Liquid ejection device and printhead

Abstract

This invention provides a liquid ejection device and a printhead, which can protect the drive circuit that outputs the drive signal from the ejected liquid. The drive signal output circuit for outputting the drive signal of the piezoelectric element includes: an integrated circuit, on which a basic drive signal is input and which outputs a first control signal; a first switching element that operates according to the first control signal; and a wiring substrate on which the integrated circuit and the first switching element are disposed. The first switching element includes: a first transistor chip; a first terminal, a second terminal, and a third terminal electrically connected to the first transistor chip; and a first molding component covering the first transistor chip. The conduction states of the second and third terminals are controlled according to the first control signal input to the first terminal. Along the normal direction of the wiring substrate, the first, second, and third terminals are only disposed at positions overlapping with the first molding component.

Description

Technical Field

[0001] This invention relates to a liquid ejection device and a printhead. Background Technology

[0002] In liquid ejection devices that form images or documents on a medium by ejecting liquid, for example, liquid ejection devices using piezoelectric elements such as piezoelectric components are known. These piezoelectric elements are arranged with the liquid corresponding to multiple nozzles, and each piezoelectric element is actuated according to a drive signal, causing ink to be ejected from its corresponding nozzle. Electrically, such a piezoelectric element is a capacitive load like a capacitor, and sufficient current needs to be supplied for it to operate. Therefore, the liquid ejection device has a drive signal output circuit capable of supplying sufficient current to drive the piezoelectric elements.

[0003] For example, Patent Document 1 discloses a liquid ejection device that includes a drive circuit that outputs a drive signal to drive a piezoelectric element.

[0004] Patent Document 1: Japanese Patent Application Publication No. 2022-117050

[0005] However, the liquid ejection device described in Patent Document 1 is insufficient from the viewpoint that the drive circuit for protecting the output drive signal is not affected by the ejected liquid, and there is room for improvement. Summary of the Invention

[0006] One embodiment of the liquid ejection device according to the present invention comprises:

[0007] The nozzle ejects liquid driven by a piezoelectric element;

[0008] A drive signal output circuit outputs a drive signal to drive the piezoelectric element; and

[0009] The basic drive signal output circuit outputs a basic drive signal that serves as the basis for the aforementioned drive signal.

[0010] The drive signal output circuit has:

[0011] An integrated circuit, wherein the basic driving signal is input to the integrated circuit, and the integrated circuit outputs a first control signal;

[0012] The first switching element is activated by the first control signal; and

[0013] The wiring substrate is provided with the integrated circuit and the first switching element.

[0014] The first switching element includes:

[0015] First transistor chip;

[0016] The first terminal, the second terminal, and the third terminal are electrically connected to the first transistor chip; and

[0017] A first molded component covers the first transistor chip.

[0018] The conduction states of the second terminal and the third terminal are controlled according to the first control signal input to the first terminal.

[0019] Along the normal direction of the wiring substrate, the first terminal, the second terminal, and the third terminal are disposed only at positions overlapping with the first molded component.

[0020] One embodiment of the printhead involved in this invention comprises:

[0021] The nozzle ejects liquid according to the drive of a piezoelectric element; and

[0022] The drive signal output circuit outputs a drive signal to drive the piezoelectric element.

[0023] The drive signal output circuit has:

[0024] An integrated circuit, which serves as the basis for the piezoelectric element, receives a basic drive signal as input to the integrated circuit, and the integrated circuit outputs a first control signal.

[0025] The first switching element is activated by the first control signal; and

[0026] The wiring substrate is provided with the integrated circuit and the first switching element.

[0027] The first switching element includes:

[0028] First transistor chip;

[0029] The first terminal, the second terminal, and the third terminal are electrically connected to the first transistor chip; and

[0030] A first molded component covers the first transistor chip.

[0031] The conduction state between the second terminal and the third terminal is controlled according to the first control signal input to the first terminal.

[0032] Along the normal direction of the wiring substrate, the first terminal, the second terminal, and the third terminal are disposed only at positions overlapping with the first molded component. Attached Figure Description

[0033] Figure 1 This is a diagram showing the general structure of a liquid ejection device.

[0034] Figure 2 This is a diagram showing the functional structure of a liquid ejection device.

[0035] Figure 3 This is a diagram showing a rough structure of the ejection section.

[0036] Figure 4 This is a diagram showing the structure of the drive signal output circuit.

[0037] Figure 5 This is a diagram illustrating an example of the structure of a switching element.

[0038] Figure 6 This is a diagram illustrating an example of the structure of a switching element.

[0039] Figure 7 This is a diagram illustrating an example of the structure of a switching element.

[0040] Figure 8 This is a diagram illustrating an example of the structure of a switching element.

[0041] Figure 9 This is a diagram used to illustrate the structure of the drive signal output circuit.

[0042] Explanation of reference numerals in the attached figures

[0043] 1…Liquid ejection device, 5…Liquid container, 10…Control unit, 20…Print head, 40…Conveyor unit, 41…Conveyor motor, 50…Drive circuit, 51a, 51b…Drive signal output circuit, 52…Reference voltage output circuit, 55…Wireline substrate, 60…Piezoelectric element, 80…Ink container, 100…Control circuit, 110…Voltage output circuit, 200…Ejector head, 210…Selection control circuit, 230…Selection circuit, 500…Integrated circuit, 510…Modulation circuit, 512, 513…Adder, 514…Comparator, 515…Inverter, 516…Integral attenuator, 517…Attenuator, 520…Gate drive circuit, 521, 522…Gate driver, 550…Amplifier circuit, 560…Demodulation circuit, 570, 572…Feedback circuit, 580…Power supply circuit, 600…Ejection section, 601…Piezoelectric element, 611, 612…electrodes, 621…vibrator plate, 631…mold cavity, 632…nozzle plate, 641…reservoir, 651…nozzle, 661…supply port, AMs…amplifier and modulation signal, C1~C5, Cd…capacitors, D1…diode, L1…coil, M, M1, M2…switching elements, Mo, Mo1, Mo2…molding part, Mrk…reference direction mark, P…dielectric, R1~R6…resistors, Sb… Sb1, Sb2, Sd, Sd1, Sd2, Sf, Sf1, Sf2, Sl, Sr, Su, Su1, Su2… surface, Tr, Tr1, Tr2… transistor chip, p1~p5… wiring pattern, pg… ground wiring pattern, td, td1, td2… terminal, tdm, tds… electrode, tg, tg1, tg2… terminal, ts, ts1, ts2… terminal, tsm, tss… electrode. Detailed Implementation

[0044] Preferred embodiments of the present invention will now be described using the accompanying drawings. The drawings are for illustrative purposes only. Furthermore, the embodiments described below do not constitute an undue limitation on the scope of the invention as set forth in the claims. Additionally, not all of the components described below are necessarily essential elements of the present invention.

[0045] 1. Structure of the liquid ejection device

[0046] Figure 1This diagram shows a schematic structure of the liquid ejection device 1. The liquid ejection device 1 of this embodiment is a line-printing inkjet printer that forms a desired image on a medium P by ejecting ink from a printhead 20 at predetermined intervals from a medium P transported along the transport direction. The medium P in this liquid ejection device 1 can be any printing material such as printing paper, resin film, or fabric. Furthermore, the liquid ejection device 1 is not limited to line-printing inkjet printers; it can also be a serial-printing inkjet printer. Additionally, the liquid ejection device 1 is not limited to inkjet printers; it can also be a color material ejection device used in the manufacture of color filters for liquid crystal displays, an electrode material ejection device used in the electrode formation of organic EL displays and FEDs (fiber emitting diodes), a bio-organic material ejection device used in the manufacture of biochips, a three-dimensional modeling device, and a printing and dyeing device, etc.

[0047] like Figure 1 As shown, the liquid ejection device 1 includes a control unit 10, a printhead 20, a delivery unit 40, and an ink container 80.

[0048] The ink container 80 stores various inks, such as cyan (C), magenta (M), yellow (Y), and black (Bk), which are sprayed onto the medium P. The ink container 80 can be an ink cartridge, a pouch-shaped ink bag made of a flexible film, or an ink canister for refilling ink.

[0049] The control unit 10 includes processing circuits such as a CPU (Central Processing Unit), an FPGA (Field Programmable Gate Array), and storage circuits such as a semiconductor memory, and controls various elements of the liquid ejection device 1, including the print head 20.

[0050] The printhead 20 includes a plurality of ejector heads 200. The plurality of ejector heads 200 are arranged side-by-side along a scanning axis intersecting the transport direction of the medium P, such that they are at least as wide as the transported medium P. A control signal Ctrl-H output from the control unit 10 is input to the printhead 20. Furthermore, ink stored in the ink container 80 is supplied to the printhead 20 via a tube (not shown). The printhead 20 ejects the ink supplied from the ink container 80 based on the input control signal Ctrl-H.

[0051] The conveying unit 40 operates based on the control signal Ctrl-T input from the control unit 10, thereby conveying the medium P along the conveying direction.

[0052] In the liquid ejection device 1 configured as described above, the print head 20 ejects ink onto the medium P in conjunction with the transport of the medium P by the transport unit 40. Thus, the ink lands at any position on the medium P, forming the desired image on the medium P.

[0053] 2. Functional structure of the liquid ejection device

[0054] Figure 2 This is a diagram showing the functional structure of the liquid ejection device 1. For example... Figure 2 As shown, the liquid ejection device 1 has a control unit 10, a print head 20, and a delivery unit 40.

[0055] The control unit 10 has a control circuit 100 and a voltage output circuit 110.

[0056] The control circuit 100 generates various control signals corresponding to the image signals supplied from external devices such as the host computer, and outputs them to the corresponding structures.

[0057] Specifically, the control circuit 100 generates and outputs a control signal Ctrl-T by receiving an image signal and performing printing processing on the medium P. The control signal Ctrl-T output by the control circuit 100 is input to the conveyor motor 41 included in the conveying unit 40. The conveyor motor 41 is driven according to the control signal Ctrl-T. Through the driving force of the conveyor motor 41, the medium P is conveyed along the conveying direction. Furthermore, in addition to the conveyor motor 41, the conveying unit 40 may also include one or more conveying rotors. Additionally, the conveying unit 40 may also include a conveyor motor drive circuit for converting the control signal Ctrl-T into a specified signal to drive the conveyor motor 41.

[0058] In addition, the control circuit 100 generates a clock signal SCK, a print data signal SI, a latch signal LAT, a change signal CH, and basic drive signals dA and dB as control signals Ctrl-H based on the image signal supplied from an external device, and outputs them to the print head 20.

[0059] The voltage output circuit 110 generates, for example, a 42V DC voltage VHV and outputs this voltage VHV to the printhead 20. This voltage VHV is used as the power supply voltage for various structures of the printhead 20. Furthermore, the voltage VHV output by the voltage output circuit 110 can also be used as the power supply voltage for various structures of the liquid ejection device 1, including the control unit 10 and the delivery unit 40. In addition to the 42V DC voltage VHV, the voltage output circuit 110 can also generate multiple DC voltages, such as 5V and 3.3V, and supply these DC voltages to the corresponding structures.

[0060] The printhead 20 has a drive circuit 50 and multiple nozzles 200.

[0061] The drive circuit 50 includes drive signal output circuits 51a and 51b. The drive signal output circuit 51a receives a digital basic drive signal dA (as a control signal Ctrl-H) and a voltage VHV. The drive signal output circuit 51a performs a digital-to-analog conversion on the input basic drive signal dA and amplifies the converted analog signal (D-stage) to a voltage value corresponding to the voltage VHV, thereby outputting a drive signal COMA. The drive signal COMA output by the drive signal output circuit 51a is then supplied to the nozzle 200. Similarly, the drive signal output circuit 51b receives a digital basic drive signal dB (as a control signal Ctrl-H) and a voltage VHV. The drive signal output circuit 51b performs a digital-to-analog conversion on the input basic drive signal dB and amplifies the converted analog signal (D-stage) to a voltage value corresponding to the voltage VHV, thereby outputting a drive signal COMB. The drive signal COMB output by the drive signal output circuit 51b is then supplied to the nozzle 200.

[0062] That is, the basic drive signal dA is the signal that forms the basis of the drive signal COMA, defining the waveform of the drive signal COMA. The basic drive signal dB is the signal that forms the basis of the drive signal COMB, defining the waveform of the drive signal COMB. Here, the basic drive signals dA and dB can be any signals that can define the waveforms of the drive signals COMA and COMB, and can also be analog signals.

[0063] Furthermore, the drive circuit 50 includes a reference voltage output circuit 52. The reference voltage output circuit 52 generates a reference voltage signal VBS with a constant DC voltage value of 5.5V, 6V, etc., and outputs this reference voltage signal VBS to the nozzle 200. This reference voltage signal VBS functions as a reference potential for driving the piezoelectric element 60 (described later) in the nozzle 200. The potential of this reference voltage signal VBS is not limited to 5.5V or 6V; it can also be a ground potential.

[0064] The nozzle 200 includes a selection control circuit 210, multiple selection circuits 230, and multiple nozzles 600 corresponding to the multiple selection circuits 230.

[0065] The selection control circuit 210 is input with a clock signal SCK (which serves as the control signal Ctrl-H), a print data signal SI, a latch signal LAT, and a change signal CH. Based on the input clock signal SCK, print data signal SI, latch signal LAT, and change signal CH, the selection control circuit 210 generates a selection signal corresponding to each of the multiple selection circuits 230, and outputs the selection signal to the corresponding selection circuit 230.

[0066] Each selection circuit 230 receives drive signals COMA and COMB and corresponding selection signals output by the selection control circuit 210. Based on the input selection signals, the selection circuit 230 sets the waveforms of the drive signals COMA and COMB to either select or deselect, thereby generating a drive signal VOUT based on the drive signals COMA and COMB, and outputting the drive signal VOUT to the corresponding ejection section 600.

[0067] Each of the multiple ejection sections 600 includes a piezoelectric element 60. A drive signal VOUT, output from a corresponding selection circuit 230, is supplied to one end of each piezoelectric element 60, and a reference voltage signal VBS is supplied to the other end. The piezoelectric element 60 is then driven according to the potential difference between the drive signal VOUT supplied to one end and the reference voltage signal VBS supplied to the other end. An amount of ink corresponding to the drive of the piezoelectric element 60 is ejected from the ejection section 600.

[0068] Here, in the liquid ejection device 1 of this embodiment, the print head 20 includes a total of more than 5,000 ejection sections 600, and a drive signal COMA and COMB output by a drive circuit 50 is supplied to the more than 5,000 ejection sections 600 of the print head 20. That is, the drive signal output circuits 51a and 51b supply drive signals COMA and COMB to the more than 5,000 piezoelectric elements 60 included in the multiple ejection heads 200.

[0069] In the inkjet printer of the line printing method shown in this embodiment, when printing on a single sheet of paper (media P) of A4 size (210mm × 297mm: 8.27 inches × 11.69 inches) at 600 dpi, at least "600 prints / inch × 8.27 inches = 4962 prints" are arranged side by side on the print head 20 along the scanning axis. At this time, in the liquid ejection device 1, since multiple print heads 200 are used, therefore... Figure 1As shown, when viewed along the transport direction of the medium P, the multiple nozzles 200 are arranged in a manner where a portion overlaps. Therefore, when viewed along the transport direction of the medium P, a portion of the ejector portions 600 are arranged in an overlapping manner. Furthermore, the multiple ejector portions 600 are arranged on the printhead 20 to take into account the transport curvature of the medium P transported by the transport unit 40.

[0070] With this in mind, in the inkjet printer of the line printing method shown in this embodiment, when printing on a single sheet of A4 size paper, i.e., medium P, at 600 dpi, the print head 20 has at least 5,000 or more ejection sections 600 in the direction of the short side of medium P and along the scanning axis.

[0071] For the printhead 20 with more than 5,000 piezoelectric elements 60, drive signals COMA and COMB are supplied via a drive circuit 50. The ejector sections 600 arranged side-by-side along the scan axis are driven by drive signals VOUT based on the same signal waveform of drive signals COMA and COMB. This reduces the possibility of waveform deviation between the drive signals VOUT supplied to the ejector sections 600 arranged side-by-side along the scan axis. As a result, the possibility of deviation in the amount of ink ejected from the ejector sections 600 arranged side-by-side along the scan axis due to signal waveform deviation is reduced, improving the ink ejection accuracy from the printhead 20, i.e., the image quality formed on the medium P.

[0072] As described above, the liquid ejection device 1 of this embodiment includes: an ejection head 200 that ejects liquid according to the drive of the piezoelectric element 60; drive signal output circuits 51a and 51b that output drive signals COMA and COMB to drive the piezoelectric element 60; and a control circuit 100 that outputs basic drive signals dA and dB that form the basis of the drive signals COMA and COMB.

[0073] 3. Structure of the ejector section

[0074] Here, an example of the structure of the ejection section 600 of the ejection head 200 will be described. Figure 3 This is a diagram showing a schematic structure of one of the multiple ejection sections 600 of the ejection head 200. (See diagram for example.) Figure 3 As shown, the ejection section 600 includes a piezoelectric element 60, a vibrating plate 621, a mold cavity 631, and a nozzle 651.

[0075] The mold cavity 631 is filled with ink supplied from the reservoir 641. Additionally, ink is introduced from the ink container 80 into the reservoir 641 via an ink tube (not shown) and a supply port 661. That is, the mold cavity 631 is filled with ink stored in the corresponding liquid container 5.

[0076] Vibrating plate 621 passes through Figure 3 The piezoelectric element 60 disposed on the upper surface is displaced by the drive. Moreover, as the vibrating plate 621 is displaced, the internal volume of the mold cavity 631 filled with ink expands and contracts. That is, the vibrating plate 621 functions as a diaphragm that changes the internal volume of the mold cavity 631.

[0077] Nozzle 651 is disposed on nozzle plate 632 and is an opening communicating with mold cavity 631. Moreover, by changing the internal volume of mold cavity 631, an amount of ink corresponding to the change in internal volume is ejected from nozzle 651.

[0078] The piezoelectric element 60 is a structure formed by clamping a piezoelectric body 601 with a pair of electrodes 611 and 612. In this structure, the central portions of the electrodes 611 and 612 flex upwards and downwards together with the vibrating plate 621 according to the potential difference of the voltage supplied by the electrodes 611 and 612. Specifically, a drive signal VOUT is supplied to one of the electrodes 611 or 612 of the piezoelectric element 60. A reference voltage signal VBS is supplied to the other electrode 611 or 612 of the piezoelectric element 60. Furthermore, the piezoelectric element 60 flexes upwards when the voltage level of the drive signal VOUT increases, and flexes downwards when the voltage level of the drive signal VOUT decreases.

[0079] In the ejector section 600 configured as described above, the piezoelectric element 60 flexes upward, the vibrating plate 621 displaces, and the internal volume of the mold cavity 631 expands. As a result, ink is introduced from the reservoir 641. On the other hand, the piezoelectric element 60 flexes downward, the vibrating plate 621 displaces, and the internal volume of the mold cavity 631 shrinks. As a result, an amount of ink corresponding to the degree of shrinkage is ejected from the nozzle 651. That is, the ejector head 200 has a piezoelectric element 60, which includes electrodes 611 and 612, and is driven by the potential difference between electrodes 611 and 612, thereby ejecting ink by driving the piezoelectric element 60.

[0080] Furthermore, the piezoelectric element 60 is not limited to Figure 3 The structure shown can be any structure that can eject ink from the ejection section 600. That is, the piezoelectric element 60 is not limited to the bending vibration structure described above; for example, it can also be a structure using longitudinal vibration.

[0081] 4. Structure of the drive signal output circuit

[0082] Next, the structure and operation of the drive signal output circuits 51a and 51b included in the drive circuit 50 will be described. Here, the drive signal output circuits 51a and 51b are identical in structure, differing only in the input and output signals. Therefore, in the following description, the structure and operation of the drive signal output circuit 51a, which outputs the drive signal COMA based on the basic drive signal dA, will be described, while a detailed description of the structure and operation of the drive signal output circuit 51b, which outputs the drive signal COMB based on the basic drive signal dB, will be omitted.

[0083] Figure 4 This is a diagram showing the structure of the drive signal output circuit 51a. (As shown...) Figure 4 As shown, the drive signal output circuit 51a includes an integrated circuit 500 (including a modulation circuit 510), an amplifier circuit 550, a demodulation circuit 560, feedback circuits 570 and 572, and several other circuit elements. The integrated circuit 500 outputs gate signals Hgd and Lgd based on a base drive signal dA, which serves as the basis for the drive signal COMA. The amplifier circuit 550 includes a switching element M1 driven by the gate signal Hgd and a switching element M2 driven by the gate signal Lgd, and generates an amplified modulation signal Ams, which is then output to the demodulation circuit 560. The demodulation circuit 560 smooths the amplified modulation signal Ams and outputs it as the drive signal COMA.

[0084] Integrated circuit 500 is electrically connected to an external source via a plurality of terminals including terminals In, Bst, Hdr, Sw, Gvd, Ldr, Gnd, Ifb, and Vfb. Integrated circuit 500 modulates the basic drive signal dA input from terminal In and outputs the gate signal Hgd, which drives the switching element M1 of amplifier circuit 550, from terminal Hdr, and the gate signal Lgd, which drives the switching element M2, from terminal Ldr. That is, the basic drive signal dA is input to integrated circuit 500, and integrated circuit 500 outputs gate signals Hgd and Lgd.

[0085] Integrated circuit 500 includes DAC (Digital to Analog Converter) 511, modulation circuit 510, gate drive circuit 520, and power supply circuit 580.

[0086] The power supply circuit 580 generates voltages DAC_HV and DAC_LV and supplies them to DAC511.

[0087] DAC511 converts the digital fundamental drive signal dA, which defines the signal waveform of the drive signal COMA, into an analog signal, namely the fundamental drive signal aA, based on the voltage value between voltage DAC_HV and voltage DAC_LV, and outputs it to the modulation circuit 510. Furthermore, the maximum value of the voltage amplitude of the fundamental drive signal aA is defined by the voltage value of DAC_HV, and the minimum value is defined by the voltage value of DAC_LV. That is, voltage DAC_HV is the reference voltage on the high-voltage side of DAC511, and voltage DAC_LV is the reference voltage on the low-voltage side of DAC511. Moreover, the amplified signal of the analog fundamental drive signal aA output from DAC511 is equivalent to the drive signal COMA. In other words, the fundamental drive signal aA is equivalent to the analog signal that becomes the target before amplification of the drive signal COMA, and the fundamental drive signal dA is equivalent to the digital signal that becomes the target before amplification of the drive signal COMA. Furthermore, in this embodiment, the voltage amplitude of the fundamental drive signal aA is, for example, 1V to 2V.

[0088] The modulation circuit 510 generates a modulation signal Ms by modulating the basic drive signal aA, and outputs the modulation signal Ms to the amplifier circuit 550 via the gate drive circuit 520. The modulation circuit 510 includes adders 512 and 513, comparator 514, inverter 515, integrator attenuator 516, and attenuator 517.

[0089] The integrator attenuator 516 attenuates and integrates the voltage value of the drive signal COMA input via terminal Vfb at terminal Out, and supplies it to the input terminal on the - side of adder 512. Additionally, a basic drive signal aA is input to the input terminal on the + side of adder 512. Furthermore, the voltage obtained by subtracting the voltage input to the - side from the voltage input to the input terminal on the + side and integrating the result is supplied to the input terminal on the + side of adder 513.

[0090] Here, the maximum voltage amplitude of the basic drive signal aA is approximately 2V, as described above. In contrast, the maximum voltage of the drive signal COMA sometimes exceeds 40V. Therefore, when calculating the deviation, the integrator 516 attenuates the voltage of the drive signal COMA input via terminal Vfb in order to match the amplitude ranges of the two voltages.

[0091] Attenuator 517 supplies a voltage, after attenuating the high-frequency components of the drive signal COMA input via terminal Ifb, to the - input terminal of adder 513. Additionally, a voltage output from adder 512 is input to the + input terminal of adder 513. Adder 513 then outputs the voltage As obtained by subtracting the voltage input to the - input terminal from the voltage input to the + input terminal to comparator 514.

[0092] The voltage As output from the adder 513 is obtained by subtracting the voltage of the signal supplied to terminal Vfb from the voltage of the basic drive signal aA, and further subtracting the voltage of the signal supplied to terminal Ifb. Therefore, the voltage As output from the adder 513 is a signal obtained by correcting the deviation after subtracting the attenuated voltage of the drive signal COMA from the voltage of the target basic drive signal aA using the high-frequency component of the drive signal COMA.

[0093] Comparator 514 outputs a pulse-modulated signal Ms based on the voltage As output from adder 513. Specifically, when comparator 514 outputs the modulated signal Ms, if the voltage As output from adder 513 is rising and above a threshold Vth1 (described later), the modulated signal Ms becomes high-level (H); if the voltage As is falling and below a threshold Vth2 (described later), the modulated signal Ms becomes low-level (L). Here, thresholds Vth1 and Vth2 are set to a relationship where threshold Vth1 > threshold Vth2. Furthermore, the frequency and duty cycle of the modulated signal Ms vary in accordance with the fundamental drive signals dA and aA. Therefore, by adjusting the modulation gain, which corresponds to sensitivity, via attenuator 517, the amount of variation in the frequency and duty cycle of the modulated signal Ms can be adjusted.

[0094] The modulation signal Ms output from comparator 514 is supplied to the gate driver 521 included in the gate drive circuit 520. Additionally, after the logic level of the modulation signal Ms is inverted by inverter 515, it is also supplied to the gate driver 522 included in the gate drive circuit 520. That is, the logic levels of the signals supplied to gate driver 521 and gate driver 522 are mutually exclusive.

[0095] Here, timing can also be controlled so that the logic levels of the signals supplied to gate driver 521 and gate driver 522 do not simultaneously become H level. That is, the so-called exclusive relationship, strictly speaking, means that the logic levels of the signals supplied to gate driver 521 and gate driver 522 will not simultaneously become H level. More specifically, it means that the switching elements M1 and M2 included in the amplifier circuit 550 will not be turned on at the same time.

[0096] The gate drive circuit 520 includes gate driver 521 and gate driver 522.

[0097] Gate driver 521 levels-shifts the modulation signal Ms output from comparator 514 and outputs it as gate signal Hgd from terminal Hdr. The power supply voltage for gate driver 521 has a high-order side applied via terminal Bst and a low-order side applied via terminal Sw. Terminal Bst is connected to one end of capacitor C5 and the cathode of diode D1. Terminal Sw is connected to the other end of capacitor C5. The anode of diode D1 is connected to terminal Gvd. Thus, a DC voltage, such as 7.5V (Vm), supplied by a power supply circuit not shown, is supplied to the anode of diode D1. Therefore, the potential difference between terminals Bst and Sw is approximately equal to the potential difference across capacitor C5, i.e., voltage Vm. Gate driver 521 then generates a gate signal Hgd corresponding to the input modulation signal Ms and the voltage Vm relative to terminal Sw, and outputs it from terminal Hdr.

[0098] Gate driver 522 operates on a lower potential side compared to gate driver 521. Gate driver 522 levels-shifts the logic level of the modulation signal Ms output from comparator 514 after it has been inverted by inverter 515, and outputs it as the gate signal Lgd from terminal Ldr. In the power supply voltage of gate driver 522, a voltage Vm is applied to the high-order side, and a ground potential, for example, 0V, is supplied to the low-order side via terminal Gnd. Then, a gate signal Lgd is generated based on the voltage Vm relative to the high-order voltage Vm of the signal input to gate driver 522, and output from terminal Ldr.

[0099] Here, the gate signal Hgd is the signal after level shifting the voltage value of the modulation signal Ms. In addition, the gate signal Lgd is the signal after level shifting the voltage value of the inverted signal after the logic level of the modulation signal Ms is reversed. In view of this, the gate signal Hgd and the gate signal Lgd are also equivalent to the signals after modulating the basic drive signal dA and the basic drive signal aA.

[0100] Amplifier circuit 550 includes switching elements M1 and M2. Switching element M1 is a semiconductor device such as a FET (Field Effect Transistor), including a transistor chip Tr1 with a FET formed thereon, a terminal tg1 electrically connected to the gate of transistor chip Tr1, a terminal td1 electrically connected to the drain of transistor chip Tr1, and a terminal ts1 electrically connected to the source of transistor chip Tr1. A DC voltage, such as 42V, is supplied to terminal td1 of switching element M1. Terminal tg1 of switching element M1 is electrically connected to one end of resistor R1, and the other end of resistor R1 is electrically connected to terminal Hdr of integrated circuit 500. That is, a gate signal Hgd output from terminal Hdr of integrated circuit 500 is supplied to terminal tg1 of switching element M1. Furthermore, terminal ts1 of switching element M1 is electrically connected to terminal Sw of integrated circuit 500. In other words, switching element M1 includes transistor chip Tr1, and terminals tg1, ts1, and td1 electrically connected to transistor chip Tr1.

[0101] In the switching element M1 configured as described above, the gate signal Hgd input to terminal tg1 is supplied to the drain of transistor chip Tr1. This controls the conduction state between the drain and source of transistor chip Tr1, i.e., between terminals td1 and ts1 of switching element M1. In other words, switching element M1 operates based on the gate signal Hgd. Specifically, switching element M1 controls the conduction state of terminals ts1 and td1 according to the gate signal Hgd input to terminal tg1. Here, in the following explanation, the state where terminals td1 and ts1 of switching element M1 are controlled to be conductive is sometimes referred to as "on," and the state where terminals td1 and ts1 of switching element M1 are controlled to be non-conductive is sometimes referred to as "off."

[0102] Switching element M2 is a semiconductor device such as a FET, including a transistor chip Tr2 with a FET formed thereon, a terminal tg2 electrically connected to the gate of transistor chip Tr2, a terminal td2 electrically connected to the drain of transistor chip Tr2, and a terminal ts2 electrically connected to the source of transistor chip Tr2. Terminal td2 of switching element M2 is electrically connected to terminal Sw of integrated circuit 500. That is, terminal td2 of switching element M2 is electrically connected to terminal ts1 of switching element M1. Terminal tg2 of switching element M2 is electrically connected to one end of resistor R2, and the other end of resistor R2 is electrically connected to terminal Ldr of integrated circuit 500. That is, the gate signal Lgd output from terminal Ldr of integrated circuit 500 is supplied to terminal tg2 of switching element M2. Furthermore, a ground potential is supplied to terminal ts2 of switching element M2. In other words, switching element M2 includes transistor chip Tr2, terminal tg2, terminal ts2, and terminal td2 electrically connected to transistor chip Tr2.

[0103] In the switching element M2 configured as described above, the gate signal Lgd input to terminal tg2 is supplied to the drain of transistor chip Tr2. This controls the conduction state between the drain of transistor chip Tr2 and terminals td2 and ts2 of switching element M2. In other words, switching element M2 operates based on the gate signal Lgd. Specifically, switching element M2 controls the conduction state of terminals td2 and ts2 according to the gate signal Lgd input to terminal tg2. Here, in the following explanation, the state where terminals td2 and ts2 of switching element M2 are controlled to be conducting is sometimes referred to as "on," and the state where terminals td2 and ts2 of switching element M2 are controlled to be non-conducting is sometimes referred to as "off."

[0104] In the amplifier circuit 550 configured as described above, when switching element M1 is controlled to be open and switching element M2 is controlled to be closed, the voltage at the node connected to terminal Sw becomes ground potential. At this time, voltage Vm is supplied to terminal Bst. On the other hand, when switching element M1 is controlled to be closed and switching element M2 is controlled to be open, the voltage at the node connected to terminal Sw becomes voltage VHV. Therefore, a voltage signal of potential VHV+Vm is supplied to terminal Bst.

[0105] That is, the gate driver 521 driving the switching element M1 uses capacitor C5 as a floating power source. The potential of the other end of capacitor C5, i.e. terminal Sw, changes to 0V or voltage VHV according to the operation of switching element M1 and switching element M2. Thus, the gate driver 521 supplies the gate signal Hgd, with the L level being the potential of voltage VHV and the H level being the potential of voltage VHV + voltage Vm, to the gate terminal of switching element M1.

[0106] On the other hand, the gate driver 522 that drives the switching element M2 supplies a gate signal Lgd with an L level of ground potential and an H level of voltage Vm to the gate terminal of the switching element M2, regardless of the operation of the switching elements M1 and M2.

[0107] As described above, the amplifier circuit 550 amplifies the modulated signal Ms, which is modulated by the fundamental drive signals dA and aA, based on the voltage VHV, by operating the switching elements M1 and M2 according to the gate signals Hgd and Lgd. Then, the amplifier circuit 550 outputs the amplified signal as the amplified modulated signal AMs from the connection point where the terminals ts1 of the switching element M1 and td2 of the switching element M2 are connected.

[0108] In addition, such as Figure 4As shown, capacitor Cd is located on the propagation path of the voltage VHV input to amplifier circuit 550. Voltage VHV is supplied to one end of capacitor Cd, and ground potential is supplied to the other end. This capacitor Cd is, for example, an electrolytic capacitor, reducing the possibility of potential fluctuations in voltage VHV caused by the operation of amplifier circuit 550.

[0109] The demodulation circuit 560 smooths the amplified modulation signal AMs output from the amplifier circuit 550, generates a drive signal COMA, and outputs it from the drive signal output circuit 51a.

[0110] The demodulation circuit 560 includes a coil L1 and a capacitor C1. One end of the coil L1 is electrically connected to terminal ts1 of switching element M1 and terminal td2 of switching element M2. Thus, the amplified modulation signal AMs output from the amplifier circuit 550 is input to one end of the coil L1. The other end of the coil L1 is connected to terminal Out, which is the output of the drive signal output circuit 51a. The other end of the coil L1 is also connected to one end of the capacitor C1. Furthermore, a ground potential is supplied to the other end of the capacitor C1. In other words, the coil L1 and capacitor C1 demodulate the amplified modulation signal AMs output from the amplifier circuit 550 by smoothing it, and output it as the drive signal COMA.

[0111] The feedback circuit 570 includes resistors R3 and R4. One end of resistor R3 is connected to the Out terminal of the output drive signal COMA, and the other end is connected to the terminal Vfb and one end of resistor R4. A voltage VHV is supplied to the other end of resistor R4. Thus, the drive signal COMA from the Out terminal through the feedback circuit 570 is fed back to the Vfb terminal in a pulled-up state.

[0112] The feedback circuit 572 includes capacitors C2, C3, and C4, and resistors R5 and R6. One end of capacitor C2 is connected to the Out terminal of the output drive signal COMA, and the other end is connected to one end of resistor R5 and one end of resistor R6. Ground potential is supplied to the other end of resistor R5. Thus, capacitor C2 and resistor R5 function as a high-pass filter. Furthermore, the cutoff frequency of the high-pass filter is set to, for example, approximately 9MHz. The other end of resistor R6 is connected to one end of capacitor C4 and one end of capacitor C3. Ground potential is supplied to the other end of capacitor C3. Thus, resistor R6 and capacitor C3 function as a low-pass filter. Furthermore, the cutoff frequency of the low-pass filter is set to, for example, approximately 160MHz. Therefore, by incorporating a high-pass filter and a low-pass filter, the feedback circuit 572 functions as a band-pass filter that allows a predetermined frequency band of the drive signal COMA to pass through.

[0113] Furthermore, the other end of capacitor C4 is connected to terminal Ifb of integrated circuit 500. Thus, the DC component of the high-frequency component of the drive signal COMA, which functions as a feedback circuit 572 that allows specified frequency components to pass, is cut off and fed back to terminal Ifb.

[0114] Furthermore, the drive signal COMA output from terminal Out is a signal smoothed by the demodulation circuit 560 after the amplified modulation signal AMs based on the fundamental drive signal dA. Then, the drive signal COMA is integrated / subtracted via terminal Vfb and fed back to adder 512. Therefore, the drive signal output circuit 51a oscillates self-excitedly at a frequency determined by the feedback delay and the feedback transfer function. However, the delay of the feedback path via terminal Vfb is relatively large, so sometimes the self-excited oscillation frequency cannot be high enough to sufficiently ensure the accuracy of the drive signal COMA through feedback alone via terminal Vfb. Therefore, by setting a path for the high-frequency components of the feedback drive signal COMA via terminal Ifb, different from the path via terminal Vfb, the delay from the perspective of the entire circuit is reduced. Thus, compared to the case where there is no path via terminal Ifb, the frequency of voltage As can be increased to a level sufficient to ensure the accuracy of the drive signal COMA.

[0115] Here, from the viewpoint of reducing heat generation in the drive signal output circuit 51a while ensuring sufficient accuracy of the drive signal COMA, the oscillation frequency of the self-excited oscillation in the drive signal output circuit 51a of this embodiment is preferably 1MHz or more and 8MHz or less. In particular, when reducing the power consumption of the liquid ejection device 1, the oscillation frequency of the self-excited oscillation in the drive signal output circuit 51a is preferably 1MHz or more and 4MHz or less. In other words, from the viewpoint of reducing heat generation in the switching elements M1 and M2, the drive frequency of the switching elements M1 and M2 is preferably 1MHz or more and 8MHz or less. Furthermore, when reducing the power consumption of the liquid ejection device 1 by reducing the losses generated in the switching elements M1 and M2, the drive frequency of the switching elements M1 and M2 is preferably 1MHz or more and 4MHz or less.

[0116] In the liquid ejection device 1 of this embodiment, the drive signal output circuit 51a smooths the amplified modulation signal AMs to generate a drive signal COMA, and supplies the drive signal COMA to the piezoelectric element 60 of the printhead 20. Then, the piezoelectric element 60 is driven by the signal waveform included in the supplied drive signal COMA. Then, an amount of ink corresponding to the drive of the piezoelectric element 60 is ejected from the ejection section 600.

[0117] After performing spectral analysis on the signal waveform of the drive signal COMA that drives the piezoelectric element 60, it is known that the drive signal COMA includes frequency components of 50 kHz or higher. When generating a signal waveform of the drive signal COMA that includes such frequency components of 50 kHz or higher with high precision, if the frequency of the modulation signal is lower than 1 MHz, passivation occurs at the edges of the signal waveform of the drive signal COMA output from the drive signal output circuit 51a. In other words, in order to generate a signal waveform of the drive signal COMA with high precision, the frequency of the modulation signal Ms needs to be 1 MHz or higher. Moreover, when the oscillation frequency of the self-excited oscillation of the drive signal output circuit 51a, i.e., the drive frequency of the switching elements M1 and M2, is lower than 1 MHz, the waveform precision of the drive signal COMA decreases, thus reducing the drive precision of the piezoelectric element 60. As a result, the ejection characteristics of the ink ejected from the liquid ejection device 1 may deteriorate.

[0118] To address this issue, by setting the frequency of the modulation signal Ms and the oscillation frequency of the self-excited oscillation of the drive signal output circuit 51a, i.e., the drive frequency of the switching elements M1 and M2, to 1MHz or higher, the possibility of passivation occurring at the edges of the drive signal COMA signal waveform is reduced. In other words, the waveform accuracy of the drive signal COMA signal waveform is improved, and the driving accuracy of the piezoelectric element 60 driven based on the drive signal COMA is improved. Therefore, the possibility of deterioration in the ejection characteristics of the ink ejected from the liquid ejection device 1 is reduced.

[0119] However, if the frequency of the modulation signal Ms and the oscillation frequency of the self-excited oscillation of the drive signal output circuit 51a, i.e., the driving frequency of the switching elements M1 and M2, are increased, the switching losses on the switching elements M1 and M2 will increase. These switching losses from the switching elements M1 and M2 increase the power consumption and heat generation in the drive signal output circuit 51a. In other words, if the oscillation frequency of the self-excited oscillation of the drive signal output circuit 51a, i.e., the driving frequency of the switching elements M1 and M2, is made too high, the switching losses in the switching elements M1 and M2 will increase. As a result, one of the advantages of Class D amplifiers, which offer linear amplification compared to Class AB amplifiers,—namely, power saving and heat saving—may be compromised. From the viewpoint of reducing the switching losses of such switching elements M1 and M2, the frequency of the modulation signal Ms and the oscillation frequency of the self-excited oscillation of the drive signal output circuit 51a, i.e. the driving frequency of the switching elements M1 and M2, are preferably 8MHz or less. In particular, when it is required to improve the power saving of the liquid ejection device 1, the driving frequency of the switching elements M1 and M2 is preferably 4MHz or less.

[0120] Therefore, in the drive signal output circuit 51a using a Class D amplifier, from the viewpoint of balancing the improvement of the accuracy of the output drive signal COMA signal waveform and power saving, the oscillation frequency of the self-excited oscillation of the drive signal output circuit 51a, i.e. the drive frequency of the switching elements M1 and M2, is preferably 1MHz or more and 8MHz or less. In particular, in order to reduce the power consumption of the liquid ejection device 1, the oscillation frequency of the self-excited oscillation of the drive signal output circuit 51a, i.e. the drive frequency of the switching elements M1 and M2, is preferably 1MHz or more and 4MHz or less.

[0121] Here, the oscillation frequency of the self-excited oscillation of the drive signal output circuit 51a, i.e. the drive frequency of the switching elements M1 and M2, includes the frequency of the modulation signal Ms, the frequency of the gate signals Hgd and Lgd, and the frequency of the amplified modulation signal AMs, etc.

[0122] As described above, the drive signal output circuit 51a includes an integrated circuit 500 that receives a basic drive signal dA and outputs gate signals Hgd and Lgd, a switching element M1 that operates via the gate signal Hgd, a switching element M2 that operates via the gate signal Lgd, and a demodulation circuit 560. The integrated circuit 500 outputs gate signals Hgd and Lgd corresponding to the modulation signal Ms obtained by modulating the basic drive signal dA. The terminal ts1 of the switching element M1 is electrically connected to the terminal td2 of the switching element M2. The demodulation circuit 560 demodulates the signal at the connection point where the terminals ts1 and td2 are electrically connected and outputs it as a drive signal COMA.

[0123] 5. Structure of the drive circuit board with the drive signal output circuit installed.

[0124] Here, in the liquid ejection device 1, most of the ink ejected from the nozzle 651 lands on the medium P, thereby forming an image. However, a portion of the ink ejected from the nozzle 651 atomizes before landing on the medium P and floats inside the liquid ejection device 1. Furthermore, even after the ink ejected from the nozzle 651 lands on the medium P, it may sometimes atomize again and float due to airflow or other factors accompanying the transport of the medium P. This ink mist floating inside the liquid ejection device 1 is extremely small, so it becomes charged through the Lenard effect and is attracted to various circuits provided inside the liquid ejection device 1. Moreover, when this ink mist adheres to the circuits provided inside the liquid ejection device 1, the stability of the operation of the liquid ejection device 1 decreases.

[0125] In particular, in the liquid ejection device 1 of this embodiment, drive signal output circuits 51a and 51b supply drive signals COMA and COMB to more than 5,000 piezoelectric elements 60. Therefore, a large current flows through the various circuits included in drive signal output circuits 51a and 51b that generate drive signals COMA and COMB based on voltage VHV, and along the propagation path of the drive signals COMA and COMB output from drive signal output circuits 51a and 51b. As a result, a large amount of ink mist is attracted into these circuits and the wiring path. If ink mist adheres to the various circuits included in drive signal output circuits 51a and 51b that generate drive signals COMA and COMB based on voltage VHV, and along the propagation path of the drive signals COMA and COMB output from drive signal output circuits 51a and 51b, the waveform accuracy of the drive signals COMA and COMB may be reduced, leading to a decrease in the ejection accuracy of the ink from the printhead 20.

[0126] Therefore, in the liquid ejection device 1, for the various circuits including the drive signal output circuits 51a and 51b that generate drive signals COMA and COMB based on voltage VHV, the propagation path of drive signals COMA and COMB, and especially for the exposed part of the charging section, it is required to reduce the possibility of ink mist adhesion.

[0127] To address this requirement, the liquid ejection device 1 of this embodiment includes drive signal output circuits 51a and 51b that can reduce the possibility of ink mist adhering to the charging unit. Hereinafter, an example of the structure of the drive signal output circuits 51a and 51b that can reduce the possibility of ink mist adhering to the charging unit will be described. Furthermore, as described above, drive signal output circuits 51a and 51b have the same structure; therefore, drive signal output circuit 51a will be used for description hereafter, and the description of the structure of drive signal output circuit 51b will be omitted.

[0128] In describing one example of the structure of the drive signal output circuits 51a and 51b, the structure of the switching elements M1 and M2 used in the drive signal output circuits 51a and 51b of this embodiment will first be described. Furthermore, since switching elements M1 and M2 have the same structure, in the following description, unless it is necessary to distinguish between switching elements M1 and M2, they will sometimes be referred to simply as switching element M. In this case, we will assume that switching element M includes the transistor chip Tr1 corresponding to switching element M1 and the transistor chip Tr2 corresponding to switching element M2, the terminal tg1 corresponding to switching element M1 and the terminal tg2 corresponding to switching element M2, the terminal td1 corresponding to switching element M1 and the terminal td2 corresponding to switching element M2, and the terminal ts1 corresponding to switching element M1 and the terminal ts2 corresponding to switching element M2.

[0129] Figures 5-8 This is a diagram illustrating an example of the structure of the switching element M. In the following description, mutually orthogonal X-axis, Y-axis, and Z-axis will be used. Furthermore, in the following description, when the direction along the X-axis is specified, the starting side of the arrow in the diagram is sometimes referred to as the -X side, and the selected side as the +X side; when the direction along the Y-axis is specified, the starting side of the arrow in the diagram is sometimes referred to as the -Y side, and the selected side as the +Y side; when the direction along the Z-axis is specified, the starting side of the arrow in the diagram is sometimes referred to as the -Z side, and the selected side as the +Z side.

[0130] like Figures 5-8 As shown, the switching element M has a molded portion Mo and terminals tg, td, and ts disposed around the molded portion Mo.

[0131] The molding part Mo is a roughly hexahedron comprising surfaces Su, Sd, Sf, Sb, Sl, and Sr. Specifically, surfaces Su and Sd are arranged relative to each other along the Z-axis with Sd as the -Z side and Su as the +Z side, surfaces Sf and Sb are arranged relative to each other along the X-axis with Sf as the -X side and Sb as the +X side, and surfaces Sl and Sr are arranged relative to each other along the Y-axis with Sl as the -Y side and Sr as the +Y side.

[0132] Furthermore, a reference direction mark Mrk is provided on the surface Su of the molding portion Mo. The reference direction mark Mrk is a mark indicating the position of a reference terminal among the terminals tg, td, and ts of the switching element M. In the case of the switching element M in this embodiment, it is provided at the position corresponding to terminal ts. That is, the molding portion Mo includes a reference direction mark Mrk indicating the direction of the switching element M. This reference direction mark Mrk can be formed, for example, by embossing the molding portion Mo, or by printing specific text or symbols on the molding portion Mo.

[0133] The aforementioned transistor chip Tr is located inside the molding portion Mo. That is, the molding portion Mo covers the transistor chip Tr. Thus, the molding portion Mo protects the transistor chip Tr from external impacts and the influence of external air, and insulates the transistor chip Tr.

[0134] Here, the liquids used in the liquid ejection device 1 are diverse. Besides water-based inks such as water-based pigment inks and water-based dye inks, solvent-based inks such as solvent-based inks using organic solvents, and UV-curable inks that cure by irradiation with ultraviolet light, etc., are also included. Therefore, the properties of the ink mist floating inside the liquid ejection device 1 are also diverse, requiring the molding part Mo to have high tolerance to the properties of various liquids. In particular, when using solvent-based inks using organic solvents, the organic solvent reacts with the molding part Mo, causing it to dissolve, which may reduce the reliability of the drive signal output circuits 51a and 51b.

[0135] In the liquid ejection device 1 of this embodiment, the molding portion Mo of each of the switching elements M1 and M2, which are the drive signal output circuits 51a and 51b, is made of epoxy resin containing glycidyl polybutadiene. That is, the molding portion Mo of each of the switching elements M1 and M2 is an epoxy resin containing glycidyl polybutadiene. Therefore, the molding portion Mo has high tolerance to the properties of a wide variety of liquids, and even when dripping with solvent-based inks, the possibility of dissolution of the molding portion Mo can be reduced. As a result, even when the liquid ejection device 1 is used for a long period of time, the reliability of the switching elements M1 and M2, as well as the drive signal output circuits 51a and 51b including the switching elements M1 and M2, can be improved.

[0136] When viewing the switching element M along the Z-axis from the +Z side to the -Z side, and when viewing the molded portion Mo from surface Su to surface Sd, terminals tg, ts, and td are all positioned overlapping surface Su of the molded portion Mo. In other words, when viewing the switching element M along the Z-axis from the +Z side to the -Z side, and when viewing the molded portion Mo from surface Su to surface Sd, terminals tg, ts, and td are only positioned overlapping surface Su of the molded portion Mo, and not positioned not overlapping surface Su. That is, when viewing the switching element M from the +Z side to the -Z side, and when viewing the molded portion Mo from surface Su to surface Sd, terminals tg, ts, and td do not protrude from any of the +X, -X, +Y, and -Y sides of the molded portion Mo.

[0137] Specifically, the terminal td includes an electrode tdm and four electrodes tds. The electrode tdm is formed on the surface Sd of the molding portion Mo. The four electrodes tds are located on the +X side of the electrode tdm, and are arranged side-by-side along the Y-axis while in contact with the electrode tdm on the -X side. At this time, the four electrodes tds are formed within the range from surface Sd to surface Sb of the molding portion Mo. Furthermore, a recess is formed in the area where the four electrodes tds are located within surface Sb of the molding portion Mo. That is, the four electrodes tds included in the terminal td are respectively located at positions corresponding to the four recesses formed on surface Sb. Therefore, when viewing the switching element M along the Z-axis from the +Z side to the -Z side, and when viewing the molding portion Mo from surface Su to surface Sd, the terminal td does not protrude from the +X side of the molding portion Mo, but is only positioned at a position overlapping with surface Su of the molding portion Mo.

[0138] Terminal ts includes electrode tsm and three electrodes tss. Electrode tsm is formed on surface Sd of molding portion Mo, on the -X side of electrode tdm. The three electrodes tss are located on the -X side of electrode tsm, and are arranged side by side along the Y-axis while in contact with electrode tdm on the +X side. At this time, the three electrodes tss are formed within the range from surface Sd to surface Sf of molding portion Mo. In addition, a recess is formed in the area where the three electrodes tss are located in surface Sf of molding portion Mo. That is, the three electrodes tss included in terminal ts are located at positions corresponding to the three recesses formed in surface Sf. Therefore, when viewing the switching element M along the Z-axis from the +Z side to the -Z side, and when viewing the molding portion Mo from surface Su to surface Sd, terminal ts does not protrude from the -X side of molding portion Mo, but is only provided at a position overlapping surface Su of molding portion Mo.

[0139] In the surface Sd of the molding portion Mo, a terminal tg is formed on the -X side of the electrode tdm and the +Y side of the electrode tsm. At this time, the terminal tg is formed within the range from surface Sd to surface Sf of the molding portion Mo. Furthermore, a recess is formed in the area where the terminal tg is located within surface Sf of the molding portion Mo. That is, the terminal tg is located at a position corresponding to the recess formed in surface Sf. Therefore, when viewing the switching element M along the Z-axis from the +Z side to the -Z side, and when viewing the molding portion Mo from surface Su to surface Sd, the terminal tg does not protrude from the -X side of the molding portion Mo, but is only positioned at a position overlapping with surface Su of the molding portion Mo.

[0140] As described above, the switching element M used in the drive signal output circuits 51a and 51b of this embodiment includes: a transistor chip Tr; terminals tg, td, and ts electrically connected to the transistor chip Tr; and a molded portion Mo covering the transistor chip Tr. In the direction of moving the switching element M along the Z-axis from the +Z side to the -Z side, and in the direction of moving the molded portion Mo from the surface Su to the surface Sd, the terminals tg, td, and ts are only disposed at positions overlapping with the molded portion Mo.

[0141] Next, the structure of the drive signal output circuit 51a of the switching elements M, namely switching elements M1 and M2, including the structure described above, will be explained. Here, in the following description, the molding portion Mo included in the switching element M1 will sometimes be referred to as molding portion Mo1, and the surfaces Su, Sd, Sf, Sb, Sl, and Sr included in the molding portion Mo1 will sometimes be referred to as surfaces Su1, Sd1, Sf1, Sb1, Sl1, and Sr1. The molding portion Mo included in the switching element M2 will sometimes be referred to as molding portion Mo2, and the surfaces Su, Sd, Sf, Sb, Sl, and Sr included in the molding portion Mo2 will sometimes be referred to as surfaces Su2, Sd2, Sf2, Sb2, Sl2, and Sr2.

[0142] Figure 9 This is a diagram illustrating the structure of the drive signal output circuit 51a. Here, in Figure 9 In this section, we will explain the use of x-axis, y-axis, and z-axis, which are independent of the aforementioned x-axis, y-axis, and z-axis, i.e., mutually orthogonal. Furthermore, in the following explanation, when the direction along the x-axis is specified, the starting side of the arrow in the illustration is sometimes referred to as the -x side, and the selected side as the +x side; when the direction along the y-axis is specified, the starting side of the arrow in the illustration is sometimes referred to as the -y side, and the selected side as the +y side; when the direction along the z-axis is specified, the starting side of the arrow in the illustration is sometimes referred to as the -z side, and the selected side as the +z side. Additionally, in Figure 9 The diagrams of circuit elements that constitute part of the drive signal output circuit 51a are omitted or simplified.

[0143] like Figure 9 As shown, the drive signal output circuit 51a includes an integrated circuit 500, switching elements M1 and M2, a coil L1, capacitors C1 and Cd, and a wiring substrate 55. Furthermore, in the drive signal output circuit 51a, the integrated circuit 500, switching elements M1 and M2, coil L1, and capacitors C1 and Cd are disposed on the wiring substrate 55. This wiring substrate 55 has a wiring pattern for electrically connecting various circuit elements including the integrated circuit 500, switching elements M1 and M2, coil L1, and capacitors C1 and Cd. Additionally, in... Figure 9The diagram illustrates a case where the integrated circuit 500, switching elements M1 and M2, coil L1, and capacitors C1 and Cd are mounted only on the +z side of the wiring substrate 55. However, any one of the switching elements M1, M2, coil L1, and capacitors C1 and Cd can also be mounted on the -z side. Furthermore, the wiring substrate 55 can also be a so-called multilayer substrate having multiple wiring layers between the +z side and the -z side.

[0144] Switching element M1 and switching element M2 are arranged side by side along the x-axis of wiring substrate 55 with switching element M1 on the -x side and switching element M2 on the +x side.

[0145] Specifically, the switching element M1 is disposed on the wiring substrate 55 such that the surface Sf1, on which a portion of terminal tg1 and a portion of terminal ts1 are disposed, is located on the +x side; the surface Sb1, on which a portion of terminal td1 is disposed, is located on the -x side; and the surface Sd1, on which terminals tg1, td1, and ts1 are disposed, is in contact with the surface of the wiring substrate 55 on the +z side. That is, along the z-axis, the switching element M1 has surface Sf1 on the +z side, surface Sd1 on the -z side, and surface Sd1 in contact with the wiring substrate 55. Therefore, when viewing the switching element M1 along the z-axis from the +z side to the -z side in the direction normal to the wiring substrate 55, terminals tg1, td1, and ts1 are only disposed at positions overlapping with the molding portion Mo1. In other words, when viewing the switching element M1 along the z-axis from the +z side to the -z side in the direction normal to the wiring substrate 55, terminals tg1, ts1, and td1 are only provided at positions overlapping with the surface Su1 of the molding portion Mo1, and are not provided at positions not overlapping with the surface Su1 of the molding portion Mo1. That is, when viewing the switching element M1 along the z-axis from the +z side to the -z side in the direction normal to the wiring substrate 55, terminals tg1, ts1, and td1 do not protrude from any of the +X side, -X side, +Y side, and -Y side of the molding portion Mo1.

[0146] Furthermore, in the switching element M1, terminal td1 is electrically connected to the wiring pattern p1 of the wiring substrate 55, terminal tg1 is electrically connected to the wiring pattern p2 of the wiring substrate 55, and terminal ts1 is electrically connected to the wiring pattern p3 of the wiring substrate 55.

[0147] Switching element M2 is disposed on the wiring substrate 55 on the +x side of switching element M1, with surface Sf2, where a portion of terminal tg2 and a portion of terminal ts2 are disposed on the +x side, surface Sb2, where a portion of terminal td2 is disposed on the -x side, and surface Sd2, where terminals tg2, td2, and ts2 are disposed, contacting the surface of wiring substrate 55 on the +z side. That is, along the z-axis, surface Sf2 of switching element M2 is located on the +z side, surface Sd2 is located on the -z side, and surface Sd2 is in contact with wiring substrate 55. Therefore, when viewing switching element M2 along the z-axis from the +z side to the -z side in the direction normal to wiring substrate 55, terminals tg2, td2, and ts2 are only disposed at positions overlapping with molding portion Mo2. In other words, when viewing the switching element M2 along the z-axis from the +z side to the -z side in the direction normal to the wiring substrate 55, terminals tg2, ts2, and td2 are only provided at positions overlapping with the surface Su2 of the molding portion Mo2, and are not provided at positions not overlapping with the surface Su2 of the molding portion Mo2. That is, when viewing the switching element M2 along the z-axis from the +z side to the -z side in the direction normal to the wiring substrate 55, terminals tg2, ts2, and td2 do not protrude from any of the +X side, -X side, +Y side, and -Y side of the molding portion Mo2.

[0148] Furthermore, terminal td2 is electrically connected to wiring pattern p3 of wiring substrate 55, terminal tg2 is electrically connected to wiring pattern p4 of wiring substrate 55, and terminal ts2 is electrically connected to ground wiring pattern pg of wiring substrate 55.

[0149] Integrated circuit 500 is located on the +y side of switching elements M1 and M2, which are arranged side-by-side along the x-axis. Furthermore, in integrated circuit 500, the terminal In for inputting the basic drive signal dA is located on the +y side, while the terminal Hdr for outputting the gate signal Hgd to switching element M1, the terminal Ldr for outputting the gate signal Lgd to switching element M2, and the terminal Sw electrically connected to switching elements M1 and M2 are located on the -y side of integrated circuit 500. Moreover, terminal Hdr is electrically connected to wiring pattern p2, terminal Ldr is electrically connected to wiring pattern p4, and terminal Sw is electrically connected to wiring pattern p3. Additionally, in... Figure 9 The diagrams of resistor R1, which is located between terminal Hdr and terminal tg1 of switching element M1, and resistor R2, which is located between terminal Ldr and terminal tg2 of switching element M2, are omitted.

[0150] Coil L1 is located on the -y side of switching elements M1 and M2, which are arranged side by side along the x-axis. Moreover, one end of coil L1 is electrically connected to wiring pattern p3, and the other end of coil L1 is electrically connected to wiring pattern p5.

[0151] Capacitor C1 is located on the +X side of switching elements M1 and M2 and coil L1, which are arranged in parallel along the x-axis. One end of capacitor C1 is electrically connected to wiring pattern p5, and the other end of capacitor C1 is electrically connected to ground wiring pattern pg.

[0152] Capacitor Cd is located on the -X side of coil L1. One end of capacitor Cd is electrically connected to wiring pattern p1, and the other end of capacitor C1 is electrically connected to ground wiring pattern pg.

[0153] In the drive signal output circuit 51a configured as described above, a voltage VHV is supplied to the wiring pattern p1. The wiring pattern p1 is electrically connected to the positive terminal of the capacitor Cd, which is an electrolytic capacitor, and the terminal td1 of the switching element M1. At this time, the capacitor Cd functions as a stabilizing capacitor to reduce the possibility of voltage fluctuations in VHV.

[0154] Furthermore, terminal tg1 of switching element M1 is electrically connected to terminal Hdr of integrated circuit 500 via wiring pattern p2, and terminal ts1 of switching element M1 is electrically connected to wiring pattern p3. The switching element M1, disposed on wiring substrate 55 as described above, changes the electrical connection between terminals td1 and ts1 based on the gate signal Hgd input via wiring pattern p2. That is, switching element M1 switches the conduction state between terminals td1 and ts1 based on the gate signal Hgd, thereby switching whether to supply voltage VHV to wiring pattern p3.

[0155] Terminal td2 of switching element M2 is electrically connected to wiring pattern p3. Additionally, terminal tg2 of switching element M2 is electrically connected to terminal Ldr of integrated circuit 500 via wiring pattern p4, and terminal ts2 of switching element M2 is electrically connected to ground wiring pattern pg, which is supplied with ground potential. The switching element M2, disposed on wiring substrate 55 as described above, changes the electrical connection between terminals td2 and ts2 based on the gate signal Lgd input via wiring pattern p4. That is, switching element M2 switches the conduction state between terminals td2 and ts2 based on the gate signal Lgd, thereby switching whether the potential of wiring pattern p3 is set to ground potential.

[0156] As described above, wiring pattern p3 is electrically connected to terminal ts1 of switching element M1 and terminal td2 of switching element M2. Therefore, based on gate signals Hgd and Lgd, an amplified modulation signal AMs is output to wiring pattern p3, with a voltage value varying between voltage VHV and ground potential.

[0157] Additionally, one end of coil L1 is electrically connected to wiring pattern p3. The other end of coil L1 is electrically connected to wiring pattern p5. One end of capacitor C1 is connected to wiring pattern p5, and the other end of capacitor C1 is electrically connected to ground wiring pattern pg. Thus, coil L1 and capacitor C1 constitute a low-pass filter. As a result, a drive signal COMA is generated in wiring pattern p5 after demodulating the amplified modulation signal Ams. The drive signal COMA generated in wiring pattern p5 is output from drive signal output circuit 51a.

[0158] Here, the drive signal output circuit 51b of the drive circuit 50 can be disposed together with the drive signal output circuit 51a on the wiring substrate 55, or it can be disposed on a different substrate than the wiring substrate 55.

[0159] Here, the drive signal COMA is an example of a drive signal, and since the drive signal VOUT is generated by selecting or not selecting the signal waveform of the drive signal COMA, the drive signal VOUT is also an example of a drive signal. Furthermore, the control circuit 100 that outputs the basic drive signal dA is an example of a basic drive signal output circuit. Additionally, the gate signal Hgd included in the drive signal output circuit 51a is an example of a first control signal, the gate signal Lgd is an example of a second control signal, the switching element M1 is an example of a first switching element, and the switching element M2 is an example of a second switching element. Furthermore, the transistor chip Tr1 included in the switching element M1 is an example of a first transistor chip, the terminal tg1 is an example of a first terminal, the terminal ts1 is an example of a second terminal, the terminal td1 is an example of a third terminal, the molding portion Mo1 is an example of a first molding component, and the reference direction mark Mrk formed on the molding portion Mo1 is an example of a direction indicator mark. Furthermore, the transistor chip Tr2 included in the switching element M2 is an example of a second transistor chip, the terminal tg2 is an example of a fourth terminal, the terminal td2 is an example of a fifth terminal, the terminal ts2 is an example of a sixth terminal, and the molding part Mo2 is an example of a second molding component. Moreover, in the direction along the z-axis, the direction from the +z side to the -z side is an example of a normal direction.

[0160] 6. Effects

[0161] As described above, in the liquid ejection device 1 of this embodiment, when viewing the switching element M1 along the z-axis from the +z side to the -z side along the normal direction of the wiring substrate 55, the terminals tg1, td1, and ts1 are only provided at positions overlapping with the molding portion Mo1. That is, the terminals tg1, ts1, and td1 of the switching element M1, which are exposed at the charging portion of the various circuits that generate the drive signal COMA based on the voltage VHV included in the drive signal output circuit 51a through which a large current flows, are blocked by the molding portion Mo1. As a result, the possibility of ink mist adhering to the terminals tg1, ts1, and td1 of the switching element M1 is reduced. Consequently, the signal accuracy of the drive signal COMA output by the drive signal output circuit 51a is improved, and the ejection accuracy of the ink from the printhead 20 including the drive signal output circuit 51a is improved.

[0162] Furthermore, in the liquid ejection device 1 of this embodiment, when viewing the switching element M2 along the z-axis from the +z side to the -z side along the normal direction of the wiring substrate 55, the terminals tg2, td2, and ts2 are only disposed at positions overlapping with the molding portion Mo2. That is, the terminals tg2, ts2, and td2 of the switching element M2, which are exposed at the charging portion and include various circuits in the drive signal output circuit 51a that generate the drive signal COMA based on the voltage VHV, are blocked by the molding portion Mo2. As a result, the possibility of ink mist adhering to the terminals tg2, ts2, and td2 of the switching element M2 is reduced. Consequently, the signal accuracy of the drive signal COMA output by the drive signal output circuit 51a is further improved, and the ejection accuracy of the ink from the printhead 20 including the drive signal output circuit 51a is further improved.

[0163] The embodiments and variations have been described above, but the present invention is not limited to these embodiments and can be implemented in various ways without departing from its spirit. For example, the embodiments described above can also be appropriately combined.

[0164] This invention includes structures that are substantially the same as those described in the embodiments (e.g., structures with the same function, method, and result, or structures with the same purpose and effect). Additionally, this invention includes structures that replace non-essential parts of the structures described in the embodiments. Furthermore, this invention includes structures that perform the same function or effect as those described in the embodiments, or structures that can achieve the same purpose. Additionally, this invention includes structures incorporating known techniques into the configurations described in the embodiments.

[0165] The following content is derived from the above implementation method.

[0166] One method of liquid ejection device includes:

[0167] The nozzle ejects liquid driven by a piezoelectric element;

[0168] A drive signal output circuit outputs a drive signal to drive the piezoelectric element; and

[0169] The basic drive signal output circuit outputs a basic drive signal that serves as the basis for the aforementioned drive signal.

[0170] The drive signal output circuit has:

[0171] An integrated circuit, wherein the basic driving signal is input to the integrated circuit, and the integrated circuit outputs a first control signal;

[0172] The first switching element is activated by the first control signal; and

[0173] The wiring substrate is provided with the integrated circuit and the first switching element.

[0174] The first switching element includes:

[0175] First transistor chip;

[0176] The first terminal, the second terminal, and the third terminal are electrically connected to the first transistor chip; and

[0177] A first molded component covers the first transistor chip.

[0178] The conduction state between the second terminal and the third terminal is controlled according to the first control signal input to the first terminal.

[0179] Along the normal direction of the wiring substrate, the first terminal, the second terminal, and the third terminal are disposed only at positions overlapping with the first molded component.

[0180] According to this liquid ejection device, along the normal direction of the wiring substrate, the first, second, and third terminals of the first switching element are only disposed at positions overlapping with the first molding component, thereby reducing the possibility of liquid mist adhering to the first, second, and third terminals of the first switching element. As a result, the waveform accuracy of the drive signal output by the drive signal output circuit is improved, and the ejection accuracy of the ink from the ejector head is improved.

[0181] In one embodiment of the liquid ejection device,

[0182] Alternatively, the first molded component may include a direction indicator mark representing the direction of the first switching element.

[0183] According to the liquid ejection device, even when the first terminal, second terminal and third terminal of the first switching element are located at positions overlapping with the first molding component, the mounting direction of the first switching element can be determined.

[0184] In one embodiment of the liquid ejection device,

[0185] Alternatively, the first molded component may be made of an epoxy resin containing polybutadiene with glycidyl groups.

[0186] According to this liquid ejection device, even when using solvent inks or other materials that use organic solvents as a medium, the possibility of malfunction in the first switching element is reduced.

[0187] In one embodiment of the liquid ejection device,

[0188] Alternatively, the drive signal output circuit may supply the drive signal to more than 5,000 piezoelectric elements.

[0189] According to this liquid ejection device, since the possibility of liquid mist adhering to the first, second, and third terminals of the first switching element is reduced, and since the drive signal output circuit supplies drive signals to more than 5,000 piezoelectric elements, even when a large current is generated along with the propagation of the drive signal, the possibility of the waveform accuracy of the drive signal output by the drive signal output circuit is reduced, and the possibility of the ejection accuracy of the ink from the ejection head is reduced.

[0190] In one embodiment of the liquid ejection device,

[0191] Alternatively, the integrated circuit may output a second control signal.

[0192] The drive signal output circuit has a second switching element, which is disposed on the wiring substrate and is activated by the second control signal.

[0193] The second switching element includes:

[0194] Second transistor chip;

[0195] The fourth, fifth, and sixth terminals are electrically connected to the second transistor chip; and

[0196] A second molded component covers the second transistor chip.

[0197] The conduction state of the fifth terminal and the sixth terminal is controlled according to the second control signal input to the fourth terminal.

[0198] Along the normal direction of the wiring substrate, the fourth terminal, the fifth terminal, and the sixth terminal are disposed only at positions overlapping with the second molded component.

[0199] According to this liquid ejection device, along the normal direction of the wiring substrate, the fourth, fifth, and sixth terminals of the second switching element are only disposed at positions overlapping with the second molding component, thereby reducing the possibility of liquid mist adhering to the fourth, fifth, and sixth terminals of the second switching element. As a result, the waveform accuracy of the drive signal output by the drive signal output circuit is further improved, and the ejection accuracy of the ink from the ejector head is further improved.

[0200] In one embodiment of the liquid ejection device,

[0201] Alternatively, the drive signal output circuit may include a demodulation circuit.

[0202] The integrated circuit outputs a first control signal and a second control signal corresponding to a modulation signal obtained by modulating the basic drive signal.

[0203] The second terminal is electrically connected to the fifth terminal.

[0204] The demodulation circuit demodulates the signal at the connection point where the second terminal and the fifth terminal are electrically connected and outputs it as the drive signal.

[0205] According to the liquid ejection device, the drive signal output circuit amplifies the basic drive signal and outputs a drive signal by switching the first and second switching elements. That is, the drive signal output circuit performs a D-level amplification on the basic drive signal and outputs the drive signal. This improves the amplification efficiency in the drive signal output circuit and reduces the possibility of increased power consumption even when outputting a drive signal accompanied by a large current.

[0206] One way the printhead has this feature:

[0207] The nozzle ejects liquid according to the drive of a piezoelectric element; and

[0208] The drive signal output circuit outputs a drive signal to drive the piezoelectric element.

[0209] The drive signal output circuit has:

[0210] An integrated circuit is used as the basis for the driving signal, the basic driving signal is input to the integrated circuit, and the integrated circuit outputs a first control signal;

[0211] The first switching element is activated by the first control signal; and

[0212] The wiring substrate is provided with the integrated circuit and the first switching element.

[0213] The first switching element includes:

[0214] First transistor chip;

[0215] The first terminal, the second terminal, and the third terminal are electrically connected to the first transistor chip; and

[0216] A first molded component covers the first transistor chip.

[0217] The conduction state between the second terminal and the third terminal is controlled according to the first control signal input to the first terminal.

[0218] Along the normal direction of the wiring substrate, the first terminal, the second terminal, and the third terminal are disposed only at positions overlapping with the first molded component.

[0219] According to this printhead, along the normal direction of the wiring substrate, the first, second, and third terminals of the first switching element are only located at positions overlapping with the first molding component, thereby reducing the possibility of liquid mist adhering to the first, second, and third terminals of the first switching element. As a result, the waveform accuracy of the drive signal output by the drive signal output circuit is improved, and the ink ejection accuracy from the printhead is improved.

[0220] In one configuration of the printhead,

[0221] Alternatively, the first molded component may include a direction indicator mark representing the direction of the first switching element.

[0222] According to this printhead, even when the first terminal, second terminal, and third terminal of the first switching element are located at positions overlapping with the first molding component, the mounting direction of the first switching element can be determined.

[0223] In one configuration of the printhead,

[0224] Alternatively, the first molded component may be made of an epoxy resin containing polybutadiene with glycidyl groups.

[0225] According to this printhead, even when using solvent inks or other materials that use organic solvents as a medium, the possibility of malfunction in the first switching element is reduced.

[0226] In one configuration of the printhead,

[0227] Alternatively, the drive signal output circuit may supply the drive signal to more than 5,000 piezoelectric elements.

[0228] According to this printhead, since the possibility of liquid mist adhering to the first, second, and third terminals of the first switching element is reduced, and since the drive signal output circuit supplies drive signals to more than 5,000 piezoelectric elements, even when a large current is generated along with the propagation of the drive signal, the possibility of the waveform accuracy of the drive signal output by the drive signal output circuit is reduced, and the possibility of the ink ejection accuracy from the printhead is reduced.

[0229] In one configuration of the printhead,

[0230] Alternatively, the integrated circuit may output a second control signal.

[0231] The drive signal output circuit has a second switching element, which is disposed on the wiring substrate and is activated by the second control signal.

[0232] The second switching element includes:

[0233] Second transistor chip;

[0234] The fourth, fifth, and sixth terminals are electrically connected to the second transistor chip; and

[0235] A second molded component covers the second transistor chip.

[0236] The conduction states of the fifth and sixth terminals are controlled according to the second control signal input to the fourth terminal.

[0237] Along the normal direction of the wiring substrate, the fourth terminal, the fifth terminal, and the sixth terminal are disposed only at positions overlapping with the second molded component.

[0238] According to this printhead, along the normal direction of the wiring substrate, the fourth, fifth, and sixth terminals of the second switching element are only located at positions overlapping with the second molding component, thereby reducing the possibility of liquid mist adhering to the fourth, fifth, and sixth terminals of the second switching element. As a result, the waveform accuracy of the drive signal output by the drive signal output circuit is further improved, and the ink ejection accuracy from the printhead is further improved.

[0239] In one configuration of the printhead,

[0240] Alternatively, the drive signal output circuit may include a demodulation circuit.

[0241] The integrated circuit outputs a first control signal and a second control signal corresponding to a modulation signal obtained by modulating the basic drive signal.

[0242] The second terminal is electrically connected to the fifth terminal.

[0243] The demodulation circuit demodulates the signal at the connection point where the second terminal and the fifth terminal are electrically connected and outputs it as the drive signal.

[0244] According to this printhead, the drive signal output circuit amplifies the basic drive signal and outputs a drive signal by switching the first and second switching elements. That is, the drive signal output circuit performs D-level amplification on the basic drive signal and outputs the drive signal. This improves the amplification efficiency in the drive signal output circuit and reduces the possibility of increased power consumption even when outputting a drive signal accompanied by a large current.

Claims

1. A liquid ejection device, characterized in that, have: The nozzle ejects liquid driven by a piezoelectric element; A drive signal output circuit outputs a drive signal to drive the piezoelectric element; and The basic drive signal output circuit outputs a basic drive signal that serves as the basis for the aforementioned drive signal. The drive signal output circuit has: An integrated circuit, wherein the basic driving signal is input to the integrated circuit, and the integrated circuit outputs a first control signal; The first switching element operates upon the first control signal; as well as The wiring substrate is provided with the integrated circuit and the first switching element. The first switching element includes: First transistor chip; The first terminal, the second terminal, and the third terminal are electrically connected to the first transistor chip; and A first molded component covers the first transistor chip. The conduction state between the second terminal and the third terminal is controlled according to the first control signal input to the first terminal. Along the normal direction of the wiring substrate, the first terminal, the second terminal, and the third terminal are only disposed at positions overlapping with the first molded component. The first molded component includes a direction indicator mark indicating the direction of the first switching element. The first molded component is made of an epoxy resin containing polybutadiene containing glycidyl groups.

2. The liquid ejection device according to claim 1, characterized in that, The drive signal output circuit supplies the drive signal to more than 5,000 piezoelectric elements.

3. The liquid ejection device according to claim 1 or 2, characterized in that, The integrated circuit outputs a second control signal. The drive signal output circuit has a second switching element, which is disposed on the wiring substrate and is activated by the second control signal. The second switching element includes: Second transistor chip; The fourth, fifth, and sixth terminals are electrically connected to the second transistor chip; and A second molded component covers the second transistor chip. The conduction state of the fifth terminal and the sixth terminal is controlled according to the second control signal input to the fourth terminal. Along the normal direction of the wiring substrate, the fourth terminal, the fifth terminal, and the sixth terminal are only disposed at positions overlapping with the second molded component.

4. The liquid ejection device according to claim 3, characterized in that, The drive signal output circuit includes a demodulation circuit. The integrated circuit outputs a first control signal and a second control signal corresponding to a modulation signal obtained by modulating the basic drive signal. The second terminal is electrically connected to the fifth terminal. The demodulation circuit demodulates the signal at the connection point where the second terminal and the fifth terminal are electrically connected and outputs it as the drive signal.

5. A printhead, characterized in that, have: The nozzle ejects liquid according to the drive of a piezoelectric element; and The drive signal output circuit outputs a drive signal to drive the piezoelectric element. The drive signal output circuit has: An integrated circuit is used as the basis for the driving signal, the basic driving signal is input to the integrated circuit, and the integrated circuit outputs a first control signal; The first switching element operates upon the first control signal; as well as The wiring substrate is provided with the integrated circuit and the first switching element. The first switching element includes: First transistor chip; The first terminal, the second terminal, and the third terminal are electrically connected to the first transistor chip; and A first molded component covers the first transistor chip. The conduction state between the second terminal and the third terminal is controlled according to the first control signal input to the first terminal. Along the normal direction of the wiring substrate, the first terminal, the second terminal, and the third terminal are only disposed at positions overlapping with the first molded component. The first molded component includes a direction indicator mark indicating the direction of the first switching element. The first molded component is made of an epoxy resin containing polybutadiene containing glycidyl groups.

6. The printhead according to claim 5, characterized in that, The drive signal output circuit supplies the drive signal to more than 5,000 piezoelectric elements.

7. The printhead according to claim 5 or 6, characterized in that, The integrated circuit outputs a second control signal. The drive signal output circuit has a second switching element, which is disposed on the wiring substrate and is activated by the second control signal. The second switching element includes: Second transistor chip; The fourth, fifth, and sixth terminals are electrically connected to the second transistor chip; and A second molded component covers the second transistor chip. The conduction states of the fifth and sixth terminals are controlled according to the second control signal input to the fourth terminal. Along the normal direction of the wiring substrate, the fourth terminal, the fifth terminal, and the sixth terminal are only disposed at positions overlapping with the second molded component.

8. The printhead according to claim 7, characterized in that, The drive signal output circuit includes a demodulation circuit. The integrated circuit outputs a first control signal and a second control signal corresponding to a modulation signal obtained by modulating the basic drive signal. The second terminal is electrically connected to the fifth terminal. The demodulation circuit demodulates the signal at the connection point where the second terminal and the fifth terminal are electrically connected and outputs it as the drive signal.

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