.3V, and thus the voltages of the pump drive signals 658a and 658b complementarily repeat 0V and 72V.

[0085] As described above, a so-called class B amplifier circuit can be used as the AC conversion circuit 607. Moreover, in the present embodiment, it is possible to prevent a signal having a high voltage necessary for driving the circulation pump 303 from existing on the path from the first terminal group 603 to the second terminal group 604. Therefore, it is possible to prevent a signal having a high voltage from existing at the flexible flat cable (FFC) 501, the carriage board 122, and the electrical connection portion 504. Thus, it is possible to reduce an undesirable influence on user operation and peripheral components due to electrical connection.

[0086] [Second Embodiment]

[0087] Figure 10 FIG. is a circuit schematic diagram of the boost circuit 606 according to the second embodiment. Figure 10The boost circuit 606 shown in [figure] is a charge pump 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. The reference voltage signal 654d is supplied to these three interconnected terminals. The 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 this 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.

[0088] 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 from here. The second terminals of the capacitors 1015 and 1019 are grounded.

[0089] Since the switching element 1012 is effective in a state where the boost control signal 656 is at an effective potential of 24V, the second terminals of the capacitors 1013 and 1017 are grounded. In this state, charge flows through the four diodes into the four capacitors, such that the voltage at the first terminals of the four capacitors becomes equal to the voltage of the reference voltage signal 654c. The four capacitors are the capacitors 1013, 1015, 1017, and 1019, and the four diodes are the diodes 1011, 1014, 1016, and 1018. Subsequently, when the voltage of the boost control signal 656 changes from the effective voltage to the ground voltage, the switching element 1012 is turned off. Thus, the voltage at the second terminal of the capacitor 1013 becomes equal to the voltage of the reference voltage signal 654d, which is 24V. There is a potential difference of 24V between the terminals of the capacitor 1013. Thus, charge flows from the terminal of the reference voltage signal 654c through the diode 1011 into the capacitor 1013, such that the voltage at the first terminal of the capacitor 1013 has a potential difference of 24V between the terminals with respect to the voltage at the second terminal (which is 24V). As a result, the voltage at the first terminal of the capacitor 1013 becomes 48V with respect to the ground voltage of 0V. Then, since the diode 1014 has 48V on the anode side and 24V on the cathode side, charge flows through the diode 1014 into the capacitor 1015, such that 48V is obtained on the cathode side. Similarly, charge flows into the capacitors 1017 and 1019, such that 48V is obtained on the cathode sides of the diodes 1016 and 1018.

[0090] Subsequently, when the boost control signal 656 transitions from the ground voltage to the effective voltage, the switching element 1012 becomes effective. Consequently, the second terminals of the capacitors 1013 and 1017 are grounded. Additionally, when the boost control signal 656 transitions from the effective voltage to the ground voltage, the switching element 1012 is turned off. Consequently, the voltage at the second terminal of the capacitor 1017 becomes equal to the voltage of the reference voltage signal 654d, which is 24V. There is a potential difference of 48V between the terminals of the capacitor 1017. Therefore, charge flows from the terminal of the reference voltage signal 654c through the diode 1016 into the capacitor 1017, such that the voltage at the first terminal of the capacitor 1013 has a potential difference of 48V with respect to the voltage at the second terminal (which is 24V) between the terminals. In other words, charge flows through the diode 1016 into the capacitor 1017, such that the potential at the first terminal of the capacitor 1017 becomes equal to 72V with respect to the ground voltage of 0V. Thus, since the diode 1018 has 72V on the anode side and 48V on the cathode side, charge flows through the diode 1018 into the capacitor 1019, such that 72V is obtained on the cathode side.

[0091] In this way, as described above, a so-called charge pump circuit can be used as the boost circuit 606.

[0092] [Third Embodiment]

[0093] Figure 11 is a circuit schematic diagram of the AC conversion 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 through the 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 each used as the switching elements 1111a and 1111b, and n-channel FETs are used as the switching elements 1112a and 1112b.

[0094] Note that the "a" and "b" attached to the reference symbols 655, 658, 1111, and 1112 respectively correspond to the counter electrode terminals "a" and "b" provided at the circulation pump 303.

[0095] The following description Figure 11 The operation of the AC conversion circuit 607 shown in Figure 11 . Since the operation is common to sequences "a" and "b", the above "a" and "b" are omitted in the description.

[0096] When the voltage of the AC conversion control signal 655 is equal to the ground voltage of 0V, the switching element 1111 is effective and the switching element 1112 is open. In this 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 at the effective voltage of 3.3V, the switching element 1112 is effective and the switching element 1111 is open. In this state, the pump drive signal 658 is grounded through the switching element 1112. Since the voltages of the AC conversion control signals 655a and 655b alternately repeat the ground voltage and the effective voltage of 3.3V, the voltages of the pump drive signals 658a and 658b alternately repeat the ground voltage and 72V, which is the voltage of the drive voltage signal 657.

[0097] In this way, as described above, a so-called full-bridge circuit can be used as the AC conversion circuit 607.

[0098] [Fourth Embodiment]

[0099] Figure 12 FIG. Figure 12 is a circuit schematic diagram of the AC conversion circuit 607 in the fourth embodiment. The drive voltage signal 657 having 72V is supplied to the collectors of the transistors 1221a and 1221b through the 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 the constant current source 1222a. Similarly, the emitter of the transistor 1221b is connected to the 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.

[0100] Note that the "a" and "b" attached to the reference symbols 1221 and 1222 respectively correspond to the counter electrode terminals "a" and "b" provided at the circulation pump 303.

[0101] The following description Figure 12 The operation of the AC conversion circuit 607 shown in Figure 12 . Since the operation is common to sequences "a" and "b", the above "a" and "b" are omitted in the description.

[0102] When the voltage of the AC conversion control signal 655 is equal to the ground voltage of 0 V, the transistor 1221 is open. In this state, the constant current source 1222 draws current from the signal line of the pump drive signal 658, and thus the pump drive signal 658 is reduced to the ground voltage. When the AC conversion control signal 655 is at the effective voltage of 3.3 V, the transistor 1221 is effective. In this state, current flows from the signal line of the drive voltage signal 657 through the resistor 1223 and the transistor 1221 to the constant current source 1222 and the signal line of the pump drive signal 658, and thus the drive voltage signal 657 is output as the pump drive signal 658. In this way, the voltages of the AC conversion control signals 655a and 655b repeatedly alternate between the ground voltage and the effective voltage of 3.3 V complementarily, and thus the voltages of the pump drive signals 658a and 658b repeatedly alternate between the ground voltage and 72 V, which is the voltage of the drive voltage signal 657, complementarily.

[0103] As described above, the so-called class A amplifier circuit can be used as the AC conversion circuit 607.

[0104] [Fifth Embodiment]

[0105] Figure 13 is a schematic configuration diagram of the liquid discharge 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 boost / AC conversion circuit 1301. The pump drive signal 658 is output from the boost / AC conversion circuit 1301 to the third terminal group 608. The composite control signal 1351 includes 1351a and 1351b corresponding to the respective counter electrode terminals provided at the circulation pump 303. Other configurations are the same as those in the first embodiment.

[0106] Figure 14 is a circuit schematic diagram of the boost / AC conversion circuit 1301 according to the fifth embodiment. Figure 14The boost / AC conversion circuit 1301 shown in [Figure 0] has a configuration in which a boost chopper circuit on the positive side and a boost chopper circuit on the negative side are integrated. A reference voltage signal 654 with 24V is supplied to the drain of the switching element 1421b and the first terminal of the bypass capacitor 1420. In the present embodiment, n-channel field effect transistors (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 its drain is connected to the second terminal of the inductor 1422 and the anode of the diode 1423a. Composite control signals 1351a and 1351b are respectively supplied to the gates of the switching elements 1421a and 1421b. 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 interconnected, and a pump drive signal 658 is output from their connection point. In the present embodiment, a PNP-type transistor is used as the transistor 1427a, and an NPN-type transistor is used as the transistor 1427b.

[0107] 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.

[0108] In a state where the voltages of the composite control signals 1351a and 1351b are equal to the effective voltage of 24V, the switching elements 1421a and 1421b are effective. Thus, 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.

[0109] When the voltage of the composite control signal 1351a transitions from the effective voltage to the ground voltage, the switching element 1421a is turned off. However, since the inductor 1422 is located between the terminal of the reference voltage signal 654 and the ground voltage, the charge flows into the capacitor 1424a through the diode 1423a due to the back electromotive force generated during the transition. The charge that has flowed in and accumulated in the capacitor 1424a cannot return to the anode side of the diode 1423a due to the diode 1423a. In this way, each time the composite control signal 1351a drives the switching element 1421a, the charge flows and accumulates in the capacitor 1424a, and thus 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 equal to the ground voltage, due to the voltage difference between the above-divided voltage and the ground voltage, current flows from the gate of the transistor 1427a to its collector. Consequently, the transistor 1427a becomes effective, and the boosted voltage is output from the output terminal of the pump drive signal 658. The composite control signal 1351a is driven such that the voltage of the pump drive signal 658 becomes equal to the pump drive voltage of 72V.

[0110] Subsequently, when the voltage of the composite control signal 1351b transitions from the effective voltage to the ground voltage while the composite control signals 1351a and 1351b are in the effective voltage state, the switching element 1421b is turned off. However, since the inductor 1422 is located between the switching element 1421b and the ground voltage, the charge flows out of the capacitor 1424b through the diode 1423b due to the back electromotive force generated during the transition. The charge that has flowed out of and accumulated in the capacitor 1424b cannot return to the cathode side of the diode 1423b due to the diode 1423b. In this way, each time the composite control signal 1351b drives the switching element 1421b, the charge flows out of and accumulates in the capacitor 1424b, and 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 above-divided voltage and the collector, current flows from the collector of the transistor 1427b to its gate. Consequently, the transistor 1427b becomes effective, and the stepped-down voltage is output to the output terminal of the pump drive signal 658. The composite control signal 1351b is driven such that the voltage of the pump drive signal 658 becomes equal to -72V.

[0111] Figure 15This 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 changes from the ground voltage of 0 V to 24 V.

[0112] Thereafter, the voltage of the composite control signal 1351b becomes equal to the effective voltage of 24 V, and the voltage of the composite control signal 1351a changes to the ground voltage of 0 V and the effective voltage of 24 V according to the defined rules. Along with the change of the composite control signal 1351a, the voltage of the pump drive signal 658 rises from the ground voltage of 0 V to 72 V which is the voltage necessary for pump drive.

[0113] Thereafter, the voltage of the composite control signal 1351a becomes equal to the effective voltage of 24 V, and the voltage of the composite control signal 1351b changes to the ground voltage of 0 V and the effective voltage of 24 V according to the defined rules. By using the change of the composite control signal 1351b, the voltage of the pump drive signal 658 drops from the ground voltage of 0 V to -72 V which is the voltage necessary for pump drive.

[0114] In this way, when the signal changes of the composite control signals 1351a and 1351b are alternately switched, 72 V and -72 V which are the positive voltage and negative voltage necessary for pump drive are alternately output to the output terminal of the pump drive signal 658.

[0115] As described above, when the AC conversion control signal 655a repeats the change between the effective voltage and the ground voltage while the AC conversion control signal 655b is fixed at the effective voltage, +72 V is output to the output terminal of the pump drive signal 658. When the AC conversion control signals 655a and 655b are reversed, -72 V is output to the output terminal of the pump drive signal 658. By connecting one of the counter electrode terminals provided at the circulation pump 303 to the ground and supplying the pump drive signal 658 to the other counter electrode terminal, the same pump drive capability as that of the first embodiment can be obtained.

[0116] [Sixth Embodiment]

[0117] Figure 16It is a schematic configuration diagram of a liquid discharge 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 a "control unit") 1601 provided in a liquid discharge head 201. In accordance with 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 supplies an AC conversion control signal 655 to an AC conversion circuit 607. Note that the pump drive circuit control unit 1601 also inputs a reference voltage signal 654 to achieve electrical matching at the interface between the boost circuit 606 and the AC conversion circuit 607. The pump drive circuit control unit 1601 does not adjust the drive voltage specified by the boost control signal 656 using 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 through the boost control signal 656. In addition, the pump drive circuit control unit 1601 assigns the same switching period as the switching period specified by the pump drive circuit control signal 1651 to the AC conversion control signal 655.

[0118] 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 ratio of the boost control signal 656 in accordance with the pump drive circuit control signal 1651.

[0119] In this embodiment, a field programmable gate array (FPGA) is used as the pump drive circuit control unit 1601. However, the pump drive circuit control unit 1601 can be configured in any manner that can implement the above functions. For example, the pump drive circuit control unit 1601 can be configured as a circuit formed of discrete components, or can be configured as a programmable logic device (PLD), a microcomputer, an application specific integrated circuit (ASIC), or the like. Other configurations are the same as those in the first embodiment.

[0120] When the pump drive circuit control unit 1601 is provided separately from the processor 142 in this way, the pump drive circuit can be controlled by a signal in a frequency band not supported by any 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 any output port of the processor 142. Moreover, the AC conversion circuit 607 can be controlled by a signal in a frequency band not supported by any output port of the processor 142. Therefore, a configuration can be achieved in which at least one of the boost control signal 656 or the AC conversion control signal 655 has a frequency band exceeding the frequency band of the pump drive circuit control signal 1651 output from the processor 142.

[0121] [Seventh Embodiment]

[0122] Figure 17 It is a schematic configuration diagram of the liquid ejecting apparatus 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. In accordance with the supply of the pump drive circuit control signal 1651, the pump drive circuit control unit 1601 outputs a boost control signal 656 to the boost circuit 606 and outputs an AC conversion control signal 655 to the AC conversion circuit 607 via the first terminal group 603 and the second terminal group 604. In this embodiment, an FPGA is used as the pump drive circuit control unit 1601. Other configurations are the same as those in the sixth embodiment.

[0123] In the case where the pump drive circuit control unit 1601 is provided on the main board 141 in this manner, the number of components in the liquid ejection head 201 can be reduced.

[0124] [Eighth Embodiment]

[0125] Figure 18 It is a schematic configuration diagram of the liquid ejecting apparatus 101 according to the eighth embodiment. A head information storage unit 1801 is provided in the liquid ejection head 201. In this embodiment, an electrically erasable programmable read-only memory (EEPROM) 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 can be configured in any manner that can implement the function of a storage unit, and can be configured by using, for example, a mask ROM or a fuse ROM. 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 inter-integrated circuit (I2C) or (I 2C) The standard is composed of a data line and a clock line. In this embodiment, an IC compliant with the I2C standard is used as the header information storage unit 1801 and the pump drive circuit control unit 1601. With such a configuration, the header information storage unit 1801 and the pump drive circuit control unit 1601 can be controlled using a common signal line, and thus an increase in the number of control signals can be suppressed. However, the head element control signal 1851 may include signals for the header information storage unit 1801 and signals for the pump drive circuit control unit 1601 as independent signals. In this embodiment, the pump drive circuit control unit 1601 reads the pump drive condition information written to the header information storage unit 1801 and outputs an AC conversion control signal 655 and a boost control signal 656 according to this information. For example, the pump drive condition information may include information specifying the voltage of the drive voltage signal and information specifying the frequency of the pump drive signal. In addition, for example, the pump drive condition signal may include multiple pairs of information specifying the voltage of the drive voltage signal and an index. Then, the pump drive circuit control unit 1601 can read the information specifying the voltage of the drive voltage signal corresponding to the index transmitted from the processor 142 from the header information storage unit 1801. Similarly, for example, the pump drive condition signal may include multiple pairs of information specifying the frequency of the pump drive signal and an index. Then, the pump drive circuit control unit 1601 can read the information specifying the frequency of the pump drive signal corresponding to the index transmitted from the processor 142 from the header information storage unit 1801.

[0126] With such a configuration, the processor 142 does not need to supply the pump drive condition information to the pump drive circuit control unit 1601 every time the pump is driven, and thus the efficiency of transmission and reception of control signals can be increased. However, the pump drive circuit control unit 1601 can directly obtain the pump drive condition information from the head element control signal 1851 supplied from the processor 142.

[0127] [Ninth Embodiment]

[0128] Figure 19 is a schematic configuration diagram of the liquid discharging device 101 according to the ninth embodiment. In this embodiment, a boost circuit 606 and an AC conversion circuit 607 are provided in each liquid circulation unit 204. Other configurations are the same as those in the first embodiment.

[0129] With 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. Moreover, the same effect can be achieved with a configuration in which an AC conversion circuit 607 is provided in each liquid circulation unit 204 and a boost circuit 606 is provided at a portion of the liquid discharging head 201 other than the liquid circulation unit 204.

[0130] [Tenth Embodiment]

[0131] Figure 20 It is a schematic configuration diagram of the liquid discharging device 101 according to the tenth embodiment. In this embodiment, the pump drive circuit control unit 1601, the booster circuit 606, and the AC conversion circuit 607 are included in one package IC 2001 mounted on the circuit board 205. Other configurations are the same as those in the sixth embodiment.

[0132] With such a configuration, the area of the pump drive circuit can be reduced. The same effect can be achieved by a configuration in which some, rather than all, of the pump drive circuit control unit 1601, the booster circuit 606, and the AC conversion circuit 607 are included in one package IC 2001.

[0133] [Eleventh Embodiment]

[0134] When the booster circuit 606 mounted on the liquid discharge head 201 has failed, over-boosting may occur and adversely affect peripheral components due to abnormal operations and the like. This embodiment provides a configuration for preventing abnormal boosting caused by a booster circuit failure.

[0135] Figure 21 It is a circuit schematic diagram of the booster circuit and the voltage divider circuit. Figure 21 The booster circuit 606 shown in Figure 7 is the same as the booster circuit shown in the above first embodiment, and thus any repeated description is omitted. The voltage divider circuit 2101 divides the voltage of the drive voltage signal 657 by the serially connected voltage divider resistors 2102 and 2103 and outputs a divided voltage signal (also referred to as a "voltage sensing signal") 2151 having a divided voltage.

[0136] In this embodiment, the boost control signal 656 is input to the switching element 702 such that a drive voltage signal 657 having a voltage of 72V is generated based on a reference voltage signal 654 having a voltage of 24V. The voltage divider circuit 2101 outputs a divided voltage signal 2151 having a voltage approximately 1 / 20 of the voltage of the drive voltage signal 657.

[0137] (Description of operations during over-boost detection)

[0138] Figure 22It is a schematic configuration diagram of a liquid discharge device 101 according to the eleventh embodiment. A voltage divider circuit 2101 is included in the pump drive circuit 605. The voltage divider circuit 2101 divides the drive voltage signal 657 output from the boost circuit 606 and outputs a divided voltage signal 2151 having a divided voltage. The pump drive circuit control unit 1601 performs control to be described later based on the divided voltage signal 2151. Other configurations are the same as those in the sixth embodiment, and thus any repeated description is omitted. Note that, as Figure 7 or Figure 10 The circuit shown in can be used as the boost circuit 606. The boost circuit 606 and the AC conversion circuit 607 can be replaced with the boost / AC conversion circuit 1301 shown in Figure 14 .

[0139] In the case where it has been detected that the voltage of the drive voltage signal 657 has exceeded the maximum allowable voltage (for example, 80V), the pump drive circuit control unit 1601 performs control to reduce the voltage of the drive voltage signal 657. This control is, for example, to stop the boost control signal 656, or to reduce or set the pump drive voltage of 0V specified by the boost control signal 656. Thus, the switching element included in the boost circuit 606 or the boost / AC conversion circuit 1301 can be stopped, or the voltage of the drive voltage signal 657 or the pump drive signal 658 output from the boost circuit 606 or the boost / AC conversion circuit 1301 can be reduced.

[0140] The control can include controlling the processor 142 through the processor control signal 2252 to adjust the pump drive circuit control signal 1651 or the power supply control signal 653. The adjustment includes, for example, changing the pump drive voltage specified by the pump drive circuit control signal 1651 to a low voltage or 0V. The adjustment also includes setting the power supply control signal 653 to be inactive. Thus, the voltage of the reference voltage signal 654 output from the power supply unit 602 becomes 0V. Therefore, the pump drive circuit control unit 1601 can stop the boost circuit 606 by intervening in the specification of the voltage of the pump drive signal 658 by the processor 142 of the liquid discharge device 101. Moreover, the pump drive circuit control unit 1601 can reduce or set the voltage of the drive voltage signal 657 output from the boost circuit 606 to 0V by intervening in the specification of the voltage of the pump drive signal 658 by the processor 142 of the liquid discharge device 101.

[0141] Note that the divided voltage signal 2151 can be used to perform feedback control on the voltage of the drive voltage signal 657 during normal operation. Specifically, the voltage indicated by the boost control signal 656 can be changed based on the difference between the actual voltage of the drive voltage signal 657 represented by the divided voltage signal 2151 and the voltage indicated by the pump drive circuit control signal 1651. The boost control signal 656 is, for example, a PWM signal, and the voltage of the drive voltage signal 657 output from the boost circuit 606 can be adjusted by adjusting the duty ratio of the boost control signal 656 according to this difference. Specifically, when the actual voltage of the drive voltage signal 657 represented by the divided voltage 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 decreases. For example, the duty ratio of the boost control signal 656 decreases. When the actual voltage of the drive voltage signal 657 represented by the divided voltage 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 increases. For example, the duty ratio of the boost control signal 656 increases. Moreover, a dead zone voltage range can be provided in this feedback control. Specifically, when the voltage of the drive voltage signal 657 is within a predetermined voltage range, feedback control is not performed, and when the voltage of the drive voltage signal 657 deviates from the predetermined voltage range, feedback control can be performed. The target voltage in this case can be appropriately selected from the predetermined voltage range. The target voltage can be, for example, the center voltage of the predetermined voltage range. With the feedback control, a more stable pump drive signal 658 can be supplied to the circulation pump 303.

[0142] [Twelfth Embodiment]

[0143] Figure 23 FIG. 7 is a schematic configuration diagram of the liquid ejecting apparatus 101 according to the twelfth embodiment. The difference between this embodiment and the eleventh embodiment is that the deployment location of the pump drive circuit control unit 1601 is changed from the 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 divider circuit 2101 are mounted on the circuit board 205, and the pump drive circuit control unit 1601 is mounted on the carriage board 122.

[0144] According to this embodiment, the circuits included in the circuit board 205 are simplified. When performing an electrical inspection during the manufacturing process of the liquid ejection head 201, the defect rate caused by the circuit board 205 is reduced due to the simplification of the circuits included in the circuit board 205, and as a result, the productivity of the liquid ejection head 201 is expected to increase. In particular, in a system where the liquid ejection head 201 is a replaceable component, the increase in productivity is meaningful.

[0145] Note that the divided voltage signal 2151 returns from the circuit board 205 to the carriage board 122, and the output signal from the pump drive circuit control unit 1601 is supplied from the carriage board 122 to the circuit board 205. Since the carriage board 122 and the circuit board 205 are in contact connection at the electrical connection part 504 as shown in Figure 5 the signal quality of the signal across the boards 122 and 205 is ensured.

[0146] [Thirteenth Embodiment]

[0147] Figure 24 is a schematic configuration diagram of the liquid discharge device 101 according to the thirteenth embodiment. The difference between this embodiment and the eleventh embodiment is that the deployment location of the pump drive circuit control unit 1601 is changed from the 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 divider circuit 2101 are installed on the circuit board 205, and the pump drive circuit control unit 1601 is installed on the main board 141.

[0148] In the case of a scanning type liquid discharge head, the sizes of the liquid discharge head 201 and the carriage 121 may affect the size of the device, and there are often space constraints. With the configuration of this embodiment, since the pump drive circuit control unit 1601 is not deployed in either the liquid discharge head 201 or the carriage 121, the liquid discharge head 201 and the carriage 121 can be miniaturized. Moreover, as in the twelfth embodiment, the productivity of the liquid discharge head 201 can be improved.

[0149] [Fourteenth Embodiment]

[0150] Figure 25 is a configuration diagram of the main part of the liquid discharge device 101 according to the fourteenth embodiment, and Figure 26 is a schematic configuration diagram of the liquid discharge device 101 according to the fourteenth embodiment.

[0151] 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 liquid discharge devices designed for personal and office use, the carriage board 122 and the main board 141 are usually directly connected to each other by an FFC. However, in devices for large-format output such as posters, the scanning range of the liquid discharge head can be large, and in the above configuration, the FFC can be long, which may degrade the signal quality. As a measure against this, a relay board 2501 can be inserted between the carriage board 122 and the main board 141 to prevent signal quality degradation. In this embodiment, as shown in Figure 26 the pump drive circuit control unit 1601 is installed on the relay board 2501.

[0152] With this configuration, as in the thirteenth embodiment, miniaturization design can be achieved and the productivity of the liquid ejection head 201 can be improved.

[0153] [Fifteenth Embodiment]

[0154] As derived from Figure 6 the configuration of the first embodiment shown in Figure 16 and as in the sixth embodiment shown in Figure 13 the fifteenth embodiment shown in Figure 27 can be derived from the configuration of the fifth embodiment shown in. In this case, the pump drive circuit control unit 1601 does not generate the boost control signal 656 nor the AC conversion control signal 655, but generates the composite control signal 1351. In other words, 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 the generated composite control signal 1351 to the boost / AC conversion circuit 1301.

[0155] [Sixteenth Embodiment]

[0156] As derived from Figure 6 the configuration of the first embodiment shown in Figure 17 and as in the seventh embodiment shown in Figure 13 the sixteenth embodiment shown in Figure 28 can be derived from the configuration of the fifth embodiment shown in. In this case, the pump drive circuit control unit 1601 does not generate the boost control signal 656 nor the AC conversion control signal 655, but generates the composite control signal 1351. In other words, 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 the generated composite control signal 1351 to the boost / AC conversion circuit 1301 through the first terminal group 603 and the second terminal group 604.

[0157] [Seventeenth Embodiment]

[0158] As derived from Figure 6 the configuration of the first embodiment shown in Figure 18 and as in the eighth embodiment shown in Figure 13 the seventeenth embodiment shown in Figure 29The seventeenth embodiment shown in [description]. In this case, the pump drive circuit control unit 1601 does not generate a boost control signal 656 nor an AC conversion control signal 655, but generates a composite control signal 1351. In other words, the pump drive circuit control unit 1601 according to the fifteenth embodiment generates a composite control signal 1351 based on the pump drive circuit control signal and supplies the generated composite control signal 1351 to the boost / AC conversion circuit 1301.

[0159] [Eighteenth Embodiment]

[0160] As derived from Figure 6 the configuration of the first embodiment shown in Figure 20 as in the tenth embodiment shown in Figure 13 the configuration of the fifth embodiment shown in Figure 30 the eighteenth embodiment shown in

[0161] [Nineteenth Embodiment]

[0162] As derived from Figure 6 the configuration of the first embodiment shown in Figure 22 as in the eleventh embodiment shown in Figure 13 the configuration of the fifth embodiment shown in Figure 31 the nineteenth embodiment shown in

[0163] [Twentieth Embodiment]

[0164] As derived from Figure 6 the configuration of the first embodiment shown in Figure 23 as in the twelfth embodiment shown inFigure 13 The configuration of the fifth embodiment shown in Figure 32 is derived from the twentieth embodiment shown in

[0165] [Twenty - first Embodiment]

[0166] Just as Figure 6 the configuration of the first embodiment shown in Figure 24 is derived from the thirteenth embodiment shown in Figure 13 the configuration of the fifth embodiment shown in Figure 33 is derived from the twenty - first embodiment shown in

[0167] [Twenty - second Embodiment]

[0168] Just as Figure 6 the configuration of the first embodiment shown in Figure 26 is derived from the fourteenth embodiment shown in Figure 13 the configuration of the fifth embodiment shown in Figure 34 is derived from the twenty - second embodiment shown in

[0169] Although the present disclosure has been described with reference to exemplary embodiments, it is to be understood that the present disclosure is not limited to the disclosed exemplary embodiments. The scope of the appended claims is to be accorded the broadest interpretation so as to cover all such modifications as well as equivalent structures and functions.

Claims

1. A liquid discharge head, comprising: a discharge unit configured to discharge the liquid inside the pressure chamber; a supply flow path through which liquid to be supplied to the pressure chamber flows; a collecting flow path connected to the supply flow path through the pressure chamber and through which the liquid collected from the pressure chamber flows; a circulation pump capable of supplying liquid to the pressure chamber through the supply flow path, collecting liquid from the pressure chamber through the collection flow path, and recirculating the collected liquid to the supply flow path based on an AC pump drive signal; as well as A pump driving circuit is configured to generate the pump driving signal by boosting a DC reference voltage signal having a voltage lower than a peak-to-peak voltage of the pump driving signal and converting it into an AC.

2. The liquid discharge head according to claim 1, wherein the pump driving circuit includes a boosting circuit configured to generate a DC driving voltage signal by boosting the reference voltage signal, and An AC conversion circuit is configured to generate the pump driving signal by converting the driving voltage signal into an AC. 3 . The liquid discharge head according to claim 2 , wherein the voltage boosting circuit generates the driving voltage signal by boosting the reference voltage signal based on a voltage boosting control signal for controlling the voltage boosting circuit.

4. The liquid discharge head according to claim 2, wherein the AC conversion circuit generates the pump driving signal by converting the driving voltage signal into an AC based on an AC conversion control signal for controlling the AC conversion circuit.

5. The liquid discharge head according to claim 2, wherein The boost circuit generates the driving voltage signal by boosting the reference voltage signal based on a boost control signal for controlling the boost circuit. The AC conversion circuit generates the pump driving signal by converting the driving voltage signal into an AC based on an AC conversion control signal for controlling the AC conversion circuit, and The liquid discharge head further includes a control unit configured to generate the voltage boost control signal and the AC conversion control signal based on a pump drive circuit control signal.

6. The liquid discharge head according to claim 5, wherein The pump drive circuit control signal includes information specifying the voltage of the drive voltage signal, and The control unit adjusts the boost control signal so that the drive voltage signal has a voltage specified by the pump drive circuit control signal.

7. The liquid discharge head according to claim 5, wherein The pump drive circuit control signal includes information specifying the voltage of the drive voltage signal, The liquid discharge head further includes a circuit configured to generate a voltage sensing signal indicative of a voltage of the driving voltage signal, and The control unit adjusts the boost control signal so that a voltage of the driving voltage signal indicated by the voltage sensing signal becomes equal to a voltage specified by the pump driving circuit control signal.

8. The liquid discharge head according to claim 5, wherein The pump drive circuit control signal includes information specifying a period of the AC conversion control signal, and The control unit gives the AC conversion control signal a cycle specified by the pump drive circuit control signal.

9. The liquid discharge head according to claim 5 further includes a circuit configured to generate a voltage sensing signal indicating the voltage of the driving voltage signal, wherein when the voltage of the driving voltage signal indicated by the voltage sensing signal has exceeded the maximum allowable voltage, the control unit sets the voltage of the driving voltage signal generated by the boost circuit to be lower than the maximum allowable voltage or to 0 V by adjusting the boost control signal.

10. The liquid discharge head according to claim 5, further comprising a circuit configured to generate a voltage sensing signal indicating a voltage of the driving voltage signal, wherein The voltage of the driving voltage signal is specified by a liquid discharge device on which the liquid discharge head is mounted, and When the voltage of the driving voltage signal indicated by the voltage sensing signal has exceeded the maximum allowable voltage, the control unit sets the voltage of the driving voltage signal generated by the boost circuit to be lower than the maximum allowable voltage or to 0 V by intervening in the liquid discharge device's designation of the voltage of the driving voltage signal.

11. The liquid discharge head according to claim 5, further comprising a storage unit storing pump driving condition information, wherein the control unit refers to the pump driving condition information stored in the storage unit.

12. The liquid discharge head according to claim 5, wherein at least one of the voltage step-up control signal and the AC conversion control signal has a frequency band exceeding a frequency band of the pump drive circuit control signal.

13. The liquid discharge head according to claim 1, wherein the pump driving circuit generates the pump driving signal by boosting the reference voltage signal based on a composite control signal for controlling the pump driving circuit and converting into an alternating current. 14 . The liquid discharge head according to claim 13 , wherein the liquid discharge head further comprises a control unit configured to generate the composite control signal based on a pump drive circuit control signal.

15. The liquid discharge head according to claim 14, wherein The composite control signal includes information specifying a voltage of the pump drive signal, and The control unit adjusts the composite control signal so that the pump driving signal has a voltage specified by the pump driving circuit control signal.

16. The liquid discharge head according to claim 14, wherein The composite control signal includes information specifying the voltage of the pump drive signal, The liquid discharge head further includes a circuit configured to generate a voltage sensing signal indicative of a voltage of the pump drive signal, and The control unit adjusts the composite control signal so that a voltage of the pump driving signal indicated by the voltage sensing signal becomes equal to a voltage specified by the pump driving circuit control signal.

17. The liquid discharge head according to claim 14, wherein The pump drive circuit control signal includes information specifying a period of the composite control signal, and The control unit gives the composite control signal a cycle specified by the pump drive circuit control signal.

18. The liquid discharge head according to claim 14, further comprising a circuit configured to generate a voltage sensing signal indicating a voltage of the pump drive signal, wherein when the voltage of the pump drive signal indicated by the voltage sensing signal has exceeded a maximum allowable voltage, the control unit sets the voltage of the pump drive signal generated by the pump drive circuit to be lower than the maximum allowable voltage or to 0 V by adjusting the composite control signal.

19. The liquid discharge head according to claim 14, further comprising a circuit configured to generate a voltage sensing signal indicative of a voltage of the pump driving signal, wherein The voltage of the pump driving signal is specified by a liquid discharge device on which the liquid discharge head is mounted, and When the voltage of the pump drive signal indicated by the voltage sensing signal has exceeded the maximum allowable voltage, the control unit sets the voltage of the pump drive signal generated by the pump drive circuit to be lower than the maximum allowable voltage or to 0 V by intervening in the liquid discharge device's designation of the voltage of the pump drive signal.

20. The liquid discharge head according to claim 14, further comprising a storage unit storing pump driving condition information, wherein the control unit refers to the pump driving condition information stored in the storage unit.

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

22. The liquid discharge head according to claim 1, further comprising: a circuit configured to generate a voltage sense signal indicative of a voltage of the pump drive signal; as well as A control unit is configured to control the pump driving circuit based on the voltage sensing signal.

23. The liquid discharge head according to claim 22, wherein the control unit stops the pump drive circuit in a case where the voltage of the pump drive signal indicated by the voltage sensing signal has exceeded a maximum allowable voltage.

24. The liquid discharge head according to claim 1, further comprising: a first pressure regulating unit disposed between an outlet of the circulation pump and an inlet of the supply flow path and configured to adjust a pressure of the liquid at the inlet of the supply flow path; as well as A second pressure regulating unit is disposed between an inlet of the circulation pump and an outlet of the collection flow path and is configured to adjust a pressure at the outlet of the collection flow path.

25. A liquid discharge device, comprising: A liquid discharge head comprising a discharge unit configured to discharge the liquid inside the pressure chamber, a supply flow path through which the liquid to be supplied to the pressure chamber flows, a collecting flow path through which the liquid collected from the pressure chamber flows, and a collecting flow path connected to the supply flow path through the pressure chamber. a circulation pump capable of supplying liquid to the pressure chamber through the supply flow path, collecting liquid from the pressure chamber through the collection flow path, and recirculating the collected liquid to the supply flow path based on an AC pump drive signal, a boost circuit configured to generate a DC driving voltage signal by boosting a reference voltage signal having a voltage lower than a peak-to-peak voltage of the pump driving signal based on a boost control signal for controlling the boost circuit, and an AC conversion circuit configured to generate the pump driving signal by converting the driving voltage signal into an AC based on an AC conversion control signal for controlling the AC conversion circuit; as well as A control unit is configured to generate the AC conversion control signal and the boost control signal based on a pump drive circuit control signal.

26. The liquid discharge device according to claim 25, wherein The pump drive circuit control signal includes information specifying the voltage of the drive voltage signal, and The control unit adjusts the boost control signal so that the drive voltage signal has a voltage specified by the pump drive circuit control signal.

27. The liquid discharge device according to claim 25, wherein The pump drive circuit control signal includes information specifying the voltage of the drive voltage signal, The liquid discharge head further includes a circuit configured to generate a voltage sensing signal indicative of a voltage of the driving voltage signal, and The control unit adjusts the boost control signal so that a voltage of the driving voltage signal indicated by the voltage sensing signal becomes equal to a voltage specified by the pump driving circuit control signal.

28. The liquid discharge device according to claim 25, wherein The pump drive circuit control signal includes information specifying a period of the AC conversion control signal, and The control unit gives the AC conversion control signal a cycle specified by the pump drive circuit control signal.

29. The liquid discharge device according to claim 25, wherein The liquid discharge head further includes a circuit configured to generate a voltage sensing signal indicative of a voltage of the driving voltage signal, and When the voltage of the driving voltage signal indicated by the voltage sensing signal exceeds the maximum allowable voltage, the control unit sets the voltage of the driving voltage signal generated by the boost circuit to be lower than the maximum allowable voltage or to 0V by adjusting the boost control signal.

30. The liquid discharge device according to claim 25, wherein the liquid discharge head further comprising a circuit configured to generate a voltage sensing signal indicative of a voltage of the driving voltage signal, The voltage of the driving voltage signal is specified by the liquid discharge device, and When the voltage of the driving voltage signal indicated by the voltage sensing signal has exceeded the maximum allowable voltage, the control unit sets the voltage of the driving voltage signal generated by the boost circuit to be lower than the maximum allowable voltage or to 0 V by intervening in the liquid discharge device's designation of the voltage of the driving voltage signal.

31. A liquid discharge device according to claim 25, wherein the control unit is provided at any one of a slide plate, a main board, and a relay board, the slide plate is provided at a slide on which the liquid discharge head is mounted, the main board is provided at a main body of the liquid discharge device, and the relay board is inserted between the main board and the slide plate.

32. The liquid discharge device according to claim 25, wherein the liquid discharge head further comprises a first pressure regulating unit disposed between an outlet of the circulation pump and an inlet of the supply flow path and configured to adjust a pressure of the liquid at the inlet of the supply flow path, and A second pressure regulating unit is disposed between an inlet of the circulation pump and an outlet of the collection flow path and is configured to adjust a pressure at the outlet of the collection flow path.

33. A liquid discharge device, comprising: A liquid discharge head comprising a discharge unit configured to discharge the liquid inside the pressure chamber, a supply flow path through which the liquid to be supplied to the pressure chamber flows, a collecting flow path through which the liquid collected from the pressure chamber flows, and a collecting flow path connected to the supply flow path through the pressure chamber. a circulation pump capable of supplying liquid to the pressure chamber through the supply flow path, collecting liquid from the pressure chamber through the collection flow path, and recirculating the collected liquid to the supply flow path based on an AC pump drive signal, and A pump driving circuit, the pump driving circuit being configured to generate the pump driving signal by boosting a DC reference voltage signal having a voltage lower than a peak-to-peak voltage of the pump driving signal based on a composite control signal and converting it into an AC voltage; and a control unit, the control unit being configured to generate the composite control signal based on the pump driving circuit control signal.

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

35. The liquid discharge device according to claim 33, wherein The pump drive circuit control signal includes information specifying a voltage of the pump drive signal, The liquid discharge head further includes a circuit configured to generate a voltage sensing signal indicative of a voltage of the pump drive signal, and The control unit adjusts the composite control signal so that a voltage of the pump driving signal indicated by the voltage sensing signal becomes equal to a voltage specified by the pump driving circuit control signal.

36. The liquid discharge device according to claim 33, wherein The pump drive circuit control signal includes information specifying a period of the composite control signal, and The control unit gives the composite control signal a cycle specified by the pump drive circuit control signal.

37. The liquid discharge device according to claim 33, wherein The liquid discharge head further includes a circuit configured to generate a voltage sensing signal indicative of a voltage of the pump drive signal, and When the voltage of the pump driving signal indicated by the voltage sensing signal has exceeded a maximum allowable voltage, the control unit sets the voltage of the pump driving signal generated by the pump driving circuit to be lower than the maximum allowable voltage or to 0V by adjusting the composite control signal.

38. The liquid discharge device according to claim 33, wherein the liquid discharge head further comprising a circuit configured to generate a voltage sensing signal indicative of a voltage of the pump drive signal, The voltage of the pump drive signal is specified by the liquid discharge device, and When the voltage of the pump drive signal indicated by the voltage sensing signal has exceeded the maximum allowable voltage, the control unit sets the voltage of the pump drive signal generated by the pump drive circuit to be lower than the maximum allowable voltage or to 0 V by intervening in the liquid discharge device's designation of the voltage of the pump drive signal.

39. A liquid discharge device according to claim 33, wherein the control unit is provided at any one of a slide plate, a main board, and a relay board, the slide plate is provided at a slide on which the liquid discharge head is mounted, the main board is provided at a main body of the liquid discharge device, and the relay board is inserted between the main board and the slide plate.

40. The liquid discharge device according to claim 33, wherein the liquid discharge head further comprises a first pressure regulating unit disposed between an outlet of the circulation pump and an inlet of the supply flow path and configured to adjust a pressure of the liquid at the inlet of the supply flow path, and A second pressure regulating unit is disposed between an inlet of the circulation pump and an outlet of the collection flow path and is configured to adjust a pressure at the outlet of the collection flow path.

Images