Liquid ejection device and print head

Abstract

To provide a liquid ejection device enabling solution of the problem that arises since a temperature detection portion is disposed inside a print head.SOLUTION: A liquid ejection device is provided, comprising a drive signal output circuit outputting a drive signal, and a print head ejecting liquid by receiving the drive signal. The print head includes a temperature detection portion detecting temperature information on a pressure chamber. The drive signal output circuit includes: a modulation circuit outputting a modulated signal; an amplification circuit outputting an amplified and modulated signal; a smoothing circuit outputting the drive signal which is the smoothed amplified and modulated signal; and a base drive signal output circuit outputting a base drive signal corrected by the temperature information. The frequency of the amplified and modulated signal when the temperature detection portion detects the temperature information used for correction of the base drive signal by the base drive signal output circuit is higher than the frequency of the amplified and modulated signal when the temperature detection portion detects the temperature information not used for correction of the base drive signal by the base drive signal output circuit.SELECTED DRAWING: Figure 18

Description

Technical Field

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

Background Art

[0002] A liquid ejection device for ejecting a liquid is known to have a configuration including a print head having a piezoelectric element, a pressure chamber, and a nozzle communicating with the pressure chamber. The print head changes the volume of the pressure chamber by driving the piezoelectric element, and ejects the liquid supplied to the pressure chamber from the nozzle. In such a liquid ejection device, there is known a configuration in which the piezoelectric element is driven and controlled based on the temperature of the ink stored in the print head, thereby realizing ejection control suitable for the temperature of the ink. For example, Patent Document 1 discloses a liquid ejection device and a liquid ejection head (print head) that have a temperature detection unit inside a print head having a piezoelectric element, a pressure chamber, and a nozzle, thereby reducing the temperature difference between the detected temperature and the temperature inside the pressure chamber and improving the detection accuracy of the temperature of the pressure chamber.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the liquid ejection device described in Patent Document 1, since a temperature detection unit is provided inside the print head, there is a new possibility of reducing the detection accuracy of the temperature of the pressure chamber, and there is room for further improvement.

Means for Solving the Problems

[0005] One aspect of the liquid ejection device according to the present invention is a drive signal output circuit that outputs a drive signal, A print head that receives the aforementioned drive signal and ejects liquid, Equipped with, The aforementioned print head is A piezoelectric element comprising a first electrode, a second electrode, and a piezoelectric body, wherein in the stacking direction in which the first electrode, the second electrode, and the piezoelectric body are stacked, the piezoelectric body is positioned between the first electrode and the second electrode, and the piezoelectric element is driven by receiving the drive signal, A diaphragm is located on one side of the stacking direction relative to the piezoelectric element and deforms when the piezoelectric element is driven, A pressure chamber substrate is provided with a plurality of pressure chambers located on one side of the stacking direction relative to the diaphragm, the pressure chambers whose volume changes due to the deformation of the diaphragm, A switch circuit that switches whether or not to supply the drive signal to the piezoelectric element, A wiring board on which the aforementioned switch circuit is provided, A temperature detection unit is located on the other side of the stacking direction relative to the diaphragm, electrically connected to the wiring board, and detects temperature information of the pressure chamber. Includes, The aforementioned drive signal output circuit is A modulation circuit that outputs a modulated signal obtained by modulating the base drive signal which is the basis of the drive signal, An amplification circuit that outputs an amplified modulated signal obtained by amplifying the aforementioned modulated signal, A smoothing circuit that outputs the drive signal obtained by smoothing the amplified modulated signal, A feedback circuit that feeds back the drive signal to the modulation circuit, A base drive signal output circuit that outputs the base drive signal corrected based on the temperature information, Includes, The frequency of the amplified modulated signal when the temperature detection unit detects the temperature information used by the base drive signal output circuit to correct the base drive signal is higher than the frequency of the amplified modulated signal when the temperature detection unit detects the temperature information that the base drive signal output circuit does not use to correct the base drive signal.

[0006] One embodiment of the print head according to the present invention is: A print head that receives a drive signal output from a drive signal output circuit and ejects liquid, The aforementioned drive signal output circuit is A modulation circuit that outputs a modulated signal obtained by modulating the aforementioned base drive signal, An amplification circuit that outputs an amplified modulated signal obtained by amplifying the aforementioned modulated signal, A smoothing circuit that outputs the drive signal obtained by smoothing the amplified modulated signal, A feedback circuit that feeds back the drive signal to the modulation circuit, A base drive signal output circuit outputs a base drive signal which is the basis of the drive signal corrected based on the temperature information output by the print head, Includes, The aforementioned print head is A piezoelectric element comprising a first electrode, a second electrode, and a piezoelectric body, wherein in the stacking direction in which the first electrode, the second electrode, and the piezoelectric body are stacked, the piezoelectric body is positioned between the first electrode and the second electrode, and the piezoelectric element is driven by receiving the drive signal, A diaphragm is located on one side of the stacking direction relative to the piezoelectric element and deforms when the piezoelectric element is driven, A pressure chamber substrate is provided with a plurality of pressure chambers located on one side of the stacking direction relative to the diaphragm, the pressure chambers whose volume changes due to the deformation of the diaphragm, A switch circuit that switches whether or not to supply the drive signal to the piezoelectric element, A wiring board on which the aforementioned switch circuit is provided, A temperature detection unit is located on the other side of the stacking direction relative to the diaphragm, electrically connected to the wiring board, and detects the temperature information of the pressure chamber. Includes, The frequency of the amplified modulated signal when the temperature information detected by the temperature detection unit is output to the base drive signal output circuit is higher than the frequency of the amplified modulated signal when the temperature information detected by the temperature detection unit is not output to the base drive signal output circuit. [Brief explanation of the drawing]

[0007] [Figure 1] This is a diagram showing the schematic configuration of a liquid dispensing device. [Figure 2] It is a diagram showing the functional configuration of the liquid ejection device. [Figure 3] It is a diagram showing the configuration of the drive circuit. [Figure 4] It is a diagram showing the configuration of the drive signal selection circuit. [Figure 5] It is a diagram for explaining the relationship between the latch signal LAT, the change signal CH, the clock signal SCK, and the head control signal DI and the selection signal S. [Figure 6] It is a diagram showing an example of the data configuration of the head control signal DI. [Figure 7] It is a diagram showing the decoding content of the decoder. [Figure 8] It is a diagram showing the configuration of the selection circuit corresponding to the piezoelectric element. [Figure 9] It is a diagram showing an example of the signal waveform of the drive signal COM. [[ID=二十五]] [Figure 10] It is a diagram showing an example of the head control signal DI. [Figure 11] It is a diagram showing a specific example of the decoding content of the decoder. [Figure 12] It is a diagram showing an example of the drive signal VOUT output from the selection circuit when the selection signal S shown in FIG. 11 is supplied. [[ID=3三十三]] [Figure 13] It is an exploded perspective view showing the structure of the ejection module. [Figure 14] It is a plan view of the ejection module. [Figure 15] It is a cross-sectional view showing the IV-IV cross-section shown in FIG. 14. [Figure 16] It is a detailed view of the main part of FIG. 15. [Figure 17] It is a cross-sectional view showing the VI-VI cross-section shown in FIG. 14. [Figure 18] It is a diagram showing an example of the acquisition timing at which the ejection module included in the print head acquires the temperature.

Embodiments for Carrying Out the Invention

[0008] Preferred embodiments of the present invention will be described below with reference to the drawings. The drawings used are for illustrative purposes only. The embodiments described below are not intended to unduly limit the scope of the present invention as described in the claims. Furthermore, not all of the configurations described below are essential components of the present invention.

[0009] 1. Structure of the liquid dispensing device Figure 1 shows a schematic configuration of the liquid ejection device 1. In this embodiment, the liquid ejection device 1 is described using a serial printing inkjet printer as an example, in which a carriage 21 equipped with a print head 20 that ejects ink as an example of a liquid reciprocates along the scanning axis and ejects ink onto a medium P that is transported along the transport direction, thereby forming an image on the medium P. As the medium P used in such a liquid ejection device 1, any printing material such as printing paper, resin film, or fabric can be used.

[0010] As shown in Figure 1, the liquid dispensing device 1 comprises an ink container 2, a control mechanism 10, a carriage 21, a moving mechanism 30, and a transport mechanism 40.

[0011] The ink container 2 stores multiple types of ink that are dispensed onto the medium P. The colors of the ink stored in the ink container 2 include black, cyan, magenta, yellow, red, and gray. The ink container 2 can be an ink cartridge, a bag-shaped ink pack made of flexible film, or an ink tank that allows for ink replenishment.

[0012] The control mechanism 10 includes, for example, processing circuits such as a CPU (Central Processing Unit) and an FPGA (Field Programmable Gate Array), and storage circuits such as semiconductor memory, and controls each element of the liquid ejection device 1, including the print head 20.

[0013] The carriage 21 mounts the print head 20 and is fixed to an endless belt 32 included in the moving mechanism 30. The ink container 2 may also be mounted on the carriage 21.

[0014] The print head 20 mounted on the carriage 21 receives a control signal Ctrl-H, output by the control mechanism 10 to control the print head 20, and a drive signal COM, which drives the print head 20. Ink stored in the ink container 2 is supplied to the print head 20 via a tube (not shown). The print head 20 then ejects the ink supplied from the ink container 2 based on the input control signal Ctrl-H and drive signal COM.

[0015] The moving mechanism 30 includes a carriage motor 31 and an endless belt 32. The carriage motor 31 operates based on a control signal Ctrl-C input from the control mechanism 10. The endless belt 32 rotates in accordance with the operation of the carriage motor 31. This causes the carriage 21, which is fixed to the endless belt 32, to reciprocate along the scanning axis. That is, the carriage 21 reciprocates along the scanning axis which intersects the transport direction in which the medium P is transported.

[0016] The conveying mechanism 40 includes a conveying motor 41 and conveying rollers 42. The conveying motor 41 operates based on a control signal Ctrl-T input from the control mechanism 10. The conveying rollers 42 rotate in accordance with the operation of the conveying motor 41. As the conveying rollers 42 rotate, the medium P is conveyed in the conveying direction.

[0017] As described above, the liquid ejection device 1 is linked to the transport of the medium P by the transport mechanism 40 and the reciprocating motion of the carriage 21 by the moving mechanism 30. The print head 20 mounted on the carriage 21 ejects ink onto the medium P, causing the ink to land at any position on the surface of the medium P and forming a desired image on the medium P.

[0018] 2. Functional configuration of the liquid dispensing device Next, the functional configuration of the liquid dispensing device 1 will be described. Figure 2 is a diagram showing the functional configuration of the liquid dispensing device 1. As shown in Figure 2, the liquid dispensing device 1 comprises a control mechanism 10, a print head 20, a carriage motor 31, a transport motor 41, and a linear encoder 90.

[0019] The control mechanism 10 includes a drive circuit 50, a reference voltage signal output circuit 52, a frequency measurement circuit 54, and a control circuit 100. The control circuit 100 includes, for example, a processing circuit such as a CPU or FPGA and a storage circuit such as a semiconductor memory. The control circuit 100 receives image information signals, including image data, from an external device such as a host computer that is communicably connected to the outside of the liquid dispensing device 1. Based on the input image information signals, the control circuit 100 generates various signals for controlling the liquid dispensing device 1 and outputs them to the corresponding configurations.

[0020] In a specific example, the control circuit 100 receives, in addition to the image information signal described above, a detection signal based on the scanning position of the carriage 21 from the linear encoder 90. Based on the input detection signal, the control circuit 100 determines the scanning position of the print head 20 mounted on the carriage 21. The control circuit 100 then generates and outputs various signals corresponding to the scanning position of the print head 20 and the image information signal.

[0021] In detail, the control circuit 100 generates a control signal Ctrl-C to control the movement of the print head 20 along the scanning axis according to the scanning position of the print head 20, and outputs it to the carriage motor 31. This causes the carriage motor 31 to operate, controlling the movement of the print head 20 mounted on the carriage 21 along the scanning axis and its scanning position. The control circuit 100 also generates a control signal Ctrl-T to control the transport of the medium P, and outputs it to the transport motor 41. This causes the transport motor 41 to operate, controlling the movement of the medium P along the transport direction. Note that the control signal Ctrl-C may be converted via a driver circuit (not shown) before being input to the carriage motor 31, and the control signal Ctrl-T may be converted via a driver circuit (not shown) before being input to the transport motor 41.

[0022] Furthermore, based on the image information signal input from the external device and the scanning position of the print head 20 input from the linear encoder 90, the control circuit 100 generates the head control signals DI1~DIn, the change signal CH, the latch signal LAT, and the clock signal SCK as control signals Ctrl-H for controlling the print head 20, and outputs them to the print head 20.

[0023] Furthermore, the control circuit 100 outputs a digital base drive signal dO to the drive circuit 50. The drive circuit 50 converts the input base drive signal dO from digital to analog, then generates a drive signal COM by class D amplification of the converted analog signal, and outputs it to the print head 20. In other words, the base drive signal dO output by the control circuit 100 is a digital signal that defines the waveform of the drive signal COM. Here, the base drive signal dO only needs to define the waveform of the drive signal COM output by the drive circuit 50, and may be an analog signal. Details of the drive circuit 50 will be described later.

[0024] The reference voltage signal output circuit 52 generates a reference voltage signal VBS and outputs it to the print head 20. The reference voltage signal VBS output by this reference voltage signal output circuit 52 is a potential signal that serves as a reference for driving the piezoelectric element 60, which will be described later. For example, it may be a constant signal at ground potential, or it may be a constant DC voltage signal at a potential such as 5.5V or 6V. This reference voltage signal output circuit 52 may be configured integrally with the drive circuit 50.

[0025] The frequency measurement circuit 54 detects the frequency of the amplified modulation signal AMs output by the drive circuit 50. The frequency measurement circuit 54 then generates a frequency determination signal Fm that becomes high for a certain period of time when the frequency of the detected amplified modulation signal AMs reaches its maximum value, and outputs it to the control circuit 100. The control circuit 100 calculates the voltage value of the drive signal COM at the moment the input frequency determination signal Fm becomes high, based on the base drive signal dO output to the drive circuit 50, and stores the calculation result. Note that the frequency determination signal Fm output by the frequency measurement circuit 54 is not limited to a signal that becomes high when the frequency of the measured amplified modulation signal AMs is at its maximum value, but may also be a signal that becomes high when the frequency of the measured amplified modulation signal AMs is above a predetermined threshold.

[0026] Furthermore, the control circuit 100 generates a temperature acquisition request signal TD at a predetermined timing to acquire the temperature of the print head 20 and outputs it to the print head 20. The control circuit 100 also receives a temperature information signal TI that the print head 20 outputs in response to the temperature acquisition request signal TD. In other words, the control circuit 100 receives a temperature information signal TI containing information about the temperature of the print head 20. Based on the input temperature information signal TI, the control circuit 100 corrects the control signals Ctrl-H, Ctrl-C, Ctrl-T, and the base drive signal dO. In other words, the control circuit 100 outputs the base drive signal dO that has been corrected based on the temperature information signal TI.

[0027] The print head 20 includes ejection modules 22-1 to 22-n and a temperature information output circuit 26. Each of the ejection modules 22-1 to 22-n also includes a drive signal selection circuit 200, a temperature detection circuit 24, and piezoelectric elements 60[1] to 60[m].

[0028] The ejection module 22-1 receives the head control signal DI1, change signal CH, latch signal LAT, and clock signal SCK output by the control circuit 100, the drive signal COM output by the drive circuit 50, and the reference voltage signal VBS output by the reference voltage signal output circuit 52.

[0029] The clock signal SCK, latch signal LAT, change signal CH, head control signal DI1, and drive signal COM input to the ejection module 22-1 are input to the drive signal selection circuit 200. Based on the input clock signal SCK, latch signal LAT, change signal CH, and head control signal DI1, the drive signal selection circuit 200 selects or deselects the signal waveform of the drive signal COM to generate drive signals VOUT[1]~VOUT[m]. The drive signal selection circuit 200 then outputs the generated drive signals VOUT[1]~VOUT[m] individually to one end of the corresponding piezoelectric elements 60[1]~60[m]. A reference voltage signal VBS is commonly input to the other end of the piezoelectric elements 60[1]~60[m]. The piezoelectric elements 60[1]~60[m] are driven by the potential difference between the drive signals VOUT[1]~VOUT[m] individually input to one end and the reference voltage signal VBS commonly input to the other end. An amount of ink corresponding to the drive of each of these piezoelectric elements 60[1] to 60[m] is ejected from the ejection module 22-1.

[0030] In this embodiment, the print head 20 is described as having a drive signal VOUT[1] corresponding to the piezoelectric element 60[1] and a drive signal VOUT[m] corresponding to the piezoelectric element 60[m]. That is, the drive signal VOUT[1] generated by the drive signal selection circuit 200 is input to one end of the piezoelectric element 60[1], and the drive signal VOUT[m] generated by the drive signal selection circuit 200 is input to one end of the piezoelectric element 60[m].

[0031] Here, the piezoelectric elements 60[1] to 60[m] all have the same configuration and, when there is no need to distinguish between them, may be referred to simply as piezoelectric element 60. In this case, it will be explained that a drive signal VOUT is supplied to one end of the piezoelectric element 60 as a drive signal VOUT[1] to VOUT[m]. That is, it may be explained that the piezoelectric element 60 is 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.

[0032] Furthermore, the temperature detection circuit 24 of the discharge module 22-1 detects the temperature of the discharge module 22-1. The temperature detection circuit 24 then outputs the detected temperature of the discharge module 22-1 as temperature detection information TH1 to the temperature information output circuit 26.

[0033] Here, the discharge modules 22-2 to 22-n have the same configuration as discharge module 22-1 and perform the same operation, differing only in the input signals and output signals.

[0034] Specifically, the ejection module 22-n receives a clock signal SCK, a latch signal LAT, a change signal CH, a head control signal DIn, a drive signal COM, and a reference voltage signal VBS. The drive signal selection circuit 200 in the ejection module 22-n generates drive signals VOUT[1]~VOUT[m] by selecting or deselecting the signal waveform of the drive signal COM based on the input clock signal SCK, latch signal LAT, change signal CH, and head control signal DIn. The drive signals VOUT[1]~VOUT[m] generated by the drive signal selection circuit 200 in the ejection module 22-n are input to one end of the corresponding piezoelectric elements 60[1]~60[m] in the ejection module 22-n. The reference voltage signal VBS is commonly input to the other end of the piezoelectric elements 60[1]~60[m] in the ejection module 22-n. As a result, the piezoelectric elements 60[1]~60[m] of the ejection module 22-n are driven, and an amount of ink corresponding to the drive of the piezoelectric elements 60[1]~60[m] is ejected from the ejection module 22-n. Furthermore, the temperature detection circuit 24 of the ejection module 22-n detects the temperature of the ejection module 22-n and outputs the detected temperature as temperature detection information THn.

[0035] In the following explanation, when it is not necessary to distinguish between ejection modules 22-1 to 22-n, they may be referred to simply as "ejection module 22." In this case, ejection module 22 is assumed to receive a clock signal SCK, a latch signal LAT, a change signal CH, a head control signal DI, a drive signal COM, and a reference voltage signal VBS, and to output temperature detection information TH indicating the temperature of ejection module 22.

[0036] The temperature information output circuit 26 receives temperature detection information TH1 to THn output by the temperature detection circuits 24 of each of the discharge modules 22-1 to 22-n, and a temperature acquisition request signal TD output by the control circuit 100. The temperature information output circuit 26 amplifies and stores each of the temperature detection information TH1 to THn. Then, in response to the temperature acquisition request signal TD input from the control circuit 100, the temperature information output circuit 26 outputs the corresponding signal from the amplified signals of each of the stored temperature detection information TH1 to THn as a temperature information signal TI. Such a temperature information output circuit 26 includes an amplification circuit that amplifies the temperature detection information TH1 to THn, a processor such as a microcomputer that receives the input temperature acquisition request signal TD and outputs a temperature information signal TI which is an amplified version of the temperature detection information TH1 to THn, and a memory circuit that amplifies and stores each of the temperature detection information TH1 to THn.

[0037] The temperature information output circuit 26 may also hold the temperature detection information TH1 to THn output by the temperature detection circuit 24 of each of the discharge modules 22-1 to 22-n, and in response to the temperature acquisition request signal TD input from the control circuit 100, amplify each of the held temperature detection information TH1 to THn and output the amplified signal as a temperature information signal TI.

[0038] As described above, the liquid ejection device 1 of this embodiment comprises a drive circuit 50 that outputs a drive signal COM, and a print head 20 that ejects ink upon receiving the drive signal COM. In other words, the print head 20 ejects ink upon receiving the drive signal COM output by the drive circuit 50.

[0039] 3. Drive Circuit Configuration Next, the configuration and operation of the drive circuit 50, which outputs the drive signal COM, will be described. Figure 3 shows the configuration of the drive circuit 50. The drive circuit 50 includes an integrated circuit 500, an amplification circuit 550, a smoothing circuit 560, feedback circuits 570 and 572, and other electronic components. Figure 3 also shows a frequency measurement circuit 54 that measures the frequency of the amplified modulation signal AMs output by the drive circuit 50.

[0040] The integrated circuit 500 has multiple terminals, including terminals In, Bst, Hdr, Sw, Gvd, Ldr, Gnd, Vfb, and Ifb. The integrated circuit 500 is electrically connected to an externally provided substrate (not shown) via these multiple terminals. The integrated circuit 500 also includes a DAC (Digital to Analog Converter) 511, a modulation circuit 510, and a gate drive circuit 520.

[0041] The DAC511 converts the base drive signal dO of the input digital signal into the base drive signal aO of the analog signal and outputs it to the modulation circuit 510. The amplified signal of the base drive signal aO output by the DAC511 corresponds to the drive signal COM. In other words, the base drive signal aO corresponds to the target signal before amplification of the drive signal COM, and the base drive signals dO and aO are signals that define the signal waveform of the drive signal COM.

[0042] The modulation circuit 510 generates a modulated signal Ms by modulating the base drive signal aO and outputs it to the gate drive circuit 520. The modulation circuit 510 includes adders 512, 513, a comparator 514, an inverter 515, an integral attenuator 516, and an attenuator 517.

[0043] The integrating attenuator 516 attenuates and integrates the drive signal COM input via terminal Vfb, and outputs it to the negative input terminal of the adder 512. The base drive signal aO is input to the positive input terminal of the adder 512. The adder 512 then outputs the voltage obtained by subtracting the voltage input to the negative input terminal from the voltage input to the positive input terminal and integrating it to the positive input terminal of the adder 513.

[0044] The attenuator 517 outputs a voltage obtained by attenuating the high-frequency component of the drive signal COM input via terminal Ifb to the negative input terminal of the adder 513. The voltage output from adder 512 is input to the positive input terminal of adder 513. The adder 513 then generates a voltage signal Os by subtracting the voltage input to the negative input terminal from the voltage input to the positive input terminal and outputs it to the comparator 514.

[0045] The comparator 514 outputs a modulated signal Ms, which is obtained by pulse modulating the voltage signal Os input from the adder 513. Specifically, the comparator 514 generates and outputs a modulated signal Ms that becomes H level when the voltage value of the voltage signal Os input from the adder 513 rises above a predetermined threshold Vth1, and becomes L level when the voltage value of the voltage signal Os falls below a predetermined threshold Vth2. Here, the thresholds Vth1 and Vth2 are set in the relationship Vth1 => Vth2.

[0046] The modulated signal Ms output by the comparator 514 is input to the gate driver 521 included in the gate drive circuit 520, and also to the gate driver 522 included in the gate drive circuit 520 via the inverter 515. That is, signals with mutually exclusive logic levels are input to the gate driver 521 and the gate driver 522. Here, mutually exclusive logic levels include the fact that the logic levels of the signals input to the gate driver 521 and the gate driver 522 cannot be at the same time at the H level. Therefore, the modulation circuit 510 may include, in place of or in addition to the inverter 515, a timing control circuit for controlling the timing between the modulated signal Ms input to the gate driver 521 and the signal obtained by inverting the logic level of the modulated signal Ms input to the gate driver 522.

[0047] The gate drive circuit 520 includes gate drivers 521 and 522. Gate driver 521 generates an amplification control signal Hgd by level-shifting the modulated signal Ms output from comparator 514 and outputs it from terminal HDr.

[0048] Specifically, the gate driver 521's power supply voltage is supplied via terminal Bst for the higher voltage and via terminal Sw for the lower voltage. Terminal Bst is connected to one end of capacitor C5 and the cathode of diode D1, which prevents reverse current. Terminal Sw is connected to the other end of capacitor C5. The anode of diode D1 is connected to terminal Gvd. Terminal Gvd is supplied with a voltage signal Vm, which is a DC voltage of, for example, 7.5V output by a power supply circuit (not shown). In other words, the anode of diode D1 is supplied with a voltage signal Vm. Therefore, the potential difference between terminal Bst and terminal Sw is approximately equal to the voltage value of the voltage signal Vm. As a result, the gate driver 521 generates an amplified control signal Hgd with a voltage value that is greater than the voltage value of the voltage signal Vm relative to terminal Sw, according to the input modulation signal Ms, and outputs it from terminal Hdr.

[0049] The gate driver 522 operates at a lower potential than the gate driver 521. The gate driver 522 generates an amplified control signal Lgd by level-shifting the signal obtained by inverting the logic level of the modulated signal Ms output from the comparator 514 by the inverter 515, and outputs it from terminal Ldr.

[0050] Specifically, the high-voltage side of the gate driver 522's power supply is supplied with a voltage signal Vm, while the low-voltage side is supplied with ground potential via terminal Gnd. The gate driver 522 then outputs an amplification control signal Lgd from terminal Ldr with a voltage value greater than the voltage value of the voltage signal Vm relative to terminal Gnd, according to the signal obtained by inverting the logic level of the input modulation signal Ms. Here, the ground potential is the reference potential of the drive circuit 50, which is, for example, 0V.

[0051] The amplification circuit 550 includes transistors M1 and M2.

[0052] Transistor M1 is a surface-mount type FET (Field Effect Transistor). A voltage signal VHV, for example a 42V DC voltage, is supplied to the drain of transistor M1 as the amplification power supply voltage for the amplification circuit 550. The gate of transistor 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. In other words, the amplification control signal Hgd is input to the gate of transistor M1. The source of transistor M1 is electrically connected to terminal Sw of integrated circuit 500.

[0053] Transistor M2 is a surface-mount FET, and its drain is electrically connected to terminal Sw of integrated circuit 500. That is, the drain of transistor M2 and the source of transistor M1 are electrically connected to each other. The gate of transistor 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 amplification control signal Lgd is input to the gate of transistor M2. Also, ground potential is supplied to the source of transistor M2.

[0054] When the drain and source of transistor M1 are controlled to be non-conductive and the drain and source of transistor M2 are controlled to be conductive, the potential of the node to which terminal Sw is connected becomes ground potential. Therefore, the voltage signal Vm is supplied to terminal Bst. On the other hand, when the drain and source of transistor M1 are controlled to be conductive and the drain and source of transistor M2 are controlled to be non-conductive, the potential of the node to which terminal Sw is connected becomes the voltage value of the voltage signal VHV. Therefore, the voltage supplied to terminal Bst is the sum of the voltage value of the voltage signal VHV and the voltage value of the voltage signal Vm. In other words, the gate driver 521 that drives transistor M1 uses capacitor C5 as a floating power supply, and in accordance with the operation of transistors M1 and M2, the potential of terminal Sw changes to either ground potential or the voltage value of the voltage signal VHV. This generates an amplified control signal Hgd where the L level is the voltage value of the voltage signal VHV and the H level is the voltage value of the sum of the voltage values ​​of the voltage signal VHV and the voltage value of the voltage signal Vm, and outputs this to the gate of transistor M1.

[0055] On the other hand, the gate driver 522 that drives transistor M2 generates an amplification control signal Lgd, where the L level is ground potential and the H level is the voltage value of the voltage signal Vm, regardless of the operation of transistors M1 and M2, and outputs it to the gate of transistor M2.

[0056] The amplifier circuit 550, configured as described above, generates an amplified modulated signal AMs at the connection point between the source of transistor M1 and the drain of transistor M2, by amplifying the modulated signal Ms based on the voltage signal VHV. The amplifier circuit 550 then outputs the generated amplified modulated signal AMs to the smoothing circuit 560 and also to the frequency measurement circuit 54.

[0057] Here, a capacitor C7 is provided in the propagation path through which the voltage signal VHV input to the amplification circuit 550 propagates. Specifically, one end of capacitor C7 is electrically connected to the drain of transistor M1, which is in the propagation path through which the voltage signal VHV propagates, and the other end of capacitor C7 is supplied with ground potential. This reduces the risk of fluctuations in the voltage value of the voltage signal VHV input to the amplification circuit 550, and also reduces the risk of noise being superimposed on the voltage signal VHV, thereby improving the waveform accuracy of the amplified modulated signal AMs output by the amplification circuit 550. For this reason, a high-voltage, large-capacity electrolytic capacitor is used. Note that capacitor C7 may be provided to correspond to one drive circuit 50, or it may be provided to correspond to multiple drive circuits 50.

[0058] The smoothing circuit 560 generates a drive signal COM by demodulating the amplified modulation signal AMs output by the amplification circuit 550, and outputs it from the drive circuit 50. The smoothing circuit 560 includes an inductor L1 and a capacitor C1. One end of the inductor L1 is connected to one end of the capacitor C1. The amplified modulation signal AMs is input to the other end of the inductor L1. The other end of the capacitor C1 is supplied with ground potential. In other words, in the smoothing circuit 560, the inductor L1 and the capacitor C1 constitute a low-pass filter. The smoothing circuit 560 then demodulates the amplified modulation signal AMs by smoothing it with this low-pass filter, and outputs the demodulated signal as the drive signal COM. That is, the drive circuit 50 outputs the drive signal COM from one end of the inductor L1 and one end of the capacitor C1 included in the smoothing circuit 560.

[0059] The feedback circuit 570 includes resistors R3 and R4. One end of resistor R3 is supplied with the drive signal COM, and the other end is connected to terminal Vfb and one end of resistor R4. The other end of resistor R4 is supplied with the voltage signal VHV. As a result, the drive signal COM, which has passed through the feedback circuit 570, is fed back to terminal Vfb in a state where it is pulled up with the voltage value of the voltage signal VHV.

[0060] The feedback circuit 572 includes capacitors C2, C3, and C4, and resistors R5 and R6. One end of capacitor C2 is input to the drive signal COM, 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. As a result, capacitor C2 and resistor R5 function as a high-pass filter. 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. As a result, resistor R6 and capacitor C3 function as a low-pass filter. In other words, the feedback circuit 572 includes a high-pass filter and a low-pass filter, and functions as a band-pass filter that allows signals in a predetermined frequency range included in the drive signal COM to pass through.

[0061] The other end of capacitor C4 is connected to terminal Ifb of integrated circuit 500. As a result, terminal Ifb receives a signal from which the DC component of the high-frequency component of the drive signal COM, which has passed through the feedback circuit 572 (which functions as a bandpass filter), has been cut off.

[0062] The drive signal COM is a signal obtained by smoothing the amplified modulated signal AMs based on the base drive signal dO using the smoothing circuit 560. The drive signal COM is then integrated and subtracted via terminal Vfb and fed back to the adder 512. As a result, the drive circuit 50 self-oscillates at a frequency determined by the feedback delay and the feedback transfer function. However, the feedback path via terminal Vfb has a large delay, and therefore, the self-oscillation frequency may not be high enough to ensure sufficient accuracy of the drive signal COM with only feedback via terminal Vfb. Therefore, a separate path is provided to feed back the high-frequency component of the drive signal COM via terminal Ifb, in addition to the path via terminal Vfb, thereby reducing the overall delay of the circuit. This allows the frequency of the voltage signal Os to be increased to a level that ensures sufficient accuracy of the drive signal COM compared to the case where the path via terminal Ifb does not exist.

[0063] As described above, the drive circuit 50 includes a modulation circuit 510 that outputs a modulated signal Ms obtained by modulating the base drive signal dO, which is the basis of the drive signal COM; an amplification circuit 550 that outputs an amplified modulated signal AMs obtained by amplifying the modulated signal Ms; a smoothing circuit 560 that outputs a drive signal COM obtained by smoothing the amplified modulated signal AMs; and feedback circuits 570 and 572 that feed the drive signal COM back to the modulation circuit 510. The drive circuit 50 then converts the input base drive signal dO from digital to analog, generates the drive signal COM by class D amplification of the analog signal, and outputs the generated drive signal COM. In other words, the drive circuit 50 includes a class D amplification circuit, and the print head 20 receives the drive signal COM output by the drive circuit 50, which includes the class D amplification circuit, and ejects ink.

[0064] Furthermore, the frequency measurement circuit 54 detects the frequency of the amplified modulation signal AMs output by the amplification circuit 550. The frequency measurement circuit 54 then generates a frequency determination signal Fm that is at a high level for a certain period of time when the frequency of the detected amplified modulation signal AMs reaches its maximum value, and outputs it to the control circuit 100.

[0065] Here, we will explain the relationship between the frequency of the amplified modulation signal AMs and the voltage value of the drive signal COM.

[0066] As described above, the drive circuit 50 of this embodiment self-oscillates at a frequency determined by the feedback delay and feedback transfer function of the feedback circuits 570 and 572. The self-oscillation frequency of this drive circuit 50 is the switching frequency of the amplification circuit 550 and corresponds to the frequency of the amplified modulation signal AMs. In the case of such a self-oscillating circuit, the self-oscillation frequency is a voltage value between the maximum and minimum voltages of the output signal, preferably at a voltage near the average voltage between the maximum and minimum voltages, and the frequency decreases as the voltage value increases or decreases.

[0067] In view of the frequency characteristics of the drive circuit 50, the frequency measurement circuit 54 detects the frequency of the amplified modulation signal AMs, generates a frequency determination signal Fm that is at a high level for a certain period of time at the moment the detected frequency changes from rising to falling, and outputs it to the control circuit 100. In this case, the frequency measurement circuit 54 may also detect the frequency of the amplified modulation signal AMs, calculate a moving average of the detected frequencies, generate a frequency determination signal Fm that is at a high level at the moment the calculated moving average value changes from rising to falling, and output it to the control circuit 100.

[0068] Furthermore, the frequency measurement circuit 54 may be controlled not to output a high-level frequency determination signal Fm if the voltage value of the drive signal COM is not within a predetermined range, or if the frequency of the amplified modulation signal AMs is lower than a predetermined frequency. This improves the detection accuracy of the maximum frequency of the amplified modulation signal AMs in the frequency measurement circuit 54.

[0069] 4. Configuration of the drive signal selection circuit Next, the configuration and operation of the drive signal selection circuit 200 will be described. As mentioned above, the drive signal selection circuit 200 generates the drive signal VOUT by selecting or deselecting the signal waveform of the drive signal COM, and outputs it to one end of the piezoelectric element 60.

[0070] Figure 4 shows the configuration of the drive signal selection circuit 200. As shown in Figure 4, the drive signal selection circuit 200 includes a selection control circuit 210 and selection circuits 230[1] to 230[m] corresponding to each of the piezoelectric elements 60[1] to 60[m].

[0071] The selection control circuit 210 receives the clock signal SCK, latch signal LAT, change signal CH, and head control signal DI as inputs. Based on the input clock signal SCK, latch signal LAT, change signal CH, and head control signal DI, the selection control circuit 210 generates selection signals S[1] to S[m] to switch whether or not to output the signal waveform included in the drive signal COM as the drive signal VOUT. The selection signals S[1] to S[m] generated by the selection control circuit 210 are input to the corresponding selection circuits 230[1] to 230[m]. Based on the input selection signals S[1] to S[m], the selection circuits 230[1] to 230[m] select or deselect the signal waveform of the drive signal COM, thereby generating drive signals VOUT[1] to VOUT[m] corresponding to the piezoelectric elements 60[1] to 60[m], and output them to the corresponding piezoelectric elements 60[1] to 60[m]. Here, the selection circuits 230[1] to 230[m] all have the same configuration, and the selection circuits 230[1] to 230[m] corresponding to piezoelectric element 60 among the piezoelectric elements 60[1] to 60[m] are referred to as selection circuit 230. In this explanation, the selection circuit 230 will be described as selecting or deselecting the signal waveform of the drive signal COM based on the selection signal S among the selection signals S[1] to S[m].

[0072] To explain the operation of the selection control circuit 210 in detail, we will describe the latch signal LAT, change signal CH, clock signal SCK, and head control signal DI that are input to the selection control circuit 210. Figure 5 is a diagram illustrating the relationship between the latch signal LAT, change signal CH, clock signal SCK, head control signal DI, and selection signal S.

[0073] The latch signal LAT is a pulse signal based on a signal output by the linear encoder 90 indicating the scanning position of the print head 20, and defines the period tp during which the print head 20 forms dots on the medium P. The change signal CH is a pulse signal that defines the switching timing for whether or not to supply the signal waveform included in the drive signal COM to the piezoelectric element 60, and divides the period tp into periods t1, t2, and t3. The drive signal selection circuit 200 generates the drive signal VOUT and outputs it to the piezoelectric element 60 by selecting or deselecting the signal waveform included in the drive signal COM in each of the periods t1, t2, and t3 into which the period tp defined by the latch signal LAT is divided by the change signal CH.

[0074] Furthermore, the head control signal DI serially includes the ejection control signal SI and the waveform selection signal SP. The ejection control signal SI individually defines the amount of ink ejected by driving the piezoelectric element 60 for each of the piezoelectric elements 60[1] to 60[m]. The waveform selection signal SP defines the relationship between the logic level of the selection signal S output during periods t1, t2, and t3 and the ejection control signal SI.

[0075] As shown in Figure 5, the head control signal DI is input to the selection control circuit 210 in synchronization with the clock signal SCK during the period tp before the latch signal LAT rises. At this time, the head control signal DI input to the selection control circuit 210 is held in the registers corresponding to each of the piezoelectric elements 60[1] to 60[m]. The head control signals DI held in these registers are then latched simultaneously on the rising edge of the latch signal LAT. That is, at the start of the period tp, the head control signals DI held in these registers are latched simultaneously. Based on the simultaneously latched head control signals DI, the selection control circuit 210 generates selection signals S corresponding to periods t1, t2, and t3 in the period tp after the latch signal LAT rises, and outputs them to the selection circuit 230.

[0076] Here, we will describe the details of the head control signal DI, which includes the ejection control signal SI and the waveform selection signal SP. Figure 6 shows an example of the data structure of the head control signal DI. As shown in Figure 6, the head control signal DI includes the ejection control signal SI and the waveform selection signal SP.

[0077] The ejection control signal SI is a signal that defines the amount of ink ejected by driving the piezoelectric element 60, and includes upper ejection data SIH and lower ejection data SIL. That is, the ejection control signal SI includes 2 bits of data, upper ejection data SIH and lower ejection data SIL, for controlling the driving of the piezoelectric element 60, corresponding to each of the piezoelectric elements 60[1] to 60[m].

[0078] Specifically, the ejection control signal SI includes, serially, m bits of upper ejection data SIH corresponding to each of the piezoelectric elements 60[1] to 60[m], in the order of upper ejection data SIH corresponding to piezoelectric element 60[m], upper ejection data SIH corresponding to piezoelectric element 60[m-1], ..., upper ejection data SIH corresponding to piezoelectric element 60[1], followed by m bits of lower ejection data SIL corresponding to each of the piezoelectric elements 60[1] to 60[m], in the order of lower ejection data SIL corresponding to piezoelectric element 60[m], lower ejection data SIL corresponding to piezoelectric element 60[m-1], ..., lower ejection data SIL corresponding to piezoelectric element 60[1], in that order. In other words, the ejection control signal SI is a 2m-bit signal that serially includes m bits of upper ejection data SIH corresponding to piezoelectric elements 60[m] to 60[1] and m bits of lower ejection data SIL corresponding to piezoelectric elements 60[m] to 60[1]. The amount of ink ejected by driving the piezoelectric element 60[i] (where i is one from 1 to m) is defined by two bits: the upper ejection data SIH corresponding to the piezoelectric element 60[i] and the lower ejection data SIL corresponding to the piezoelectric element 60[i].

[0079] In the following explanation, the upper ejection data SIH corresponding to the piezoelectric element 60[i] may be referred to as upper ejection data SIHi, and the lower ejection data SIL corresponding to the piezoelectric element 60[i] may be referred to as lower ejection data SILi. Furthermore, in the following explanation, the upper ejection data SIH and lower ejection data SIL corresponding to the piezoelectric element 60 may be collectively referred to as ejection data [SIH,SIL], and the upper ejection data SIHi and lower ejection data SILi corresponding to the piezoelectric element 60[i] may be collectively referred to as ejection data [SIHi,SILi]. In other words, the amount of ink ejected by driving the piezoelectric element 60[i] is determined by the ejection data [SIHi,SILi].

[0080] The waveform selection signal SP is a signal for defining the drive pattern of the piezoelectric element 60 corresponding to the discharge data [SIH, SIL] in each of the periods t1, t2, and t3, and defines the logic level of the selection signal S output in each of the periods t1, t2, and t3 corresponding to the discharge data [SIH, SIL]. In this embodiment, the waveform selection signal SP is a 12-bit signal including setting information SP00~SP03, SP10~SP13, and SP20~SP23.

[0081] Specifically, the waveform selection signal SP includes setting information SP00 to SP03 that defines the driving pattern of the piezoelectric element 60 during period t1 determined by the discharge data [SIH, SIL], setting information SP10 to SP13 that defines the driving pattern of the piezoelectric element 60 during period t2 determined by the discharge data [SIH, SIL], and setting information SP20 to SP23 that defines the driving pattern of the piezoelectric element 60 during period t3 determined by the discharge data [SIH, SIL], in the order of setting information SP23, SP22, SP21, SP20, SP13, SP12, SP11, SP10, SP03, SP02, SP01, SP00. Note that the waveform selection signal SP is not limited to a 12-bit signal, and may be a signal of 12 bits or more, or 12 bits or less, depending on the number of periods in which the period tp is divided by the change signal CH and the number of driving patterns of the piezoelectric element 60 defined by the discharge control signal SI.

[0082] Returning to Figure 4, the selection control circuit 210 includes a control logic circuit 260 and selection signal output sections 270[1] to 270[m] corresponding to the piezoelectric elements 60[1] to 60[m]. The selection control circuit 210 generates selection signals S[1] to S[m] corresponding to each of the piezoelectric elements 60[1] to 60[m] based on the head control signal DI propagated in synchronization with the clock signal SCK at the timing defined by the input latch signal LAT and change signal CH, and outputs them to the corresponding selection circuits 230[1] to 230[m].

[0083] The control logic circuit 260 includes a group of SP registers 261 and a selection control signal generation unit 262. The SP register group 261 includes multiple serially connected registers and constitutes a so-called shift register that sequentially propagates the head control signal DI, which is input in synchronization with the clock signal SCK, to the subsequent registers. When the supply of the clock signal SCK is stopped, the SP register group 261 holds the setting information SP00 to SP23 included in the waveform selection signal SP from the head control signal DI.

[0084] The selection control signal generation unit 262 latches the setting information SP00 to SP23 held in the SP register group 261 on the rising edge of the latch signal LAT. Then, the selection control signal generation unit 262 generates selection control signals Q0, Q1, and Q2 by translating the latched setting information SP00 to SP23 and outputs them to the decoders 226 of each of the selection signal output units 270[1] to 270[m]. The selection control signal Q0 includes the setting information SP00, SP01, SP02, and SP03 and defines the logic level of the selection signal S output from the selection control circuit 210 during period t1. The selection control signal Q1 includes the setting information SP10, SP11, SP12, and SP13 and defines the logic level of the selection signal S output from the selection control circuit 210 during period t2. The selection control signal Q2 includes the setting information SP20, SP21, SP22, and SP23, and defines the logic level of the selection signal S output from the selection control circuit 210 during period t3. Hereinafter, in the following description, the selection control signal Q0 including the setting information SP00, SP01, SP02, and SP03 will be referred to as selection control signal Q0[SP00, SP01, SP02, SP03], the selection control signal Q1 including the setting information SP10, SP11, SP12, and SP13 will be referred to as selection control signal Q1[SP10, SP11, SP12, SP13], and the selection control signal Q2 including the setting information SP20, SP21, SP22, and SP23 will be referred to as selection control signal Q2[SP20, SP21, SP22, SP23].

[0085] Each of the selection signal output sections 270[1] to 270[m] includes a first register 222a, a second register 222b, a first latch circuit 224a, a second latch circuit 224b, and a decoder 226.

[0086] Each of the selection signal output sections 270[1] to 270[m] contains a second register 222b which is connected in series to the SP register group 261 which contains multiple registers, and each of the selection signal output sections 270[1] to 270[m] contains a first register 222a which is connected in series to the m serially connected second registers 222b.

[0087] Specifically, the second register 222b included in the selection signal output unit 270[1] is connected after the SP register group 261, and the second register 222b included in the selection signal output unit 270[2], the second register 222b included in the selection signal output unit 270[3], ..., and the second register 222b included in the selection signal output unit 270[m] are connected in serial order after the second register 222b included in the selection signal output unit 270[m]. Then, the first register 222a included in the selection signal output unit 270[1] is connected after the second register 222b included in the selection signal output unit 270[m]. Furthermore, the first register 222a included in the selection signal output unit 270[1] is sequentially connected in series to the first register 222a included in the selection signal output unit 270[2], the first register 222a included in the selection signal output unit 270[3], ..., and the first register 222a included in the selection signal output unit 270[m].

[0088] In other words, the SP register group 261, the m second registers 222b included in each of the selection signal output sections 270[1] to 270[m], and the m first registers 222a included in each of the selection signal output sections 270[1] to 270[m] constitute a shift register. The head control signal DI input to the SP register group 261 is propagated to the subsequent stages in the order of the m second registers 222b included in each of the selection signal output sections 270[1] to 270[m] and the m first registers 222a included in each of the selection signal output sections 270[1] to 270[m], synchronized with the clock signal SCK. Subsequently, when the supply of the clock signal SCK is stopped, the second register 222b included in the selection signal output unit 270[i] holds the lower output data SILi corresponding to the piezoelectric element 60[i], and the first register 222a included in the selection signal output unit 270[i] holds the upper output data SIHi corresponding to the piezoelectric element 60[i].

[0089] The upper output data SIH held in the first register 222a of each of the selection signal output units 270[1] to 270[m] is latched by the corresponding first latch circuit 224a on the rising edge of the latch signal LAT, and the lower output data SIL held in the second register 222b of each of the selection signal output units 270[1] to 270[m] is latched by the corresponding second latch circuit 224b on the rising edge of the latch signal LAT. The first latch circuit 224a then outputs the latched upper output data SIH as latch data LTa to the decoder 226, and the second latch circuit 224b then outputs the latched lower output data SIL as latch data LTb to the decoder 226.

[0090] In the following explanation, the latch data LTa output by the first latch circuit 224a of the selection signal output unit 270[i] may be referred to as latch data LTai, and the latch data LTb output by the second latch circuit 224b of the selection signal output unit 270[i] may be referred to as latch data LTbi. In addition, latch data LTa and LTb may be collectively referred to as latch data [LTa, LTb], and latch data LTai and LTbi corresponding to the selection signal output unit 270[i] may be collectively referred to as latch data [LTai, LTbi].

[0091] Each of the selection signal output units 270[1] to 270[m] has a decoder 226 which is commonly input to the selection control signals Q0[SP00,SP01,SP02,SP03], Q1[SP10,SP11,SP12,SP13], and Q2[SP20,SP21,SP22,SP23] output by the selection control signal generation unit 262, as well as latch data[LTa,LTb] output by the corresponding first latch circuit 224a and second latch circuit 224b. In other words, the decoder 226 of the selection signal output unit 270[i] receives the selection control signals Q0[SP00,SP01,SP02,SP03], Q1[SP10,SP11,SP12,SP13], and Q2[SP20,SP21,SP22,SP23] output by the selection control signal generation unit 262, as well as latch data [LTai,LTbi] corresponding to the output data [SIHi,SILi]. The decoder 226 of the selection signal output unit 270[i] then generates a selection signal S[i] by decoding the latch data [LTai,LTbi] based on the selection control signals Q0,Q1,Q2, and outputs it to the selection circuit 230[i].

[0092] Figure 7 shows the decoding content of decoder 226 based on selection control signals Q0, Q1, and Q2. As shown in Figure 7, decoder 226 outputs a selection signal S of a logic level defined by selection control signal Q0 [SP00, SP01, SP02, SP03] during period t1, a selection signal S of a logic level defined by selection control signal Q1 [SP10, SP11, SP12, SP13] during period t2, and a selection signal S of a logic level defined by selection control signal Q2 [SP20, SP21, SP22, SP23] during period t3.

[0093] Specifically, when latch data [LTa,LTb]=[1,1] is input to decoder 226, decoder 226 outputs the logic level of setting information SP00 as a selection signal S during period t1, the logic level of setting information SP10 as a selection signal S during period t2, and the logic level of setting information SP20 as a selection signal S during period t3, according to the contents defined by selection control signals Q0, Q1, and Q2. Similarly, when latch data [LTa,LTb]=[1,0] is input to decoder 226, decoder 226 outputs the logic level of setting information SP01 as a selection signal S during period t1, the logic level of setting information SP11 as a selection signal S during period t2, and the logic level of setting information SP21 as a selection signal S during period t3, according to the contents defined by selection control signals Q0, Q1, and Q2. Similarly, when latch data [LTa,LTb]=[0,1] is input to decoder 226, decoder 226 outputs the logic level of setting information SP02 as a selection signal S during period t1, the logic level of setting information SP12 as a selection signal S during period t2, and the logic level of setting information SP22 as a selection signal S during period t3, according to the contents defined by selection control signals Q0, Q1, and Q2. Similarly, when latch data [LTa,LTb]=[0,0] is input to decoder 226, decoder 226 outputs the logic level of setting information SP03 as a selection signal S during period t1, the logic level of setting information SP13 as a selection signal S during period t2, and the logic level of setting information SP23 as a selection signal S during period t3, according to the contents defined by selection control signals Q0, Q1, and Q2.

[0094] As described above, the selection control circuit 210 outputs selection signals S[1] to S[m] that control the state of the selection circuits 230[1] to 230[m] corresponding to each of the piezoelectric elements 60[1] to 60[m], based on the clock signal SCK, the latch signal LAT, the change signal CH, and the head control signal DI.

[0095] Next, the configuration of selection circuits 230[1] to 230[m] will be explained. Here, selection circuits 230[1] to 230[m] all have the same configuration. Therefore, when there is no need to distinguish between selection circuits 230[1] to 230[m], they may simply be referred to as selection circuit 230. The explanation will proceed assuming that the selection signal S from the selection signals S[1] to S[m] is input to selection circuit 230.

[0096] Figure 8 shows the configuration of the selection circuit 230 corresponding to the piezoelectric element 60. As shown in Figure 8, the selection circuit 230 includes an inverter 232 which is a NOT gate and a transfer gate 234.

[0097] The selection signal S output by the selection control circuit 210 is input to the positive control terminal of the transfer gate 234 that is not marked with a circle, while being logically inverted by the inverter 232 and input to the negative control terminal of the transfer gate 234 that is marked with a circle. In addition, a drive signal COM is supplied to the input terminal of the transfer gate 234. Specifically, the transfer gate 234 conducts between its input terminal and output terminal when the input selection signal S is at a high level, and does not conduct between its input terminal and output terminal when the input selection signal S is at a low level. The drive signal VOUT is then output from the output terminal of the transfer gate 234.

[0098] As described above, the drive signal selection circuit 200 in this embodiment generates drive signals VOUT[1] to VOUT[m] corresponding to each of the piezoelectric elements 60[1] to 60[m] by selecting or deselecting the signal waveform of the drive signal COM based on the input clock signal SCK, latch signal LAT, change signal CH, and head control signal DI, and outputs them to the corresponding piezoelectric elements 60[1] to 60[m].

[0099] Here, we will describe a specific example of the operation of the drive signal selection circuit 200. The drive signal selection circuit 200 generates the drive signal VOUT by selecting or deselecting the signal waveform of the drive signal COM and outputs it to one end of the piezoelectric element 60. Therefore, in order to describe a specific example of the operation of the drive signal selection circuit 200, we will describe a specific example of the signal waveform of the drive signal COM input to the drive signal selection circuit 200.

[0100] Figure 9 shows an example of the signal waveform of the drive signal COM. As shown in Figure 9, the drive signal COM is a signal waveform that includes a series of trapezoidal waveforms: Adp, which is placed during the period t1 from when the latch signal LAT rises until when the change signal CH rises; Bdp, which is placed during the period t2 from when the change signal CH rises until the next change signal CH rises; and Cdp, which is placed during the period t3 from when the change signal CH rises until when the latch signal LAT rises.

[0101] The trapezoidal waveform Adp is a signal waveform that drives the piezoelectric element 60 to eject a predetermined amount of ink from the corresponding nozzle when supplied to the piezoelectric element 60. The trapezoidal waveform Bdp is a signal waveform that drives the piezoelectric element 60 to eject a smaller amount of ink than the predetermined amount from the corresponding nozzle when supplied to the piezoelectric element 60. The trapezoidal waveform Cdp is a signal waveform that drives the piezoelectric element 60 to prevent ink from being ejected from the corresponding nozzle, even when supplied to the piezoelectric element 60. Here, the trapezoidal waveform Cdp is a signal waveform that prevents an increase in ink viscosity by moderately vibrating the ink near the nozzle opening. In the following description, the operation of vibrating the ink near the nozzle opening when the trapezoidal waveform Cdp is supplied to the piezoelectric element 60 may be referred to as micro-vibration. Furthermore, in the following explanation, the amount of ink ejected when the trapezoidal waveform Adp is supplied to the piezoelectric element 60 may be referred to as a large amount, and the amount of ink ejected when the trapezoidal waveform Bdp is supplied to the piezoelectric element 60 may be referred to as a small amount.

[0102] Furthermore, the voltage values ​​at the start and end timings of the trapezoidal waveforms Adp, Bdp, and Cdp are all the same, at voltage Vc. That is, each of the trapezoidal waveforms Adp, Bdp, and Cdp starts and ends at voltage Vc. The period tp, consisting of periods t1, t2, and t3, corresponds to the dot formation period, which is when new dots are formed on the medium P.

[0103] Figure 10 shows an example of a head control signal DI input to the drive signal selection circuit 200. Here, the ejection control signal SI included in the head control signal DI defines the amount of ink ejected by driving the piezoelectric element 60. Therefore, the logic level of the ejection control signal SI changes appropriately during the printing period in which the liquid ejection device 1 ejects ink and forms a desired image on the medium P. That is, the logic level of the ejection data [SIH,SIL] included in the ejection control signal SI changes to either 0 or 1 depending on the amount of ink ejected. In other words, the logic level of the ejection data [SIH,SIL] included in the ejection control signal SI changes every period tp according to the image formed on the medium P. Therefore, in Figure 10, only the specific logic level of the waveform selection signal SP is shown, and the specific logic level of the waveform selection signal SP is omitted.

[0104] As shown in Figure 10, the drive signal selection circuit 200 receives a head control signal DI which includes a waveform selection signal SP in which each of the setting information SP00, SP01, SP02, SP03, SP10, SP11, SP12, SP13, SP20, SP21, SP22, and SP23 is "1", "0", "0", "0", "0", "1", "0", "0", "0", "0", "1", "0". Therefore, the selection control signal generation unit 262 included in the control logic circuit 260 generates selection control signals Q0[SP00,SP01,SP02,SP03]=[1,0,0,0], selection control signals Q1[SP10,SP11,SP12,SP13]=[0,1,0,0], and selection control signals Q2[SP20,SP21,SP22,SP23]=[0,0,1,0] based on the waveform selection signal SP, and outputs them to the decoder 226.

[0105] Figure 11 shows a specific example of the decoding content of the decoder 226 when the head control signal DI, which includes the waveform selection signal SP described above, is input to the drive signal selection circuit 200. In this embodiment, the decoder 226 outputs an H-level selection signal S when the logic level of the corresponding setting information SP23~SP20, SP13~SP10, SP03~SP00 is "1", and outputs an L-level selection signal S when the logic level of the corresponding setting information SP23~SP20, SP13~SP10, SP03~SP00 is "0".

[0106] As shown in Figure 11, when the decoder 226 receives latch data [LTa,LTb]=[1,1] corresponding to the discharge data [SIH,SIL]=[1,1], the decoder 226 outputs a selection signal S that is at H, L, L levels during periods t1, t2, and t3. Also, when the decoder 226 receives latch data [LTa,LTb]=[1,0] corresponding to the discharge data [SIH,SIL]=[1,0], the decoder 226 outputs a selection signal S that is at L, H, L levels during periods t1, t2, and t3. Furthermore, when the decoder 226 receives latch data [LTa,LTb]=[0,1] corresponding to the discharge data [SIH,SIL]=[0,1], the decoder 226 outputs a selection signal S that is at L, L, H levels during periods t1, t2, and t3. Furthermore, when the decoder 226 receives latch data [LTa,LTb]=[0,1] corresponding to the discharge data [SIH,SIL]=[0,0], the decoder 226 outputs a selection signal S that is at L,L,L level during periods t1, t2, and t3.

[0107] Figure 12 shows an example of the drive signal VOUT output from the selection circuit 230 when the selection signal S shown in Figure 11 is supplied.

[0108] As shown in Figure 12, when the decoder 226 receives latch data [LTa,LTb]=[1,1], the logic level of the selection signal S becomes high during period t1, low during period t2, and low during period t3. Therefore, the input and output terminals of the selection circuit 230 conduct during period t1, become non-conductive during period t2, and become non-conductive during period t3. As a result, the selection circuit 230 outputs a drive signal VOUT that is trapezoidal Adp during period t1, constant at voltage Vc during period t2, and constant at voltage Vc during period t3.

[0109] During this time, the piezoelectric element 60 is driven, causing a large amount of ink to be ejected during period t1, no ink to be ejected during period t2, and no ink to be ejected during period t3. Consequently, a large amount of ink lands on the medium P, forming large dots on the medium P.

[0110] Furthermore, when latch data [LTa,LTb]=[1,0] is input to decoder 226, the logic level of the selection signal S becomes L level in period t1, H level in period t2, and L level in period t3. Consequently, the connection between the input and output terminals of the selection circuit 230 becomes non-conductive in period t1, conductive in period t2, and non-conductive in period t3. As a result, the selection circuit 230 outputs a drive signal VOUT that is constant at voltage Vc in period t1, trapezoidal waveform Bdp in period t2, and constant at voltage Vc in period t3.

[0111] During this time, the piezoelectric element 60 is driven so that no ink is ejected during period t1, a small amount of ink is ejected during period t2, and no ink is ejected during period t3. Therefore, a small amount of ink lands on the medium P, forming small dots on the medium P.

[0112] Furthermore, when latch data [LTa,LTb]=[0,1] is input to decoder 226, the logic level of the selection signal S becomes L level in period t1, L level in period t2, and H level in period t3. Consequently, the connection between the input and output terminals of the selection circuit 230 becomes non-conductive in period t1, non-conductive in period t2, and conductive in period t3. As a result, the selection circuit 230 outputs a drive signal VOUT that is constant at voltage Vc in period t1, constant at voltage Vc in period t2, and trapezoidal waveform Cdp in period t3.

[0113] In this state, due to the driving of the piezoelectric element 60, ink is not ejected during period t1, ink is not ejected during period t2, and ink is not ejected during period t3. Therefore, no ink lands on the medium P, no dots are formed on the medium P, and micro-vibrations are performed.

[0114] Furthermore, when latch data [LTa,LTb]=[0,0] is input to decoder 226, the logic level of the selection signal S becomes L level in period t1, L level in period t2, and L level in period t3. Therefore, the connection between the input terminal and output terminal of the selection circuit 230 becomes non-conductive in period t1, non-conductive in period t2, and non-conductive in period t3. As a result, the selection circuit 230 outputs a drive signal VOUT that is constant at voltage Vc in period t1, constant at voltage Vc in period t2, and constant at voltage Vc in period t3. At this time, due to the driving of the piezoelectric element 60, no ink is ejected in period t1, no ink is ejected in period t2, and no ink is ejected in period t3. Therefore, no ink lands on the medium P, and no dots are formed on the medium P. At this time, the ink near the opening of the nozzle corresponding to the piezoelectric element 60 does not vibrate even slightly.

[0115] As described above, the discharge module 22 of this embodiment includes a plurality of piezoelectric elements 60, and the drive signal selection circuit 200 has a plurality of selection circuits 230 that switch whether or not to supply a drive signal VOUT based on a drive signal COM to the plurality of piezoelectric elements 60 included in the discharge module 22. The drive signal selection circuit 200 outputs a drive signal VOUT to form a large dot on the medium P by controlling the selection circuit 230 to conduct during period t1 and to non-conduct during periods t2 and t3 of the period tp; controlling the selection circuit 230 to conduct during period t2 and to non-conduct during periods t1 and t2 of the period tp to form a small dot on the medium P; controlling the selection circuit 230 to conduct during period t3 and to non-conduct during periods t1 and t2 of the period tp to output a drive signal VOUT that does not form a dot on the medium P and performs micro-vibrations; and controlling the selection circuit 230 to non-conduct during all periods t1 to t3 of the period tp to output a drive signal VOUT that does not form a dot on the medium P and does not perform micro-vibrations.

[0116] Here, the drive signal VOUT output by the drive signal selection circuit 200 is a continuous signal waveform consisting of a selected trapezoidal waveform (Adp, Bdp, or Cdp) included in the drive signal COM, and a constant voltage Vc held by the capacitive component of the piezoelectric element 60 to which the drive signal VOUT is supplied. In other words, the drive signal VOUT output by the drive signal selection circuit 200 is synonymous with the drive signal VOUT supplied to the piezoelectric element 60.

[0117] 5. Structure of the ejection module 22 of the print head 20 Next, the structure of the ejection module 22 of the print head 20 will be described. Figure 13 is an exploded perspective view showing the structure of the ejection module 22, Figure 14 is a plan view of the ejection module 22, Figure 15 is a cross-sectional view showing the IV-IV section shown in Figure 14, Figure 16 is a detailed view of the main part of Figure 15, and Figure 17 is a cross-sectional view showing the VI-VI section shown in Figure 14. In describing the structure of the print head 20, each figure shows three mutually orthogonal spatial axes, X, Y, and Z. In this embodiment, the directions along these axes are referred to as the X-axis direction, Y-axis direction, and Z-axis direction, and when specifying the direction, the positive direction is indicated by "+" and the negative direction by "-", and positive and negative signs are used in the direction notation, with the direction pointed to by the arrow in each figure being the + direction and the opposite direction of the arrow being the - direction. The Z-axis direction indicates the vertical direction, the +Z-axis direction indicates the vertically downward direction, and the -Z-axis direction indicates the vertically upward direction. Furthermore, the three spatial axes X, Y, and Z, which are not limited to positive or negative directions, are referred to as the X-axis, Y-axis, and Z-axis.

[0118] As shown in Figure 13, the ejection module 22 ejects ink in the Z-axis direction, more specifically in the +Z-axis direction. The ejection module 22 has as its constituent components a pressure chamber substrate 310, a communication plate 315, a nozzle plate 320, a compliance substrate 345, a diaphragm 350 (described later), a piezoelectric element 60 (described later), a protective substrate 330, a case member 340, and a wiring substrate 420.

[0119] The pressure chamber substrate 310 is made of, for example, a silicon substrate, a glass substrate, an SOI substrate, or various ceramic substrates. As shown in Figure 14, the pressure chamber substrate 310 has two rows of pressure chambers arranged in the X-axis direction, each row containing multiple pressure chambers 312 aligned along the Y-axis direction. In other words, the ejection module 22 of the print head 20 has multiple pressure chambers 312, and these multiple pressure chambers 312 form rows of pressure chambers arranged along the Y-axis direction. Here, of the two rows of pressure chambers, the row on the +X direction side may be called the first pressure chamber row, and the row of pressure chambers separated from the first pressure chamber row in the -X direction in the X-axis direction may be called the second pressure chamber row. Note that Figure 14 is a plan view of the ejection module 22, but it shows the configuration around the pressure chamber substrate 310, and omits the illustration of the protective substrate 330 and case member 340.

[0120] Furthermore, the multiple pressure chambers 312 constituting each row of pressure chambers are arranged on a straight line along the Y-axis so that their positions in the X-axis direction are the same. Pressure chambers 312 adjacent to each other in the Y-axis direction are separated by partition walls 311 as shown in Figure 17. Of course, the arrangement of the pressure chambers 312 is not particularly limited. For example, the arrangement of multiple pressure chambers 312 aligned in the Y-axis direction may be a so-called staggered arrangement, where each pressure chamber 312 is shifted by one in the X-axis direction.

[0121] Furthermore, the pressure chamber 312 in this embodiment is formed in a rectangular shape, for example, where the length in the X-axis direction is longer than the length in the Y-axis direction when viewed from the +Z direction in a plan view. Of course, the shape of the pressure chamber 312 when viewed from the +Z direction in a plan view is not particularly limited and may be a parallelogram, polygon, circle, oval, etc. Note that the oval shape referred to here is a shape based on a rectangle with semicircular ends in the longitudinal direction, and includes rounded rectangles, ellipses, egg shapes, etc.

[0122] As shown in Figures 13 and 16, a communication plate 315, a nozzle plate 320, and a compliance substrate 345 are sequentially stacked on the +Z axis side of the pressure chamber substrate 310.

[0123] The communication plate 315 is provided with a nozzle communication passage 316 that connects the pressure chamber 312 and the nozzle 321. The communication plate 315 is also provided with a first manifold section 317 and a second manifold section 318 that constitute part of a manifold 400, which is a common liquid chamber through which multiple pressure chambers 312 communicate. The first manifold section 317 is provided penetrating the communication plate 315 in the Z-axis direction. The second manifold section 318 is provided opening on the +Z-axis side surface without penetrating the communication plate 315 in the Z-axis direction.

[0124] Furthermore, the communication plate 315 is provided with a supply passage 319 that communicates with one end of the pressure chamber 312 in the X-axis direction, independently of each pressure chamber 312. The supply passage 319 connects the second manifold section 318 to each pressure chamber 312, supplying ink from the manifold 400 to each pressure chamber 312.

[0125] As the connecting plate 315, a silicon substrate, glass substrate, SOI substrate, various ceramic substrates, metal substrates, etc., can be used. Examples of metal substrates include stainless steel substrates. It is preferable that the connecting plate 315 be made of a material with a coefficient of thermal expansion approximately the same as that of the pressure chamber substrate 310. This reduces the risk of warping occurring in the pressure chamber substrate 310 and the connecting plate 315 due to differences in their coefficients of thermal expansion when their temperatures change.

[0126] The nozzle plate 320 is provided on the side of the communication plate 315 opposite to the pressure chamber substrate 310, that is, on the +Z axis side. Nozzles 321 are formed on the nozzle plate 320, which communicate with each pressure chamber 312 via nozzle communication passages 316.

[0127] In this embodiment, the multiple nozzles 321 are arranged in a line along the Y-axis. The nozzle plate 320 has two rows of nozzles, each row of multiple nozzles 321, spaced apart in the X-axis direction. The two rows of nozzles correspond to the first pressure chamber row and the second pressure chamber row, respectively. The multiple nozzles 321 in each row are arranged so that they are at the same position in the X-axis direction. The arrangement of the nozzles 321 is not particularly limited. For example, nozzles 321 arranged in a line along the Y-axis may be positioned with every other nozzle offset in the X-axis direction.

[0128] The material of the nozzle plate 320 is not particularly limited, and for example, silicon substrates, glass substrates, SOI substrates, various ceramic substrates, and metal substrates can be used. Examples of metal substrates include stainless steel substrates. Furthermore, organic materials such as polyimide resin can also be used as the material of the nozzle plate 320. However, it is preferable to use a material for the nozzle plate 320 that has approximately the same thermal expansion coefficient as the communication plate 315. This reduces the risk of warping of the nozzle plate 320 and the communication plate 315 due to differences in thermal expansion coefficients when the temperature of the nozzle plate 320 and the communication plate 315 changes.

[0129] The compliance substrate 345 is provided together with the nozzle plate 320 on the side of the communication plate 315 opposite to the pressure chamber substrate 310, i.e., on the +Z axis side. This compliance substrate 345 is provided around the nozzle plate 320 and seals the openings of the first manifold section 317 and the second manifold section 318 provided on the communication plate 315. The compliance substrate 345 includes a sealing film 346 made of a flexible thin film and a fixed substrate 347 made of a hard material such as metal. The region of the fixed substrate 347 facing the manifold 400 is an opening 348 that is completely removed in the thickness direction. Therefore, one side of the manifold 400 is a compliance section 349 sealed only by the flexible sealing film 346.

[0130] On the other hand, on the side of the pressure chamber substrate 310 opposite to the nozzle plate 320, i.e., the side in the -Z direction, a diaphragm 350 and a piezoelectric element 60 that causes the diaphragm 350 to bend and deform, thereby generating a pressure change in the ink in the pressure chamber 312, are laminated together, as will be described in more detail later. In other words, the diaphragm 350 is positioned in the +Z direction relative to the piezoelectric element 60, and the pressure chamber substrate 310 is positioned in the +Z direction relative to the diaphragm 350. Note that Figure 15 is a diagram illustrating the overall configuration of the ejection module 22, and the configuration of the piezoelectric element 60 is shown in a simplified manner.

[0131] A protective substrate 330, having approximately the same size as the pressure chamber substrate 310, is further bonded to the -Z-axis side of the pressure chamber substrate 310 using an adhesive or the like. The protective substrate 330 has a holding portion 331, which is a space for protecting the piezoelectric elements 60. The holding portion 331 is provided independently for each row of piezoelectric elements 60 arranged in the Y-axis direction, and two of them are formed side by side in the X-axis direction. In addition, the protective substrate 330 has a through hole 332 that penetrates in the Z-axis direction between the two holding portions 331 arranged side by side in the X-axis direction.

[0132] Furthermore, a case member 340 is fixed to the protective substrate 330, which together defines a manifold 400 communicating with multiple pressure chambers 312, in conjunction with the pressure chamber substrate 310. The case member 340 has substantially the same shape as the aforementioned communication plate 315 when viewed from the -Z axis, and is joined to the protective substrate 330 as well as to the aforementioned communication plate 315.

[0133] Such a case member 340 has a housing section 341 on the side of the protective substrate 330, which is a space with a depth capable of accommodating the pressure chamber substrate 310 and the protective substrate 330. This housing section 341 has an opening area larger than the surface of the protective substrate 330 that is joined to the pressure chamber substrate 310. When the pressure chamber substrate 310 and the protective substrate 330 are housed in the housing section 341, the opening surface of the housing section 341 on the nozzle plate 320 side is sealed by a communication plate 315.

[0134] Furthermore, the case member 340 has third manifold sections 342 defined on both outer sides of the housing section 341 in the X-axis direction. The manifold 400 is composed of the first manifold section 317 and the second manifold section 318 provided on the communication plate 315, and the third manifold section 342. The manifold 400 is provided continuously in the Y-axis direction, and the supply passages 319 that connect each pressure chamber 312 to the manifold 400 are arranged side by side in the Y-axis direction.

[0135] Furthermore, the case member 340 is provided with supply ports 344 that communicate with the manifold 400 and supply ink to each manifold 400. In addition, the case member 340 is provided with connection ports 343 that communicate with the through holes 332 of the protective substrate 330 and through which the wiring substrate 420 is inserted.

[0136] In this embodiment of the ejection module 22, ink stored in the ink container 2 is taken in from the supply port 344, and the inside is filled with ink from the manifold 400 to the nozzle 321. Then, the integrated circuit 421, which includes a drive signal selection circuit 200, supplies a drive signal VOUT based on the drive signal COM to each piezoelectric element 60 corresponding to the pressure chamber 312. As a result, the diaphragm 350 flexes and deforms together with the piezoelectric element 60, increasing the pressure in each pressure chamber 312, and ink is ejected from each nozzle 321. The print head 20 is composed of multiple ejection modules 22 as described above.

[0137] Next, the configuration in which the diaphragm 350 and piezoelectric element 60 described above are laminated on the -Z axis side of the pressure chamber substrate 310 will be explained in detail. The discharge module 22, as a configuration laminated on the -Z axis side of the pressure chamber substrate 310, has individual lead electrodes 391, a common lead electrode 392, a measuring lead electrode 393, and resistance wiring 401 in addition to the diaphragm 350 and piezoelectric element 60.

[0138] As shown in Figures 15 to 17, the diaphragm 350 is composed of an elastic film 351 made of silicon oxide provided on the pressure chamber substrate 310 side, and an insulating film 352 made of zirconium oxide provided on the elastic film 351. Liquid channels such as the pressure chamber 312 are formed by anisotropic etching of the pressure chamber substrate 310 from the +Z axis side, and the -Z axis side of the liquid channels such as the pressure chamber 312 is composed of the elastic film 351.

[0139] The composition of the diaphragm 350 is not particularly limited. For example, the diaphragm 350 may be composed of either an elastic film 351 or an insulating film 352, or it may also include other films besides the elastic film 351 and the insulating film 352. Examples of materials for the other films include silicon and silicon nitride.

[0140] The piezoelectric element 60 is an example of a piezoelectric actuator that generates a pressure change in the ink in the pressure chamber 312. This piezoelectric element 60 has a first electrode 360, a piezoelectric body 370, and a second electrode 380, which are sequentially stacked from the +Z axis side (the side of the diaphragm 350) toward the -Z axis side. In other words, the piezoelectric element 60 includes the first electrode 360, the second electrode 380, and the piezoelectric body 370, and in the Z axis direction in which the first electrode 360, the second electrode 380, and the piezoelectric body 370 are stacked, the piezoelectric body 370 is provided between the first electrode 360 ​​and the second electrode 380.

[0141] The first electrode 360 ​​and the second electrode 380 are both electrically connected to the wiring board 420 and supply the piezoelectric element 370 with a drive signal VOUT supplied from a drive signal selection circuit 200 included in an integrated circuit 421 mounted on the wiring board 420, and a reference voltage signal VBS propagating through the wiring board 420. The first electrode 360 ​​is supplied with a different drive signal VOUT depending on the amount of ink ejected, and the second electrode 380 is supplied with a constant reference voltage signal VBS regardless of the amount of ink ejected. This creates a potential difference between the first electrode 360 ​​and the second electrode 380, causing the piezoelectric element 370 to deform. That is, when the piezoelectric element 60 is driven, the diaphragm 350 deforms or vibrates, and the volume of the pressure chamber 312 changes, thereby applying pressure to the ink contained in the pressure chamber 312. As a result, ink is ejected from the nozzle 321 via the nozzle communication passage 316. In this case, the amount of change in the volume of the pressure chamber 312 becomes the amount of ink ejected.

[0142] Of the piezoelectric element 60, the portion of the piezoelectric body 370 that experiences piezoelectric strain when a voltage is applied between the first electrode 360 ​​and the second electrode 380 is called the active portion 410. Conversely, the portion of the piezoelectric body 370 that does not experience piezoelectric strain is called the inactive portion 415. That is, of the piezoelectric element 60, the portion of the piezoelectric body 370 sandwiched between the first electrode 360 ​​and the second electrode 380 is the active portion 410, and the portion of the piezoelectric body 370 not sandwiched between the first electrode 360 ​​and the second electrode 380 is the inactive portion 415. Furthermore, when the piezoelectric element 60 is driven, the portion that is displaced in the Z-axis direction is called the flexible portion, and the portion that is not displaced in the Z-axis direction is called the inflexible portion. That is, of the piezoelectric element 60, the portion facing the pressure chamber 312 in the Z-axis direction is the flexible portion, and the portion outside the pressure chamber 312 is the inflexible portion. The active portion 410 is also called the active part, and the inactive portion 415 is also called the inactive part.

[0143] Generally, one electrode of the active section 410 is configured as an individual electrode independent of each active section 410, while the other electrode is configured as a common electrode common to multiple active sections 410. In this embodiment, the first electrode 360 ​​constitutes an individual electrode, and the second electrode 380 constitutes a common electrode.

[0144] Specifically, the first electrode 360 ​​is provided on the +Z-axis side of the piezoelectric body 370 in the Z-axis direction, and is divided for each pressure chamber 312 to form an independent individual electrode for each active part 410. That is, the first electrode 360 ​​is provided individually for each of the multiple pressure chambers 312. The first electrode 360 ​​is formed with a width narrower than the width of the pressure chamber 312 in the Y-axis direction. That is, in the Y-axis direction, the end of the first electrode 360 ​​is located inside the region facing the pressure chamber 312.

[0145] Furthermore, the +X-direction end 360a and the -X-direction end 360b of the first electrode 360 ​​are located outside the pressure chamber 312. For example, in the first pressure chamber row, as shown in Figure 16, the end 360a of the first electrode 360 ​​is positioned further to the +X-axis side than the +X-axis end 312a of the pressure chamber 312. The end 360b of the first electrode 360 ​​is positioned further to the -X-axis side than the -X-axis end 312b of the pressure chamber 312.

[0146] The material of the first electrode 360 ​​is not particularly limited, but conductive materials such as metals like platinum (Pt), iridium (Ir), gold (Au), and titanium (Ti), or conductive metal oxides such as indium tin oxide (ITO), can be used. Alternatively, multiple materials such as platinum (Pt), iridium (Ir), gold (Au), and titanium (Ti) may be layered to form the electrode. In this embodiment, platinum (Pt) was used as the first electrode 360.

[0147] As shown in Figure 14, the piezoelectric element 370 is provided continuously along the Y-axis direction with a predetermined length in the X-axis direction. That is, the piezoelectric element 370 is provided continuously along the direction in which the pressure chambers 312 are arranged side by side with a predetermined thickness. The thickness of the piezoelectric element 370 is not particularly limited, but it is formed to a thickness of about 1000 nanometers to 4000 nanometers.

[0148] Furthermore, as shown in Figure 16, the length of the piezoelectric element 370 in the X-axis direction is longer than the length of the pressure chamber 312 in the X-axis direction. Therefore, on both sides of the pressure chamber 312 in the X-axis direction, the piezoelectric element 370 extends to the outside of the pressure chamber 312. This extension of the piezoelectric element 370 to the outside of the pressure chamber 312 in the X-axis direction improves the strength of the diaphragm 350. Consequently, when the active part 410 is driven to displace the piezoelectric element 60, the risk of cracks or other damage occurring in the diaphragm 350 or the piezoelectric element 60 can be reduced.

[0149] Furthermore, for example, in the first pressure chamber row, as shown in Figure 16, the +X-direction end 370a of the piezoelectric element 370 is located on the +X-axis side, outside the end 360a of the first electrode 360. That is, the end 360a of the first electrode 360 ​​is covered by the piezoelectric element 370. On the other hand, the -X-direction end 370b of the piezoelectric element 370 is located on the +X-axis side, inside the end 360b of the first electrode 360, and the end 360b of the first electrode 360 ​​is not covered by the piezoelectric element 370.

[0150] Furthermore, as shown in Figures 14 and 17, the piezoelectric element 370 has grooves 371 formed in each partition wall 311, which are thinner than other areas. In this embodiment, the grooves 371 are formed by completely removing the piezoelectric element 370 in the Z-axis direction. That is, having a portion of the piezoelectric element 370 that is thinner than other areas includes portions where the piezoelectric element 370 has been completely removed in the Z-axis direction. Of course, the piezoelectric element 370 may also be formed thinner than other portions on the bottom surface of the grooves 371.

[0151] Furthermore, the length of the groove 371 in the Y-axis direction, that is, the width of the groove 371, is the same as or wider than the width of the partition wall 311. In this embodiment, the width of the groove 371 is wider than the width of the partition wall 311.

[0152] Such grooves 371 are formed to be rectangular in shape when viewed from the -Z-axis direction. Of course, the shape of the groove 371 when viewed from the -Z-axis direction is not limited to a rectangle, but may be a polygon with five or more sides, or it may be circular or elliptical, etc.

[0153] By providing grooves 371 in the piezoelectric body 370, the rigidity of the portion of the diaphragm 350 facing the Y-axis end of the pressure chamber 312, the so-called arm portion of the diaphragm 350, is reduced, thereby allowing the piezoelectric element 60 to be displaced more effectively.

[0154] Examples of piezoelectric material 370 include a perovskite crystal film made of a ferroelectric ceramic material exhibiting electromechanical conversion activity, formed on the first electrode 360, so-called perovskite crystal. As the material for piezoelectric material 370, for example, ferroelectric piezoelectric materials such as lead zirconate titanate (PZT) or materials to which metal oxides such as niobium oxide, nickel oxide, or magnesium oxide are added can be used. Specifically, lead titanate (PbTiO3), lead zirconate titanate (Pb(Zr,Ti)O3), lead zirconate (PbZrO3), lead lanthanum titanate ((Pb,La),TiO3), lead zirconate titanate lanthanum ((Pb,La)(Zr,Ti)O3), or magnesium zirconium titanate lead (Pb(Zr,Ti)(Mg,Nb)O3) can be used. In this embodiment, lead zirconate titanate (PZT) was used as the piezoelectric element 370.

[0155] Furthermore, the material for the piezoelectric element 370 is not limited to lead-based piezoelectric materials containing lead; lead-free piezoelectric materials can also be used. Examples of lead-free piezoelectric materials include bismuth ironate ((BiFeO3), abbreviated as "BFO"), barium titanate ((BaTiO3), abbreviated as "BT"), potassium sodium niobate ((K,Na)(NbO3), abbreviated as "KNN"), potassium sodium lithium niobate ((K,Na,Li)(NbO3)), potassium sodium lithium tantalate niobate ((K,Na,Li)(Nb,Ta)O3), potassium bismuth titanate ((Bi1 / 2K1 / 2)TiO3, abbreviated as "BKT"), sodium bismuth titanate ((Bi1 / 2Na1 / 2)TiO3, abbreviated as "BNT"), and manganese. Examples include bismuth oxide (BiMnO3, abbreviated as "BM"), a composite oxide containing bismuth, potassium, titanium, and iron and having a perovskite structure (x[(BixK1-x)TiO3]-(1-x)[BiFeO3], abbreviated as "BKT-BF"), a composite oxide containing bismuth, iron, barium, and titanium and having a perovskite structure ((1-x)[BiFeO3]-x[BaTiO3], abbreviated as "BFO-BT"), and those to which metals such as manganese, cobalt, and chromium are added ((1-x)[Bi(Fe1-yMy)O3]-x[BaTiO3] (where M is Mn, Co, or Cr)).

[0156] As shown in Figures 14, 16, and 17, the second electrode 380 is provided on the -Z-axis side of the piezoelectric body 370, opposite to the first electrode 360, and constitutes a common electrode common to multiple active parts 410. That is, the second electrode 380 is provided in common to multiple pressure chambers 312. The second electrode 380 is provided continuously in the Y-axis direction with a predetermined length in the X-axis direction. This second electrode 380 is also provided on the inner surface of the groove 371, that is, on the side surface of the groove 371 of the piezoelectric body 370 and on the insulating film 352 which is the bottom surface of the groove 371. Regarding the inside of the groove 371, the second electrode 380 may be provided only on a part of the inner surface of the groove 371, or it may not be provided over the entire inner surface of the groove 371.

[0157] Furthermore, for example, in the first pressure chamber row, as shown in Figure 16, the +X-direction end 380a of the second electrode 380 is positioned on the +X-axis side such that it is outside the end 360a of the first electrode 360, which is covered by the piezoelectric element 370. That is, the end 380a of the second electrode 380 is located on the +X-axis side, outside the end 312a of the pressure chamber 312, and outside the end 360a of the first electrode 360. In this embodiment, the end 380a of the second electrode 380 substantially coincides with the end 370a of the piezoelectric element 370 in the X-axis direction. Therefore, the +X-axis end of the active part 410, i.e., the boundary between the active part 410 and the inactive part 415, is defined by the end 360a of the first electrode 360.

[0158] On the other hand, the -X-axis end 380b of the second electrode 380 is located on the -X-axis side, outside the -X-axis end 312b of the pressure chamber 312, but on the +X-axis side, inside the end 370b of the piezoelectric element 370. As described above, the end 370b of the piezoelectric element 370 is located inside the +X-axis side of the end 360b of the first electrode 360. Therefore, the end 380b of the second electrode 380 is located on the piezoelectric element 370 on the +X-axis side of the end 360b of the first electrode 360. As a result, there is an exposed portion of the piezoelectric element 370 surface on the -X-axis side of the end 380b of the second electrode 380.

[0159] Thus, since the end 380b of the second electrode 380 is positioned on the +X axis side more than the end 370b of the piezoelectric body 370 and the end 360b of the first electrode 360, the -X axis side of the active portion 410, i.e., the boundary between the active portion 410 and the inactive portion 415, is defined by the end 380b of the second electrode 380.

[0160] The material of the second electrode 380 is not particularly limited, but, similar to the first electrode 360, conductive materials such as metals like platinum (Pt), iridium (Ir), gold (Au), and titanium (Ti), or conductive metal oxides such as indium tin oxide (ITO) can be used. Alternatively, multiple materials such as platinum (Pt), iridium (Ir), gold (Au), and titanium (Ti) may be laminated to form the second electrode 380. In this embodiment, iridium (Ir) was used as the second electrode 380.

[0161] Furthermore, outside the end 380b of the second electrode 380, that is, further towards the -X axis direction from the end 380b of the second electrode 380, there is a wiring section 385 which is on the same layer as the second electrode 380 but is electrically discontinuous from the second electrode 380. The wiring section 385 is formed on the piezoelectric body 370 and extends over the first electrode 360 ​​which extends further in the -X axis direction than the piezoelectric body 370, with a gap so as not to contact the end 380b of the second electrode 380. This wiring section 385 is provided independently for each active section 410. In other words, multiple wiring sections 385 are arranged at predetermined intervals along the Y axis. The wiring section 385 may be formed in a different layer from the second electrode 380, but it is preferable that it be formed in the same layer as the second electrode 380. This simplifies the manufacturing process of the wiring section 385 and reduces costs.

[0162] Furthermore, the first electrode 360 ​​and the second electrode 380 constituting the piezoelectric element 60 are electrically connected to the first electrode 360, with an individual lead electrode 391 connected to the first electrode 360 ​​and a common lead electrode 392, which is a common drive electrode, connected to the second electrode 380. A flexible wiring board 420 is electrically connected to the ends of the individual lead electrode 391 and the common lead electrode 392 that are opposite to the ends connected to the piezoelectric element 60. Multiple wirings for connecting to the control mechanism 10, the temperature information output circuit 26, and multiple circuits (not shown) are formed on the wiring board 420. In this embodiment, the wiring board 420 is made of, for example, an FPC (Flexible Printed Circuit). However, instead of an FPC, it may be made of any flexible substrate such as an FFC (Flexible Flat Cable).

[0163] In this embodiment, the individual lead electrodes 391 and the common lead electrode 392 extend to be exposed within through holes 332 formed in the protective substrate 330, and are electrically connected to the wiring board 420 within these through holes 332. The wiring board 420 is also equipped with an integrated circuit 421 that includes a drive signal selection circuit 200 that outputs a drive signal VOUT for driving the piezoelectric element 60.

[0164] In this embodiment, the individual lead electrodes 391 and the common lead electrode 392 are made of the same layer but are formed to be electrically discontinuous. This simplifies the manufacturing process and reduces costs compared to forming the individual lead electrodes 391 and the common lead electrode 392 separately. Of course, the individual lead electrodes 391 and the common lead electrode 392 may be formed from different layers.

[0165] The material of the individual lead electrodes 391 and the common lead electrode 392 is not particularly limited as long as it is an conductive material, and for example, gold (Au), copper (Cu), titanium (Ti), tungsten (W), nickel (Ni), chromium (Cr), platinum (Pt), aluminum (Al), etc. can be used. In this embodiment, gold (Au) was used for the individual lead electrodes 391 and the common lead electrode 392. In addition, the individual lead electrodes 391 and the common lead electrode 392 may have an adhesion layer to improve adhesion with the first electrode 360 ​​and the second electrode 380 and the diaphragm 350.

[0166] Individual lead electrodes 391 are provided for each active section 410, that is, for each first electrode 360. As shown in Figure 16, for example, in the first pressure chamber row, the individual lead electrodes 391 are connected via the wiring section 385 to the vicinity of the end 360b of the first electrode 360, which is located outside the piezoelectric element 370, and are led out in the -X axis direction onto the pressure chamber substrate 310, and actually onto the diaphragm 350.

[0167] On the other hand, as shown in Figure 14, for example, in the first pressure chamber row, the common lead electrode 392 is drawn out in the -X direction from the second electrode 380, which constitutes the common electrode on the piezoelectric body 370, to the diaphragm 350 at both ends in the Y-axis direction. The common lead electrode 392 also has an extended portion 392a and an extended portion 392b. As shown in Figures 14 and 16, for example, in the first pressure chamber row, the extended portion 392a extends along the Y-axis direction to a region corresponding to the end 312a of the pressure chamber 312, and the extended portion 392b extends along the Y-axis direction to a region corresponding to the end 312b of the pressure chamber 312. These extended portions 392a and 392b are provided continuously in the Y-axis direction for a plurality of active portions 410.

[0168] Furthermore, the extensions 392a and 392b extend from the inside of the pressure chamber 312 to the outside of the pressure chamber 312 in the X-axis direction. In this embodiment, the active portion 410 of the piezoelectric element 60 extends to the outside of the pressure chamber 312 at both ends of the pressure chamber 312 in the X-axis direction, and the extensions 392a and 392b extend along this active portion 410 to the outside of the pressure chamber 312.

[0169] As shown in Figure 16, a resistance wiring 401 is provided on the -Z-axis side surface of the diaphragm 350. The resistance wiring 401 constitutes at least a part of the temperature detection circuit 24 for detecting the temperature of the pressure chamber 312. The temperature detection circuit 24 in this embodiment utilizes the characteristic that the electrical resistance value of metals, semiconductors, etc., changes with temperature. The material of the resistance wiring 401 is not particularly limited as long as it is a material whose electrical resistance value is temperature-dependent, and for example, gold (Au), platinum (Pt), iridium (Ir), aluminum (Al), copper (Cu), titanium (Ti), tungsten (W), nickel (Ni), chromium (Cr), etc. can be used. Of these, platinum (Pt) can be suitably adopted as the material for the resistance wiring 401 from the viewpoint of its large change in resistance value with temperature, and high stability and accuracy. In this embodiment, the resistance wiring 401 is laminated on the -Z-axis side surface of the diaphragm 350 so as to be in the same layer as the first electrode 360, and electrically discontinuous with the first electrode 360. Therefore, the material of the resistive wiring 401 is platinum (Pt), the same as that of the first electrode 360. This simplifies the manufacturing process and reduces costs compared to forming the resistive wiring 401 separately from the first electrode 360. Of course, the resistive wiring 401 may also be formed in a different layer from the first electrode 360.

[0170] As shown in Figure 14, the resistance wiring 401 is continuous, with one end of the resistance wiring 401 on the +X-axis side in the X-axis direction connected to the measuring lead electrode 393a, and the other end of the resistance wiring 401 on the -X-axis side in the X-axis direction connected to the measuring lead electrode 393b. The measuring lead electrodes 393a and 393b are electrically connected to the wiring board 420. As a result, the resistance wiring 401 is electrically connected to the temperature information output circuit 26, and the temperature information output circuit 26 is able to measure the electrical resistance value of the resistance wiring 401. In this embodiment, the resistance wiring 401 is covered by the piezoelectric element 370 and is located between the diaphragm 350 and the piezoelectric element 370 in the Z-axis direction.

[0171] The resistance wiring 401 comprises a first pressure chamber row-side meandering pattern that is on the +X-axis side in the X-axis direction, and a second pressure chamber row-side meandering pattern that is on the -X-axis side in the X-axis direction. The first pressure chamber row-side meandering pattern, when viewed from the -Z-axis direction, meanders along the Y-axis direction at a position that overlaps with the supply communication passage 319 that communicates with each pressure chamber 312 constituting the first pressure chamber row. The second pressure chamber row-side meandering pattern, when viewed from the -Z-axis direction, meanders along the Y-axis direction at a position that overlaps with the supply communication passage 319 that communicates with each pressure chamber 312 constituting the second pressure chamber row. In other words, the resistance wiring 401 comprises a first pressure chamber row-side meandering pattern corresponding to a first pressure chamber row formed by a plurality of pressure chambers 312, and a second pressure chamber row-side meandering pattern corresponding to a second pressure chamber row formed by a plurality of pressure chambers 312. Furthermore, as shown in Figures 15 and 16, the distance in the Z-axis direction between the -Z-axis end of the pressure chamber 312 and the resistance wiring 401 is shorter than the Z-axis dimension of the pressure chamber 312. Also, for example, in the first pressure chamber row, the longest distance in the X-axis direction between the +X-direction end 312a of the pressure chamber 312 and the resistance wiring 401 is shorter than the X-axis dimension of the pressure chamber 312. For this reason, the electrical resistance value of the resistance wiring 401 is prone to changing in response to temperature changes in the pressure chamber 312.

[0172] In this embodiment, the measuring lead electrode 393, including measuring lead electrodes 393a and 393b, is made of the same single layer as the individual lead electrodes 391 and the common lead electrode 392, but is formed to be electrically discontinuous. This simplifies the manufacturing process and reduces costs compared to forming the measuring lead electrode 393 separately from the individual lead electrodes 391 and the common lead electrode 392. Of course, the measuring lead electrode 393 may also be formed from a different layer than the individual lead electrodes 391 and the common lead electrode 392.

[0173] The material of the measuring lead electrode 393 is not particularly limited as long as it is a conductive material, and for example, gold (Au), copper (Cu), titanium (Ti), tungsten (W), nickel (Ni), chromium (Cr), platinum (Pt), aluminum (Al), etc. can be used. In this embodiment, gold (Au) was used as the measuring lead electrode 393. Therefore, the material of the measuring lead electrode 393 is the same as that of the individual lead electrodes 391 and the common lead electrode 392. In addition, the measuring lead electrode 393 may have an adhesion layer to improve adhesion with the resistance wiring 401 and the diaphragm 350.

[0174] In this embodiment, the measuring lead electrode 393 extends to be exposed within a through hole 332 formed in the protective substrate 330, and is electrically connected to the wiring board 420 within this through hole 332. This allows the temperature information output circuit 26 to acquire the electrical resistance value of the resistor wiring 401 via the wiring board 420. The temperature information output circuit 26 then outputs the acquired electrical resistance value of the resistor wiring 401 as a temperature information signal TI in response to the temperature acquisition request signal TD from the control circuit 100. The temperature information output circuit 26 may also store in advance the correspondence between the electrical resistance value of the resistor wiring 401 and the temperature. The temperature information output circuit 26 may then output the temperature corresponding to the electrical resistance value of the resistor wiring 401 as a temperature information signal TI in response to the temperature acquisition request signal TD from the control circuit 100.

[0175] For example, if the temperature detection circuit 24 is located outside the ejection module 22, the difference between the temperature measured by the temperature detection circuit 24 and the temperature inside the pressure chamber 312 may become larger than the difference between the temperature inside the ejection module 22 and the temperature inside the pressure chamber 312. In this case, the correction control by which the control circuit 100 corrects the control signals Ctrl-H, Ctrl-C, and Ctrl-T based on the temperature information signal TI may be reduced, and optimal ejection control of the ejection module 22 suitable for the ink temperature inside the pressure chamber 312 may not be possible. In this embodiment, the resistance wiring 401 is stacked on the diaphragm 350 located inside the ejection module 22. This makes it possible to reduce the difference between the temperature detected based on the electrical resistance value of the resistance wiring 401, which is the temperature detection circuit 24, and the temperature inside the pressure chamber 312, thereby improving the detection accuracy of the temperature inside the pressure chamber 312 detected by the temperature detection circuit 24. As a result, the control circuit 100 can perform ejection control of the ejection module 22 that is suitable for the ink temperature inside the pressure chamber 312.

[0176] In other words, the print head 20 of this embodiment includes an ejection module 22 which includes a first electrode 360, a second electrode 380, and a piezoelectric element 370, and in the Z-axis direction which is the stacking direction in which the first electrode 360, the second electrode 380, and the piezoelectric element 370 are stacked, the piezoelectric element 370 is located between the first electrode 360 ​​and the second electrode 380 and is driven by a drive signal VOUT based on a drive signal COM, and a diaphragm 350 is located on the +Z-axis side which is one side of the Z-axis direction which is the stacking direction with respect to the piezoelectric element 60 and is deformed by the driving of the piezoelectric element 60, and in the stacking direction with respect to the diaphragm 350 The device includes a pressure chamber substrate 310 located on the +Z-axis side, which is one side in the Z-axis direction, and provided with a plurality of pressure chambers 312 whose volume changes due to the deformation of the diaphragm 350; a drive signal selection circuit 200 that switches whether or not to supply a drive signal COM to the piezoelectric element 60; a wiring board 420 on which an integrated circuit 421 including the drive signal selection circuit 200 is provided; and a resistance wiring 401 located on the -Z-axis side, which is the other side in the Z-axis direction relative to the diaphragm 350, which is electrically connected to the wiring board 420 and constitutes at least a part of a temperature detection circuit 24 that detects temperature information of the pressure chambers 312.

[0177] This reduces the difference between the temperature detected based on the electrical resistance value of the resistor wiring 401, which is the temperature detection circuit 24, and the temperature inside the pressure chamber 312, thereby improving the detection accuracy of the temperature in the pressure chamber 312 detected by the temperature detection circuit 24. As a result, the control circuit 100 enables the ejection control of the ejection module 22 to be appropriate for the ink temperature inside the pressure chamber 312.

[0178] Furthermore, since at least a portion of the resistor wiring 401, which constitutes the temperature detection circuit 24, is laminated on the diaphragm 350, the resistor wiring 401 of the temperature detection circuit 24 can be positioned closer to the pressure chamber 312, further improving the detection accuracy of the temperature of the pressure chamber 312 detected by the temperature detection circuit 24. As a result, the control circuit 100 can control the ejection of the ejection module 22 in a manner more suitable for the ink temperature in the pressure chamber 312.

[0179] 6. Temperature detection operation As described above, in the liquid ejection device 1 of this embodiment, since the diaphragm 350 is provided with a resistor wiring 401 for detecting the temperature of the ejection module 22 inside the ejection module 22 of the print head 20, the resistor wiring 401, which is the temperature detection circuit 24, can be placed near the pressure chamber 312 where the ink is stored.

[0180] This reduces the difference between the temperature detected based on the electrical resistance of the resistor wiring 401 and the temperature inside the pressure chamber 312, improving the detection accuracy of the pressure chamber 312 temperature detected by the temperature detection circuit 24. As a result, the signal waveform of the drive signal COM can be corrected to an optimal signal waveform corresponding to the temperature of the pressure chamber 312 and the temperature of the ink stored in the pressure chamber 312, thereby improving the ink ejection accuracy.

[0181] On the other hand, the following problems arose because the resistor wiring 401, which is the temperature detection circuit 24, is located near the pressure chamber 312 where the ink is stored.

[0182] In recent years, from the perspective of improving the image quality formed on the medium P, the ejection module 22 has been densely arranged with hundreds or more nozzles 321. As a result, hundreds or more piezoelectric elements 60 corresponding to hundreds or more nozzles 321 are densely arranged in the ejection module 22, and therefore, signal wiring through which the drive signal VOUT supplied to the corresponding piezoelectric element 60 propagates is densely arranged in the ejection module 22. When a resistor wiring 401 is placed on such a diaphragm 350, the resistor wiring 401 is placed near the signal wiring through which the drive signal VOUT propagates. As a result, the voltage value of the drive signal VOUT is likely to be superimposed on the signal propagated by the resistor wiring 401, and if the voltage value of the drive signal VOUT is superimposed on the signal propagated by the resistor wiring 401, the detection accuracy of the temperature of the pressure chamber 312 detected by the temperature detection circuit 24 including the resistor wiring 401 will decrease.

[0183] In particular, in the drive circuit 50 shown in this embodiment, the power consumption in the drive circuit 50 can be reduced because the drive circuit 50 modulates and digitally amplifies the base drive signal aO corresponding to the base drive signal dO. On the other hand, a high-frequency ripple voltage is superimposed on the signal waveform of the drive signal COM output by the drive circuit 50, and the signal waveform of the drive signal VOUT based on the drive signal COM. As a result, the possibility of the drive signal VOUT being superimposed on the signal propagating through the resistor wiring 401 increases further, and even when the signal waveform of the drive signal COM is corrected using the temperature of the pressure chamber 312 detected by the temperature detection circuit 24 including the resistor wiring 401, there is a risk that optimal correction of the signal waveform of the drive signal COM will become difficult.

[0184] To address the aforementioned problem, the liquid discharge device 1 of this embodiment has a characteristic configuration in which the frequency of the amplified modulation signal AMs when the temperature detection circuit 24 detects temperature detection information TH, which the control circuit 100 uses to correct the base drive signal dO, is higher than the frequency of the amplified modulation signal AMs when the temperature detection circuit 24 detects temperature detection information TH, which the control circuit 100 does not use to correct the base drive signal dO. The print head 20 has a characteristic configuration in which the frequency of the amplified modulation signal AMs when the temperature detection information TH detected by the temperature detection circuit 24 is output to the control circuit 100 is higher than the frequency of the amplified modulation signal AMs when the temperature detection information TH detected by the temperature detection circuit 24 is not output to the control circuit 100.

[0185] This reduces the influence of ripple voltage on the temperature detection information TH input to the control circuit 100, improving the detection accuracy of the temperature detection information TH used by the control circuit 100 to correct the base drive signal dO. As a result, the accuracy of correcting the signal waveform of the drive signal COM can be improved when the signal waveform of the drive signal COM is corrected using the temperature of the pressure chamber 312 detected by the temperature detection circuit 24 including the resistor wiring 401.

[0186] A specific example of the operation of the liquid ejection device 1, which operates as described above, will now be explained. Figure 18 shows an example of the timing at which the ejection module 22 of the print head 20 acquires the temperature.

[0187] When power voltage is supplied, the liquid discharge device 1 starts up and begins operation. At this time, as an initial setting for the liquid discharge device 1, the control circuit 100 holds the temperature detection flag Ft, which indicates whether or not temperature detection of the pressure chamber 312 by the temperature detection circuit 24 is necessary, at an L level, indicating that temperature detection is not necessary. That is, the control circuit 100 sets the temperature detection flag Ft = "L" (step S10).

[0188] Subsequently, when an image information signal, including image data, is input from an external device, and a print request is generated for the liquid dispensing device 1 (step S20), the control circuit 100 outputs a control signal Ctrl-C to move the carriage 21 along the scanning axis. As a result, the carriage 21 moves along the scanning axis (step S30).

[0189] As the carriage 21 moves, the linear encoder 90 outputs a detection signal to the control circuit 100 based on the scanning position of the carriage 21. Based on the input detection signal, the control circuit 100 determines whether the scanning position of the carriage 21 and the scanning position of the print head 20 is within the printing area (step S40). Here, the printing area is the area in which the print head 20 mounted on the carriage 21 ejects ink onto the medium P, and is defined based on the scanning range of the carriage 21 and the width of the transported medium P in the direction along the scanning axis. Furthermore, in the following description, the area within the scanning range of the carriage 21 other than the printing area described above will be referred to as the non-printing area.

[0190] When the control circuit 100 determines that the scanning position of the carriage 21 is within the printing area (Y in step S40), the liquid ejection device 1 performs a printing process (step S50). The printing process is a process in which the print head 20 ejects ink to a desired position on the medium P to form a desired image on the medium P, and includes, for example, the process in which the control circuit 100 outputs a head control signal DI to the print head 20 according to the image data input from an external device.

[0191] Furthermore, during the printing process, the frequency measurement circuit 54 measures the frequency of the amplified modulation signal AMs of the drive circuit 50. The frequency measurement circuit 54 then outputs a frequency determination signal Fm to the control circuit 100, which becomes high for a certain period of time at the moment when the frequency of the amplified modulation signal AMs reaches its maximum and the frequency of the amplified modulation signal AMs changes from rising to falling. Based on the base drive signal dO output at the moment the frequency determination signal Fm becomes high, the control circuit 100 calculates the voltage value of the drive signal COM at the moment the frequency determination signal Fm becomes high and stores the calculated voltage value of the drive signal COM as voltage Vbe. In other words, the control circuit 100 obtains the voltage value of the drive signal COM when the frequency of the amplified modulation signal AMs is at its maximum as voltage Vbe (step S60).

[0192] In Figure 18, steps S50 and S60 are described as if step S50 is executed followed by step S60. However, during the period in step S50 when the printing process is being performed, the voltage value of the drive signal COM when the frequency of the amplified modulation signal AMs shown in step S60 is at its maximum may be obtained.

[0193] Then, after the printing process and the acquisition of the voltage value of the drive signal COM when the frequency of the amplified modulation signal AMs is at its maximum are completed, the control circuit 100 determines whether or not a temperature detection request for the pressure chamber 312 has occurred by the temperature detection circuit 24 based on the usage status of the liquid discharge device 1 and requests from the user (step S70). If the control circuit 100 determines that a temperature detection request for the pressure chamber 312 has occurred by the temperature detection circuit 24 (Y in step S70), the control circuit 100 holds the temperature detection flag Ft at an H level, indicating that temperature detection of the pressure chamber 312 by the temperature detection circuit 24 is required. That is, the control circuit 100 sets the temperature detection flag Ft = "H" (step S80).

[0194] Then, if the control circuit 100 determines that there is no request for temperature detection of the pressure chamber 312 by the temperature detection circuit 24 (N in step S70), or if the control circuit 100 determines that there is a request for temperature detection of the pressure chamber 312 by the temperature detection circuit 24 and sets the temperature detection flag Ft = "H" (step S80), the control circuit 100 determines whether or not the printing process corresponding to the image data input from the external device has been completed (step S90).

[0195] Then, if the control circuit 100 determines that the printing process is not yet complete (N in step S90), the control circuit 100 determines again, based on the input detection signal, whether the scanning position of the carriage 21 and the scanning position of the print head 20 are within the printing area (step S40). On the other hand, if the control circuit 100 determines that the printing process is complete (Y in step S90), the control circuit 100 stops the movement of the carriage 21 (step S170), and the liquid ejection device 1 stops operating.

[0196] If the control circuit 100 determines that the scanning position of the carriage 21 is not within the printing area (N in step S40), that is, if the control circuit 100 determines that the scanning position of the carriage 21 is outside the printing area, the control circuit 100 determines whether the temperature detection flag Ft it holds is at an L level, indicating that temperature detection of the pressure chamber 312 by the temperature detection circuit 24 is unnecessary (step S100).

[0197] If the temperature detection flag Ft held by the control circuit 100 is at the H level (N in step S100), the control circuit 100 outputs all of the ejection data [SIH,SIL] included in the ejection control signal SI of the head control signal DI as ejection data [SIH,SIL]=[0,0] (step S110). As a result, all selection circuits 230 included in the drive signal selection circuit 200 are controlled to be non-conductive.

[0198] Subsequently, the control circuit 100 reads the voltage Vbe acquired in step S60 and outputs a base drive signal dO to output a drive signal COM with a constant voltage value of voltage Vbe. As a result, the drive circuit 50 outputs a signal with a constant voltage value of voltage Vbe as the drive signal COM (step S120). Subsequently, the control circuit 100 generates a temperature acquisition request signal TD to acquire the temperature of the ejection module 22 of the print head 20 and outputs it to the temperature information output circuit 26. Based on the input temperature acquisition request signal TD, the temperature information output circuit 26 generates a temperature information signal TI corresponding to the temperature detection information TH corresponding to the temperature of the pressure chamber 312, which is input from the temperature detection circuit 24, and outputs it to the control circuit 100. As a result, the control circuit 100 acquires the temperature of the pressure chamber 312 detected by the temperature detection circuit 24 (step S130).

[0199] Specifically, the temperature information output circuit 26 holds and amplifies the temperature detection information TH corresponding to the temperature of the pressure chamber 312, which is input from the temperature detection circuit 24 at the timing when the temperature acquisition request signal TD is input. Then, it outputs the amplified signal of the temperature detection information TH as the temperature information signal TI. In other words, the temperature detection information TH corresponding to the temperature of the pressure chamber 312 detected by the temperature detection circuit 24 is input to the control circuit 100 as the temperature information signal TI. At this time, all selection circuits 230 included in the drive signal selection circuit 200 are controlled to be non-conductive, and the drive circuit 50 outputs a drive signal COM with a constant voltage value of voltage Vbe, which is the voltage value at which the frequency of the amplified modulation signal AMs is maximized. In other words, the control circuit 100 receives temperature detection information TH corresponding to the temperature of the pressure chamber 312 detected by the temperature detection circuit 24 during periods when none of the multiple selection circuits 230 supply the drive signal COM to the multiple piezoelectric elements 60, and when the drive circuit 50 outputs a constant drive signal COM at a voltage Vbe, which is the voltage value at which the frequency of the amplified modulation signal AMs is maximized. In other words, the print head 20 outputs temperature detection information TH corresponding to the temperature of the pressure chamber 312 detected by the temperature detection circuit 24 during periods when none of the multiple selection circuits 230 supply the drive signal COM to the multiple piezoelectric elements 60, and when a constant drive signal COM is input at a voltage Vbe, which is the voltage value at which the frequency of the amplified modulation signal AMs is maximized.

[0200] At this time, the temperature information output circuit 26 may, when the temperature acquisition request signal TD is input, hold all of the temperature detection information TH1 to THn output by the temperature detection circuit 24 of each of the discharge modules 22-1 to 22-n, and output a signal amplified from each of the held temperature detection information TH1 to THn as the temperature information signal TI to the control circuit 100. Alternatively, when the temperature acquisition request signal TD is input, the temperature detection information TH1 to THn specified by the temperature acquisition request signal TD is held from among the temperature detection information TH1 to THn output by the temperature detection circuit 24 of each of the discharge modules 22-1 to 22-n, and output a signal amplified from the held temperature detection information TH1 to THn as the temperature information signal TI to the control circuit 100.

[0201] Then, the control circuit 100 corrects the control signals Ctrl-H, Ctrl-C, Ctrl-T, and the base drive signal dO based on the temperature information signal TI, which includes temperature detection information TH corresponding to the temperature of the pressure chamber 312 detected by the temperature detection circuit 24. In other words, the control circuit 100 corrects the base drive signal dO based on the temperature of the pressure chamber 312 (step S140). To put it another way, the control circuit 100 corrects the base drive signal dO based on the temperature detection information TH corresponding to the temperature of the pressure chamber 312 detected by the temperature detection circuit 24 when the drive circuit 50 outputs a drive signal COM with a constant voltage value of a constant voltage Vbe and the frequency of the amplified modulation signal AMs is at its maximum.

[0202] Subsequently, the control circuit 100 determines that it has completed acquiring the temperature of the pressure chamber 312 of the discharge module 22 and holds the temperature detection flag Ft at an L level, indicating that temperature detection of the pressure chamber 312 by the temperature detection circuit 24 is no longer required. That is, the control circuit 100 sets the temperature detection flag Ft to "L" (step S150).

[0203] Then, when the scanning position of the carriage is in the non-printing area and the temperature detection flag Ft held by the control circuit 100 is at the L level (Y in step S100), or when the control circuit 100 has finished acquiring the temperature of the pressure chamber 312 and the temperature detection flag Ft has been set to "L" (step S150), the scanning position of the carriage 21 reaches a predetermined area, and the control circuit 100 outputs a control signal Ctrl-C that reverses the direction of movement of the carriage 21. As a result, the carriage 21 moves along the scanning axis in the reversed direction of movement. That is, the direction of movement is reversed and the carriage 21 moves along the scanning axis (step S160).

[0204] After the carriage's direction of movement is reversed, the control circuit 100 determines whether a temperature detection request for the pressure chamber 312 has been issued by the temperature detection circuit 24 based on the usage status of the liquid discharge device 1 and requests from the user (step S70). If the control circuit 100 determines that a temperature detection request for the pressure chamber 312 has been issued by the temperature detection circuit 24 (Y in step S70), the control circuit 100 holds the temperature detection flag Ft at an H level, indicating that temperature detection of the pressure chamber 312 by the temperature detection circuit 24 is required. That is, the control circuit 100 sets the temperature detection flag Ft = "H" (step S80).

[0205] Then, if the control circuit 100 determines that there is no request for temperature detection of the pressure chamber 312 by the temperature detection circuit 24 (N in step S70), or if the control circuit 100 determines that there is a request for temperature detection of the pressure chamber 312 by the temperature detection circuit 24 and sets the temperature detection flag Ft = "H" (step S80), the control circuit 100 determines whether or not the printing process corresponding to the image data input from the external device has been completed (step S90).

[0206] Then, if the control circuit 100 determines that the printing process is not yet complete (N in step S90), the control circuit 100 determines again, based on the input detection signal, whether the scanning position of the carriage 21 and the scanning position of the print head 20 are within the printing area (step S40). On the other hand, if the control circuit 100 determines that the printing process is complete (Y in step S90), the control circuit 100 stops the movement of the carriage 21 (step S170), and the liquid ejection device 1 stops operating.

[0207] Here, the control circuit 100 is an example of a base drive signal output circuit, the configuration including the drive circuit 50 and the control circuit 100 is an example of a drive signal output circuit, and the drive signal COM is an example of a drive signal. Furthermore, considering that the trapezoidal waveforms Adp, Bdp, and Cdp included in the drive signal COM are supplied to the piezoelectric element 60, the trapezoidal waveforms Adp, Bdp, and Cdp included in the drive signal COM are also an example of a drive signal. Also, the Z-axis direction is an example of a stacking direction, the +Z-axis side of the Z-axis direction which is the stacking direction is an example of one side of the stacking direction, and the -Z-axis side of the Z-axis direction which is the stacking direction is an example of the other side of the stacking direction. Furthermore, the selection circuit 230 is an example of a switch circuit. And the temperature detection circuit 24 is an example of a temperature detection unit, and the temperature detection information TH output by the temperature detection circuit 24 is an example of temperature information.

[0208] 7. Effects As described above, in the liquid discharge device 1 of this embodiment, the frequency of the amplified modulation signal AMs when the temperature detection circuit 24 detects temperature detection information TH, which the control circuit 100 uses to correct the base drive signal dO, is set higher than the frequency of the amplified modulation signal AMs when the temperature detection circuit 24 detects temperature detection information TH, which the control circuit 100 does not use to correct the base drive signal dO. This reduces the amplitude of the ripple voltage superimposed on the drive signal COM when the control circuit 100 acquires temperature detection information TH, which the control circuit 100 uses to correct the base drive signal dO. In other words, the print head 20 reduces the amplitude of the ripple voltage superimposed on the input drive signal COM because the frequency of the amplified modulation signal AMs when the temperature detection information TH detected by the temperature detection circuit 24 is output to the control circuit 100 is higher than the frequency of the amplified modulation signal AMs when the temperature detection information TH detected by the temperature detection circuit 24 is not output to the control circuit 100.

[0209] This reduces the risk of ripple voltage superimposed on the drive signal COM superimposing on the temperature detection information TH detected by the temperature detection circuit 24, thereby improving the detection accuracy of the temperature detection information TH used by the control circuit 100 to correct the base drive signal dO. As a result, the accuracy of correcting the signal waveform of the drive signal COM when correcting the signal waveform of the drive signal COM using the temperature of the pressure chamber 312 detected by the temperature detection circuit 24, which includes the resistor wiring 401, can be improved.

[0210] Furthermore, the control circuit 100 can further reduce the amplitude of the ripple voltage superimposed on the drive signal COM by correcting the base drive signal dO based on the temperature detection information TH corresponding to the temperature of the pressure chamber 312 detected by the temperature detection circuit 24 during the period when the drive circuit 50 outputs a drive signal COM with a constant voltage value of a constant voltage Vbe, and when the frequency of the amplified modulation signal AMs is at its maximum. This further reduces the risk that the ripple voltage superimposed on the drive signal COM will superimpose on the temperature detection information TH detected by the temperature detection circuit 24, and further improves the detection accuracy of the temperature detection information TH used by the control circuit 100 to correct the base drive signal dO. As a result, the accuracy of correcting the signal waveform of the drive signal COM when correcting the signal waveform of the drive signal COM using the temperature of the pressure chamber 312 detected by the temperature detection circuit 24 including the resistor wiring 401 can be further improved.

[0211] 8. Variations In the liquid dispensing device 1 of this embodiment described above, the frequency measurement circuit 54 of the control mechanism 10 outputs a high-level frequency determination signal Fm at the timing when the frequency of the amplified modulation signal AMs is at its maximum, and the control circuit 100 calculates the voltage value of the drive signal COM at the timing when the high-level frequency determination signal Fm is input. Then, under the control of the control circuit 100, the drive circuit 50 outputs a constant drive signal COM at the voltage value when the frequency of the amplified modulation signal AMs is at its maximum. As a result, when the control circuit 100 acquires the temperature detection information TH used to correct the base drive signal dO, the amplitude of the ripple voltage superimposed on the drive signal COM can be minimized, reducing the risk that the ripple voltage superimposed on the drive signal COM will superimpose on the temperature detection information TH detected by the temperature detection circuit 24, and improving the detection accuracy of the temperature detection information TH used by the control circuit 100 to correct the base drive signal dO.

[0212] In contrast, when correcting the signal waveform of the drive signal COM using the temperature of the pressure chamber 312 detected by the temperature detection circuit 24 including the resistor wiring 401, it is sufficient to reduce the ripple voltage superimposed on the drive signal COM to such an extent that the risk of the ripple voltage superimposed on the temperature detection information TH detected by the temperature detection circuit 24 is reduced. Therefore, if the ripple voltage can be reduced to such an extent that the risk of the ripple voltage superimposed on the temperature detection information TH detected by the temperature detection circuit 24 is reduced and the frequency is known, the frequency measurement circuit 54 may output a frequency determination signal Fm according to whether the frequency of the amplified modulation signal AMs is above a predetermined threshold, and the control circuit 100 may control the voltage value of the drive signal COM so that the frequency of the amplified modulation signal AMs is above a predetermined threshold.

[0213] This configuration simplifies the configuration of the frequency measurement circuit 54, making it possible to miniaturize the control mechanism 10 and the liquid dispensing device 1.

[0214] Furthermore, considering that the drive circuit 50 self-oscillates at a frequency determined by the feedback delay and feedback transfer function of the feedback circuits 570 and 572, the frequency of this self-oscillation is, from the viewpoint of circuit efficiency, waveform accuracy of the output signal, and operational stability, a voltage value between the maximum and minimum voltages of the output signal, and preferably, is maximum near the average voltage of the maximum and minimum voltages.

[0215] Therefore, the liquid discharge device 1 does not have a frequency measurement circuit 54, and the voltage value of the drive signal COM when the control circuit 100 acquires temperature detection information TH used to correct the base drive signal dO may be kept constant at the average voltage value of the maximum voltage signal VHV and the minimum ground potential. In other words, the control circuit 100 may correct the base drive signal dO based on the temperature of the pressure chamber 312 detected by the temperature detection circuit 24 including the resistor wiring 401 when the voltage value of the drive signal COM is the voltage value obtained by dividing the sum of the voltage value of the voltage signal VHV, which is the maximum voltage that the drive circuit 50 can output, and the voltage value of the ground potential, which is the minimum voltage that the drive circuit 50 can output, by 2.

[0216] As a result, the liquid dispensing device 1 achieves the same effects as the liquid dispensing device described in the embodiment, and because it does not have the configuration of the frequency measurement circuit 54, it becomes possible to further miniaturize the control mechanism 10 and the liquid dispensing device 1.

[0217] Although embodiments and modified examples have been described above, the present invention is not limited to these embodiments and can be implemented in various forms without departing from its spirit. For example, the above embodiments can be combined as appropriate.

[0218] The present invention includes configurations that are substantially identical to those described in the embodiments (for example, configurations with the same function, method, and result, or configurations with the same purpose and effect). Furthermore, the present invention includes configurations in which non-essential parts of the configurations described in the embodiments are replaced. Furthermore, the present invention includes configurations that produce the same effects or achieve the same purpose as those described in the embodiments. Furthermore, the present invention includes configurations that add known technology to the configurations described in the embodiments.

[0219] The following conclusions can be drawn from the embodiments described above.

[0220] One embodiment of a liquid dispensing device is: A drive signal output circuit that outputs a drive signal, A print head that receives the aforementioned drive signal and ejects liquid, Equipped with, The aforementioned print head is A piezoelectric element comprising a first electrode, a second electrode, and a piezoelectric body, wherein in the stacking direction in which the first electrode, the second electrode, and the piezoelectric body are stacked, the piezoelectric body is positioned between the first electrode and the second electrode, and the piezoelectric element is driven by receiving the drive signal, A diaphragm is located on one side of the stacking direction relative to the piezoelectric element and deforms when the piezoelectric element is driven, A pressure chamber substrate is provided with a plurality of pressure chambers located on one side of the stacking direction relative to the diaphragm, the pressure chambers whose volume changes due to the deformation of the diaphragm, A switch circuit that switches whether or not to supply the drive signal to the piezoelectric element, A wiring board on which the aforementioned switch circuit is provided, A temperature detection unit is located on the other side of the stacking direction relative to the diaphragm, electrically connected to the wiring board, and detects temperature information of the pressure chamber. Includes, The aforementioned drive signal output circuit is A modulation circuit that outputs a modulated signal obtained by modulating the base drive signal which is the basis of the drive signal, An amplification circuit that outputs an amplified modulated signal obtained by amplifying the aforementioned modulated signal, A smoothing circuit that outputs the drive signal obtained by smoothing the amplified modulated signal, A feedback circuit that feeds back the drive signal to the modulation circuit, A base drive signal output circuit that outputs the base drive signal corrected based on the temperature information, Includes, The frequency of the amplified modulated signal when the temperature detection unit detects the temperature information used by the base drive signal output circuit to correct the base drive signal is higher than the frequency of the amplified modulated signal when the temperature detection unit detects the temperature information that the base drive signal output circuit does not use to correct the base drive signal.

[0221] With this liquid ejection device, the temperature sensing unit is located inside the print head, allowing for accurate detection of the pressure chamber temperature. Furthermore, the frequency of the amplified and modulated signal when the temperature sensing unit detects temperature information used by the base drive signal output circuit for correcting the base drive signal is higher than the frequency of the amplified and modulated signal when the temperature sensing unit detects temperature information not used by the base drive signal output circuit for correcting the base drive signal. This reduces the ripple voltage superimposed on the drive signal input to the print head when the temperature sensing unit detects temperature information used by the base drive signal output circuit for correcting the base drive signal. As a result, the risk of interference between the temperature information detected by the temperature sensing unit and the temperature information used by the drive signal output circuit for correcting the base drive signal is reduced.

[0222] In one embodiment of the above-described liquid dispensing device, At least a portion of the temperature sensing unit may be laminated on the diaphragm.

[0223] This liquid dispensing device allows the temperature sensing unit to be positioned closer to the pressure chamber, further improving the accuracy of temperature detection by the temperature sensing unit.

[0224] In one embodiment of the above-described liquid dispensing device, The drive signal output circuit may correct the drive signal based on the temperature information detected by the temperature detection unit during the period when the drive signal output circuit outputs the drive signal at a constant voltage value.

[0225] With this liquid dispensing device, when the temperature detection unit detects the temperature information used by the base drive signal output circuit to correct the base drive signal, the risk of interference between the drive signal and the temperature information is reduced.

[0226] In one embodiment of the above-described liquid dispensing device, The base drive signal output circuit may correct the base drive signal based on the temperature information detected by the temperature detection unit when the frequency of the amplified modulation signal is at its maximum.

[0227] This liquid dispensing device can further reduce the ripple voltage superimposed on the drive signal.

[0228] In one embodiment of the above-described liquid dispensing device, The drive signal output circuit may correct the drive signal based on the temperature information detected by the temperature detection unit when the voltage value of the drive signal is the sum of the maximum voltage value that the drive signal output circuit can output and the minimum voltage value that the drive signal output circuit can output, divided by 2.

[0229] This liquid dispensing device makes it possible to further reduce the ripple voltage superimposed on the drive signal without detecting the frequency of the amplified and modulated signal.

[0230] One form of a print head is, A print head that receives a drive signal output from a drive signal output circuit and ejects liquid, The aforementioned drive signal output circuit is A modulation circuit that outputs a modulated signal obtained by modulating the base drive signal, An amplification circuit that outputs an amplified modulated signal obtained by amplifying the aforementioned modulated signal, A smoothing circuit that outputs the drive signal obtained by smoothing the amplified modulated signal, A feedback circuit that feeds back the drive signal to the modulation circuit, A base drive signal output circuit that outputs the base drive signal which is the basis of the drive signal corrected based on the temperature information output by the print head, Includes, The aforementioned print head is A piezoelectric element comprising a first electrode, a second electrode, and a piezoelectric body, wherein in the stacking direction in which the first electrode, the second electrode, and the piezoelectric body are stacked, the piezoelectric body is positioned between the first electrode and the second electrode, and the piezoelectric element is driven by receiving the drive signal, A diaphragm is located on one side of the stacking direction relative to the piezoelectric element and deforms when the piezoelectric element is driven, A pressure chamber substrate is provided with a plurality of pressure chambers located on one side of the stacking direction relative to the diaphragm, the pressure chambers whose volume changes due to the deformation of the diaphragm, A switch circuit that switches whether or not to supply the drive signal to the piezoelectric element, A wiring board on which the aforementioned switch circuit is provided, A temperature detection unit is located on the other side of the stacking direction relative to the diaphragm, electrically connected to the wiring board, and detects the temperature information of the pressure chamber. Includes, The frequency of the amplified modulated signal when the temperature information detected by the temperature detection unit is output to the base drive signal output circuit is higher than the frequency of the amplified modulated signal when the temperature information detected by the temperature detection unit is not output to the base drive signal output circuit.

[0231] With this printhead, the temperature sensing unit is located inside the printhead, allowing for accurate detection of the pressure chamber temperature. Furthermore, the frequency of the amplified and modulated signal when the temperature information detected by the temperature sensing unit is output to the base drive signal output circuit is higher than the frequency of the amplified and modulated signal when the temperature information detected by the temperature sensing unit is not output to the base drive signal output circuit. This reduces the ripple voltage superimposed on the drive signal input to the printhead when the temperature sensing unit detects the temperature information input to the base drive signal output circuit. As a result, the accuracy of the temperature information detected by the temperature sensing unit and output to the drive signal output circuit is improved.

[0232] In one embodiment of the above print head, At least a portion of the temperature sensing unit may be laminated on the diaphragm.

[0233] This printhead allows the temperature sensing unit to be positioned closer to the pressure chamber, further improving the accuracy of temperature detection by the temperature sensing unit.

[0234] In one embodiment of the above print head, During the period when the drive signal output circuit outputs the drive signal at a constant voltage, the temperature information detected by the temperature detection unit may be output to the base drive signal output circuit.

[0235] With this printhead, when the temperature sensing unit detects the temperature information used by the base drive signal output circuit to correct the base drive signal, the risk of the drive signal interfering with said temperature information is reduced.

[0236] In one embodiment of the above print head, When the frequency of the amplified modulation signal is at its maximum, the temperature information detected by the temperature detection unit may be output to the base drive signal output circuit.

[0237] This printhead further reduces the ripple voltage superimposed on the drive signal, improving the signal accuracy of the outputted temperature information.

[0238] In one embodiment of the above print head, The temperature information detected by the temperature detection unit may be output to the base drive signal output circuit if the voltage value of the drive signal is the sum of the maximum voltage value that the drive signal output circuit can output and the minimum voltage value that the drive signal output circuit can output, divided by 2.

[0239] This printhead allows for further reduction of the ripple voltage superimposed on the drive signal without detecting the frequency of the amplified modulation signal, thereby improving the signal accuracy of the output temperature information. [Explanation of Symbols]

[0240] 1...Liquid ejection device, 2...Ink container, 10...Control mechanism, 20...Print head, 21...Carriage, 22...Ejection module, 24...Temperature detection circuit, 26...Temperature information output circuit, 30...Movement mechanism, 31...Carriage motor, 32...Endless belt, 40...Conveying mechanism, 41...Conveying motor, 42...Conveying roller, 50...Drive circuit, 52...Reference voltage signal output circuit, 54...Frequency measurement circuit, 60...Piezoelectric element, 90...Linear encoder, 100...Control circuit, 200...Drive signal selection circuit, 210...Selection control circuit, 222a...First register, 222b...First 2 registers, 224a...first latch circuit, 224b...second latch circuit, 226...decoder, 230...selection circuit, 232...inverter, 234...transfer gate, 260...control logic circuit, 261...SP register group, 262...selection control signal generation unit, 270...selection signal output unit, 310...pressure chamber substrate, 311...partition wall, 312...pressure chamber, 312a,312b...ends, 315...communication plate, 316...nozzle communication passage, 317...first manifold section, 318...second manifold section, 319...supply communication passage, 320...nozzle plate, 321...nozzle 330…Protective substrate, 331…Holding part, 332…Through hole, 340…Case member, 341…Housing part, 342…Third manifold part, 343…Connection port, 344…Supply port, 345…Compliance substrate, 346…Sealing film, 347…Fixing substrate, 348…Opening, 349…Compliance part, 350…Diaphragm, 351…Elastic film, 352…Insulating film, 360…First electrode, 360a,360b…End part, 370…Piezoelectric body, 370a,370b…End part, 371…Groove part, 380…Second electrode, 380a,380b…End part, 385…Wiring part, 391…Individual Lead electrodes, 392... Common lead electrodes, 392a, 392b... Extension parts, 393, 393a, 393b... Measuring lead electrodes, 400... Manifold, 401... Resistor wiring, 410... Active part, 415... Inactive part, 420... Wiring board, 421, 500... Integrated circuits, 510... Modulation circuit, 512, 513... Adder, 514... Comparator, 515... Inverter, 516... Integral attenuator, 517... Attenuator, 520... Gate drive circuit, 521, 522... Gate drivers, 550... Amplifier circuit, 560... Smoothing circuit, 570, 572... Feedback circuit, C1~C5,C7...Capacitor, D1...Diode, L1...Inductor, M1, M2...Transistors, P...Media, R1~R6...Resistors

Claims

1. A drive signal output circuit that outputs a drive signal, A print head that receives the aforementioned drive signal and ejects liquid, Equipped with, The aforementioned print head is A piezoelectric element comprising a first electrode, a second electrode, and a piezoelectric body, wherein in the stacking direction in which the first electrode, the second electrode, and the piezoelectric body are stacked, the piezoelectric body is positioned between the first electrode and the second electrode, and the piezoelectric element is driven by receiving the drive signal, A diaphragm is located on one side of the stacking direction relative to the piezoelectric element and deforms when the piezoelectric element is driven, A pressure chamber substrate is provided with a plurality of pressure chambers located on one side of the stacking direction relative to the diaphragm, the pressure chambers whose volume changes due to the deformation of the diaphragm, A switch circuit that switches whether or not to supply the drive signal to the piezoelectric element, A wiring board on which the aforementioned switch circuit is provided, A temperature detection unit is located on the other side of the stacking direction relative to the diaphragm, electrically connected to the wiring board, and detects temperature information of the pressure chamber. Includes, The aforementioned drive signal output circuit is A modulation circuit that outputs a modulated signal obtained by modulating the base drive signal which is the basis of the drive signal, An amplification circuit that outputs an amplified modulated signal obtained by amplifying the aforementioned modulated signal, A smoothing circuit that outputs the drive signal obtained by smoothing the amplified modulated signal, A feedback circuit that feeds back the drive signal to the modulation circuit, A base drive signal output circuit that outputs the base drive signal corrected based on the temperature information, Includes, The frequency of the amplified modulated signal when the temperature detection unit detects the temperature information used by the base drive signal output circuit for correcting the base drive signal is higher than the frequency of the amplified modulated signal when the temperature detection unit detects the temperature information not used by the base drive signal output circuit for correcting the base drive signal. A liquid dispensing device characterized by the following features.

2. At least a portion of the temperature sensing unit is laminated on the diaphragm. The liquid dispensing device according to feature 1.

3. The drive signal output circuit corrects the drive signal based on the temperature information detected by the temperature detection unit during the period when the drive signal output circuit outputs the drive signal at a constant voltage value. The liquid dispensing device according to feature 1.

4. The drive signal output circuit corrects the drive signal based on the temperature information detected by the temperature detection unit when the frequency of the amplified modulation signal is at its maximum. A liquid dispensing device according to any one of claims 1 to 3.

5. The drive signal output circuit corrects the drive signal based on the temperature information detected by the temperature detection unit when the voltage value of the drive signal is the sum of the maximum voltage value that the drive signal output circuit can output and the minimum voltage value that the drive signal output circuit can output, divided by two. A liquid dispensing device according to any one of claims 1 to 3.

6. A print head that receives a drive signal output from a drive signal output circuit and ejects liquid, The aforementioned drive signal output circuit is A modulation circuit that outputs a modulated signal obtained by modulating the base drive signal, An amplification circuit that outputs an amplified modulated signal obtained by amplifying the aforementioned modulated signal, A smoothing circuit that outputs the drive signal obtained by smoothing the amplified modulated signal, A feedback circuit that feeds back the drive signal to the modulation circuit, A base drive signal output circuit that outputs the base drive signal which is the basis of the drive signal corrected based on the temperature information output by the print head, Includes, The aforementioned print head is A piezoelectric element comprising a first electrode, a second electrode, and a piezoelectric body, wherein in the stacking direction in which the first electrode, the second electrode, and the piezoelectric body are stacked, the piezoelectric body is positioned between the first electrode and the second electrode, and the piezoelectric element is driven by receiving the drive signal, A diaphragm is located on one side of the stacking direction relative to the piezoelectric element and deforms when the piezoelectric element is driven, A pressure chamber substrate is provided with a plurality of pressure chambers located on one side of the stacking direction relative to the diaphragm, the pressure chambers whose volume changes due to the deformation of the diaphragm, A switch circuit that switches whether or not to supply the drive signal to the piezoelectric element, A wiring board on which the aforementioned switch circuit is provided, A temperature detection unit is located on the other side of the stacking direction relative to the diaphragm, electrically connected to the wiring board, and detects the temperature information of the pressure chamber. Includes, When the temperature information detected by the temperature detection unit is output to the base drive signal output circuit, the frequency of the amplified modulation signal is higher than the frequency of the amplified modulation signal when the temperature information detected by the temperature detection unit is not output to the base drive signal output circuit. A print head characterized by the following features.

7. At least a portion of the temperature sensing unit is laminated on the diaphragm. The print head according to feature 6.

8. During the period when the drive signal output circuit outputs the drive signal of a constant voltage value, the temperature information detected by the temperature detection unit is output to the base drive signal output circuit. The print head according to feature 6.

9. When the frequency of the amplified modulation signal is at its maximum, the temperature information detected by the temperature detection unit is output to the base drive signal output circuit. A liquid dispensing device according to any one of claims 6 to 8.

10. When the voltage value of the drive signal is the sum of the maximum voltage value that the drive signal output circuit can output and the minimum voltage value that the drive signal output circuit can output, divided by two, the temperature information detected by the temperature detection unit is output to the base drive signal output circuit. A liquid dispensing device according to any one of claims 6 to 8.

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