Liquid ejection device and method for controlling liquid ejection device

Abstract

To provide a method for appropriately and easily determining a waveform of a drive signal that suppresses the occurrence of electrical crosstalk under the operating conditions of a liquid ejection device.SOLUTION: A liquid ejection device 100 comprises: a liquid ejection head 1 including a plurality of nozzles NZ, a plurality of piezoelectric elements PZ, a vibration plate 14, and a detection circuit 19 configured to detect a residual vibration of a vibration plate 14 after at least one piezoelectric element PZ is driven; and a waveform determination unit 40. The waveform determination unit 40 is configured to: cause the detection circuit 19 to detect, as a first residual vibration, the residual vibration of the vibration plate 14 after N pieces of the piezoelectric elements PZ corresponding to N nozzles NZ out of the plurality of nozzles NZ are driven with an evaluation waveform WE1 whose potential change rate is a potential change rate DE1; cause the detection circuit 19 to detect, as a second residual vibration, the residual vibration of the vibration plate 14 after N pieces of the piezoelectric elements PZ are driven with an evaluation waveform WE2 whose potential change rate is a potential change rate DE2 that is smaller than the potential change rate DE1; and determine a waveform of a drive signal COM on the basis of the first residual vibration and the second residual vibration.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a liquid ejection apparatus and a method for controlling the liquid ejection apparatus. [Background technology]

[0002] Liquid ejection devices are known that print images by ejecting liquid, such as ink, from nozzles using piezoelectric elements. For example, a liquid ejection device has a liquid ejection head that ejects liquid from pressure chambers through nozzles by vibrating a diaphragm that constitutes part of the pressure chambers using piezoelectric elements. In this type of liquid ejection device, when ink is ejected from multiple nozzles simultaneously, multiple piezoelectric elements are simultaneously driven. When multiple piezoelectric elements are simultaneously driven, there is a risk of electrical crosstalk, in which the waveform of the drive signal is distorted due to the influence of resistance, capacitance, and inductance components of the signal wiring from the circuit that generates the drive signal for the piezoelectric elements to each piezoelectric element. For this reason, various technologies have been proposed to suppress electrical crosstalk. For example, Patent Document 1 discloses a liquid ejection device that is configured to suppress electrical crosstalk by shifting the timing of driving the piezoelectric elements between adjacent nozzles or between adjacent nozzle rows. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-159573 Summary of the Invention [Problem to be solved by the invention]

[0004] Electrical crosstalk depends not only on the number of simultaneously driven piezoelectric elements but also on the drive waveform, i.e., the potential change rate of specific waveform elements, such as waveform elements with large potential change amounts. A business model is conceivable in which a head manufacturer that manufactures liquid ejection heads also assembles liquid ejection devices. In this type of business model, the head manufacturer can predetermine an appropriate drive waveform that suppresses the occurrence of electrical crosstalk under the operating conditions of the liquid ejection device by, for example, pre-adjusting the potential change rate of specific waveform elements. In contrast to the business model in which a head manufacturer assembles a liquid ejection device, a head sales business model is also conceivable in which the head manufacturer sells the liquid ejection head to a printing device manufacturer, which then assembles the liquid ejection device. In the head sales business model, the operating conditions of the liquid ejection device change depending on the specifications of the printing device manufacturer, making it difficult for the head manufacturer to predetermine the potential change rate of specific waveform elements. For this reason, it is desirable for the head sales business model to be able to appropriately and easily determine a drive waveform that suppresses the occurrence of electrical crosstalk under the operating conditions of the liquid ejection device. The above-mentioned problem is desirable, although to a relatively small extent, even if the manufacturer of the liquid ejection device and the manufacturer of the liquid ejection head share the same business model. For example, it is conceivable that a user may independently set usage conditions that differ from those assumed in advance by the manufacturer of the liquid ejection head or liquid ejection device, and in such cases, similar problems arise. [Means for solving the problem]

[0005] In order to solve the above problems, the liquid ejection device of the present invention comprises a liquid ejection head including a plurality of nozzles that eject liquid, a plurality of piezoelectric elements that are provided corresponding to the plurality of nozzles and are driven by supplying a drive signal, a vibration plate that vibrates by driving at least one of the plurality of piezoelectric elements, and a detection unit that detects the residual vibration of the vibration plate after at least one of the plurality of piezoelectric elements is driven, and a control unit, wherein the control unit causes the detection unit to detect, as a first residual vibration, the residual vibration of the vibration plate after driving N piezoelectric elements corresponding to N nozzles out of the plurality of nozzles with a first evaluation waveform in which a potential change rate, which is the amount of change in potential per unit time, is a first potential change rate, and causes the detection unit to detect, as a second residual vibration, the residual vibration of the vibration plate after driving the N piezoelectric elements with a second evaluation waveform in which the potential change rate is a second potential change rate that is smaller than the first potential change rate, and determines the waveform of the drive signal based on the first residual vibration and the second residual vibration.

[0006] In addition, a control method for a liquid ejection device according to the present invention is a control method for a liquid ejection device having a liquid ejection head including a plurality of nozzles that eject liquid, a plurality of piezoelectric elements that are provided corresponding to the plurality of nozzles and are driven by supplying a drive signal, a vibration plate that vibrates by driving at least one of the plurality of piezoelectric elements, and a detection unit that detects the residual vibration of the vibration plate after at least one of the plurality of piezoelectric elements is driven, wherein the detection unit detects, as a first residual vibration, the residual vibration of the vibration plate after driving N piezoelectric elements corresponding to N nozzles out of the plurality of nozzles with a first evaluation waveform in which a potential change rate, which is the amount of change in potential per unit time, is a first potential change rate, and the detection unit detects, as a second residual vibration, the residual vibration of the vibration plate after driving the N piezoelectric elements with a second evaluation waveform in which the potential change rate is a second potential change rate that is smaller than the first potential change rate, and the waveform of the drive signal is determined based on the first residual vibration and the second residual vibration. [Brief explanation of the drawings]

[0007] [Figure 1]1 is a block diagram showing an example of a configuration of a liquid ejection apparatus according to an embodiment of the present invention. [Figure 2] FIG. 1 is a configuration diagram schematically illustrating a liquid ejection device. [Figure 3] FIG. 2 is an exploded perspective view of the liquid ejection head. [Figure 4] FIG. 4 is a cross-sectional view taken along the line III-III shown in FIG. [Figure 5] FIG. 2 is a block diagram showing an example of the configuration of a liquid ejection head. [Figure 6] 10 is a timing chart showing an example of an operation of the liquid ejection device in a unit period. [Figure 7] 10A and 10B are diagrams showing examples of an evaluation waveform and a waveform of residual vibration; [Figure 8] 10 is a flowchart showing an example of the operation of the liquid ejection device when determining the waveform of a drive signal. [Figure 9] 9 is a flowchart showing an example of a waveform determination process shown in FIG. 8. [Figure 10] 10 is a flowchart showing an example of the operation of the liquid ejection device according to the first modified example. [Figure 11] 11 is a flowchart showing an example of a waveform determination process shown in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0008] Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, in each drawing, the dimensions and scale of each part are appropriately different from those of the actual parts. Furthermore, since the embodiments described below are preferred examples of the present invention, various technically preferable limitations are applied, but the scope of the present invention is not limited to these embodiments unless otherwise specified in the following description to the effect that the present invention is limited.

[0009] [1. Embodiment] First, an overview of a liquid ejection device 100 according to this embodiment will be described with reference to Fig. 1. In this embodiment, it is assumed as an example that the liquid ejection device 100 is an inkjet printer that forms an image by ejecting ink onto a medium PP. In this embodiment, it is assumed that the medium PP is recording paper shown in Fig. 2, which will be described later. Ink is an example of a "liquid."

[0010] FIG. 1 is a block diagram showing an example of the configuration of a liquid ejection device 100 according to an embodiment of the present invention.

[0011] Print data IMG indicating an image to be formed by the liquid ejection device 100 is supplied from a host computer such as a personal computer or a digital camera to the liquid ejection device 100. The liquid ejection device 100 executes a printing process to form, on a medium PP, an image indicated by the print data IMG supplied from the host computer.

[0012] The liquid ejection device 100 includes a liquid ejection head 1 provided with an ejection section D including a nozzle NZ that ejects ink, a drive signal generation unit 2 that generates a drive signal COM for driving the ejection section D, and an analysis unit 3 that analyzes residual vibrations (described later). The nozzles NZ will be described later with reference to FIGS. 3 and 4. The liquid ejection device 100 also includes a control unit 4 that controls each section of the liquid ejection device 100, and a storage unit 5 that stores various information such as print data IMG and a control program PG for the liquid ejection device 100. The liquid ejection device 100 also includes a maintenance unit 7 that performs maintenance processing for the liquid ejection head 1, a medium transport mechanism 8 that transports a medium PP, a carriage transport mechanism 9 that reciprocates a carriage 91, and an ink container 60 that stores ink. The carriage 91 will be described later with reference to FIG. 2.

[0013] In this embodiment, it is assumed that the liquid ejection head 1 and the drive signal generation unit 2 correspond to each other, and that the liquid ejection head 1 and the analysis unit 3 correspond to each other. For example, the liquid ejection device 100 may have a plurality of liquid ejection heads 1, a plurality of drive signal generation units 2, and a plurality of analysis units 3. In this case, for example, the plurality of drive signal generation units 2 correspond to the plurality of liquid ejection heads 1 one-to-one, and the plurality of analysis units 3 correspond to the plurality of liquid ejection heads 1 one-to-one. Alternatively, the liquid ejection device 100 may have one liquid ejection head 1, one drive signal generation unit 2 corresponding to the liquid ejection head 1, and one analysis unit 3 corresponding to the liquid ejection head 1.

[0014] In this embodiment, it is assumed that the liquid ejection device 100 has four liquid ejection heads 1 corresponding to four types of ink: cyan, magenta, yellow, and black. That is, in this embodiment, it is assumed that the liquid ejection device 100 has four liquid ejection heads 1, four drive signal generation units 2, and four analysis units 3. However, for convenience of explanation, the following description may focus on one of the four liquid ejection heads 1, one drive signal generation unit 2 corresponding to that one liquid ejection head 1, and the analysis unit 3 corresponding to that one liquid ejection head 1, as exemplified in FIG. 1.

[0015] First, before describing the liquid ejection head 1, the control unit 4, the drive signal generating unit 2, and the storage unit 5 will be described.

[0016] The control unit 4 is configured to include one or more CPUs (Central Processing Units). Note that the control unit 4 may be configured to include a programmable logic device such as an FPGA (field-programmable gate array) instead of or in addition to a CPU. Also, for example, the control unit 4 operates in accordance with a control program PG stored in the storage unit 5 to generate signals for controlling the operation of each part of the liquid ejection device 100, such as a print signal SI and a waveform designation signal dCOM.

[0017] Here, the waveform designation signal dCOM is a digital signal that defines the waveform of the drive signal COM. Furthermore, the drive signal COM is an analog signal for driving the discharge section D. In this embodiment, it is assumed that one drive signal COM is output from the drive signal generation unit 2 to the liquid discharge head 1, but multiple drive signals COM may be output from the drive signal generation unit 2 to the liquid discharge head 1. Furthermore, the print signal SI is a digital signal for designating the type of operation of the discharge section D. Specifically, the print signal SI is a signal that designates whether or not to supply the drive signal COM to the discharge section D, thereby designating the type of operation of the discharge section D.

[0018] In this embodiment, the control unit 4 functions as a waveform determination unit 40 by operating in accordance with a control program PG stored in the storage unit 5. The control program PG may be provided, for example, by a head manufacturer that produces the liquid ejection head 1. Details of the operation of the waveform determination unit 40 are described in FIGS. 8 and 9 . For example, the waveform determination unit 40 evaluates electrical crosstalk between multiple nozzles NZ based on the residual vibration analyzed by the analysis unit 3. The waveform determination unit 40 then determines the waveform of the drive signal COM, defined by the waveform designation signal dCOM, based on the results of the electrical crosstalk evaluation. Electrical crosstalk is a phenomenon in which noise is superimposed on the drive signal COM due to, for example, multiple ejectors D being driven simultaneously. Specifically, electrical crosstalk is a phenomenon in which the waveform of the drive signal COM is distorted due to the influence of resistance, capacitance, and inductance components of the signal wiring from the drive signal generation unit 2 to each ejector D when multiple ejectors D are driven simultaneously.

[0019] In addition to electrical crosstalk, so-called structural crosstalk is known as crosstalk that occurs due to the structure of the liquid ejection head 1, such as the arrangement of the ejection sections D. However, in this embodiment, attention is focused on electrical crosstalk. For example, in this embodiment, as described above, electrical crosstalk is evaluated by the waveform determination section 40. The waveform determination section 40 is an example of a "control section."

[0020] The drive signal generation unit 2 includes, for example, a DAC (Digital Analog Converter), and generates the drive signal COM based on the waveform designation signal dCOM supplied from the control unit 4. For example, the drive signal COM generated by the drive signal generation unit 2 includes a waveform defined by the waveform designation signal dCOM. The drive signal generation unit 2 outputs the drive signal COM generated based on the waveform designation signal dCOM to a switching circuit 18 included in the liquid ejection head 1.

[0021] The storage unit 5 includes one or both of a volatile memory such as a RAM (Random Access Memory) and a non-volatile memory such as a ROM (Read Only Memory), an EEPROM (Electrically Erasable Programmable Read-Only Memory), or a PROM (Programmable ROM). The storage unit 5 may be included in the control unit 4.

[0022] The liquid ejection head 1 includes a switching circuit 18, a recording head 10, and a detection circuit 19. The detection circuit 19 is an example of a "detection section."

[0023] The print head 10 has K ejection sections D. In this embodiment, it is assumed that the value K is an even number equal to or greater than 2. Hereinafter, the kth ejection section D of the K ejection sections D provided in the print head 10 may be referred to as ejection section D[k]. Here, the variable k is a natural number satisfying "1≦k≦K." Furthermore, hereinafter, when a component or signal of the liquid ejection device 100 corresponds to a ejection section D[k] of the K ejection sections D, the subscript [k] may be added to the symbol representing the component or signal.

[0024] The switching circuit 18 switches whether to supply the drive signal COM to the discharge section D[k] based on the print signal SI. Note that, hereinafter, as shown in FIG. 5 and other figures, the drive signal COM supplied to the discharge section D[k] may be referred to as the individual drive signal Vin[k]. The switching circuit 18 also switches whether to electrically connect the discharge section D[k] to the detection circuit 19 based on the print signal SI. When the discharge section D[k] is electrically connected to the detection circuit 19, for example, a detection signal Vout[k] detected from the discharge section D[k] is supplied to the detection circuit 19 via the switching circuit 18. The detection signal Vout[k] is, for example, an analog signal representing the waveform of residual vibration, which is vibration remaining in the discharge section D[k] after the discharge section D[k] is driven by the individual drive signal Vin[k]. Specifically, for example, the detection signal Vout[k] represents the waveform of the residual vibration of the diaphragm 14 after the piezoelectric element PZ[k] is driven. The piezoelectric element PZ and the diaphragm 14 will be described later with reference to FIGS.

[0025] The detection circuit 19 generates the residual vibration signal VR[k] based on the detection signal Vout[k]. For example, the detection circuit 19 amplifies the amplitude of the detection signal Vout[k] or removes noise components contained in the detection signal Vout[k], thereby shaping the detection signal Vout[k] into a waveform suitable for processing in the analysis unit 3. In this way, the residual vibration signal VR[k] is generated. For example, the detection circuit 19 may be configured to include a negative feedback amplifier for amplifying the detection signal Vout[k], a low-pass filter for attenuating high frequency components of the detection signal Vout[k], and a voltage follower for converting impedance and outputting a low-impedance residual vibration signal VR[k].

[0026] For example, the residual vibration signal VR[k] generated based on the detection signal Vout[k] is an analog signal that indicates the waveform of the residual vibration of the diaphragm 14 after the piezoelectric element PZ[k] is driven by the individual drive signal Vin[k]. The detection circuit 19 outputs the residual vibration signal VR[k] generated based on the detection signal Vout[k] to the analysis unit 3. In this way, the detection circuit 19 detects the residual vibration of the diaphragm 14 caused by driving the piezoelectric element PZ[k] based on the detection signal Vout[k].

[0027] The analysis unit 3 includes, for example, an ADC (Analog to Digital Converter) and converts the analog residual vibration signal VR[k] into a digital signal. The analysis unit 3 then analyzes, for example, the residual vibration detected by the detection circuit 19 using the digitally converted residual vibration signal VR[k]. The analysis unit 3 also generates residual vibration information Vinf indicating the analysis result of the residual vibration and outputs the generated residual vibration information Vinf to the control unit 4. The residual vibration information Vinf indicates, for example, the amplitude of the residual vibration. However, the residual vibration information Vinf may also include information other than the amplitude of the residual vibration as long as it includes information indicating the amplitude of the residual vibration. The information other than the amplitude of the residual vibration may, for example, include one or both of the period and phase of the residual vibration, or may include information other than the period and phase of the residual vibration. The waveform determination unit 40 described above evaluates the electrical crosstalk between the multiple nozzles NZ based on, for example, the residual vibration information Vinf. The analysis unit 3 may be included in the control unit 4. For example, the control unit 4 may function as the analysis unit 3 by operating in accordance with the control program PG stored in the storage unit 5. Also, a part of the analysis unit 3 may be included in the control unit 4. Specifically, an ADC may be provided outside the control unit 4, and the control unit 4 may include a function of analyzing the residual vibration using the residual vibration signal VR converted into a digital signal.

[0028] Furthermore, in this embodiment, as described above, the maintenance process is performed by the maintenance unit 7. For example, the maintenance unit 7 performs the maintenance process under the control of the control unit 4. The maintenance process includes, for example, a flushing process that discharges ink from the ejection portion D, a wiping process that wipes off foreign matter such as ink adhering to the vicinity of the nozzle NZ of the ejection portion D with a wiper, and a pumping process that sucks ink from inside the ejection portion D with a tube pump or the like.

[0029] The maintenance unit 7 has a discharged ink receiving section for receiving the discharged ink when the ink in the discharge section D is discharged during the flushing process, a wiper for wiping off foreign matter such as ink adhering to the vicinity of the nozzle NZ of the discharge section D, and a tube pump for sucking ink, air bubbles, etc. from the discharge section D. The discharged ink receiving section, wiper, and tube pump are not shown in the drawings.

[0030] Next, the overall configuration of the liquid ejection device 100 will be described with reference to FIG.

[0031] Fig. 2 is a schematic diagram showing the configuration of the liquid ejection device 100. In Fig. 2, the ink container 60, the medium transport mechanism 8, and the carriage transport mechanism 9 will be mainly described.

[0032] The ink container 60 stores ink. Examples of the ink container 60 include a cartridge that is detachable from the liquid ejection device 100, a bag-shaped ink pack made of flexible film, and an ink tank that can be refilled with ink. The type of ink stored in the ink container 60 is not particularly limited and can be any type. As described above, this embodiment assumes that the liquid ejection device 100 has four liquid ejection heads 1, each corresponding to one of four inks: cyan, magenta, yellow, and black. Therefore, in this embodiment, the ink container 60 stores the four inks: cyan, magenta, yellow, and black. The ink container 60 supplies the stored ink to the liquid ejection head 1.

[0033] The medium conveying mechanism 8 conveys the medium PP in the Y1 direction along the Y axis under the control of the control unit 4. Hereinafter, the Y1 direction and the Y2 direction opposite to the Y1 direction will be collectively referred to as the Y-axis direction. Hereinafter, the X1 direction along the X axis intersecting the Y axis and the X2 direction opposite to the X1 direction will be collectively referred to as the X-axis direction. Hereinafter, the Z1 direction along the Z axis intersecting the X and Y axes and the Z2 direction opposite to the Z1 direction will be collectively referred to as the Z-axis direction. In this embodiment, as an example, a case will be described in which the X axis, Y axis, and Z axis are orthogonal to one another. However, the present invention is not limited to this example. It is sufficient that the X axis, Y axis, and Z axis intersect with one another.

[0034] The carriage transport mechanism 9 reciprocates the plurality of liquid ejection heads 1 in the X1 and X2 directions under the control of the control unit 4. As shown in Fig. 2, the carriage transport mechanism 9 has a substantially box-shaped carriage 91 that houses the plurality of liquid ejection heads 1, and an endless belt 92 to which the carriage 91 is fixed. Note that the ink containers 60 may be housed in the carriage 91 together with the liquid ejection heads 1.

[0035] The liquid ejection head 1 is driven by a drive signal COM under the control of a print signal SI, and ejects ink in the Z1 direction from some or all of the multiple nozzles NZ provided in the liquid ejection head 1. That is, the liquid ejection head 1 ejects ink from some or all of the multiple nozzles NZ in conjunction with the transport of the medium PP by the medium transport mechanism 8 and the reciprocating movement of the liquid ejection head 1 by the carriage transport mechanism 9, and forms a desired image on the surface of the medium PP by causing the ejected ink to land on the surface of the medium PP. In this embodiment, as described above, the Z1 direction is the direction in which ink is ejected from the nozzles NZ.

[0036] Next, the general structure of the liquid ejection head 1 will be described with reference to FIGS.

[0037] FIG. 3 is an exploded perspective view of the liquid ejection head 1. FIG. 4 is a cross-sectional view taken along line III-III in FIG. 3. The cross section taken along line III-III is parallel to the XZ plane and passes through inlets HL1 and HL2, which will be described later. In FIGS. 3 and 4, the numerals "1" and "2" are added to the end of the reference numerals of the nozzle rows Ln to distinguish between the two nozzle rows Ln, which will be described later. In addition, in FIGS. 3 and 4, for ease of explanation, the numeral "1" is added to the end of the reference numerals of the nozzles NZ included in the nozzle row Ln1, and the numeral "2" is added to the end of the reference numerals of the nozzles NZ included in the nozzle row Ln2.

[0038] 3 and 4, the liquid ejection head 1 has a nozzle substrate 11, compliance sheets CS1 and CS2, a communication plate 12, a pressure chamber substrate 13, a vibration plate 14, a sealing substrate 15, a flow path forming substrate 16, and a wiring board 17 on which electronic components EC are mounted. The electronic components EC include, for example, electrical circuits such as a switching circuit 18 and a detection circuit 19. For example, the recording head 10 is electrically connected to the switching circuit 18, the detection circuit 19, etc. via the wiring board 17.

[0039] As shown in FIG. 3, the recording head 10 includes, for example, a nozzle substrate 11, compliance sheets CS1 and CS2, a communication plate 12, a pressure chamber substrate 13, a vibration plate 14, a sealing substrate 15, and a flow path forming substrate 16.

[0040] The nozzle substrate 11 is a plate-like member that is elongated in the Y-axis direction and extends approximately parallel to the XY plane. Here, "approximately parallel" is a concept that includes not only completely parallel but also a case where it can be considered to be parallel when an error is taken into consideration. In this embodiment, "approximately parallel" is a concept that includes a case where it can be considered to be parallel when an error of about 10% is taken into consideration. Like "approximately parallel," the term "approximately perpendicular," which will be described later, is a concept that includes not only completely perpendicular but also perpendicular when an error is taken into consideration. The nozzle substrate 11 is manufactured by processing a silicon single crystal substrate using semiconductor manufacturing techniques such as etching, for example, but known materials and manufacturing methods may be arbitrarily adopted for manufacturing the nozzle substrate 11.

[0041] K nozzles NZ are formed on the nozzle substrate 11. Here, the nozzles NZ are through-holes formed in the nozzle substrate 11. In this embodiment, it is assumed that the multiple nozzles NZ formed on the nozzle substrate 11 include multiple nozzles NZ1 arranged to extend in the Y-axis direction and multiple nozzles NZ2 arranged to extend in the Y-axis direction at positions in the X2 direction as viewed from the multiple nozzles NZ1. Hereinafter, the multiple nozzles NZ1 arranged to extend in the Y-axis direction will be referred to as a nozzle row Ln1, and the multiple nozzles NZ2 arranged to extend in the Y-axis direction will be referred to as a nozzle row Ln2. For example, the number of nozzles NZ included in each of the nozzle rows Ln1 and Ln2 is half the value K. Hereinafter, the nozzle row Ln1 and the nozzle row Ln2 may be collectively referred to as the nozzle row Ln. Also, in Figures 3 and 4, to make the explanation easier to understand, the numeral "1" is added to the end of the reference numeral of the component of the liquid ejection head 1 that corresponds to nozzle row Ln1, and the numeral "2" is added to the end of the reference numeral of the component that corresponds to nozzle row Ln2.

[0042] 3 and 4, a communicating plate 12 is provided at a position in the Z2 direction as viewed from the nozzle substrate 11. The communicating plate 12 is a plate-shaped member that is long in the Y-axis direction and extends approximately parallel to the XY plane. The communicating plate 12 is manufactured, for example, by processing a silicon single crystal substrate using semiconductor manufacturing technology, but the communicating plate 12 may be manufactured using any known material and method.

[0043] Ink flow paths are formed in the communicating plate 12. Specifically, the communicating plate 12 is formed with one supply flow path BA1 extending in the Y-axis direction and one supply flow path BA2 extending in the Y-axis direction at a position in the X2 direction as viewed from the supply flow path BA1. The communicating plate 12 also is formed with a plurality of connection flow paths BK1 corresponding to the plurality of nozzles NZ1, a plurality of connection flow paths BK2 corresponding to the plurality of nozzles NZ2, a plurality of communication flow paths BR1 corresponding to the plurality of nozzles NZ1, and a plurality of communication flow paths BR2 corresponding to the plurality of nozzles NZ2.

[0044] As shown in FIG. 4, the connection flow path BK1 communicates with the supply flow path BA1 and is provided so as to extend in the Z-axis direction at a position in the X2 direction as viewed from the supply flow path BA1. The communication flow path BR1 is provided so as to extend in the Z-axis direction at a position in the X2 direction as viewed from the connection flow path BK1. The communication flow path BR1 communicates with the nozzle NZ1 corresponding to the communication flow path BR1. The connection flow path BK2 communicates with the supply flow path BA2 and is provided so as to extend in the Z-axis direction at a position in the X1 direction as viewed from the supply flow path BA2. The communication flow path BR2 is provided so as to extend in the Z-axis direction at a position in the X1 direction as viewed from the connection flow path BK2 and at a position in the X2 direction as viewed from the communication flow path BR1. The communication flow path BR2 communicates with the nozzle NZ2 corresponding to the communication flow path BR2.

[0045] The supply flow paths BA1 and BA2 are also referred to as supply flow paths BA without any particular distinction, the connection flow paths BK1 and BK2 are also referred to as connection flow paths BK without any particular distinction, and the communicating flow paths BR1 and BR2 are also referred to as communicating flow paths BR without any particular distinction.

[0046] 3 and 4, a pressure chamber substrate 13 is provided at a position in the Z2 direction as viewed from the communication plate 12. The pressure chamber substrate 13 is a plate-shaped member that is long in the Y-axis direction and extends approximately parallel to the XY plane. The pressure chamber substrate 13 is manufactured, for example, by processing a silicon single crystal substrate using semiconductor manufacturing technology, but the pressure chamber substrate 13 may be manufactured using any known material and manufacturing method.

[0047] Ink flow paths are formed in the pressure chamber substrate 13. Specifically, the pressure chamber substrate 13 is formed with a plurality of pressure chambers CV1 corresponding to the plurality of nozzles NZ1 and a plurality of pressure chambers CV2 corresponding to the plurality of nozzles NZ2. For example, as shown in FIG. 3, the plurality of pressure chambers CV1 are partitioned by partition walls WL1 of the pressure chamber substrate 13 and are arranged in the Y-axis direction. The plurality of pressure chambers CV2 are partitioned by partition walls WL2 of the pressure chamber substrate 13 and are arranged in the Y-axis direction at positions in the X2 direction as viewed from the plurality of pressure chambers CV1. As shown in FIG. 4, the pressure chamber CV1 is provided so as to connect the X2-direction end of the connection flow path BK1 and the X1-direction end of the communication flow path BR1 when viewed in the Z-axis direction, and extend in the X-axis direction. The pressure chamber CV2 is provided so as to connect the X1-direction end of the connection flow path BK2 and the X2-direction end of the communication flow path BR2 when viewed in the Z-axis direction, and extend in the X-axis direction. The pressure chambers CV1 and CV2 are also referred to as pressure chambers CV without any particular distinction, and the partition walls WL1 and WL2 are also referred to as partition walls WL without any particular distinction.

[0048] As shown in FIGS. 3 and 4 , a diaphragm 14 is provided at a position in the Z2 direction as viewed from the pressure chamber substrate 13. The diaphragm 14 is a plate-shaped member that is elongated in the Y-axis direction and extends substantially parallel to the XY plane, and is capable of elastically vibrating. In this embodiment, the diaphragm 14 has, for example, an elastic layer made of silicon oxide and an insulating layer made of zirconium oxide provided at a position in the Z2 direction as viewed from the elastic layer. That is, in this embodiment, the Z2-direction surface of the diaphragm 14 is formed of a non-conductive material. Here, the first-direction surface of element A is a surface of element A that is substantially perpendicular to the first direction and is the surface that is visible when element A is viewed from the first direction to the second direction. The second direction is the direction opposite to the first direction. Note that the elastic layer of the diaphragm 14 is not limited to an elastic layer made of silicon oxide. Similarly, the insulating layer of the diaphragm 14 is not limited to an insulating layer made of zirconium oxide.

[0049] 3 and 4, a plurality of piezoelectric elements PZ1 corresponding to the plurality of pressure chambers CV1 and a plurality of piezoelectric elements PZ2 corresponding to the plurality of pressure chambers CV2 are provided in positions in the Z2 direction as viewed from the vibration plate 14. Note that the piezoelectric elements PZ1 and PZ2 are also referred to as piezoelectric elements PZ without any particular distinction. The piezoelectric elements PZ are driven by the supply of a drive signal COM.

[0050] Although not shown in FIGS. 3 and 4 , the piezoelectric element PZ includes a common electrode Zc to which a predetermined bias potential VBS is supplied, an individual electrode Za to which an individual drive signal Vin is supplied, and a piezoelectric body Zb disposed between the individual electrode Za and the common electrode Zc, as shown in FIG. 5 . For example, the individual electrode Za, the piezoelectric body Zb, and the common electrode Zc are disposed in this order on the Z2-direction surface of the diaphragm 14 along the Z2 direction. Here, the expression “element B is formed on the surface of element A” in this specification does not intend to limit the configuration to one in which element A and element B are in direct contact with each other. In other words, even if element C is formed on the surface of element A and element B is formed on the surface of element C, the concept of “element B is formed on the surface of element A” is encompassed as long as at least a portion of element A and element B overlap in a planar view. Note that in this embodiment, the common electrode Zc is a so-called upper electrode and the individual electrode Za is a so-called lower electrode. However, the common electrode Zc may be a lower electrode and the individual electrode Za may be an upper electrode.

[0051] The piezoelectric element PZ is a passive element that deforms in response to changes in the potential of the drive signal COM supplied to the individual electrode Za as the individual drive signal Vin. In other words, the piezoelectric element PZ is an example of an energy conversion element that converts the electrical energy of the drive signal COM into kinetic energy. Specifically, the piezoelectric element PZ is driven and deforms in response to changes in the potential of the drive signal COM.

[0052] As shown in FIGS. 3 and 4, a piezoelectric element PZ is provided on the Z2-direction surface of the vibration plate 14, and the vibration plate 14 vibrates in conjunction with the deformation of the piezoelectric element PZ. That is, the vibration plate 14 vibrates when the piezoelectric element PZ is driven. When the vibration plate 14 vibrates, the pressure in the pressure chamber CV fluctuates. Then, as the pressure in the pressure chamber CV fluctuates, ink filled in the pressure chamber CV is ejected from the nozzle NZ via the communication flow path BR. In this way, the pressure chamber CV is filled with ink, and pressure for ejecting the ink from the nozzle NZ is applied by the vibration of the vibration plate 14. Furthermore, the vibration remaining in the ejection section D[k] described in FIG. 1 can also be considered, for example, as vibration remaining in the ink in the pressure chamber CV of the ejection section D.

[0053] 3 and 4, a sealing substrate 15 for protecting the plurality of piezoelectric elements PZ1 and the plurality of piezoelectric elements PZ2 is provided at a position in the Z2 direction as viewed from the pressure chamber substrate 13. The sealing substrate 15 is a plate-like member that is elongated in the Y-axis direction and extends approximately parallel to the XY plane. The sealing substrate 15 is manufactured, for example, by processing a silicon single crystal substrate using semiconductor manufacturing technology, but the sealing substrate 15 may be manufactured using any known material and manufacturing method.

[0054] 4, the surface of the sealing substrate 15 in the Z1 direction is provided with recesses for covering the plurality of piezoelectric elements PZ1 and recesses for covering the plurality of piezoelectric elements PZ2. Hereinafter, the sealed space covering the plurality of piezoelectric elements PZ1 and formed between the vibration plate 14 and the sealing substrate 15 will be referred to as the sealed space SP1, and the sealed space covering the plurality of piezoelectric elements PZ2 and formed between the vibration plate 14 and the sealing substrate 15 will be referred to as the sealed space SP2. The sealed spaces SP1 and SP2 will also be referred to as the sealed space SP without any particular distinction. The sealed space SP is a space for sealing the piezoelectric elements PZ and preventing the piezoelectric elements PZ from being altered by the influence of moisture, etc.

[0055] A through hole 15h is provided in the sealing substrate 15. When the sealing substrate 15 is viewed in the Z1 direction, the through hole 15h is located between the sealed space SP1 and the sealed space SP2, and is a hole that penetrates from the surface of the sealing substrate 15 in the Z1 direction to the surface of the sealing substrate 15 in the Z2 direction. The wiring substrate 17 is inserted into the through hole 15h.

[0056] 3 and 4, a flow path forming substrate 16 is provided at a position in the Z2 direction as viewed from the communication plate 12. The flow path forming substrate 16 is a plate-like member that is elongated in the Y-axis direction and extends substantially parallel to the XY plane. The flow path forming substrate 16 is formed, for example, by injection molding of a resin material, but the flow path forming substrate 16 may be manufactured using any known material and method.

[0057] As shown in FIG. 4, ink flow paths are formed in the flow path forming substrate 16. Specifically, one supply flow path BB1 and one supply flow path BB2 are formed in the flow path forming substrate 16. Of these, supply flow path BB1 communicates with supply flow path BA1 and is provided so as to extend in the Y-axis direction at a position in the Z2 direction as viewed from supply flow path BA1. Supply flow path BB2 communicates with supply flow path BA2 and is provided so as to extend in the Y-axis direction at a position in the Z2 direction as viewed from supply flow path BA2 and at a position in the X2 direction as viewed from supply flow path BB1. Note that supply flow paths BB1 and BB2 are also referred to as supply flow paths BB without any particular distinction being made.

[0058] The flow channel forming substrate 16 is provided with an inlet HL1 that communicates with the supply channel BB1 and an inlet HL2 that communicates with the supply channel BB2. Ink is supplied to the supply channel BB1 from the ink container 60 via the inlet HL1. The ink supplied to the supply channel BB1 from the ink container 60 via the inlet HL1 flows into the supply channel BA1. Some of the ink that flows into the supply channel BA1 passes through the connecting channel BK1 and fills the pressure chamber CV1. When the piezoelectric element PZ1 is driven by the drive signal COM, some of the ink that has filled the pressure chamber CV1 is ejected from the nozzle NZ1 via the communicating channel BR1.

[0059] Furthermore, ink is supplied to supply flow path BB2 from the ink container 60 via inlet HL2. The ink supplied from the ink container 60 to supply flow path BB2 via inlet HL2 flows into supply flow path BA2. Some of the ink that flows into supply flow path BA2 passes through connecting flow path BK2 and fills pressure chamber CV2. When piezoelectric element PZ2 is driven by drive signal COM, some of the ink that has filled pressure chamber CV2 is ejected from nozzle NZ2 via communicating flow path BR2.

[0060] A through hole 16h is provided in the flow path forming substrate 16. When the flow path forming substrate 16 is viewed in the Z1 direction, the through hole 16h is located between the supply flow path BB1 and the supply flow path BB2, and is a hole that penetrates from the surface of the flow path forming substrate 16 in the Z1 direction to the surface of the flow path forming substrate 16 in the Z2 direction. The wiring substrate 17 is inserted into the through hole 16h.

[0061] 3 and 4, a wiring board 17 is mounted on the Z2 direction surface of the diaphragm 14. The wiring board 17 is a component for electrically connecting the liquid ejection head 1 to the control unit 4. For example, a flexible wiring board such as an FPC (Flexible Printed Circuit) or an FFC (Flexible Flat Cable) is preferably used as the wiring board 17. As described above, electronic components EC including the switching circuit 18 and the detection circuit 19 are mounted on the wiring board 17.

[0062] 3 and 4, a compliance sheet CS1 is provided in a position in the Z1 direction as viewed from the communicating plate 12 so as to block the supply flow path BA1 and the connecting flow path BK1, and a compliance sheet CS2 is provided so as to block the supply flow path BA2 and the connecting flow path BK2. The compliance sheets CS1 and CS2 are also referred to as the compliance sheet CS without any particular distinction. The compliance sheet CS is a plate-like member that is elongated in the Y-axis direction and extends substantially parallel to the XY plane. The compliance sheet CS is made of an elastic material and absorbs pressure fluctuations of the ink in the supply flow path BA and the connecting flow path BK.

[0063] 4, the ejection section D1 has a piezoelectric element PZ1, a pressure chamber CV1, a nozzle NZ1 communicating with the pressure chamber CV1, and a portion of the vibration plate 14 that contacts the piezoelectric element PZ1. Similarly, the ejection section D2 has a piezoelectric element PZ2, a pressure chamber CV2, a nozzle NZ2 communicating with the pressure chamber CV2, and a portion of the vibration plate 14 that contacts the piezoelectric element PZ2. The ejection sections D1 and D2 are also referred to as ejection section D without any particular distinction. In the following, the second element of the first element and second element included in one ejection section D will also be referred to as the second element corresponding to the first element. Specifically, for example, the piezoelectric element PZ included in the ejection section D that has one nozzle NZ will also be referred to as the piezoelectric element PZ corresponding to the one nozzle NZ.

[0064] Furthermore, although not shown, the liquid ejection head 1 has a cap for sealing the nozzle surface, which is the surface in the Z1 direction of the nozzle substrate 11. The cap seals the nozzle surface of the nozzle substrate 11 on which the nozzles NZ are formed, during periods when ink is not ejected from the nozzles NZ.

[0065] Next, an overview of the liquid ejection head 1 will be described with reference to FIG.

[0066] FIG. 5 is a block diagram showing an example of the configuration of the liquid ejection head 1. As shown in FIG.

[0067] 1, the liquid ejection head 1 has a recording head 10, a switching circuit 18, and a detection circuit 19. The liquid ejection head 1 also has a wiring La to which a drive signal COM is supplied from the drive signal generating unit 2, and a wiring Ls that supplies a detection signal Vout to the detection circuit 19. The liquid ejection head 1 also has a wiring Li[k] that supplies an individual drive signal Vin[k] to the ejection section D[k], and a wiring Ld that is supplied with a bias potential VBS. In this embodiment, it is assumed that the drive signal COM supplied to the wiring La is the drive signal COM that causes ink to be ejected from the nozzle NZ.

[0068] The switching circuit 18 has K switches SWa[1] to SWa[K] that correspond one-to-one to the K discharge units D[1] to D[K], and K switches SWs[1] to SWs[K] that correspond one-to-one to the K discharge units D[1] to D[K].

[0069] The switching circuit 18 also has a connection state designation circuit CSC. The connection state designation circuit CSC designates the connection state of each of the K switches SWa and K switches SWs. For example, the connection state designation circuit CSC generates connection state designation signals Qa[k] and Qs[k] based on at least a portion of the print signal SI and the latch signal LAT supplied from the control unit 4.

[0070] For example, the connection state designation signal Qa[k] is a signal that designates whether the switch SWa[k] is on or off, and the connection state designation signal Qs[k] is a signal that designates whether the switch SWs[k] is on or off.

[0071] The switch SWa[k] switches between electrical continuity and non-conduction between the wiring La and the individual electrode Za[k] of the piezoelectric element PZ[k] provided in the discharge section D[k] based on the connection state designation signal Qa[k]. That is, the switch SWa[k] switches between electrical continuity and non-conduction between the wiring La and the wiring Li[k] connected to the individual electrode Za[k] based on the connection state designation signal Qa[k]. In this embodiment, the switch SWa[k] is turned on when the connection state designation signal Qa[k] is high level and turned off when the connection state designation signal Qa[k] is low level. When the switch SWa[k] is on, the drive signal COM supplied to the wiring La is supplied as an individual drive signal Vin[k] to the individual electrode Za[k] of the discharge section D[k] via the wiring Li[k]. That is, the individual drive signal Vin[k] is the drive signal COM supplied to the piezoelectric element PZ[k] of the discharge section D[k] via the switch SWa[k].

[0072] The switch SWs[k] switches between electrical continuity and non-conduction between the wiring Ls and the individual electrode Za[k] of the piezoelectric element PZ[k] provided in the discharge portion D[k] based on the connection state designation signal Qs[k]. That is, the switch SWs[k] switches between electrical continuity and non-conduction between the wiring Ls and the wiring Li[k] connected to the individual electrode Za[k] based on the connection state designation signal Qs[k]. In this embodiment, the switch SWs[k] is turned on when the connection state designation signal Qs[k] is high level and turned off when the connection state designation signal Qs[k] is low level.

[0073] For example, the connection state designation signal Qs[k] becomes high level when detecting residual vibration of a discharge section D[k]. Hereinafter, the discharge section D whose residual vibration is detected may be referred to as the discharge section D of the detection target. Hereinafter, the piezoelectric element PZ of the discharge section D of the detection target may be referred to as the piezoelectric element PZ of the detection target. When the switch SWs[k] is turned on, a detection signal Vout[k] indicating the potential of the individual electrode Za[k] of the piezoelectric element PZ[k] of the discharge section D[k] of the detection target is supplied to the detection circuit 19 via the wiring Li[k] and the wiring Ls. The detection circuit 19 generates a residual vibration signal VR[k] based on the detection signal Vout[k]. As described above, the residual vibration signal VR[k] is used to evaluate electrical crosstalk.

[0074] Next, the operation of the liquid ejection device 100 in the unit period TU will be described with reference to FIG.

[0075] 6 is a timing chart showing an example of the operation of the liquid ejection device 100 in a unit period TU. In this embodiment, when the liquid ejection device 100 executes a printing process, a printing process period including one or more unit periods TU is set as the operating period of the liquid ejection device 100. The liquid ejection device 100 according to this embodiment can drive each ejection section D for the printing process in each unit period TU. Furthermore, the liquid ejection device 100 according to this embodiment can drive the ejection section D to be detected and detect the detection signal Vout[k] from the ejection section D to be detected in each unit period TU.

[0076] FIG. 6 illustrates an example of the waveform of the drive signal COM determined based on the evaluation results of the electric crosstalk.

[0077] The control unit 4 outputs a latch signal LAT having a pulse PlsL, thereby defining a unit period TU as the period from the rising edge of one pulse PlsL to the rising edge of the next pulse PlsL.

[0078] The print signal SI includes, for example, K individual designation signals Sd[1] to Sd[K] that correspond one-to-one to the K discharge sections D[1] to D[K]. The individual designation signal Sd[k] designates the driving mode of the discharge section D[k] in each unit period TU when the liquid discharger 100 executes a printing process.

[0079] Prior to each unit period TU during which printing is performed, the control unit 4 supplies a print signal SI, including individual designation signals Sd[1] to Sd[K], to the connection state designation circuit CSC in synchronization with a clock signal CL. Then, during that unit period TU, the connection state designation circuit CSC generates connection state designation signals Qa[k] and Qs[k] based on the individual designation signal Sd[k].

[0080] For example, in a unit period TP during which the printing process is executed, a discharge unit D[k] is designated by an individual designation signal Sd[k] as either a discharge unit D that forms dots, a discharge unit D that does not form dots, or a discharge unit D that is the detection target. A discharge unit D that forms dots is a discharge unit D whose piezoelectric element PZ is driven to eject ink from the nozzle NZ of that discharge unit D. In other words, it is a discharge unit D that is the target of discharge drive, in which the piezoelectric element PZ is driven by a drive signal COM that ejects ink from the nozzle NZ. Furthermore, a discharge unit D that does not form dots is a discharge unit D whose piezoelectric element PZ is driven to not eject ink from the nozzle NZ of that discharge unit D.

[0081] First, we will explain the operation of the connection state specification circuit CSC and other components when the drive mode of the discharge unit D that forms dots is specified by the individual specification signal Sd[k]. When the drive mode of the discharge unit D that forms dots is specified by the individual specification signal Sd[k], for example, the connection state specification circuit CSC sets the connection state specification signal Qa[k] to a high level and the connection state specification signal Qs[k] to a low level during the unit period TU. This causes the drive signal COM to be supplied from the drive signal generation unit 2 to the discharge unit D that forms dots.

[0082] For example, the drive signal generating unit 2 outputs a drive signal COM having a pulse PA. The pulse PA is, for example, a pulse that causes ink to be ejected from the nozzle NZ. The pulse PA has a waveform in which the potential of the drive signal COM goes from a potential V0, passes through a potential VLa lower than the potential V0, and a potential VHa higher than the potential V0, and then returns to the potential V0. The potential V0 is the potential at the start and end of the pulse PA, and is the reference potential of the drive signal COM. Furthermore, for example, the potential VLa is the minimum potential of the pulse PA and corresponds to an expansion potential. Furthermore, for example, the potential VHa is the maximum potential of the pulse PA and corresponds to a contraction potential.

[0083] For example, a pulse PA has a waveform element Pa1 whose potential changes from potential V0 to potential VLa, a waveform element Pa2 whose potential is maintained at the potential VLa at the end of waveform element Pa1, and a waveform element Pa3 whose potential changes from potential VLa to potential VHa. Furthermore, the pulse PA includes a waveform element Pa4 whose potential is maintained at the potential VHa at the end of waveform element Pa3, and a waveform element Pa5 whose potential changes from potential VHa to potential V0. Hereinafter, the waveform elements Pa1, Pa2, Pa3, Pa4, and Pa5 may be collectively referred to as waveform element Pa.

[0084] The waveform elements Pa1 and Pa5 are expansion elements for displacing the piezoelectric body Zb in the Z2 direction. In the expansion elements, the potential of the drive signal COM changes to drive the piezoelectric element PZ so as to expand the volume of the pressure chamber CV. Therefore, in the waveform elements Pa1 and Pa5, the potential of the drive signal COM changes to expand the volume of the pressure chamber CV. When the volume of the pressure chamber CV expands, the surface of the ink in the nozzle NZ is pulled in the Z2 direction, which is the opposite direction to the ejection direction. Hereinafter, pulling the surface of the ink in the nozzle NZ in the direction opposite to the ejection direction may be referred to as "pull." The waveform element Pa1 is an example of a "first expansion element," and the waveform element Pa5 is an example of a "second expansion element."

[0085] Furthermore, the waveform element Pa3 is a contraction element for displacing the piezoelectric body Zb in the Z1 direction. In the contraction element, the potential of the drive signal COM changes to drive the piezoelectric element PZ so as to contract the volume of the pressure chamber CV. Therefore, in the waveform element Pa3, the potential of the drive signal COM changes so as to contract the volume of the pressure chamber CV. When the volume of the pressure chamber CV contracts, the surface of the ink in the nozzle NZ is pushed in the Z1 direction, which is the ejection direction. Hereinafter, pushing the surface of the ink in the nozzle NZ in the ejection direction may be referred to as a push.

[0086] Furthermore, waveform elements Pa2 and Pa4 are maintaining elements for maintaining the position of the piezoelectric body Zb in the Z-axis direction. For example, waveform element Pa2 maintains the potential of the drive signal COM in order to drive the piezoelectric element PZ so as to maintain the volume of the pressure chamber CV expanded by waveform element Pa1. For example, waveform element Pa4 maintains the potential of the drive signal COM in order to drive the piezoelectric element PZ so as to maintain the volume of the pressure chamber CV contracted by waveform element Pa3.

[0087] In this way, the pulse PA has a so-called pull-push-pull waveform. However, the waveform of the drive signal COM that ejects ink from the nozzle NZ is not limited to a pull-push-pull waveform. For example, a so-called pull-push waveform may be used in which the pressure chamber CV is expanded by a first expansion element to draw ink into the pressure chamber CV in the Z2 direction, and then the pressure chamber CV is contracted by a contraction element that returns the potential to the potential before the first expansion element was applied, ejecting ink from the pressure chamber CV in the Z1 direction, and then the second expansion element is not applied.

[0088] The pulse PA is determined so that a predetermined amount of ink is ejected from the ejection section D[k] when an individual drive signal Vin[k] having the pulse PA is supplied to the ejection section D[k]. Note that in this embodiment, it is assumed that when the potential of the individual drive signal Vin[k] is high, the volume of the pressure chamber CV of the ejection section D[k] is smaller than when the potential is low. Therefore, when the ejection section D[k] is driven by the individual drive signal Vin[k] having the pulse PA, the ink in the ejection section D[k] is ejected from the nozzle NZ by the waveform element Pa3, in which the potential of the individual drive signal Vin[k] changes from low to high.

[0089] For example, the waveform elements Pa1, Pa2, Pa3, Pa4, and Pa5 included in the pulse PA are determined based on the ink ejection characteristics of the ejection unit D. The ink ejection characteristics include, for example, the amount of ink ejected as ink droplets and the ejection speed of the ejected ink droplets. In addition, in this embodiment, the potential change rate of the pulse PA is determined to suppress the occurrence of electrical crosstalk. The potential change rate is the amount of change in potential per unit time. Here, for example, electrical crosstalk occurs due to the influence of resistance components, capacitance components, and inductance components of the wiring La to which the drive signal COM is supplied. Therefore, between a waveform element Pa with a large potential change amount and a waveform element Pa with a small potential change amount, the waveform element Pa with a large potential change amount is considered to have a greater impact on the occurrence of electrical crosstalk. For example, in the pulse PA shown in FIG. 6, among the waveform elements Pa1, Pa2, Pa3, Pa4, and Pa5, the waveform element Pa3 with the largest potential change amount is considered to have the greatest impact on the occurrence of electrical crosstalk. Therefore, in this embodiment, the occurrence of electrical crosstalk is suppressed by adjusting the potential change rate of the waveform element Pa3. The potential change rate adjusted to suppress the occurrence of electrical crosstalk is not limited to the potential change rate of the waveform element Pa3, as long as the occurrence of electrical crosstalk can be suppressed. For example, in addition to the potential change rate of the waveform element Pa3, the potential change rates of one or both of the waveform elements Pa1 and Pa2 may be adjusted.

[0090] Next, we will explain the operation of the connection state designation circuit CSC and other components when the individual designation signal Sd[k] designates the drive mode of a discharge unit D that does not form dots. When the individual designation signal Sd[k] designates the drive mode of a discharge unit D that does not form dots, for example, the connection state designation circuit CSC sets the connection state designation signals Qa[k] and Qs[k] to low level during the unit period TU. As a result, if no leakage current occurs, the potential of the individual electrode Za of the piezoelectric element PZ of the discharge unit D that does not form dots is maintained at the potential before the connection state designation signal Qa[k] was set to low level, for example, potential V0.

[0091] Next, the operation of the connection state specification circuit CSC and the like when the drive mode of the discharge unit D to be detected is specified by the individual specification signal Sd[k] will be described. Hereinafter, the operation of the connection state specification circuit CSC and the like when the drive mode of the discharge unit D to be detected is specified by the individual specification signal Sd[k] will be described using the case of evaluating electric crosstalk as an example. Hereinafter, the unit period TU in which residual vibrations for evaluating electric crosstalk are detected may be referred to as the detection unit period TU. When evaluating electric crosstalk, for example, the discharge unit D to be detected operates as a discharge unit D driven by the evaluation drive signal COM in the unit period TU immediately before the detection unit period TU. That is, the piezoelectric element PZ of the discharge unit D to be detected is driven by the evaluation waveform, which is the waveform of the evaluation drive signal COM, in the unit period TU immediately before the detection unit period TU. Details of the evaluation waveform will be described later with reference to FIG. 7. For example, as the evaluation waveform, multiple evaluation waveforms with different potential change rates of the waveform element Pa3 are used. Furthermore, in this embodiment, it is assumed that each of the multiple evaluation drive signals COM, each having multiple evaluation waveforms, is a drive signal COM that causes ink to be ejected from the nozzle NZ. For this reason, when the ejection unit D to be detected is driven by the evaluation drive signal COM, it is preferable, for example, to position the ejection unit D to be detected above a discharged ink receiving unit used in the flushing process.

[0092] When the driving mode of the discharge section D to be detected is specified by the individual specification signal Sd[k], for example, the connection state specification circuit CSC sets the connection state specification signal Qa[k] to a high level and the connection state specification signal Qs[k] to a low level in the unit period TU immediately preceding the unit period TU for detection.

[0093] Furthermore, in the evaluation of electric crosstalk, a specific discharge unit D other than the discharge unit D to be detected may be designated by the individual designation signal Sd[j] as the discharge unit D to be driven by the drive signal COM for evaluation. Here, the variable j is a natural number different from the variable k and satisfies "1≦j≦K." In the unit period TU immediately preceding the unit period TU for detection, the connection state designation signals Qa[j] and Qs[j] corresponding to the specific discharge unit D described above are also set in the same manner as the connection state designation signals Qa[k] and Qs[k], respectively.

[0094] As a result, the drive signal COM for evaluation is supplied from the drive signal generation unit 2 to the discharge section D to be detected and to the specific discharge section D. Then, the connection state designation circuit CSC sets the connection state designation signal Qs[k] to a high level during the unit period TU for detection. Also, the connection state designation circuit CSC sets the connection state designation signal Qa[k] to a low level during the unit period TU for detection. Also, during the unit period TU for detection, the connection state designation signals Qa[j] and Qs[j] are set to a low level.

[0095] In this case, the piezoelectric element PZ[k] of each of the target discharge section D[k] and the specific discharge section D[j] is driven by the evaluation drive signal COM during the unit period TU immediately preceding the detection unit period TU. As a result, for example, the piezoelectric element PZ[k] is displaced by the pulse PA of the evaluation drive signal COM during the unit period TU immediately preceding the detection unit period TU. As a result, vibrations occur in the target discharge section D[k] before the detection unit period TU. The vibrations that occurred before the detection unit period TU remain during the detection unit period TU. During the detection unit period TU, the potential of the individual electrode Za[k] of the piezoelectric element PZ[k] of the target discharge section D[k] changes depending on the residual vibrations occurring in the discharge section D[k]. That is, during the detection unit period TU, the potential of the individual electrode Za of the piezoelectric element PZ of the target discharge section D becomes a potential corresponding to the electromotive force of the piezoelectric element PZ resulting from the residual vibrations occurring in the target discharge section D. The potential of the individual electrode Za is detected as a detection signal Vout during a unit period TU for detection.

[0096] The connection state designation circuit CSC may set the connection state designation signal Qs[k] to a high level during the first half of the detection unit period TU, and set the connection state designation signal Qs[k] to a low level during the second half of the detection unit period TU. The connection state designation signals Qa and Qs corresponding to the discharge units D other than the discharge unit D[k] to be detected are set to a low level during the detection unit period TU.

[0097] In this manner, in this embodiment, for example, the residual vibration signal VR[k] indicating the residual vibration of the diaphragm 14 after the piezoelectric element PZ is driven by the drive signal COM for evaluation is used to evaluate the electric crosstalk.

[0098] The operation of the liquid ejection device 100 is not limited to the example shown in FIG. 6 . For example, FIG. 6 illustrates a drive signal COM including one pulse PA that ejects ink from the nozzle NZ, but the present invention is not limited to this embodiment. For example, the drive signal COM may include multiple pulses that eject ink from the nozzle NZ to form dots of different sizes. Also, for example, FIG. 6 illustrates a case in which there is one drive signal COM that ejects ink from the nozzle NZ, but the present invention is not limited to this embodiment. For example, multiple drive signals COM corresponding to the sizes of the dots may be used as the drive signal COM that ejects ink from the nozzle NZ. Furthermore, the multiple drive signals COM may include one or both of a drive signal COM having a micro-vibration waveform that prevents ink from thickening and a drive signal COM having a micro-vibration waveform that generates residual vibrations for evaluating the ejection state.

[0099] Also, the evaluation waveform of the electromagnetic crosstalk, that is, the waveform of the driving signal COM for evaluation may be a waveform different from the waveform actually adopted as the waveform of the driving signal COM for discharging ink from the nozzle NZ. For example, when the waveform adopted as the waveform of the driving signal COM for discharging ink from the nozzle NZ is a pull-push-pull waveform, a rectangular wave whose potential returns from the potential VLa to the potential VLa via the potential VHa may be used as the evaluation waveform.

[0100] Next, an example of the relationship between the evaluation waveform and the waveform of the residual vibration will be described with reference to FIG. 7.

[0101] FIG. 7 is a diagram showing an example of the evaluation waveform and the waveform of the residual vibration. In FIG. 7, four evaluation waveforms WE1, WE2, WE3, and WE4, and the waveforms applied to the piezoelectric element PZ and the waveforms of the detected residual vibration when the piezoelectric element PZ is driven by each of the evaluation waveforms WE1, WE2, WE3, and WE4 are shown. The waveform of the detected residual vibration is, for example, the waveform of the residual vibration signal VR.

[0102] In FIG. 7, the waveforms applied to the piezoelectric element PZ and the waveforms of the detected residual vibration when only N piezoelectric elements PZ are driven are shown by solid lines, and the waveforms applied to the piezoelectric element PZ and the waveforms of the detected residual vibration when only M piezoelectric elements PZ are driven are shown by dotted lines. Although FIG. 7 shows the case where all the piezoelectric elements PZ are driven and the case where only one piezoelectric element PZ is driven, even when only N piezoelectric elements satisfying "2 ≦ N ≦ K" are driven instead of all the piezoelectric elements, and only M piezoelectric elements satisfying "1 ≦ M < N" are driven instead of one piezoelectric element PZ, the same tendency as in FIG. 7 is shown.

[0103] Therefore, hereinafter, driving only N piezoelectric elements PZ out of K piezoelectric elements PZ (including driving all K piezoelectric elements PZ) may be referred to as N - element driving, and driving only M piezoelectric elements PZ out of K piezoelectric elements PZ (including driving only one of the K piezoelectric elements) may be referred to as M - element driving.

[0104] In the following description, the evaluation waveforms WE1, WE2, WE3, and WE4 may be collectively referred to as the evaluation waveform WE. In this embodiment, the evaluation waveform WE is assumed to be a pull-push-pull waveform, similar to the pulse PA shown in FIG. 6 . However, the evaluation waveform WE may also be, for example, a rectangular wave including a waveform element Pw, or the pull-push waveform described above. For ease of viewing, FIG. 7 illustrates the evaluation waveform WE with a focus on the waveform element Pw, which corresponds to the push of the pull-push-pull waveform, and omits a portion of the pull-push-pull waveform. The waveform element Pw of the evaluation waveform WE corresponds to the waveform element Pa3 of the pulse PA shown in FIG. 6 .

[0105] In the following description, the potential change rate DE1 of the waveform element Pw of the evaluation waveform WE1, the potential change rate DE2 of the waveform element Pw of the evaluation waveform WE2, the potential change rate DE3 of the waveform element Pw of the evaluation waveform WE3, and the potential change rate DE4 of the waveform element Pw of the evaluation waveform WE4 may be collectively referred to as the potential change rate DE. The potential change rates DE of the evaluation waveforms WE1, WE2, WE3, and WE4 shown in FIG. 7 are different from one another.

[0106] The rates of potential change DE1, DE2, DE3, and DE4 are expressed by the formulas (1), (2), (3), and (4), respectively.

[0107] DE1=|VH1-VL1| / TR1=DV1 / TR1 …(1) DE2=|VH2-VL2| / TR2=DV2 / TR2 …(2) DE3=|VH3-VL3| / TR3=DV3 / TR3 …(3) DE4=|VH4-VL4| / TR4=DV4 / TR4 …(4)

[0108] The potential difference DV1 in equation (1) represents the absolute value of the potential difference between the potential VL1 at the start point and the potential VH1 at the end point of the waveform element Pw of the evaluation waveform WE1, and the time TR1 represents the time from the start point to the end point of the waveform element Pw of the evaluation waveform WE1. The potential difference DV2 in equation (2) represents the absolute value of the potential difference between the potential VL2 at the start point and the potential VH2 at the end point of the waveform element Pw of the evaluation waveform WE2, and the time TR2 represents the time from the start point to the end point of the waveform element Pw of the evaluation waveform WE2. The potential difference DV3 in equation (3) represents the absolute value of the potential difference between the potential VL3 at the start point and the potential VH3 at the end point of the waveform element Pw of the evaluation waveform WE3, and the time TR3 represents the time from the start point to the end point of the waveform element Pw of the evaluation waveform WE3. The potential difference DV4 in equation (4) represents the absolute value of the potential difference between the potential VL4 at the start point and the potential VH4 at the end point of the waveform element Pw of the evaluation waveform WE4, and the time TR4 represents the time from the start point to the end point of the waveform element Pw of the evaluation waveform WE4. Hereinafter, the times TR1, TR2, TR3, and TR4 may be collectively referred to as time TR.

[0109] In the example shown in FIG. 7, potentials VL1, VL2, VL3, and VL4 are the same potential, for example, potential VLa, and potentials VH1, VH2, VH3, and VH4 are the same potential, for example, potential VHa. Therefore, potential differences DV1, DV2, DV3, and DV4 are the same value. Hereinafter, potentials VL1, VL2, VL3, VL4, and VLa may be collectively referred to as potential VL, potentials VH1, VH2, VH3, VH4, and VHa may be collectively referred to as potential VH, and potential differences DV1, DV2, DV3, and DV4 may be collectively referred to as potential difference DV. Furthermore, among times TR1, TR2, TR3, and TR4, time TR1 is the shortest time, and time TR4 is the longest time. Furthermore, time TR2 is greater than time TR1, and time TR3 is greater than time TR2.

[0110] 7, among the potential change rates DE1, DE2, DE3, and DE4, the potential change rate DE1 is the largest potential change rate, and the potential change rate DE4 is the smallest potential change rate. The potential change rate DE2 is smaller than the potential change rate DE1, and the potential change rate DE3 is smaller than the potential change rate DE2. The potential change rate DE1 is an example of a “first potential change rate,” the potential change rate DE2 is an example of a “second potential change rate,” and the potential change rate DE3 is an example of a “third potential change rate.” The evaluation waveform WE1 is an example of a “first evaluation waveform,” the evaluation waveform WE2 is an example of a “second evaluation waveform,” and the evaluation waveform WE3 is an example of a “third evaluation waveform.” The waveform element Pw of the evaluation waveform WE1 is an example of a “first waveform element,” and the waveform element Pw of the evaluation waveform WE2 is an example of a “second waveform element.”

[0111] When the rate of potential change DE is large, the slope of the waveform element Pw becomes steeper than when the rate of potential change DE is small. When the piezoelectric element PZ is driven with a waveform with a steep potential change, an overshoot may occur, in which a potential higher than the steady-state value corresponding to the potential at the end point of the potential change is applied to the piezoelectric element PZ due to the influence of the resistance, capacitance, and inductance components of the switching circuit 18 and the wiring La. The phenomenon of an overshoot occurring in a waveform due to the influence of the resistance, capacitance, and inductance components of the wiring La is a type of electrical crosstalk. In the following, the magnitude of the overshoot may be described as the difference between the potential exceeding the steady-state value and the steady-state value.

[0112] For example, as shown in "Waveform Applied to Piezoelectric Element" in Figure 7, when driving N piezoelectric elements using evaluation waveform WE1, an overshoot occurs in the waveform applied to piezoelectric element PZ, where the potential becomes higher than steady-state value SV1 and then approaches steady-state value SV1. Note that steady-state value SV1 is a potential corresponding to potential VH1 at the end point of waveform element Pw.

[0113] Here, the overshoot depends on, for example, the amount of current flowing through the wiring La. For example, the amount of current flowing through the wiring La is larger when a large number of piezoelectric elements PZ are driven than when a small number of piezoelectric elements PZ are driven. Therefore, the overshoot tends to increase as the number of piezoelectric elements PZ driven increases. In other words, when the number of piezoelectric elements PZ driven is small, the occurrence of overshoot is suppressed. For example, as shown in "Waveform Applied to Piezoelectric Elements" in Figure 7, no overshoot occurs in the waveform applied to the piezoelectric elements PZ when M elements are driven for any of the evaluation waveforms WE1, WE2, WE3, and WE4.

[0114] If an overshoot occurs in the waveform applied to the piezoelectric element PZ, the displacement of the piezoelectric element PZ will also be proportional to the overshoot, causing a larger vibration of the diaphragm 14 than when no overshoot occurs. Therefore, if an overshoot occurs in the waveform applied to the piezoelectric element PZ, a larger ink droplet will be ejected. If the overshoot is too large, a voltage exceeding the withstand voltage of the piezoelectric element PZ will be applied to the piezoelectric element PZ, which may cause the piezoelectric element PZ to break down.

[0115] Furthermore, when an overshoot occurs, as described above, the displacement of the piezoelectric element PZ corresponds to the overshoot, and therefore the residual vibration also corresponds to the overshoot. For example, when an overshoot occurs, a larger vibration occurs in the diaphragm 14 than when no overshoot occurs, and therefore the amplitude of the residual vibration also increases. Therefore, it is possible to estimate the magnitude of the overshoot by examining the relationship between the number of driven piezoelectric elements PZ and the residual vibration. Here, for example, the analysis unit 3 identifies the amplitude of the first peak among the peaks of the potential of the residual vibration signal VR as the amplitude of the residual vibration of the diaphragm 14.

[0116] For example, as shown in the "residual vibration waveform" in Figure 7, the amplitude λN1 of the residual vibration detected when N-element driving is performed using the evaluation waveform WE1 is larger than the amplitude λM1 of the residual vibration detected when M-element driving is performed using the evaluation waveform WE1. In other words, the amplitude λN1 of the residual vibration when an overshoot occurs is larger than the amplitude λM1 of the residual vibration when no overshoot occurs. The amplitude difference DλN1 is the value obtained by subtracting the amplitude λM1 from the amplitude λN1, and is an evaluation value compared with a threshold value used in evaluating electrical crosstalk. The residual vibration detected when N-element driving is performed using the evaluation waveform WE1 is an example of the "first residual vibration," the residual vibration detected when M-element driving is performed using the evaluation waveform WE1 is an example of the "first reference residual vibration," and the amplitude difference DλN1 is an example of the "first amplitude difference." Note that, for each evaluation waveform WE, the residual vibration detected when M-element driving is performed corresponds to the "reference residual vibration."

[0117] Moreover, the overshoot tends to increase as the potential change becomes steeper. That is, the overshoot tends to increase as the potential change rate DE increases. For example, when the potential change rate DE is large, the overshoot increases compared to when the potential change rate DE is small. In other words, when the potential change rate DE is small, the overshoot decreases compared to when the potential change rate DE is large.

[0118] For example, the potential change rate DE2 of the waveform element Pw of the evaluation waveform WE2 is smaller than the potential change rate DE1 of the waveform element Pw of the evaluation waveform WE1. Therefore, as shown in the "Waveform Applied to the Piezoelectric Element" section of Figure 7, the overshoot that occurs when N-element driving is performed using the evaluation waveform WE2 is smaller than the overshoot that occurs when N-element driving is performed using the evaluation waveform WE2. The steady-state value SV2 corresponds to the potential VH2 at the end point of the waveform element Pw of the evaluation waveform WE2. Also, as shown in the "Residual Vibration Waveform" section of Figure 7, the amplitude difference DλN2 between the amplitude λN2 of the residual vibration detected when N-element driving is performed using the evaluation waveform WE2 and the amplitude λM2 of the residual vibration detected when M-element driving is performed using the evaluation waveform WE2 is smaller than the amplitude difference DλN1. The amplitude difference DλN2 is the value obtained by subtracting the amplitude λM2 from the amplitude λN2, and is an evaluation value compared with a threshold value used in evaluating electrical crosstalk. Furthermore, for example, the amplitude λN2 of the residual vibration detected when N-piece driving is performed using the evaluation waveform WE2 is smaller than the amplitude λN1 of the residual vibration detected when N-piece driving is performed using the evaluation waveform WE1. The residual vibration detected when N-piece driving is performed using the evaluation waveform WE2 is an example of a "second residual vibration," the residual vibration detected when M-piece driving is performed using the evaluation waveform WE2 is an example of a "second reference residual vibration," and the amplitude difference DλN2 is an example of a "second amplitude difference."

[0119] Furthermore, for example, the potential change rate DE3 of the waveform element Pw of the evaluation waveform WE3 is smaller than the potential change rate DE2 of the waveform element Pw of the evaluation waveform WE2. Therefore, as shown in the "Waveform Applied to the Piezoelectric Element" section of Figure 7, the overshoot that occurs when N-element driving is performed using the evaluation waveform WE3 is smaller than the overshoot that occurs when N-element driving is performed using the evaluation waveform WE3. The steady-state value SV3 corresponds to the potential VH3 at the end point of the waveform element Pw of the evaluation waveform WE3. Also, as shown in the "Residual Vibration Waveform" section of Figure 7, the amplitude difference DλN3 between the amplitude λN3 of the residual vibration detected when N-element driving is performed using the evaluation waveform WE3 and the amplitude λM3 of the residual vibration detected when M-element driving is performed using the evaluation waveform WE3 is smaller than the amplitude difference DλN2. The amplitude difference DλN3 is the value obtained by subtracting the amplitude λM3 from the amplitude λN3, and is an evaluation value compared with a threshold value used in evaluating electrical crosstalk. Furthermore, for example, the amplitude λN3 of the residual vibration detected when N-element driving is performed using the evaluation waveform WE3 is smaller than the amplitude λN2 of the residual vibration detected when N-element driving is performed using the evaluation waveform WE2. The residual vibration detected when N-element driving is performed using the evaluation waveform WE3 is an example of the "third residual vibration."

[0120] If the potential change rate DE becomes too small, overshooting is suppressed, but the waveform applied to the piezoelectric element PZ becomes dull due to the influence of the resistance, capacitance, and inductance components of the wiring La, etc. Waveform dullness refers to, for example, a slowdown in the potential change when the potential changes from the potential corresponding to the potential at the start point of the potential change to a steady value corresponding to the potential at the end point of the potential change. The phenomenon of waveform dullness due to the influence of the resistance, capacitance, and inductance components of the wiring La, etc., is also a type of electrical crosstalk. If the waveform applied to the piezoelectric element PZ becomes dull, the ink ejection characteristics may not be as desired.

[0121] For example, the potential change rate DE4 of the waveform element Pw of the evaluation waveform WE4 is the smallest potential change rate among the potential change rates DE1, DE2, DE3, and DE4. Therefore, as shown in the "Waveform Applied to Piezoelectric Element" section of Figure 7, when N-element driving is performed using the evaluation waveform WE4, the waveform applied to the piezoelectric element PZ becomes dull. For example, the potential change becomes dull when the potential changes from the potential corresponding to the potential VL4 at the start point of the waveform element Pw to the steady-state value SV4, which is the potential corresponding to the potential VH4 at the end point of the waveform element Pw. Note that when M-element driving is performed using the evaluation waveform WE4, no dulling occurs in the waveform applied to the piezoelectric element PZ. When dulling occurs in the waveform applied to the piezoelectric element PZ, the amplitude of the residual vibration tends to be smaller than when dulling does not occur.

[0122] For example, as shown in the "residual vibration waveform" in FIG. 7, the amplitude λN4 of the residual vibration detected when N elements are driven using the evaluation waveform WE4 is smaller than the amplitude λM4 of the residual vibration detected when M elements are driven using the evaluation waveform WE4. In other words, the amplitude λN4 of the residual vibration when distortion occurs in the waveform applied to the piezoelectric element PZ is smaller than the amplitude λM4 of the residual vibration when distortion does not occur in the waveform applied to the piezoelectric element PZ. The amplitude difference DλN4 is the value obtained by subtracting the amplitude λM4 from the amplitude λN4, and is an evaluation value compared with a threshold value used in evaluating electrical crosstalk. In the example shown in FIG. 7, the amplitude λN4 is smaller than the amplitude λM4, so the amplitude difference DλN4 is a negative value.

[0123] Hereinafter, amplitudes λN1, λN2, λN3 and λN4 may be collectively referred to as amplitude λN, amplitudes λM1, λM2, λM3 and λM4 may be collectively referred to as amplitude λM, and amplitude differences DλN1, DλN2, DλN3 and DλN4 may be collectively referred to as amplitude difference DλN.

[0124] 7, when an overshoot occurs in N-piece driving, the amplitude λN becomes larger than the amplitude λM, and therefore the amplitude difference DλN becomes a positive value. In contrast, when dullness occurs in N-piece driving, the amplitude λN becomes smaller than the amplitude λM, and therefore the amplitude difference DλN becomes a negative value.

[0125] In this embodiment, for example, the waveform determination unit 40 evaluates the electric crosstalk by comparing each of a plurality of amplitude differences DλN obtained by driving the piezoelectric element PZ with each of a plurality of evaluation waveforms WE having different potential change rates DE of the waveform element Pw with a threshold value. Then, the waveform determination unit 40 determines the waveform of the drive signal COM, which is specified by, for example, a waveform designation signal dCOM, based on the evaluation result of the electric crosstalk.

[0126] 7 illustrates a case where multiple potential differences DV corresponding to multiple potential change rates DE are the same value and multiple times TR corresponding to multiple potential change rates DE are different from one another, but the present invention is not limited to this example. That is, the method of making multiple potential change rates DE different from one another is not limited to the example shown in FIG. 7. For example, potential differences DV1, DV2, DV3, and DV4 may be made different from one another and times TR1, TR2, TR3, and TR4 may be made the same from one another to make potential change rates DE1, DE2, DE3, and DE4 different from one another.

[0127] Furthermore, M-element driving is less affected by electrical crosstalk than N-element driving. Therefore, the variation in the residual vibration amplitude λM detected in the M-element driving using multiple evaluation waveforms WE with different potential change rates DE of the waveform elements Pw tends to be smaller than the variation in the residual vibration amplitude λN detected in the N-element driving using the multiple evaluation waveforms WE. Therefore, the amplitude difference DλN used as the evaluation value for each evaluation waveform WE may be calculated by subtracting a reference value common to multiple evaluation waveforms WE from the residual vibration amplitude λN detected in the N-element driving.

[0128] Next, with reference to FIG. 8, the operation of the liquid ejection device 100 when determining the waveform of the drive signal COM will be described.

[0129] Fig. 8 is a flowchart showing an example of the operation of the liquid ejection device 100 when determining the waveform of the drive signal COM. In Fig. 8, in line with Fig. 7, it is assumed that the value N is the same as the value K, and the value M is "1." Note that the N piezoelectric elements PZ and the M piezoelectric elements PZ include the detection target piezoelectric element PZ whose residual vibration is detected.

[0130] In Fig. 8, it is assumed that multiple evaluation waveforms WE, each having a different rate of change in potential DE of the waveform element Pw corresponding to the waveform element Pa3 of the pulse PA, are prepared before the operation shown in Fig. 8 is performed. However, multiple evaluation waveforms WE may also be generated during the operation shown in Fig. 8. For example, multiple evaluation waveforms WE may be generated during the operation shown in Fig. 8 by changing the rate of change in potential DE of the waveform element Pw of the basic evaluation waveform WE each time the process of step S152, described below, is performed.

[0131] 8 is performed when the liquid ejection device 100 is used for the first time, or when the operating conditions of the liquid ejection device 100 are changed due to a change in the type of ink used, etc. The operating conditions of the liquid ejection device 100 also include the operating conditions of the liquid ejection head 1. The operation shown in FIG. 8 is performed, for example, for each of the multiple liquid ejection heads 1. The piezoelectric element PZ to be detected and used in the evaluation of electrical crosstalk when determining the waveform of the drive signal COM is a piezoelectric element PZ that represents the multiple piezoelectric elements PZ.

[0132] 8 is executed by the control unit 4 functioning as the waveform determination section 40. That is, the control unit 4 functions as the waveform determination section 40 in each of steps S100 to S152 and step S200 shown in FIG. 8. The process of step S100 is executed, for example, when the pressure chamber CV is filled with ink to be used by a user of the liquid ejection device 100. That is, the process of step S100 is executed after the pressure chamber CV is filled with ink to be used by the user. The process of filling the pressure chamber CV with ink may be executed by the waveform determination section 40 or may be executed by a processing section other than the waveform determination section 40. The user is, for example, a user of the liquid ejection device 100. When the manufacturer and the user of the liquid ejection device 100 are the same, the manufacturer of the liquid ejection device 100 may be regarded as the user.

[0133] First, in step S100, the waveform determination section 40 sets the variable i to 1. After executing the process of step S100, the waveform determination section 40 moves the process to step S110.

[0134] In step S110, the waveform determination unit 40 controls the liquid ejection head 1 so that N drives are performed with the i-th evaluation waveform WEi. For example, the waveform determination unit 40 selects the signal of the i-th evaluation waveform WEi as the drive signal COM, and controls the liquid ejection head 1 so that all of the K piezoelectric elements PZ are driven using the selected drive signal COM.

[0135] Next, in step S120, the waveform determination unit 40 detects residual vibrations in the piezoelectric element PZ to be detected. For example, the waveform determination unit 40 causes the detection circuit 19 to detect residual vibrations from the piezoelectric element PZ to be detected. As a result, the detection circuit 19 detects the residual vibrations of the diaphragm 14 after driving N piezoelectric elements PZ with the i-th evaluation waveform WEi. The residual vibrations detected by the detection circuit 19 are then analyzed by the analysis unit 3. The waveform determination unit 40 acquires residual vibration information Vinf from the analysis unit 3, which indicates the analysis results of the residual vibrations detected by the detection circuit 19. For example, the analysis results indicated by the residual vibration information Vinf include the amplitude λN of the residual vibrations detected when N piezoelectric elements PZ are driven with the i-th evaluation waveform WEi. Note that if the i-th evaluation waveform WEi corresponds to the "first evaluation waveform," the residual vibrations detected in step S120 are an example of the "first residual vibration." Furthermore, if the i-th evaluation waveform WEi corresponds to the "second evaluation waveform," the residual vibration detected in step S120 is an example of the "second residual vibration." Furthermore, if the i-th evaluation waveform WEi corresponds to the "third evaluation waveform," the residual vibration detected in step S120 is an example of the "third residual vibration."

[0136] Next, in step S130, the waveform determination unit 40 controls the liquid ejection head 1 so that M drives are performed with the i-th evaluation waveform WEi. For example, the waveform determination unit 40 selects the signal of the i-th evaluation waveform WEi as the drive signal COM, and controls the liquid ejection head 1 so that only one piezoelectric element PZ of the K piezoelectric elements PZ is driven using the selected drive signal COM.

[0137] Next, in step S140, the waveform determination unit 40 detects residual vibration in the piezoelectric element PZ to be detected. The process of step S140 is similar to the process of step S120. For example, the waveform determination unit 40 causes the detection circuit 19 to detect residual vibration from the piezoelectric element PZ to be detected. As a result, the detection circuit 19 detects the residual vibration of the diaphragm 14 after driving only one piezoelectric element PZ with the i-th evaluation waveform WEi. The residual vibration detected by the detection circuit 19 is then analyzed by the analysis unit 3. The waveform determination unit 40 acquires residual vibration information Vinf from the analysis unit 3, which indicates the analysis results of the residual vibration detected by the detection circuit 19. For example, the analysis results indicated by the residual vibration information Vinf include the amplitude λM of the residual vibration detected when only one piezoelectric element PZ is driven with the i-th evaluation waveform WEi. Note that if the i-th evaluation waveform WEi corresponds to the "first evaluation waveform," the residual vibration detected in step S140 is an example of the "first reference residual vibration." Furthermore, when the i-th evaluation waveform WEi corresponds to the "second evaluation waveform," the residual vibration detected in step S140 is an example of the "second reference residual vibration."

[0138] Next, in step S150, the waveform determination unit 40 determines whether the variable i is at its final value. The final value of the variable i is, for example, a natural number equal to or greater than 2, and is the number of evaluation waveforms WE prepared in advance. That is, the waveform determination unit 40 determines whether residual signals have been detected in N-driving and M-driving for all of the evaluation waveforms WE prepared in advance.

[0139] If the result of the determination in step S150 is negative, the waveform determination section 40 adds "1" to the variable i in step S152, and then returns the process to step S110. On the other hand, if the result of the determination in step S150 is positive, the waveform determination section 40 shifts the process to step S200.

[0140] In step S200, the waveform determination unit 40 executes a waveform determination process to determine the waveform of the drive signal COM. For example, for each evaluation waveform WE, the waveform determination unit 40 compares the amplitude λN of the residual vibration detected in step S120 with the amplitude λM of the residual vibration detected in step S140, and determines the waveform of the drive signal COM based on the comparison result. By executing the process of step S200, the waveform of the drive signal COM is determined, and the operation shown in FIG. 8 ends.

[0141] Next, the waveform determination process executed in step S200 will be described with reference to FIG.

[0142] Fig. 9 is a flowchart showing an example of the waveform determination process shown in Fig. 8. A series of processes from step S210 to step S260 shown in Fig. 9 corresponds to the process of step S200 shown in Fig. 8. The control unit 4 functions as the waveform determination section 40 in each of steps S210 to S260 shown in Fig. 9. The process of step S210 is executed when the result of the determination in step S150 shown in Fig. 8 is positive.

[0143] The operation shown in Fig. 9 uses amplitudes λNi and λMi determined by a series of processes from step S100 to step S152 shown in Fig. 8, a positive threshold TH1, and a negative threshold TH2. The amplitude λNi indicates the amplitude λN of the residual vibration resulting from N driving operations using the i-th evaluation waveform WEi, and is determined by the process of step S120 shown in Fig. 8. The amplitude λMi indicates the amplitude λM of the residual vibration resulting from M driving operations using the i-th evaluation waveform WEi, and is determined by the process of step S140 shown in Fig. 8. The thresholds TH1 and TH2 are determined in advance based on data obtained, for example, by simulation, experiment, etc. The threshold TH1 is an example of a "first threshold," and the threshold TH2 is an example of a "second threshold."

[0144] First, in step S210, the waveform determination section 40 sets the variable i to 1. After executing the process of step S210, the waveform determination section 40 moves the process to step S220.

[0145] In step S220, the waveform determination unit 40 determines whether the amplitude difference DλNi obtained by subtracting the amplitude λMi from the amplitude λNi is less than the threshold value TH1. In this way, the amplitude difference DλNi is used as the evaluation value of the i-th evaluation waveform WEi.

[0146] If the result of the determination in step S220 is negative, the waveform determination unit 40 determines in step S242 that an overshoot will occur, and then proceeds to step S250. That is, if the amplitude difference DλNi is equal to or greater than the threshold value TH1, the waveform determination unit 40 determines that the i-th evaluation waveform WEi is an evaluation waveform WE that will cause an overshoot, which is one type of electrical crosstalk.

[0147] When an overshoot occurs as described above, the amplitude λNi when driving N becomes larger than the amplitude λMi when driving M, and the amplitude difference DλNi becomes a positive value. If this amplitude difference DλNi is positive and is large enough to exceed the positive threshold value TH1, it is determined that a significant overshoot has occurred and may become a problem.

[0148] On the other hand, if the result of the determination in step S220 is positive, the waveform determination section 40 moves the process to step S230.

[0149] In step S230, the waveform determination unit 40 determines whether the amplitude difference DλNi, obtained by subtracting the amplitude λMi from the amplitude λNi, is greater than a threshold value TH2. As described above, the threshold value TH2 is a negative value. Therefore, for example, if the amplitude difference DλNi is a negative value and the absolute value of the amplitude difference DλNi is less than the absolute value of the threshold value TH2, the waveform determination unit 40 determines that the amplitude difference DλNi is greater than the threshold value TH2.

[0150] If the result of the determination in step S230 is negative, the waveform determination unit 40 determines in step S244 that distortion will occur, and then proceeds to step S250. That is, if the amplitude difference DλNi is equal to or smaller than the threshold TH2, the waveform determination unit 40 determines that the i-th evaluation waveform WEi is an evaluation waveform WE that will cause distortion, which is one type of electrical crosstalk.

[0151] When dulling occurs as described above, the amplitude λNi when driving N is smaller than the amplitude λMi when driving M, and the amplitude difference DλNi becomes a negative value. If this amplitude difference DλNi is negative and is so small as to be below the negative threshold value TH2, it is determined that significant dulling has occurred and may become a problem.

[0152] On the other hand, if the result of the determination in step S230 is positive, the waveform determination section 40 moves the process to step S240.

[0153] In step S240, the waveform determination unit 40 determines that no electrical crosstalk occurs. In this manner, the waveform determination unit 40 evaluates whether or not electrical crosstalk occurs in the i-th evaluation waveform WEi based on the amplitude λNi of the residual vibration resulting from N-number driving by the i-th evaluation waveform WEi and the amplitude λMi of the residual vibration resulting from M-number driving by the i-th evaluation waveform WEi. The determinations in steps S220 and S230 are preferably based on whether or not the amplitudes λNi and λMi are relatively close to each other. Thus, the evaluation of electrical crosstalk is performed through a series of processes from step S220 to step S244. The operation shown in FIG. 9 distinguishes between overshoot and dullness in determining the occurrence of electrical crosstalk, facilitating analysis of electrical crosstalk.

[0154] Hereinafter, an evaluation waveform WE determined to be free of electric crosstalk in step S240 may be referred to as an evaluation waveform WE without electric crosstalk. The potential change rate DE of the waveform element Pw of the evaluation waveform WE without electric crosstalk is, for example, a candidate for the potential change rate of the waveform of the drive signal COM. Therefore, the series of processes in steps S220, S230, and S240 can also be interpreted as a process of determining whether or not a waveform that changes at the potential change rate DE of the waveform element Pw of the i-th evaluation waveform WEi is to be a candidate for the waveform of the drive signal COM. For example, if the amplitude difference DλNi is smaller than a positive threshold TH1 and larger than a negative threshold TH2, the waveform determination unit 40 determines that a waveform that changes at the potential change rate DE of the waveform element Pw of the i-th evaluation waveform WEi is to be a candidate for the waveform of the drive signal COM. After executing the process of step S240, the waveform determination unit 40 proceeds to step S250.

[0155] In step S250, the waveform determination unit 40 determines whether the variable i is at the final value. That is, the waveform determination unit 40 determines whether the evaluation of the electric crosstalk based on the residual vibration detected by the series of processes from step S100 to step S152 shown in FIG. 8 has ended.

[0156] If the result of the determination in step S250 is negative, the waveform determination section 40 adds "1" to the variable i in step S252, and then returns the process to step S220. On the other hand, if the result of the determination in step S250 is positive, the process proceeds to step S260.

[0157] In step S260, the waveform determination unit 40 determines the waveform of the drive signal COM based on the evaluation waveform WE without electrical crosstalk. Note that determining the waveform of the drive signal COM includes, for example, determining the rate of change in potential of the waveform element Pa3 of the drive signal COM.

[0158] For example, when there is one evaluation waveform WE without electric crosstalk, the waveform determination unit 40 sets the potential change rate of the waveform element Pa3 of the drive signal COM to the potential change rate DE of the waveform element Pw of the evaluation waveform WE without electric crosstalk.

[0159] Furthermore, for example, when there are multiple evaluation waveforms WE without electrical crosstalk, the waveform determination unit 40 determines one of the potential change rates DE of the waveform elements Pw of the multiple evaluation waveforms WE as the potential change rate of the waveform element Pa3 of the drive signal COM. Note that the existence of multiple evaluation waveforms WE without electrical crosstalk corresponds to the existence of multiple waveform candidates for the drive signal COM. An example of a method for determining the potential change rate of the waveform element Pa3 of the drive signal COM when there are multiple waveform candidates for the drive signal COM is described below.

[0160] In the following, the evaluation waveform WE corresponding to the amplitude difference DλN means the evaluation waveform WE using that amplitude difference DλN as an evaluation value, and the amplitude difference DλN corresponding to the evaluation waveform WE means the amplitude difference DλN used as the evaluation value of that evaluation waveform WE. Also, in the following, the amplitude difference DλN used when determining candidate waveforms for the drive signal COM means the amplitude difference DλN corresponding to the evaluation waveform WE without electrical crosstalk.

[0161] For example, when there are multiple waveform candidates for the drive signal COM, the waveform determination unit 40 may select, among the multiple candidates, the candidate with the smallest amplitude difference DλN, obtained by subtracting the reference residual vibration amplitude λM from the residual vibration amplitude λN, as the waveform of the drive signal COM. In this case, the potential change rate DE of the candidate with the smallest amplitude difference DλN among the multiple candidates is the potential change rate of the waveform element Pa3 of the drive signal COM. Specifically, the waveform determination unit 40 may select, as the potential change rate of the waveform element Pa3 of the drive signal COM, the potential change rate DE of the waveform element Pw of the evaluation waveform WE corresponding to the amplitude difference DλN with the smallest absolute value among the multiple amplitude differences DλN used to determine the multiple waveform candidates for the drive signal COM. For example, when the amplitude difference DλN with the smallest absolute value among the multiple amplitude differences DλN used to determine the multiple waveform candidates for the drive signal COM is the amplitude difference DλN of the evaluation waveform WE1, the waveform determination unit 40 may select the potential change rate DE1 as the potential change rate of the waveform element Pa3 of the drive signal COM. In this embodiment, it is expected that the vibrations of the diaphragm 14 generated when driving N nozzles and the vibrations of the diaphragm 14 generated when driving M nozzles will be similar to each other. Therefore, in this embodiment, it is possible to prevent the difference between the ink ejection characteristics when driving N nozzles and the ink ejection characteristics when driving M nozzles from becoming too large.

[0162] Furthermore, for example, when there are multiple waveform candidates for the drive signal COM, the waveform determination unit 40 may select the candidate with the largest potential change rate DE as the waveform of the drive signal COM. In this case, the potential change rate DE of the candidate with the largest potential change rate DE among the multiple candidates becomes the potential change rate of the waveform element Pa3 of the drive signal COM. Specifically, the waveform determination unit 40 may identify the candidate with the largest potential change rate DE among the multiple waveform candidates for the drive signal COM and use the potential change rate DE of the identified candidate as the potential change rate of the waveform element Pa3 of the drive signal COM. For example, when the candidate with the largest potential change rate DE among the multiple waveform candidates for the drive signal COM is a waveform that changes at a potential change rate DE1, the waveform determination unit 40 may use the potential change rate DE1 as the potential change rate of the waveform element Pa3 of the drive signal COM. In this embodiment, the potential change rate of the waveform element Pa3 of the drive signal COM can be increased within a range in which overshoot does not occur, thereby enabling large vibration to be generated on the diaphragm 14 within a range in which overshoot does not occur. Therefore, in this embodiment, large ink droplets within a desired range can be efficiently ejected.

[0163] Note that the method for determining the potential change rate of the waveform element Pa3 of the drive signal COM when there are multiple waveform candidates for the drive signal COM is not limited to the above example. For example, the waveform determination unit 40 may determine the potential change rate of the waveform element Pa3 of the drive signal COM by averaging multiple potential change rates corresponding to multiple waveform candidates for the drive signal COM. Alternatively, the waveform determination unit 40 may present candidate information indicating waveform candidates for the drive signal COM to the user and determine the potential change rate of the waveform element Pa3 of the drive signal COM based on the user's input to the candidate information. For example, the waveform determination unit 40 may present candidate information to the user indicating multiple waveform candidates, each having multiple potential change rates set as the potential change rate of the waveform element Pa3. The waveform determination unit 40 may then have the user select a waveform to be adopted as the waveform of the drive signal COM from the multiple waveform candidates indicated by the candidate information, and determine the waveform candidate selected by the user as the waveform of the drive signal COM.

[0164] In this manner, in this embodiment, the occurrence of electric crosstalk can be easily suppressed by determining the waveform of the drive signal COM based on the evaluation results of the electric crosstalk. That is, in this embodiment, it is possible to appropriately and easily determine the waveform of the drive signal COM that suppresses the occurrence of electric crosstalk under the usage conditions of the liquid ejection device 100. When the processing of step S260 ends, the operation shown in FIGS. 8 and 9 ends.

[0165] The operation of the liquid ejection device 100 when determining the waveform of the drive signal COM is not limited to the examples shown in FIGS. 8 and 9. For example, the series of processes in steps S130 and S140 in FIG. 8 may be executed before the series of processes in steps S110 and S120. Furthermore, for example, the process in step S230 in FIG. 9 may be executed before the process in step S220. Alternatively, the process in step S230 may be executed together with the process in step S220. For example, the waveform determination unit 40 may determine whether the amplitude difference DλNi obtained by subtracting the amplitude λMi from the amplitude λNi is less than a threshold value TH1 and greater than a threshold value TH2. In this case, if the determination result in step S220, including the determination in step S230, is negative, the waveform determination unit 40 may determine that electrical crosstalk is occurring without particularly distinguishing between overshoot and dullness.

[0166] Furthermore, for example, the evaluation value of each evaluation waveform WEi, i.e., the amplitude difference DλNi, may be a value obtained by subtracting a common reference value from the amplitude λNi across multiple evaluation waveforms WE. In this case, the common reference value may be stored in advance in a storage unit (not shown) of the liquid ejection head 1. Alternatively, the common reference value may be transmitted from the head manufacturer via a network (not shown) after shipping the liquid ejection head 1 and stored in the storage unit 5. The common reference value is an example of a “first reference value.” If the evaluation waveform WEi corresponds to the “first evaluation waveform,” the amplitude difference DλNi obtained by subtracting the common reference value from the amplitude λNi as the evaluation value of the evaluation waveform WEi is an example of a “first amplitude difference.” Here, determining whether the amplitude difference DλNi calculated using the common reference value is less than the threshold value TH1 and greater than the threshold value TH2 can also be interpreted as determining whether the amplitude λNi is within a predetermined range. The lower limit of the predetermined range is the value obtained by adding the common reference value to the threshold value TH2, and the upper limit of the predetermined range is the value obtained by adding the common reference value to the threshold value TH1. Furthermore, when a common reference value is used for multiple evaluation waveforms WE, the series of processes in steps S130 and S140 shown in Fig. 8 may be omitted. In this case, the operation of the liquid ejection device 100 when determining the waveform of the drive signal COM can be simplified.

[0167] Furthermore, for example, while FIG. 8 illustrates a case in which the value N is the same as the value K, the value N may be a natural number greater than or equal to 2 and less than the value K. However, the value N is preferably set so that the amplitude difference DλN, used as the evaluation value of the evaluation waveform WE with the maximum or minimum potential change rate DE among the multiple evaluation waveforms WE, is of a certain magnitude. Furthermore, the N piezoelectric elements PZ driven by the N-element driving method may be non-adjacent piezoelectric elements PZ. That is, the N nozzles NZ corresponding to the N piezoelectric elements PZ may not be adjacent to each other. For example, the N nozzles NZ may be arranged every other nozzle NZ or every third nozzle NZ. In this embodiment, residual vibrations detected to evaluate electrical crosstalk can be prevented from being affected by structural crosstalk caused by the structure of the liquid ejection head 1, such as the arrangement of the nozzles NZ. That is, in this embodiment, residual vibrations for evaluating electrical crosstalk can be accurately detected. As a result, electrical crosstalk can be accurately evaluated in this embodiment. Therefore, in this embodiment, the rate of change in potential of the waveform element Pa3 of the drive signal COM can be appropriately determined based on the evaluation result of the electric crosstalk.

[0168] 8, for example, it is assumed that the value M is "1", but the value M may be a natural number equal to or greater than 2 and less than the value N. However, it is preferable that the value M is set so that no overshoot occurs when the M piezoelectric elements PZ are driven by any of the plurality of evaluation waveforms WE.

[0169] Furthermore, for example, in cases such as when ejecting large ink droplets within a desired range without generating an overshoot, the waveform determination unit 40 may determine the amplitude difference DλN in descending order of the potential change rate DE among the multiple evaluation waveforms WE. Then, the waveform determination unit 40 may proceed to step S260 when it identifies an amplitude difference DλNi that is smaller than threshold value TH1 and larger than threshold value TH2. In this aspect, the potential change rate of the waveform element Pa3 of the drive signal COM can be efficiently determined.

[0170] As described above, in this embodiment, the liquid ejection device 100 comprises a liquid ejection head 1 including a plurality of nozzles NZ that eject ink, a plurality of piezoelectric elements PZ that are provided corresponding to the plurality of nozzles NZ and that are driven by a supply of a drive signal COM, a vibration plate 14 that vibrates by driving at least one of the plurality of piezoelectric elements PZ, and a detection circuit 19 that detects residual vibration of the vibration plate 14 after at least one of the plurality of piezoelectric elements PZ has been driven, and a waveform determination unit 40. The waveform determination unit 40 causes the detection circuit 19 to detect, as a first residual vibration, the residual vibration of the vibration plate 14 after driving N piezoelectric elements PZ corresponding to N nozzles NZ out of the multiple nozzles NZ with an evaluation waveform WE1, whose potential change rate, which is the amount of change in potential per unit time, is a potential change rate DE1, and causes the detection circuit 19 to detect, as a second residual vibration, the residual vibration of the vibration plate 14 after driving N piezoelectric elements PZ with an evaluation waveform WE2, whose potential change rate is a potential change rate DE2 smaller than the potential change rate DE1, and determines the waveform of the drive signal COM based on the first residual vibration and the second residual vibration.

[0171] As described above, in this embodiment, the waveform of the drive signal COM is determined based on the first residual vibration after driving N piezoelectric elements PZ with the evaluation waveform WE1 having the potential change rate DE1 and the second residual vibration after driving N piezoelectric elements PZ with the evaluation waveform WE2 having the potential change rate DE2. Here, the potential change rate of the waveform of the drive signal COM affects the occurrence of electric crosstalk. Furthermore, the occurrence of electric crosstalk affects the residual vibration after driving N piezoelectric elements PZ. Therefore, in this embodiment, the potential change rate of the waveform of the drive signal COM can be determined to be a potential change rate that suppresses the occurrence of electric crosstalk based on the first residual vibration and the second residual vibration. In other words, in this embodiment, the waveform of the drive signal COM that suppresses the occurrence of electric crosstalk under the operating conditions of the liquid ejection device 100 can be appropriately and easily determined.

[0172] Furthermore, in this embodiment, the waveform determination unit 40 may cause the detection circuit 19 to detect the residual vibration of the diaphragm 14 after driving the N piezoelectric elements PZ with the evaluation waveform WE3, which has a potential change rate DE3 that is smaller than the potential change rate DE2, as the third residual vibration, and determine the waveform of the drive signal COM based on the first residual vibration, the second residual vibration, and the third residual vibration. In this aspect, since the occurrence of electric crosstalk is evaluated with various potential change rates DE, it is possible to easily determine the potential change rate of the waveform of the drive signal COM to be a potential change rate that suppresses the occurrence of electric crosstalk.

[0173] In addition, in this embodiment, the waveform determination unit 40 may cause the detection circuit 19 to detect the reference residual vibration of the diaphragm 14 after driving only M (M is a natural number less than N) of the N piezoelectric elements PZ with the evaluation waveform WE1 as the first reference residual vibration, and determine the waveform of the drive signal COM based on the first residual vibration, the second residual vibration, and the first reference residual vibration. In this embodiment, the first reference residual vibration after driving M piezoelectric elements PZ (where M is less than N) is also used to determine the waveform of the drive signal COM. Therefore, in this embodiment, the occurrence of electrical crosstalk can be accurately evaluated. As a result, in this embodiment, the potential change rate of the waveform of the drive signal COM can be accurately determined to be a potential change rate that suppresses the occurrence of electrical crosstalk.

[0174] Furthermore, in this embodiment, the N nozzles NZ do not have to be adjacent to one another. This makes it possible to prevent the residual vibration detected for evaluating electrical crosstalk from being affected by structural crosstalk that occurs due to the structure of the liquid ejection head 1, such as the arrangement of the nozzles NZ. That is, in this embodiment, the residual vibration for evaluating electrical crosstalk can be accurately detected. As a result, in this embodiment, electrical crosstalk can be accurately evaluated. As a result, in this embodiment, the potential change rate of the waveform of the drive signal COM can be accurately determined to be a potential change rate that suppresses the occurrence of electrical crosstalk.

[0175] Furthermore, in this embodiment, the waveform determination unit 40 may select a waveform that changes at a potential change rate DE1 as a candidate waveform for the drive signal COM when the amplitude difference DλN1, obtained by subtracting the amplitude λM1 of the first reference residual vibration from the amplitude λN1 of the first residual vibration, is smaller than a positive threshold TH1 and larger than a negative threshold TH2. Thus, in this embodiment, the waveform determination unit 40 selects a waveform that changes at a potential change rate DE of the evaluation waveform WE, which has a small amplitude difference DλN corresponding to the amount of change in the amplitude of the residual vibration when the number of driven piezoelectric elements PZ changes, as a candidate waveform for the drive signal COM. This allows a waveform that changes at a potential change rate DE that suppresses the occurrence of electrical crosstalk to be appropriately selected as a candidate waveform for the drive signal COM. As a result, in this embodiment, the potential change rate of the waveform of the drive signal COM can be appropriately determined to be a potential change rate that suppresses the occurrence of electrical crosstalk.

[0176] Furthermore, in this embodiment, the waveform determination unit 40 may not select a waveform that changes at a potential change rate DE1 as a candidate waveform for the drive signal COM when the amplitude difference DλN1 is greater than the threshold TH1 or less than the threshold TH2. Thus, in this aspect, the waveform determination unit 40 does not select a waveform that changes at a potential change rate DE of the evaluation waveform WE, which has a large amplitude difference DλN corresponding to the amount of change in the amplitude of the residual vibration when the number of driven piezoelectric elements PZ changes, as a candidate waveform for the drive signal COM. This prevents a waveform that changes at a potential change rate DE that generates electrical crosstalk from being selected as a candidate waveform for the drive signal COM. As a result, this aspect prevents the potential change rate of the waveform of the drive signal COM from being determined to be a potential change rate DE that generates electrical crosstalk.

[0177] Furthermore, in this embodiment, the waveform determination unit 40 may select a waveform that changes at a potential change rate DE1 as a candidate waveform for the drive signal COM when the amplitude difference DλN1, obtained by subtracting a pre-stored common reference value from the amplitude λN1 of the first residual vibration, is smaller than a positive threshold TH1 and larger than a negative threshold TH2. Thus, in this embodiment, the waveform determination unit 40 selects a waveform that changes at a potential change rate DE of the evaluation waveform WE, which has a small amplitude difference DλN corresponding to the difference between the amplitude of the residual vibration and the reference value when the number of driven piezoelectric elements PZ is large, as a candidate waveform for the drive signal COM. This allows a waveform that changes at a potential change rate DE that suppresses the occurrence of electrical crosstalk to be selected as a candidate waveform for the drive signal COM without detecting the residual vibration when the number of driven piezoelectric elements PZ is small. As a result, in this embodiment, the potential change rate of the waveform of the drive signal COM can be easily determined to be a potential change rate that suppresses the occurrence of electrical crosstalk.

[0178] Furthermore, in this embodiment, when there are multiple candidates for the waveform of the drive signal COM, the waveform determination unit 40 may select, as the waveform of the drive signal COM, the candidate with the smallest amplitude difference DλN, obtained by subtracting the reference residual vibration amplitude λM from the residual vibration amplitude λN. Thus, in this aspect, the waveform determination unit 40 selects, from among multiple potential change rates DE that suppress the occurrence of electrical crosstalk, the potential change rate DE that minimizes the amplitude difference DλN, corresponding to the amount of change in the residual vibration amplitude when the number of driven piezoelectric elements PZ changes, as the potential change rate of the waveform of the drive signal COM. Therefore, in this aspect, it is possible to suppress variations in ink ejection characteristics due to the number of driven piezoelectric elements PZ.

[0179] Furthermore, in this embodiment, when there are multiple candidates for the waveform of the drive signal COM, the waveform determination unit 40 may select the candidate with the largest potential change rate DE as the waveform of the drive signal COM. Thus, in this aspect, the waveform determination unit 40 selects the largest potential change rate DE of multiple potential change rates DE that suppress the occurrence of electrical crosstalk as the potential change rate of the waveform of the drive signal COM. Therefore, in this aspect, large vibrations can be generated in the diaphragm 14 within a range that does not cause electrical crosstalk. As a result, in this aspect, large ink droplets within a desired range can be efficiently ejected.

[0180] Furthermore, in this embodiment, the waveform determination unit 40 may present candidate information indicating candidate waveforms for the drive signal COM to the user, and determine the potential change rate of the waveform of the drive signal COM based on the user's input for the candidate information. Thus, in this aspect, the waveform determination unit 40 determines the potential change rate of the waveform of the drive signal COM based on the user's input for multiple potential change rates DE that suppress the occurrence of electric crosstalk. As a result, for example, in this aspect, the waveform determination unit 40 may set the potential change rate DE selected by the user from multiple potential change rates DE that suppress the occurrence of electric crosstalk as the potential change rate of the waveform of the drive signal COM. Thus, in this aspect, the user can select the potential change rate of the waveform of the drive signal COM from multiple potential change rates DE that suppress the occurrence of electric crosstalk.

[0181] Furthermore, in this embodiment, the evaluation waveform WE1 may include a waveform element Pw whose potential changes at a rate of potential change DE1, and the evaluation waveform WE2 may include a waveform element Pw whose potential changes at a rate of potential change DE2. The potential difference from the start point to the end point of the waveform element Pw of the evaluation waveform WE1 may be the same as the potential difference from the start point to the end point of the waveform element Pw of the evaluation waveform WE2, and the time from the start point to the end point of the waveform element Pw of the evaluation waveform WE1 may be shorter than the time from the start point to the end point of the waveform element Pw of the evaluation waveform WE2. Thus, in this embodiment, the rate of potential change DE of the waveform element Pw can be adjusted by adjusting the time from the start point to the end point of the waveform element Pw.

[0182] Furthermore, in this embodiment, the evaluation waveform WE1 may include a waveform element Pw whose potential changes at a rate of potential change DE1, and the evaluation waveform WE2 may include a waveform element Pw whose potential changes at a rate of potential change DE2. The potential difference from the start point to the end point of the waveform element Pw of the evaluation waveform WE1 may be larger than the potential difference from the start point to the end point of the waveform element Pw of the evaluation waveform WE2, and the time from the start point to the end point of the waveform element Pw of the evaluation waveform WE1 may be the same as the time from the start point to the end point of the waveform element Pw of the evaluation waveform WE2. Thus, in this embodiment, the rate of potential change DE of the waveform element Pw can be adjusted by adjusting the potential difference from the start point to the end point of the waveform element Pw.

[0183] Furthermore, in this embodiment, each of the evaluation waveforms WE1 and WE2 may include a first expansion element, which is a waveform element that expands a pressure chamber communicating with each of the multiple nozzles NZ, and a contraction element, which is a waveform element subsequent to the first expansion element and that contracts the pressure chamber. The potential change rates DE1 and DE2 may be the potential change rates of the contraction elements. Thus, in this aspect, a pull-push waveform is used as the evaluation waveform WE, and the potential change rate DE of the waveform element Pw corresponding to the push of the pull-push waveform is adjusted. Therefore, in this aspect, the occurrence of electrical crosstalk can be accurately evaluated, particularly when a pull-push waveform is used as the waveform of the drive signal COM.

[0184] Furthermore, in this embodiment, each of the evaluation waveforms WE1 and WE2 may include a first expansion element, which is a waveform element that expands a pressure chamber connected to each of the multiple nozzles NZ; a contraction element that is a waveform element subsequent to the first expansion element and that contracts the pressure chamber; and a second expansion element that is a waveform element subsequent to the contraction element and that expands the pressure chamber. The potential change rates DE1 and DE2 may be the potential change rates of the contraction elements. Thus, in this embodiment, a pull-push-pull waveform is used as the evaluation waveform WE, and the potential change rate DE of the waveform element Pw corresponding to the push of the pull-push-pull waveform is adjusted. Therefore, in this embodiment, the occurrence of electrical crosstalk can be accurately evaluated, particularly when a pull-push-pull waveform is used as the waveform of the drive signal COM.

[0185] [First Modification] In the above-described embodiment, the case where the waveform of the drive signal COM is determined based on the amplitude λN of the residual vibration detected in the case of driving N piezoelectric elements and the amplitude λM of the residual vibration detected in the case of driving M piezoelectric elements was illustrated. However, the present invention is not limited to such an aspect. For example, the waveform determination unit 40 may cause the detection circuit 19 to detect the residual vibration of the diaphragm 14 after driving only L (L is a natural number greater than M and less than N) piezoelectric elements out of the N piezoelectric elements PZ with the evaluation waveform WE1 as the fourth residual vibration. Then, the waveform determination unit 40 may determine the waveform of the drive signal COM based on the first residual vibration, the second residual vibration, the fourth residual vibration, and the first reference residual vibration. In this modified example, the value K is a natural number of 3 or more. Also, in this modified example, the value N is a natural number that satisfies "3 ≦ N ≦ K", and the values M and L are natural numbers that satisfy "1 ≦ M < L < N". For example, the L piezoelectric elements PZ may be L piezoelectric elements PZ arranged every other one, or L piezoelectric elements PZ arranged every two. Also, the N piezoelectric elements PZ may be all the piezoelectric elements PZ among the K piezoelectric elements PZ. Also, the M piezoelectric elements PZ may be one piezoelectric element PZ. Note that the examples of the N piezoelectric elements PZ, the M piezoelectric elements PZ, and the L piezoelectric elements PZ are not limited to the above examples. For example, the N piezoelectric elements PZ may be N piezoelectric elements PZ arranged every other one, and the L piezoelectric elements PZ may be L piezoelectric elements PZ arranged every two.

[0186] Next, the operation of the liquid ejection device 100 according to the first modified example will be described while referring to FIG. 10. Hereinafter, driving only L piezoelectric elements out of the K piezoelectric elements PZ may be referred to as L-driving. Also, hereinafter, the amplitude of the residual vibration detected in the case of L-driving is referred to as the amplitude λL.

[0187] Fig. 10 is a flowchart showing an example of the operation of the liquid ejection device 100 according to the first modified example. The operation shown in Fig. 10 is the operation of the liquid ejection device 100 when determining the waveform of the drive signal COM. Note that the operation shown in Fig. 10 is the same as the operation shown in Fig. 9, except that a series of processes in steps S124 and S126 are executed, and that the process in step S200A is executed instead of the process in step S200 shown in Fig. 9. Fig. 10 will mainly explain the series of processes in steps S124 and S126. For example, the series of processes in steps S124 and S126 are executed after the series of processes in steps S110 and S120 have been executed.

[0188] In step S124, the waveform determination unit 40 controls the liquid ejection head 1 so that L drives are performed with the i-th evaluation waveform WEi. For example, the waveform determination unit 40 selects the signal of the i-th evaluation waveform WEi as the drive signal COM, and controls the liquid ejection head 1 so that only L piezoelectric elements PZ out of the K piezoelectric elements PZ are driven using the selected drive signal COM.

[0189] Next, in step S126, the waveform determination unit 40 detects residual vibrations in the piezoelectric element PZ to be detected. The process of step S126 is similar to the process of step S120. For example, the waveform determination unit 40 causes the detection circuit 19 to detect residual vibrations in the piezoelectric element PZ to be detected. As a result, the detection circuit 19 detects the residual vibrations of the diaphragm 14 after only L piezoelectric elements PZ are driven with the i-th evaluation waveform WEi. The residual vibrations detected by the detection circuit 19 are then analyzed by the analysis unit 3. The waveform determination unit 40 acquires residual vibration information Vinf from the analysis unit 3, which indicates the analysis results of the residual vibrations detected by the detection circuit 19. For example, the analysis results indicated by the residual vibration information Vinf include the amplitude λL of the residual vibrations detected when only L piezoelectric elements PZ are driven with the i-th evaluation waveform WEi. Note that if the i-th evaluation waveform WEi corresponds to the "first evaluation waveform," the residual vibrations detected in step S126 are an example of the "fourth residual vibration." Furthermore, when the i-th evaluation waveform WEi corresponds to the "second evaluation waveform," the residual vibration detected in step S126 is an example of the "fifth residual vibration."

[0190] After the series of processes in steps S124 and S126 are executed, the series of processes in steps S130 and S140 are executed. However, the order in which the series of processes in steps S110 and S120, the series of processes in steps S124 and S126, and the series of processes in steps S130 and S140 are executed is not limited to the example shown in Fig. 10. For example, the series of processes in steps S124 and S126 may be executed before the series of processes in steps S110 and S120, or may be executed after the series of processes in steps S130 and S140.

[0191] The process of step S200A is executed when the result of the determination in step S150 is positive.

[0192] Next, the waveform determination process executed in step S200A will be described with reference to FIG.

[0193] Fig. 11 is a flowchart showing an example of the waveform determination process shown in Fig. 10. A series of processes from step S210 to step S260 shown in Fig. 11 corresponds to the process of step S200A shown in Fig. 10. The control unit 4 functions as the waveform determination section 40 in each of steps S210 to S260 shown in Fig. 11. The process of step S210 is executed when the result of the determination in step S150 shown in Fig. 10 is positive.

[0194] The operation shown in Fig. 11 is the same as the operation shown in Fig. 9, except that the processing of step S222 and the processing of step S232 are executed. The processing of step S222 and the processing of step S232 will be mainly described in Fig. 11. For example, the processing of step S222 is executed when the result of the determination in step S220 is positive.

[0195] In step S222, the waveform determination unit 40 determines whether the amplitude difference DλLi, obtained by subtracting the amplitude λMi from the amplitude λLi, is less than the threshold value TH1. In this manner, the amplitude difference DλLi is used as the evaluation value of the i-th evaluation waveform WEi. That is, in this modification, the amplitude differences DλNi and DλLi are used as the evaluation value of the i-th evaluation waveform WEi.

[0196] If the result of the determination in step S222 is negative, the waveform determination unit 40 determines in step S242 that an overshoot will occur, and then proceeds to step S250. That is, if the amplitude difference DλLi is equal to or greater than the threshold TH1, the waveform determination unit 40 determines that the i-th evaluation waveform WEi is an evaluation waveform WE that will cause an overshoot.

[0197] On the other hand, if the result of the determination in step S222 is positive, the waveform determination section 40 moves the process to step S230.

[0198] Also, for example, the process of step S232 is executed when the result of the determination in step S230 is positive.

[0199] In step S232, the waveform determination section 40 determines whether the amplitude difference DλLi obtained by subtracting the amplitude λMi from the amplitude λLi is greater than a threshold value TH2.

[0200] If the result of the determination in step S232 is negative, the waveform determination unit 40 determines in step S244 that dullness will occur, and then proceeds to step S250. That is, if the amplitude difference DλLi is equal to or smaller than the threshold TH2, the waveform determination unit 40 determines that the i-th evaluation waveform WEi is an evaluation waveform WE that will cause dullness.

[0201] On the other hand, if the result of the determination in step S232 is positive, the waveform determination section 40 moves the process to step S240.

[0202] As described above, in this modification, the waveform determination unit 40 evaluates whether or not electric crosstalk occurs in the i-th evaluation waveform WEi using the amplitudes λNi, λMi, and λLi. Note that the determinations in steps S222 and S232 are preferably a determination of "whether or not the amplitudes λLi and λMi are relatively close in value."

[0203] In this manner, in this modification as well, the occurrence of electric crosstalk can be easily suppressed by determining the waveform of the drive signal COM based on the results of the electric crosstalk evaluation. Furthermore, in this modification, the amplitude λLi of the residual vibration detected in the L-unit drive is also used in the evaluation of whether or not electric crosstalk occurs in the i-th evaluation waveform WEi, in addition to the amplitude λNi of the residual vibration detected in the N-unit drive. Therefore, in this modification, even if the condition for increased electric crosstalk is not N-unit drive, for example, even if electric crosstalk increases in the L-unit drive, it is possible to appropriately determine whether or not electric crosstalk occurs.

[0204] Note that the operation of the liquid ejection device 100 when determining the waveform of the drive signal COM is not limited to the examples shown in FIGS. 10 and 11. For example, the order in which the processes of steps S220, S222, S230, and S232 in FIG. 11 are performed may be different from the order shown in FIG. 11. Furthermore, the process of step S232 may be performed together with the process of step S222. For example, the waveform determination unit 40 may determine whether the amplitude difference DλLi obtained by subtracting the amplitude λMi from the amplitude λLi is less than a threshold value TH1 and greater than a threshold value TH2. In this case, if the determination result of step S222, including the determination of step S232, is negative, the waveform determination unit 40 may determine that electrical crosstalk is occurring without particularly distinguishing between overshoot and dullness.

[0205] Furthermore, for example, the evaluation value of each evaluation waveform WEi may be an amplitude difference DλNi obtained by subtracting a reference value common to multiple evaluation waveforms WE from the amplitude λNi, and an amplitude difference DλLi obtained by subtracting a reference value common to multiple evaluation waveforms WE from the amplitude λLi.

[0206] Furthermore, for example, in cases such as when ejecting large ink droplets within a desired range without generating an overshoot, the waveform determination unit 40 may execute a series of processes from step S220 to step S250 in descending order of the potential change rate DE among multiple evaluation waveforms WE. Then, once the waveform determination unit 40 has identified an evaluation waveform WEi without electrical crosstalk, it may proceed to step S260. In this mode, the potential change rate of the waveform element Pa3 of the drive signal COM can be efficiently determined.

[0207] As described above, this modification can also achieve the same effects as the above-described embodiment. Furthermore, in this modification, in addition to the residual vibration detected when N units are driven, the residual vibration detected when L units are driven is also used to evaluate whether or not electrical crosstalk occurs. Therefore, in this modification, it is possible to appropriately determine whether or not electrical crosstalk occurs.

[0208] [Second Modification] In the above-described embodiment and modified examples, waveform information indicating the evaluation waveform WE may be stored in advance in a storage unit (not shown) of the liquid ejection head 1 at the time the head manufacturer manufactures the liquid ejection head 1. Alternatively, waveform information indicating the evaluation waveform WE may be stored in a storage unit 5 or the like from the head manufacturer via a network (not shown) after shipping of the liquid ejection head 1. For example, waveform information indicating the evaluation waveform WE prepared by the head manufacturer is read from the storage unit 5 or the like in which waveform information indicating the evaluation waveform WE is stored when the operation shown in FIG. 8 is performed.

[0209] As described above, in this modified example, the same effects as those of the above-described embodiment can be obtained.

[0210] [Third Modification] In the above-described embodiment and modified example, the analysis of the residual vibration detected by the detection circuit 19 is performed by the control unit 4. However, the present invention is not limited to this configuration. For example, the analysis of the residual vibration detected by the detection circuit 19 may be performed by a control unit such as a CPU of an external server managed by the head manufacturer. In this modified example, the liquid ejection device 100 has a communication unit capable of communicating with the external server managed by the head manufacturer. Then, for example, the control unit 4 transmits residual vibration data indicating the residual vibration detected by the detection circuit 19 to the external server managed by the head manufacturer via the communication unit. The control unit of the external server analyzes the residual vibration data transmitted from the liquid ejection device 100. Specifically, for example, the control unit of the external server identifies the amplitude of the residual vibration indicated by the residual vibration data and performs the operation shown in FIG. 9 or the operation shown in FIG. 11 using the identified amplitude. Then, the control unit of the external server may transmit information indicating the waveform of the drive signal COM that suppresses crosstalk to the liquid ejection device 100.

[0211] As described above, in this modified example, the same effects as those of the above-described embodiment can be obtained.

[0212] [Fourth Modification] In the above-described embodiment, the case where candidate information indicating candidate waveforms of the drive signal COM is presented to the user as information indicating the potential change rate DE of the waveform element Pw of the evaluation waveform WE without electrical crosstalk is illustrated, but the present invention is not limited to this configuration. For example, the waveform determination unit 40 may present to the user information indicating the potential change rate DE of the waveform elements Pw of all evaluation waveforms WE used in the evaluation of electrical crosstalk in a manner that allows the user to determine whether each potential change rate DE is the potential change rate of a candidate waveform of the drive signal COM. As described above, this modification can also achieve the same effects as the above-described embodiment.

[0213] [Fifth Modification] In the above-described embodiment and modified example, the piezoelectric element Zb is displaced in the Z1 direction as the potential of the individual drive signal Vin[k] changes from a low potential to a high potential. However, the present invention is not limited to such an embodiment. For example, a piezoelectric element Zb may be used that is displaced in the Z1 direction as the potential of the individual drive signal Vin[k] changes from a high potential to a low potential. In this case, for example, the potential of the drive signal COM changes from a low potential to a high potential in a portion corresponding to an expansion element, and changes from a high potential to a low potential in a portion corresponding to a contraction element. That is, in this modified example, the potential corresponding to the expansion potential is higher than the potential V0, and the potential corresponding to the contraction potential is lower than the potential V0. This modified example also achieves the same effects as the above-described embodiment and modified example.

[0214] [Sixth Modification] In the above-described embodiment and modified example, one piezoelectric element PZ, one pressure chamber CV, and one nozzle NZ are provided for one discharge portion D, but the present invention is not limited to this configuration. For example, one discharge portion D may have two piezoelectric elements PZ, two pressure chambers CV, and one nozzle NZ. As described above, this modified example can also achieve the same effects as the above-described embodiment and modified example.

[0215] [Seventh Modification] In the above-described embodiment and modified example, a serial-type liquid ejection device 100 in which a carriage 91 carrying a liquid ejection head 1 is reciprocated in the X-axis direction is illustrated, but the present invention is not limited to such an embodiment. For example, the liquid ejection device 100 may be a line-type liquid ejection device in which multiple nozzles NZ are distributed across the entire width of the medium PP. As described above, this modified example can also achieve the same effects as the above-described embodiment and modified example.

[0216] [Eighth Modification] The liquid ejection device 100 exemplified in the above-described embodiment and modified example can be employed in various devices such as facsimile machines and copiers, as well as devices dedicated to printing. However, the use of the liquid ejection device of the present invention is not limited to printing. For example, a liquid ejection device that ejects a solution of a color material is used as a manufacturing device for forming color filters for liquid crystal display devices. Furthermore, a liquid ejection device that ejects a solution of a conductive material is used as a manufacturing device for forming wiring and electrodes for wiring boards. As described above, this modified example can also achieve the same effects as the above-described embodiment and modified example.

[0217] [Ninth Variation] In the above-described embodiment and modified examples, the evaluation of electric crosstalk may be performed while changing the value of any one of the resistance component, capacitance component, and inductance component of the signal wiring, etc., from the drive signal generating unit 2 to each discharge section D. For example, the evaluation of electric crosstalk may be performed while changing conditions such as the length of the FFC used as part of the signal path from the drive signal generating unit 2 to each discharge section D, the thickness of the conductor, etc. As described above, the present modified example can also achieve the same effects as the above-described embodiment and modified examples. Furthermore, in the present modified example, for example, the head manufacturer can propose to the user the conditions of the FFC, etc., that are suitable for suppressing the occurrence of electric crosstalk.

[0218] [3. Notes] From the above-described exemplary embodiments, the following configurations can be understood, for example.

[0219] A liquid ejection device according to a preferred aspect, aspect 1, comprises a liquid ejection head including a plurality of nozzles for ejecting liquid, a plurality of piezoelectric elements corresponding to the plurality of nozzles and driven by supplying a drive signal, a vibration plate that vibrates by driving at least one of the plurality of piezoelectric elements, and a detection unit that detects the residual vibration of the vibration plate after at least one of the plurality of piezoelectric elements is driven, and a control unit, wherein the control unit causes the detection unit to detect, as a first residual vibration, the residual vibration of the vibration plate after driving N piezoelectric elements corresponding to N nozzles among the plurality of nozzles with a first evaluation waveform in which a potential change rate, which is the amount of change in potential per unit time, is a first potential change rate, and causes the detection unit to detect, as a second residual vibration, the residual vibration of the vibration plate after driving the N piezoelectric elements with a second evaluation waveform in which the potential change rate is a second potential change rate that is smaller than the first potential change rate, and determines the waveform of the drive signal based on the first residual vibration and the second residual vibration. According to the first aspect, it is possible to appropriately and easily determine the waveform of the drive signal that suppresses the occurrence of electrical crosstalk under the conditions under which the liquid ejection device is used.

[0220] In the liquid ejection device according to aspect 2, which is a specific example of aspect 1, the control unit causes the detection unit to detect the residual vibration of the vibration plate after driving the N piezoelectric elements with a third evaluation waveform, which has a third potential change rate that is smaller than the second potential change rate, as a third residual vibration, and determines the waveform of the drive signal based on the first residual vibration, the second residual vibration, and the third residual vibration. In the second embodiment, the same effects as in the first embodiment can be obtained.

[0221] In the liquid ejection device according to aspect 3, which is a specific example of aspect 1 or aspect 2, the control unit causes the detection unit to detect the reference residual vibration of the vibration plate after driving only M (M is a natural number less than N) piezoelectric elements out of the N piezoelectric elements with the first evaluation waveform as a first reference residual vibration, and determines the waveform of the drive signal based on the first residual vibration, the second residual vibration, and the first reference residual vibration. According to the third aspect, the first reference residual vibration after driving M piezoelectric elements, which is less than N, is also used to determine the waveform of the drive signal. Therefore, in this aspect, the waveform of the drive signal can be determined more appropriately than in an aspect in which the first reference residual vibration is not used.

[0222] In the liquid ejection device according to aspect 4, which is a specific example of aspect 3, the control unit causes the detection unit to detect the residual vibration of the vibration plate after driving only L (L is a natural number greater than M and less than N) piezoelectric elements out of the N piezoelectric elements with the first evaluation waveform as a fourth residual vibration, and determines the waveform of the drive signal based on the first residual vibration, the second residual vibration, the fourth residual vibration, and the first reference residual vibration. According to the fourth aspect, in addition to the first residual vibration after driving N piezoelectric elements, the fourth residual vibration after driving L piezoelectric elements is used to determine the waveform of the drive signal. Therefore, in this aspect, the waveform of the drive signal can be determined more appropriately than in an aspect in which the fourth residual vibration is not used.

[0223] In the liquid ejection device according to Aspect 5, which is a specific example of any one of Aspects 1 to 4, the N nozzles are not adjacent to one another. According to the fifth aspect, when detecting residual vibration, it is possible to suppress the influence of structural crosstalk that occurs due to the structure of the liquid ejection head, such as the nozzle arrangement, etc. As a result, in this aspect, it is possible to detect residual vibration with high accuracy.

[0224] In a liquid ejection device according to aspect 6, which is a specific example of aspect 3 or aspect 4, the control unit selects a waveform that changes at the first potential change rate as a candidate waveform for the drive signal when a first amplitude difference obtained by subtracting the amplitude of the first reference residual vibration from the amplitude of the first residual vibration is smaller than a first threshold value, which is a positive value, and larger than a second threshold value, which is a negative value. According to the sixth aspect, a waveform that changes at a potential change rate with a small amplitude difference corresponding to the amount of change in the amplitude of residual vibration when the number of driven piezoelectric elements changes can be selected as a candidate waveform for the drive signal. As a result, in this aspect, a waveform that changes at a potential change rate that suppresses the occurrence of electrical crosstalk can be appropriately selected as a candidate waveform for the drive signal. As a result, in this aspect, the potential change rate of the waveform of the drive signal can be appropriately determined to be a potential change rate that suppresses the occurrence of electrical crosstalk.

[0225] In a liquid ejection device according to aspect 7, which is a specific example of aspect 6, the control unit does not consider a waveform that changes at the first potential change rate as a candidate waveform for the drive signal when the first amplitude difference is greater than the first threshold value or smaller than the second threshold value. In the seventh embodiment, the same effect as in the sixth embodiment can be obtained.

[0226] In the liquid ejection device according to aspect 8, which is a specific example of aspect 1 or aspect 2, the control unit determines a waveform that changes at the first potential change rate as a candidate waveform for the drive signal when the amplitude difference obtained by subtracting a pre-stored first reference value from the amplitude of the first residual vibration is smaller than a first threshold value, which is a positive value, and larger than a second threshold value, which is a negative value. In the eighth aspect, the same effect as in the first aspect can be obtained.

[0227] In a liquid ejection device according to aspect 9, which is a specific example of any one of aspects 6 to 8, when there are multiple candidates for the waveform of the drive signal, the control unit selects the candidate with the smallest amplitude difference, obtained by subtracting the amplitude of the reference residual vibration from the amplitude of the residual vibration, as the waveform of the drive signal. According to the ninth aspect, among the multiple potential change rates that suppress the occurrence of electrical crosstalk, the potential change rate of the waveform of the drive signal can be selected to be the potential change rate that has the smallest amplitude difference corresponding to the amount of change in the amplitude of the residual vibration when the number of driven piezoelectric elements changes. Therefore, in this aspect, it is possible to suppress variations in the ink ejection characteristics due to the number of driven piezoelectric elements.

[0228] In a liquid ejection device according to aspect 10, which is a specific example of any one of aspects 6 to 8, when there are multiple candidates for the waveform of the drive signal, the control unit selects the candidate with the largest rate of potential change as the waveform of the drive signal. According to the tenth aspect, the maximum potential change rate among the multiple potential change rates that suppress the occurrence of electrical crosstalk can be set to the potential change rate of the waveform of the drive signal, thereby enabling large ink droplets within a desired range to be efficiently ejected.

[0229] In a liquid ejection device according to aspect 11, which is a specific example of any one of aspects 6 to 8, the control unit presents candidate information indicating candidate waveforms of the drive signal to a user, and determines the waveform of the drive signal based on input by the user regarding the candidate information. According to the eleventh aspect, the user can select the potential change rate of the waveform of the drive signal from a plurality of potential change rates that suppress the occurrence of electrical crosstalk.

[0230] In a liquid ejection device according to aspect 12, which is a specific example of any one of aspects 1 to 11, the first evaluation waveform includes a first waveform element whose potential changes at the first potential change rate, the second evaluation waveform includes a second waveform element whose potential changes at the second potential change rate, the potential difference from the start point to the end point of the first waveform element is the same as the potential difference from the start point to the end point of the second waveform element, and the time from the start point to the end point of the first waveform element is shorter than the time from the start point to the end point of the second waveform element. According to the twelfth aspect, the rate of change in potential of a waveform element can be adjusted by adjusting the time from the start point to the end point of the waveform element.

[0231] In a liquid ejection device according to aspect 13, which is a specific example of any one of aspects 1 to 11, the first evaluation waveform includes a first waveform element whose potential changes at the first potential change rate, the second evaluation waveform includes a second waveform element whose potential changes at the second potential change rate, the potential difference from the start point to the end point of the first waveform element is greater than the potential difference from the start point to the end point of the second waveform element, and the time from the start point to the end point of the first waveform element is the same as the time from the start point to the end point of the second waveform element. According to the thirteenth aspect, the rate of change in potential of a waveform element can be adjusted by adjusting the potential difference from the start point to the end point of the waveform element.

[0232] In a liquid ejection device according to aspect 14, which is a specific example of any one of aspects 1 to 13, each of the first evaluation waveform and the second evaluation waveform includes a first expansion element, which is a waveform element that expands a pressure chamber connected to each of the plurality of nozzles, and a contraction element, which is a waveform element subsequent to the first expansion element, that contracts the pressure chamber, and the first potential change rate and the second potential change rate are the potential change rates of the contraction element. According to the fourteenth aspect, when a pull-push waveform is used as the waveform of the drive signal, the rate of change in potential of the waveform of the drive signal that suppresses the occurrence of electrical crosstalk can be determined with high accuracy.

[0233] In a liquid ejection device according to aspect 15, which is a specific example of aspect 14, each of the first evaluation waveform and the second evaluation waveform further includes a second expansion element that is a waveform element subsequent to the contraction element and expands the pressure chamber. According to the fifteenth aspect, when a pull-push-pull waveform is used as the waveform of the drive signal, the rate of change in potential of the waveform of the drive signal that suppresses the occurrence of electrical crosstalk can be determined with high accuracy.

[0234] In the liquid ejection device according to aspect 16, which is a specific example of aspect 1 or aspect 2, the control unit causes the detection unit to detect the reference residual vibration of the vibration plate after driving only M (M is a natural number less than N) piezoelectric elements out of the N piezoelectric elements with the first evaluation waveform as the first reference residual vibration, causes the detection unit to detect the reference residual vibration of the vibration plate after driving only the M piezoelectric elements with the second evaluation waveform as the second reference residual vibration, and determines the waveform of the drive signal based on the first residual vibration, the second residual vibration, the first reference residual vibration, and the second reference residual vibration. In the sixteenth aspect, the same effect as in the third aspect can be obtained.

[0235] In the liquid ejection device of aspect 17, which is a specific example of aspect 16, the control unit causes the detection unit to detect the residual vibration of the vibration plate after driving only L (L is a natural number greater than M and less than N) piezoelectric elements out of the N piezoelectric elements with the first evaluation waveform as a fourth residual vibration, causes the detection unit to detect the residual vibration of the vibration plate after driving only the L piezoelectric elements with the second evaluation waveform as a fifth residual vibration, and determines the waveform of the drive signal based on the first residual vibration, the second residual vibration, the fourth residual vibration, the fifth residual vibration, the first reference residual vibration, and the second reference residual vibration. In the seventeenth aspect, the same effect as in the fourth aspect can be obtained.

[0236] In a liquid ejection device according to aspect 18, which is a specific example of aspect 16, the control unit determines a waveform that changes at the first potential change rate as a candidate waveform for the drive signal when a first amplitude difference, obtained by subtracting the amplitude of the first standard residual vibration from the amplitude of the first residual vibration, is smaller than a first threshold value, which is a positive value, and larger than a second threshold value, which is a negative value; and determines a waveform that changes at the second potential change rate as a candidate waveform for the drive signal when a second amplitude difference, obtained by subtracting the amplitude of the second standard residual vibration from the amplitude of the second residual vibration, is smaller than the first threshold value and larger than the second threshold value. In the eighteenth embodiment, the same effect as in the sixth embodiment can be obtained.

[0237] In a liquid ejection device according to aspect 19, which is a specific example of aspect 18, the control unit determines that the waveform that changes at the first potential change rate and the waveform that changes at the second potential change rate are candidate waveforms of the drive signal, and if the absolute value of the first amplitude difference is smaller than the absolute value of the second amplitude difference, the control unit determines that the waveform that changes at the first potential change rate is the waveform of the drive signal, and if the waveform that changes at the first potential change rate and the waveform that changes at the second potential change rate are candidate waveforms of the drive signal, and if the absolute value of the second amplitude difference is smaller than the absolute value of the first amplitude difference, the control unit determines that the waveform that changes at the second potential change rate is the waveform of the drive signal. In the nineteenth aspect, the same effect as in the ninth aspect can be obtained.

[0238] In a liquid ejection device according to aspect 20, which is a specific example of aspect 18, when a waveform that changes at the first potential change rate and a waveform that changes at the second potential change rate are candidates for the waveform of the drive signal, the control unit selects the waveform that changes at the larger of the first potential change rate and the second potential change rate as the waveform of the drive signal. In the twentieth embodiment, the same effect as in the tenth embodiment can be obtained.

[0239] Furthermore, a control method for a liquid ejection device according to a preferred aspect, aspect 21, is a control method for a liquid ejection device having a liquid ejection head including a plurality of nozzles that eject liquid, a plurality of piezoelectric elements that correspond to the plurality of nozzles and are driven by supplying a drive signal, a vibration plate that vibrates by driving at least one of the plurality of piezoelectric elements, and a detection unit that detects the residual vibration of the vibration plate after at least one of the plurality of piezoelectric elements is driven, wherein the detection unit detects, as a first residual vibration, the residual vibration of the vibration plate after driving N piezoelectric elements corresponding to N nozzles out of the plurality of nozzles with a first evaluation waveform in which a potential change rate, which is the amount of change in potential per unit time, is a first potential change rate, and the detection unit detects, as a second residual vibration, the residual vibration of the vibration plate after driving the N piezoelectric elements with a second evaluation waveform in which the potential change rate is a second potential change rate that is smaller than the first potential change rate, and determines the waveform of the drive signal based on the first residual vibration and the second residual vibration. In the twenty-first embodiment, the same effect as in the first embodiment can be obtained. [Explanation of symbols]

[0240] 1...liquid ejection head, 2...drive signal generation unit, 3...analysis unit, 4...control unit, 5...storage unit, 7...maintenance unit, 8...medium transport mechanism, 9...carriage transport mechanism, 10...recording head, 18...switching circuit, 19...detection circuit, 40...waveform determination unit, 60...ink container, 100...liquid ejection device, CV...pressure chamber, D...ejection unit, NZ...nozzle, PP...medium, PZ...piezoelectric element.

Claims

1. a liquid ejection head including a plurality of nozzles for ejecting liquid, a plurality of piezoelectric elements provided corresponding to the plurality of nozzles and driven by a supply of a drive signal, a vibration plate that vibrates by driving at least one of the plurality of piezoelectric elements, and a detection unit that detects residual vibration of the vibration plate after at least one of the plurality of piezoelectric elements has been driven; A control unit; Equipped with The control unit a first residual vibration is detected by the detection unit after driving N piezoelectric elements corresponding to N nozzles among the plurality of nozzles with a first evaluation waveform, the first evaluation waveform having a potential change rate, which is a change amount of potential per unit time, being a first potential change rate; a second residual vibration of the diaphragm after the N piezoelectric elements are driven with a second evaluation waveform, the second potential change rate being a second potential change rate that is smaller than the first potential change rate, and the detection unit detects the second residual vibration; determining a waveform of the drive signal based on the first residual vibration and the second residual vibration; A liquid ejection device characterized by:

2. The control unit a third residual vibration of the diaphragm after the N piezoelectric elements are driven with a third evaluation waveform, the third potential change rate being a third potential change rate that is smaller than the second potential change rate, and the detection unit detects the third residual vibration; determining a waveform of the drive signal based on the first residual vibration, the second residual vibration, and the third residual vibration; The liquid ejection device according to claim 1 .

3. The control unit a reference residual vibration of the diaphragm after driving only M (M is a natural number less than N) piezoelectric elements among the N piezoelectric elements with the first evaluation waveform, is detected by the detection unit as a first reference residual vibration; determining a waveform of the drive signal based on the first residual vibration, the second residual vibration, and the first reference residual vibration; The liquid ejection device according to claim 1 .

4. The control unit a residual vibration of the diaphragm after driving only L (L is a natural number greater than M and less than N) piezoelectric elements among the N piezoelectric elements with the first evaluation waveform, is detected by the detection unit as a fourth residual vibration; determining a waveform of the drive signal based on the first residual vibration, the second residual vibration, the fourth residual vibration, and the first reference residual vibration; 4. The liquid ejection device according to claim 3.

5. The N nozzles are not adjacent to each other. The liquid ejection device according to claim 1 .

6. The control unit when a first amplitude difference obtained by subtracting the amplitude of the first reference residual vibration from the amplitude of the first residual vibration is smaller than a first threshold value which is a positive value and larger than a second threshold value which is a negative value, a waveform which changes at the first potential change rate is selected as a candidate waveform of the drive signal; 4. The liquid ejection device according to claim 3.

7. The control unit When the first amplitude difference is larger than the first threshold value or smaller than the second threshold value, the waveform that changes at the first potential change rate is not selected as a candidate waveform for the drive signal.

7. The liquid ejection device according to claim 6.

8. The control unit when an amplitude difference obtained by subtracting a pre-stored first reference value from the amplitude of the first residual vibration is smaller than a first threshold value which is a positive value and larger than a second threshold value which is a negative value, a waveform which changes at the first potential change rate is selected as a candidate waveform for the drive signal; The liquid ejection device according to claim 1 .

9. The control unit When there are a plurality of candidates for the waveform of the drive signal, the candidate having the smallest amplitude difference obtained by subtracting the amplitude of the reference residual vibration from the amplitude of the residual vibration is selected as the waveform of the drive signal.

8. The liquid ejection device according to claim 6 or 7.

10. The control unit When there are a plurality of candidates for the waveform of the drive signal, the candidate with the maximum rate of change in potential is selected as the waveform of the drive signal.

9. The liquid ejection device according to claim 6, wherein the ejection head is a nozzle.

11. The control unit presenting candidate information indicating candidates for the waveform of the drive signal to a user, and determining the waveform of the drive signal based on an input by the user regarding the candidate information; 9. The liquid ejection device according to claim 6, wherein the ejection head is a nozzle.

12. the first evaluation waveform includes a first waveform element whose potential changes at the first rate of potential change; the second evaluation waveform includes a second waveform element whose potential changes at the second rate of potential change, a potential difference from the start point to the end point of the first waveform element is the same as a potential difference from the start point to the end point of the second waveform element; The time from the start point to the end point of the first waveform element is shorter than the time from the start point to the end point of the second waveform element. The liquid ejection device according to claim 1 .

13. the first evaluation waveform includes a first waveform element whose potential changes at the first potential change rate, the second evaluation waveform includes a second waveform element whose potential changes at the second rate of potential change, a potential difference from the start point to the end point of the first waveform element is greater than a potential difference from the start point to the end point of the second waveform element; The time from the start point to the end point of the first waveform element is the same as the time from the start point to the end point of the second waveform element. The liquid ejection device according to claim 1 .

14. Each of the first evaluation waveform and the second evaluation waveform is a first expansion element that is a corrugated element that expands pressure chambers that communicate with each of the plurality of nozzles; a contraction element that is a wave element subsequent to the first expansion element and that contracts the pressure chamber; Including, the first potential change rate and the second potential change rate are the potential change rates of the contraction element; The liquid ejection device according to claim 1 .

15. Each of the first evaluation waveform and the second evaluation waveform is Further, the second expansion element is a wave element subsequent to the contraction element, and expands the pressure chamber.

15. The liquid ejection device according to claim 14.

16. A control method for a liquid ejection device having a liquid ejection head including a plurality of nozzles that eject liquid, a plurality of piezoelectric elements that are provided corresponding to the plurality of nozzles and that are driven by a supply of a drive signal, a vibration plate that vibrates by driving at least one of the plurality of piezoelectric elements, and a detection unit that detects residual vibration of the vibration plate after at least one of the plurality of piezoelectric elements has been driven, a first residual vibration is detected by the detection unit after driving N piezoelectric elements corresponding to N nozzles among the plurality of nozzles with a first evaluation waveform, the first evaluation waveform having a potential change rate, which is a change amount of potential per unit time, being a first potential change rate; a second residual vibration of the diaphragm after the N piezoelectric elements are driven with a second evaluation waveform, the second potential change rate being a second potential change rate that is smaller than the first potential change rate, and the detection unit detects the second residual vibration; determining a waveform of the drive signal based on the first residual vibration and the second residual vibration; A method for controlling a liquid ejection device.

Images