Liquid discharge device and control method of liquid discharge device

Abstract

To enable variation in discharge characteristics of a nozzle to be properly and easily evaluated.SOLUTION: A liquid discharge device 100 comprises: a liquid discharge head 1 that includes a nozzle N, a piezoelectric element PZ, a vibration plate 14, and a detection circuit 19 which detects residual vibration of the vibration plate 14; and an evaluation control part 40. The evaluation control part 40 makes the detection circuit 19 detect, as first residual vibration, residual vibration caused by continuously executing discharge driving for driving the piezoelectric element PZ using a vibration pulse PA for enabling the vibration plate 14 to generate vibration which is larger than vibration of the vibration plate 14 caused by non-discharge driving for driving the piezoelectric element PZ using a minute vibration pulse PB by which the nozzle N cannot discharge ink, and makes the detection circuit 19 detect, as second residual vibration, residual vibration caused by continuously driving the piezoelectric element PZ by the non-discharge driving and then the discharge driving, so as to evaluate variation in discharge characteristics of the nozzle N, between a case where the discharge driving is continuously executed and a case where the discharge driving is not continuously executed, 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 filled in a pressure chamber from a nozzle by vibrating a vibration plate that constitutes part of the pressure chamber using a piezoelectric element. It is known that in this type of liquid ejection device, changes in the viscosity of the liquid affect the ejection characteristics of the liquid from the nozzle. For this reason, for example, Patent Document 1 discloses a liquid ejection device that includes a control means that supplies a micro-vibration drive signal to a pressure generating means to generate micro-vibrations in the liquid within the pressure generating chamber without ejecting the liquid from the nozzle opening. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-163290 Summary of the Invention [Problem to be solved by the invention]

[0004] Depending on the image being printed, there may be a mixture of continuous ejection, in which ink is ejected continuously onto multiple pixels, and single ejection, in which ink is ejected onto only one pixel out of multiple pixels. In continuous ejection, ejection drive is performed continuously, driving the piezoelectric element with a drive signal including an ejection waveform that ejects liquid from the nozzle. In contrast, in single ejection, the above-mentioned ejection drive is not continuous. For this reason, variations occur in the nozzle ejection characteristics between continuous ejection and single ejection.

[0005] As described above, it is known that thickening of the liquid can be suppressed by performing a non-ejection drive, which drives the piezoelectric element with a drive signal including a micro-vibration waveform that prevents the liquid from being ejected from the nozzle. Therefore, for example, in order to suppress thickening of the liquid even in single ejection, it is conceivable to perform a non-ejection drive instead of the ejection drive during periods when the ejection drive is not performed. In this aspect, by adjusting the micro-vibration waveform, it is possible to reduce the variation in ejection characteristics between continuous ejection and single ejection.

[0006] Here, for example, a business model is conceivable in which a head manufacturer that manufactures liquid ejection heads sells the liquid ejection heads to a printing device manufacturer, which then assembles the liquid ejection device. In this business model, in many cases, the operating conditions of the liquid ejection head, such as ink conditions, are determined by the printing device manufacturer, not the head manufacturer. If the head manufacturer also assembles the liquid ejection device, the head manufacturer also determines the operating conditions, allowing the head manufacturer to appropriately evaluate the variation in the ejection characteristics described above. In contrast, in the above-mentioned business model, there is a risk that the head manufacturer will not be able to appropriately evaluate the variation in the ejection characteristics once it manufactures and sells the liquid ejection head. In this case, it is difficult for the head manufacturer to determine an appropriate micro-vibration waveform that reduces the variation in the ejection characteristics. Therefore, in the above-mentioned business model, the printing device manufacturer is required to appropriately evaluate the variation in the ejection characteristics and determine an appropriate micro-vibration waveform that reduces the variation in the ejection characteristics, which may place an excessive burden on the printing device manufacturer. For this reason, in the above-mentioned business model, it is desirable to be able to appropriately and easily evaluate the variation in ejection characteristics and determine an appropriate micro-vibration waveform that reduces the variation in ejection characteristics. In particular, it is desirable to be able to appropriately and easily evaluate the variation in ejection characteristics. Note that the above-mentioned problem is also desirable, although to a relatively small extent, even if the manufacturer of the liquid ejection device and the manufacturer of the liquid ejection head use the same business model. For example, it is conceivable that a user may independently set usage conditions that differ from the usage conditions previously assumed by the manufacturer of the liquid ejection head or liquid ejection device, and in such a case, a similar problem would arise. [Means for solving the problem]

[0007] In order to solve the above problems, the liquid ejection device of the present invention comprises a liquid ejection head including a nozzle that ejects liquid, a piezoelectric element corresponding to the nozzle, a vibration plate that vibrates when the piezoelectric element is driven, and a detection unit that detects residual vibration of the vibration plate caused by driving the piezoelectric element, and a control unit, wherein the control unit is capable of performing micro-vibration drive that drives the piezoelectric element with a micro-vibration pulse that does not cause liquid to be ejected from the nozzle, and vibration drive that drives the piezoelectric element with a vibration pulse that generates a vibration in the vibration plate that is greater than the vibration of the vibration plate caused by the micro-vibration drive, and causes the detection unit to detect the residual vibration caused by continuously performing the vibration drive as a first residual vibration, and causes the detection unit to detect the residual vibration caused by continuously driving the piezoelectric element in the order of the micro-vibration drive and the vibration drive as a second residual vibration, and evaluates the variation in the ejection characteristics of the nozzle between when the vibration drive is continuous and when the vibration drive is not continuous based on the first residual vibration and the second residual vibration detected by the detection unit.

[0008] Another liquid ejection device according to the present invention comprises a liquid ejection head including a nozzle for ejecting liquid, a piezoelectric element corresponding to the nozzle, a vibration plate that vibrates when the piezoelectric element is driven, and a detection unit that detects residual vibration of the vibration plate caused by driving the piezoelectric element, and a control unit, wherein the control unit is capable of performing micro-vibration drive, which drives the piezoelectric element with a micro-vibration pulse that does not cause liquid to be ejected from the nozzle, and vibration drive, which drives the piezoelectric element with a vibration pulse that generates a vibration in the vibration plate that is greater than the vibration of the vibration plate caused by the micro-vibration drive, and causes the detection unit to detect the residual vibration caused by consecutively performing the vibration drive as a first residual vibration, and causes the detection unit to detect the residual vibration caused by consecutively driving the piezoelectric element in the order of the micro-vibration drive and the vibration drive as a second residual vibration, and determines the waveform of the micro-vibration pulse based on the first residual vibration and the second residual vibration detected by the detection unit.

[0009] 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 nozzle that ejects liquid, a piezoelectric element corresponding to the nozzle, a vibration plate that vibrates when the piezoelectric element is driven, and a detection unit that detects residual vibration of the vibration plate caused by driving the piezoelectric element, and is capable of performing micro-vibration drive that drives the piezoelectric element with a micro-vibration pulse that does not cause liquid to be ejected from the nozzle, and vibration drive that drives the piezoelectric element with a vibration pulse that generates a vibration in the vibration plate that is greater than the vibration of the vibration plate caused by the micro-vibration drive, and the detection unit detects the residual vibration caused by continuously performing the vibration drive as a first residual vibration, and detects the residual vibration caused by continuously driving the piezoelectric element in the order of the micro-vibration drive and the vibration drive as a second residual vibration, and evaluates the variation in the ejection characteristics of the nozzle between when the vibration drive is continuous and when the vibration drive is not continuous based on the first residual vibration and the second residual vibration detected by the detection unit. [Brief explanation of the drawings]

[0010] [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] FIG. 10 is a diagram showing an example of a waveform of a residual vibration signal. [Figure 8] 10A and 10B are explanatory diagrams illustrating examples of drive signals used to evaluate variations in nozzle ejection characteristics. [Figure 9]10 is a flowchart showing an example of the operation of the liquid ejection device when evaluating variations in the ejection characteristics of the nozzles. [Figure 10] 10 is a flowchart showing an example of a comparison process of residual vibration shown in FIG. 9. [Figure 11] FIG. 10 is a block diagram showing an example of the configuration of a liquid ejection head according to a third modified example. [Figure 12] 10 is a timing chart showing an example of the operation of a liquid ejection device according to a third modified example. DETAILED DESCRIPTION OF THE INVENTION

[0011] 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.

[0012] [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."

[0013] 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.

[0014] 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.

[0015] The liquid ejection device 100 includes a liquid ejection head 1 provided with an ejection section D including nozzles N that eject ink, a drive signal generation unit 2 that generates a plurality of drive signals COM for driving the ejection section D, and an analysis unit 3 that analyzes residual vibrations (described later). The nozzles N 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.

[0016] 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.

[0017] 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 and one drive signal generation unit 2 corresponding to that one liquid ejection head 1, as exemplified in FIG.

[0018] 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.

[0019] 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.

[0020] Here, the waveform designation signal dCOM is a digital signal that defines the waveform of each of the multiple drive signals COM. Furthermore, each drive signal COM is an analog signal for driving a discharge section D. In this embodiment, as shown in FIG. 5 (to be described later), it is assumed that the multiple drive signals COM include drive signals COMa and COMb. 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 each drive signal COM to the discharge section D, thereby designating the type of operation of the discharge section D.

[0021] In this embodiment, the control unit 4 functions as the evaluation control unit 40 by operating in accordance with the control program PG stored in the storage unit 5. The control program PG may be provided, for example, by the head manufacturer that produces the liquid ejection head 1. Details of the operation of the evaluation control unit 40 are described in FIGS. 9 and 10 . For example, the evaluation control unit 40 evaluates the variation in the ejection characteristics of the nozzle N based on the residual vibration analyzed by the analysis unit 3. The ejection characteristics of the nozzle N are, for example, the ejection characteristics of the ink ejected by the ejection unit D. For example, the variation in the ejection characteristics evaluated by the evaluation control unit 40 is the variation in the ejection characteristics between continuous ejection, in which the ejection drive that drives the ejection unit D with the drive signal COM to eject ink from the nozzle N is continuous, and discontinuous ejection, in which the ejection drive is not continuous. The evaluation control unit 40 is an example of a "control unit."

[0022] The drive signal generation unit 2 includes, for example, a DAC (Digital Analog Converter), and generates a plurality of drive signals COM based on a waveform designation signal dCOM supplied from the control unit 4. For example, each of the plurality of drive signals 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 plurality of drive signals COM generated based on the waveform designation signal dCOM to a switching circuit 18 included in the liquid ejection head 1.

[0023] 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.

[0024] 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."

[0025] The print head 10 has M ejection sections D. In this embodiment, it is assumed that the value M is an even number equal to or greater than 2. Hereinafter, the m-th ejection section D of the M ejection sections D provided in the print head 10 may be referred to as ejection section D[m]. Here, the variable m is a natural number that satisfies "1≦m≦M." Furthermore, hereinafter, when a component or signal of the liquid ejection device 100 corresponds to a ejection section D[m] of the M ejection sections D, the subscript [m] may be added to the symbol representing the component or signal.

[0026] The switching circuit 18 switches whether to supply each drive signal COM to the discharge section D[m] 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[m] among the multiple drive signals COM may be referred to as an individual drive signal Vin[m]. The switching circuit 18 also switches whether to electrically connect the discharge section D[m] to the detection circuit 19 based on the print signal SI. When the discharge section D[m] is electrically connected to the detection circuit 19, for example, a detection signal Vout[m] detected from the discharge section D[m] is supplied to the detection circuit 19 via the switching circuit 18. The detection signal Vout[m] is, for example, an analog signal indicating the waveform of residual vibration, which is vibration remaining in the discharge section D[m] after the discharge section D[m] is driven by the individual drive signal Vin[m]. Specifically, for example, the detection signal Vout[m] indicates the waveform of the residual vibration of the diaphragm 14 after the piezoelectric element PZ[m] is driven. The piezoelectric element PZ and the diaphragm 14 will be described later with reference to FIGS.

[0027] The detection circuit 19 generates the residual vibration signal VR[m] based on the detection signal Vout[m]. For example, the detection circuit 19 amplifies the amplitude of the detection signal Vout[m] or removes noise components contained in the detection signal Vout[m], thereby shaping the detection signal Vout[m] into a waveform suitable for processing in the analysis unit 3. In this way, the residual vibration signal VR[m] is generated. For example, the detection circuit 19 may be configured to include a negative feedback amplifier for amplifying the detection signal Vout[m], a low-pass filter for attenuating high frequency components of the detection signal Vout[m], and a voltage follower for converting impedance and outputting a low-impedance residual vibration signal VR[m].

[0028] For example, the residual vibration signal VR[m] generated based on the detection signal Vout[m] is an analog signal that indicates the waveform of the residual vibration of the diaphragm 14 after the piezoelectric element PZ[m] is driven by the individual drive signal Vin[m]. The detection circuit 19 outputs the residual vibration signal VR[m] generated based on the detection signal Vout[m] 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[m] based on the detection signal Vout[m].

[0029] The analysis unit 3 includes, for example, an ADC (Analog to Digital Converter) and converts the analog residual vibration signal VR[m] into a digital signal. The analysis unit 3 then analyzes the residual vibration detected by, for example, the detection circuit 19 using the digitally converted residual vibration signal VR[m]. The analysis unit 3 also generates residual vibration information Vinf indicating the analysis results 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 and phase of the residual vibration. However, the residual vibration information Vinf may indicate either the amplitude or the phase of the residual vibration. Alternatively, the residual vibration information Vinf may include information indicating the period of the residual vibration, or may include information indicating something other than the amplitude, phase, and period of the residual vibration. The evaluation control unit 40 evaluates the variation in the ejection characteristics of the nozzle N 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.

[0030] 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 section D, a wiping process that wipes off foreign matter such as ink adhering to the vicinity of the nozzle N of the ejection section D with a wiper, and a pumping process that sucks ink from inside the ejection section D with a tube pump or the like.

[0031] 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 N 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.

[0032] Next, the overall configuration of the liquid ejection device 100 will be described with reference to FIG.

[0033] 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.

[0034] 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.

[0035] 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.

[0036] 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.

[0037] 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 N provided in the liquid ejection head 1. That is, the liquid ejection head 1 ejects ink from some or all of the multiple nozzles N 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 N.

[0038] Next, the general structure of the liquid ejection head 1 will be described with reference to FIGS.

[0039] 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 numeral of the nozzle N included in the nozzle row Ln1, and the numeral "2" is added to the end of the reference numeral of the nozzle N included in the nozzle row Ln2.

[0040] 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.

[0041] 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.

[0042] 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.

[0043] M nozzles N are formed on the nozzle substrate 11. Here, the nozzles N are through-holes formed in the nozzle substrate 11. In this embodiment, it is assumed that the multiple nozzles N formed on the nozzle substrate 11 include multiple nozzles N1 arranged to extend in the Y-axis direction and multiple nozzles N2 arranged to extend in the Y-axis direction at positions in the X2 direction as viewed from the multiple nozzles N1. Hereinafter, the multiple nozzles N1 arranged to extend in the Y-axis direction will be referred to as a nozzle row Ln1, and the multiple nozzles N2 arranged to extend in the Y-axis direction will be referred to as a nozzle row Ln2. For example, the number of nozzles N included in each of the nozzle rows LN1 and Ln2 is half the value M. 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.

[0044] 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.

[0045] 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 N1, a plurality of connection flow paths BK2 corresponding to the plurality of nozzles N2, a plurality of communication flow paths BR1 corresponding to the plurality of nozzles N1, and a plurality of communication flow paths BR2 corresponding to the plurality of nozzles N2.

[0046] 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 N1 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 N2 corresponding to the communication flow path BR2.

[0047] 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.

[0048] 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.

[0049] 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 N1 and a plurality of pressure chambers CV2 corresponding to the plurality of nozzles N2. Of these, 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 and extend in the X-axis direction when viewed in the Z-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 being made.

[0050] 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.

[0051] 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.

[0052] 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.

[0053] 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.

[0054] As shown in FIGS. 3 and 4, a piezoelectric element PZ is provided on the Z2-direction surface of the vibration plate 14, and therefore 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 N 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 N is applied by the vibration of the vibration plate 14. Furthermore, the vibration remaining in the ejection portion D[m] described in FIG. 1 can also be considered, for example, as vibration remaining in the ink in the pressure chamber CV of the ejection portion D.

[0055] 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.

[0056] 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.

[0057] 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.

[0058] 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.

[0059] 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.

[0060] 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 N1 via the communicating channel BR1.

[0061] 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 N2 via communicating flow path BR2.

[0062] 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.

[0063] 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.

[0064] 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.

[0065] 4, ejection section D1 has a piezoelectric element PZ1, a pressure chamber CV1, a nozzle N1 communicating with the pressure chamber CV1, and a portion of the vibration plate 14 that contacts the piezoelectric element PZ1. Similarly, ejection section D2 has a piezoelectric element PZ2, a pressure chamber CV2, a nozzle N2 communicating with the pressure chamber CV2, and a portion of the vibration plate 14 that contacts the piezoelectric element PZ2. Note that ejection sections D1 and D2 are also referred to as ejection section D without any particular distinction being made.

[0066] Although not shown, the liquid ejection head 1 also 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 N are formed, during periods when ink is not ejected from the nozzles N.

[0067] Next, an overview of the liquid ejection head 1 will be described with reference to FIG.

[0068] FIG. 5 is a block diagram showing an example of the configuration of the liquid ejection head 1. As shown in FIG.

[0069] 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 COMa is supplied from the drive signal generation unit 2, and a wiring Lb to which a drive signal COMb is supplied from the drive signal generation unit 2. The liquid ejection head 1 also has a wiring Ls that supplies a detection signal Vout to the detection circuit 19, a wiring Li[m] that supplies an individual drive signal Vin[m] to the ejection section D[m], and a wiring Ld to which a bias potential VBS is supplied.

[0070] The switching circuit 18 has M switches SWa[1] to SWa[M] that correspond one-to-one to the M discharge units D[1] to D[M], M switches SWb[1] to SWb[M] that correspond one-to-one to the M discharge units D[1] to D[M], and M switches SWs[1] to SWs[M] that correspond one-to-one to the M discharge units D[1] to D[M].

[0071] The switching circuit 18 also has a connection state designation circuit CSC. The connection state designation circuit CSC designates the connection states of the M switches SWa, M switches SWb, and M switches SWs. For example, the connection state designation circuit CSC generates connection state designation signals Qa[m], Qb[m], and Qs[m] based on at least a portion of the print signal SI and the latch signal LAT supplied from the control unit 4.

[0072] For example, the connection state designation signal Qa[m] is a signal that designates the on / off state of the switch SWa[m], the connection state designation signal Qb[m] is a signal that designates the on / off state of the switch SWb[m], and the connection state designation signal Qs[m] is a signal that designates the on / off state of the switch SWs[m].

[0073] The switch SWa[m] switches between conduction and non-conduction between the wiring La and the individual electrode Za[m] of the piezoelectric element PZ[m] provided in the discharge section D[m] based on the connection state designation signal Qa[m]. That is, the switch SWa[m] switches between conduction and non-conduction between the wiring La and the wiring Li[m] connected to the individual electrode Za[m] based on the connection state designation signal Qa[m]. In this embodiment, the switch SWa[m] is turned on when the connection state designation signal Qa[m] is high level and turned off when it is low level. When the switch SWa[m] is on, the drive signal COMa supplied to the wiring La is supplied as the individual drive signal Vin[m] to the individual electrode Za[m] of the discharge section D[m] via the wiring Li[m].

[0074] The switch SWb[m] switches between conduction and non-conduction between the wiring Lb and the individual electrode Za[m] of the piezoelectric element PZ[m] provided in the discharge section D[m] based on the connection state designation signal Qb[m]. That is, the switch SWb[m] switches between conduction and non-conduction between the wiring Lb and the wiring Li[m] connected to the individual electrode Za[m] based on the connection state designation signal Qb[m]. In this embodiment, the switch SWb[m] is turned on when the connection state designation signal Qb[m] is high level and turned off when the connection state designation signal Qb[m] is low level. When the switch SWb[m] is on, the drive signal COMb supplied to the wiring Lb is supplied as the individual drive signal Vin[m] to the individual electrode Za[m] of the discharge section D[m] via the wiring Li[m].

[0075] The switch SWs[m] switches between electrical continuity and non-conduction between the wiring Ls and the individual electrode Za[m] of the piezoelectric element PZ[m] provided in the discharge portion D[m] based on the connection state designation signal Qs[m]. That is, the switch SWs[m] switches between electrical continuity and non-conduction between the wiring Ls and the wiring Li[m] connected to the individual electrode Za[m] based on the connection state designation signal Qs[m]. In this embodiment, the switch SWs[m] is turned on when the connection state designation signal Qs[m] is high level and turned off when the connection state designation signal Qs[m] is low level.

[0076] For example, the connection state designation signal Qs[m] becomes high level when detecting residual vibration of a discharge portion D[m]. Hereinafter, the discharge portion D whose residual vibration is detected may be referred to as the discharge portion D of the detection target. When the switch SWs[m] is turned on, a detection signal Vout[m] indicating the potential of the individual electrode Za[m] of the piezoelectric element PZ[m] of the discharge portion D[m] of the detection target is supplied to the detection circuit 19 via the wiring Li[m] and the wiring Ls. The detection circuit 19 generates a residual vibration signal VR[m] based on the detection signal Vout[m].

[0077] As described above, the individual drive signal Vin[m] is the signal of the drive signals COMa and COMb that is supplied to the piezoelectric element PZ[m] of the discharge section D[m] via the switch SWa[m] or SWb[m]. In this embodiment, it is assumed that the drive signal COMa is the drive signal COM that causes ink to be discharged from the nozzle N, and the drive signal COMb is the drive signal COM that does not cause ink to be discharged from the nozzle N.

[0078] Depending on the image being printed, there may be a mixture of continuous ejection, in which ink is ejected continuously onto multiple pixels forming the image, and single ejection, in which ink is ejected onto only one pixel out of multiple pixels. In continuous ejection, ejection drive is continuously executed to drive the piezoelectric element PZ with the drive signal COMa to eject ink from the nozzle N. In contrast, in single ejection, the above-mentioned ejection drive is not continuous. For this reason, there is a risk of variation in the ejection characteristics of the nozzle N between continuous ejection and single ejection. Note that single ejection is a type of discontinuous ejection mentioned above.

[0079] It is known that, in order to suppress thickening of the ink, a non-ejection drive is performed in which the piezoelectric element PZ is driven by a drive signal COMb that does not cause ink to be ejected from the nozzle N, thereby causing the ink in the pressure chamber CV to vibrate slightly. In this embodiment, it is assumed that the non-ejection drive is performed on the ejection section D that is not subjected to the ejection drive. In this aspect, by adjusting the waveform of the drive signal COMb, it is possible to reduce the variation in the ejection characteristics between continuous ejection and discontinuous ejection. Therefore, in this embodiment, for example, the waveform of the drive signal COMb is set to an appropriate waveform, thereby suppressing the occurrence of variation in the ejection characteristics of the nozzle N. It is noted that the non-ejection drive is an example of a "micro-vibration drive," and the ejection drive is an example of a "vibration drive."

[0080] Next, the operation of the liquid ejection device 100 in the unit period TU will be described with reference to FIG.

[0081] 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[m] from the ejection section D to be detected in each unit period TU.

[0082] 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.

[0083] The print signal SI includes, for example, M individual designation signals Sd[1] to Sd[M] that correspond one-to-one to the M discharge sections D[1] to D[M]. The individual designation signal Sd[m] designates the driving mode of the discharge section D[m] in each unit period TU when the liquid discharger 100 executes a printing process.

[0084] 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[M], to the connection state designation circuit CSC in synchronization with the clock signal CL. Then, during the unit period TU, the connection state designation circuit CSC generates connection state designation signals Qa[m], Qb[m], and Qs[m] based on the individual designation signal Sd[m].

[0085] For example, in a unit period TU during which the printing process is executed, the ejection unit D[m] is designated by the individual designation signal Sd[m] as either an ejection unit D that forms dots, an ejection unit D that does not form dots, or an ejection unit D that is a detection target. An ejection unit D that forms dots is an ejection unit D that is driven so that the piezoelectric element PZ of the ejection unit D ejects ink from the nozzle N of the ejection unit D. An ejection unit D that does not form dots is an ejection unit D that is driven so that the piezoelectric element PZ of the ejection unit D does not eject ink from the nozzle N of the ejection unit D. In this embodiment, an ejection unit D that does not form dots is driven so that a minute vibration is generated in the portion of the diaphragm 14 corresponding to the ejection unit D, which is small enough to prevent ink from being ejected from the nozzle N.

[0086] First, we will explain the operation of the connection state designation circuit CSC and other components when the drive mode of the discharge unit D that forms dots is designated by the individual designation signal Sd[m]. When the drive mode of the discharge unit D that forms dots is designated by the individual designation signal Sd[m], for example, the connection state designation circuit CSC sets the connection state designation signal Qa[m] to a high level and the connection state designation signals Qb[m] and Qs[m] to a low level during the unit period TU. This causes the drive signal COMa to be supplied from the drive signal generation unit 2 to the discharge unit D that forms dots.

[0087] For example, the drive signal generating unit 2 outputs a drive signal COMa having a vibration pulse PA. Driving the piezoelectric element PZ with the drive signal COMa can also be understood as driving the piezoelectric element PZ with the vibration pulse PA. The vibration pulse PA is a pulse that generates in the vibration plate 14 a vibration that is greater than the vibration of the vibration plate 14 caused by non-ejection driving in which the piezoelectric element PZ is driven by a micro-vibration pulse PB, which will be described later. In this embodiment, the vibration pulse PA is a pulse that causes ink to be ejected from the nozzle N.

[0088] For example, the vibration pulse PA has a waveform in which the potential of the drive signal COMa changes from potential VC through potential VLa and potential VHa and returns to potential VC. Potential VC is the potential at the start and end of the vibration pulse PA and is the reference potential of the drive signal COMa. Furthermore, potential VLa is lower than potential VC, and potential VHa is higher than potential VC.

[0089] For example, the vibration pulse PA has a waveform element Pa1 whose potential changes from potential VC to potential VLa, a waveform element Pa2 whose potential is maintained at the potential VLa at the end of the waveform element Pa1, and a waveform element Pa3 whose potential changes from potential VLa to potential VHa. The vibration pulse PA further includes a waveform element Pa4 whose potential is maintained at the potential VHa at the end of the waveform element Pa3, and a waveform element Pa5 whose potential changes from potential VHa to potential VC.

[0090] 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 COMa 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 COMa changes so as 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 N 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 N in the direction opposite to the ejection direction may be referred to as "pull."

[0091] 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 COMa 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 COMa 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 N is pushed in the Z1 direction, which is the ejection direction. Hereinafter, pushing the surface of the ink in the nozzle N in the ejection direction may be referred to as a push.

[0092] Furthermore, waveform elements Pa2 and Pa4 are maintaining elements for maintaining the position of piezoelectric body Zb in the Z-axis direction. For example, waveform element Pa2 maintains the potential of drive signal COMa in order to drive piezoelectric element PZ so as to maintain the volume of pressure chamber CV expanded by waveform element Pa1. For example, waveform element Pa4 maintains the potential of drive signal COMa in order to drive piezoelectric element PZ so as to maintain the volume of pressure chamber CV contracted by waveform element Pa3.

[0093] In this way, the vibration pulse PA has a so-called pull-push-pull waveform. However, the waveform of the drive signal COMa that causes ink to be ejected from the nozzle N, that is, the waveform of the vibration pulse PA, is not limited to the pull-push-pull waveform.

[0094] The vibration pulse PA is determined so that a predetermined amount of ink is ejected from the ejection section D[m] when an individual drive signal Vin[m] having the vibration pulse PA is supplied to the ejection section D[m]. Note that in this embodiment, it is assumed that when the potential of the individual drive signal Vin[m] is high, the volume of the pressure chamber CV of the ejection section D[m] is smaller than when the potential is low. Therefore, when the ejection section D[m] is driven by the individual drive signal Vin[m] having the vibration pulse PA, the ink in the ejection section D[m] is ejected from the nozzle N by the waveform element Pa3, in which the potential of the individual drive signal Vin[m] changes from low to high.

[0095] For example, the waveform elements Pa1, Pa2, Pa3, Pa4, and Pa5 included in the vibration 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.

[0096] Next, we will explain the operation of the connection state designation circuit CSC and other components when the individual designation signal Sd[m] designates a drive mode for a discharge unit D that does not form dots. When the individual designation signal Sd[m] designates a drive mode for a discharge unit D that does not form dots, for example, the connection state designation circuit CSC sets the connection state designation signal Qb[m] to a high level and the connection state designation signals Qa[m] and Qs[m] to a low level during the unit period TU. This causes the drive signal COMb to be supplied from the drive signal generation unit 2 to the discharge unit D that does not form dots.

[0097] For example, the drive signal generating unit 2 outputs a drive signal COMb having a micro-vibration pulse PB that does not cause ink to be ejected from the nozzle N. Driving the piezoelectric element PZ with the drive signal COMb can also be understood as driving the piezoelectric element PZ with the micro-vibration pulse PB. The micro-vibration pulse PB is, for example, a waveform in which the potential of the drive signal COMb changes from a potential VC, passes through a potential VHb, and returns to a potential VC. The potential VC is the potential at the start and end of the micro-vibration pulse PB, and is the reference potential of the drive signal COMb. Furthermore, the potential VHb is a potential higher than the potential VC. The potential difference between the potential VC and the potential VHb is smaller than the potential difference between the potential VLa and the potential VHa, and is set so that ink is not ejected from the nozzle N.

[0098] For example, the micro-vibration pulse PB includes a waveform element Pb1 corresponding to a contraction element, a waveform element Pb2 corresponding to a sustain element, and a waveform element Pb3 corresponding to an expansion element. Therefore, in the waveform element Pb1, the potential of the drive signal COMb changes in order to drive the piezoelectric element PZ so as to contract the volume of the pressure chamber CV. In addition, in the waveform element Pb2, the potential of the drive signal COMb is maintained in order to drive the piezoelectric element PZ so as to maintain the volume of the pressure chamber CV contracted by the waveform element Pb1. Then, in the waveform element Pb3, the potential of the drive signal COMb changes in order to drive the piezoelectric element PZ so as to expand the volume of the pressure chamber CV.

[0099] As described above, the minute vibration pulse PB contracts the volume of the pressure chamber CV by changing the potential from VC to VHb, and expands the contracted volume of the pressure chamber CV by changing the potential from VHb to VC. This change in the volume of the pressure chamber CV vibrates the ink in the pressure chamber CV without ejecting the ink in the pressure chamber CV. Note that the vibration of the vibration plate 14 caused by the non-ejection drive in which the piezoelectric element PZ is driven by the minute vibration pulse PB is smaller than the vibration of the vibration plate 14 caused by the ejection drive in which the piezoelectric element PZ is driven by the vibration pulse PA.

[0100] Next, the operation of the connection state designation circuit CSC and the like when the drive mode of the discharge unit D to be detected is designated by the individual designation signal Sd[m] will be described. Below, the operation of the connection state designation circuit CSC and the like when the drive mode of the discharge unit D to be detected is designated by the individual designation signal Sd[m] will be described using the example of evaluating the variation in the discharge characteristics of the nozzles N.

[0101] For example, when evaluating variations in the ejection characteristics of the nozzles N, the ejection section D to be detected is specified by the individual specification signal Sd[m] during the detection unit period TU. This allows residual vibrations resulting from consecutively executing the ejection drive, or residual vibrations resulting from consecutively driving the piezoelectric element PZ in the order of non-ejection drive and ejection drive, to be detected during the detection unit period TU. For example, when detecting residual vibrations resulting from consecutively executing the ejection drive, ejection drive is executed during the unit period TU two periods before the detection unit period TU and the unit period TU one period before the detection unit period TU. Furthermore, when detecting residual vibrations resulting from consecutively driving the piezoelectric element PZ in the order of non-ejection drive and ejection drive, non-ejection drive is executed during the unit period TU two periods before the detection unit period TU, and ejection drive is executed during the unit period TU one period before the detection unit period TU.

[0102] When the drive mode of the discharge section D to be detected is specified by the individual specification signal Sd[m], the connection state specification circuit CSC sets the connection state specification signal Qs[m] to a high level during the detection unit period TU. Also, the connection state specification circuit CSC sets the connection state specification signals Qa[m] and Qb[m] to a low level during the detection unit period TU.

[0103] In this case, as described above, the piezoelectric element PZ[m] of the discharge section D[m] to be detected is driven by the drive signal COMa in the unit period TU immediately preceding the detection unit period TU. As a result, the piezoelectric element PZ[m] is displaced by the vibration pulse PA of the drive signal COMa in the unit period TU immediately preceding the detection unit period TU. As a result, vibration occurs in the discharge section D[m] to be detected in the unit period TU immediately preceding the detection unit period TU. The vibration generated in the unit period TU immediately preceding the detection unit period TU remains in the detection unit period TU. During the detection unit period TU, the potential of the individual electrode Za[m] of the piezoelectric element PZ[m] of the discharge section D[m] to be detected changes depending on the residual vibration occurring in the discharge section D[m]. That is, during the detection unit period TU, the potential of the individual electrode Za of the piezoelectric element PZ of the discharge section D to be detected becomes a potential corresponding to the electromotive force of the piezoelectric element PZ resulting from the residual vibration occurring in the discharge section D to be detected. The potential of the individual electrode Za is detected as a detection signal Vout during a unit period TU for detection.

[0104] The connection state designation signals Qa, Qb, and Qs corresponding to the discharge units D other than the discharge unit D[m] to be detected are set to a low level, for example, during the unit period TU for detection. Also, the connection state designation circuit CSC may set the connection state designation signal Qs[m] to a high level during the first half of the unit period TU for detection, and set the connection state designation signal Qs[m] to a low level during the second half of the unit period TU for detection.

[0105] Here, for example, ejection characteristics such as the ejection speed of ink droplets vary depending on the viscosity of the ink. For example, the ejection speed of ink droplets with a viscosity higher than a predetermined value is slower than the ejection speed of ink droplets with a viscosity equal to or lower than the predetermined value. In this way, the ejection characteristics of nozzle N vary depending on the viscosity of the ink. For example, the viscosity of ink in a unit period TU of interest varies depending on whether ejection driving was performed in the unit period TU immediately preceding the unit period TU of interest. Therefore, for example, in discontinuous ejection, by preventing the ink viscosity from increasing, it is possible to suppress variations in the ejection characteristics between continuous and discontinuous ejection. For this reason, in this embodiment, for example, the evaluation control unit 40 evaluates variations in the ejection characteristics of nozzle N using multiple candidates for the drive signal COMb. Then, for example, based on the evaluation results of the variations in the ejection characteristics of nozzle N, the evaluation control unit 40 selects one of the multiple candidates as the drive signal COMb that will not eject ink from nozzle N. This determines an appropriate waveform for the drive signal COMb. In this way, in this embodiment, the waveform of the drive signal COMb, i.e., the waveform of the vibration pulse PB, can be easily determined to be a waveform that suppresses variations in the ejection characteristics of the nozzles N. In FIG. 6, one candidate vibration pulse PB among multiple candidates for the drive signal COMb is shown as an example of the vibration pulse PB that the drive signal COMb has. In other words, the drive signal COMb is not limited to the example shown in FIG. 6. Multiple candidates for the drive signal COMb, i.e., examples of the vibration pulse PB used to evaluate variations in the ejection characteristics of the nozzles N, are described in FIG. 8.

[0106] The operation of the liquid ejection device 100 is not limited to the example shown in FIG. 6. For example, while FIG. 6 illustrates an example in which one drive signal COM is used to eject ink from the nozzle N, the present invention is not limited to this embodiment. For example, a plurality of drive signals COM corresponding to the size of the dots may be used as the drive signal COM to eject ink from the nozzle N. Furthermore, the plurality of drive signals COM may include a drive signal COM having a micro-vibration waveform that generates residual vibration for detecting ejection abnormalities. Note that if a process for detecting residual vibration of an ejection section D targeted for ejection abnormality detection is executed during a period other than the printing process period, the ejection abnormality of the nozzle N may be detected based on the residual vibration detected using the drive signal COMa or COMb.

[0107] In the example shown in FIG. 6, the reference potential of the drive signal COMb is the same potential VC as the reference potential of the drive signal COMa, but the reference potential of the drive signal COMb may be a potential different from the reference potential of the drive signal COMa.

[0108] Next, the operation of the analysis unit 3 will be described with reference to FIG.

[0109] Fig. 7 is a diagram showing an example of the waveform of the residual vibration signal VR. Fig. 7 schematically shows an example of the waveform of the residual vibration signal VR in continuous ejection and an example of the waveform of the residual vibration signal VR in discontinuous ejection. The vertical axis of the diagram represents the potential of the residual vibration signal VR, and the horizontal axis represents time.

[0110] For example, the residual vibration signal VR0 is a residual vibration signal VR that indicates the residual vibration resulting from consecutively executing ejection driving using the drive signal COMa. Furthermore, for example, the residual vibration signals VR1 and VR2 are residual vibration signals VR that indicate the residual vibration resulting from consecutively executing non-ejection driving using the drive signal COMb and ejection driving using the drive signal COMa in this order. Note that the waveform of the drive signal COMb used for the non-ejection driving, i.e., the waveform of the micro-vibration pulse PB, differs between the residual vibration signals VR1 and VR2. Hereinafter, the drive signal COMb used for the non-ejection driving when detecting the residual vibration signal VR1 will also be referred to as the first drive signal COMb, and the drive signal COMb used for the non-ejection driving when detecting the residual vibration signal VR2 will also be referred to as the second drive signal COMb.

[0111] For example, the difference between the residual vibration signal VR0 and the residual vibration signal VR1, and the difference between the residual vibration signal VR0 and the residual vibration signal VR2 indicate the degree of variation in the ejection characteristics between continuous ejection and discontinuous ejection. In the example shown in FIG. 7, the difference between the residual vibration signal VR0 and the residual vibration signal VR1 is smaller than the difference between the residual vibration signal VR0 and the residual vibration signal VR2. Therefore, in the example shown in FIG. 7, when the drive signal COMb used to detect the residual vibration signal VR1 is used, the variation in the ejection characteristics between continuous ejection and discontinuous ejection can be reduced compared to when the drive signal COMb used to detect the residual vibration signal VR2 is used. Note that the waveforms shown in FIG. 7 are waveforms for explaining the operation of the analysis unit 3, and do not accurately represent the relationship between the residual vibration of the vibration plate 14 caused by continuous ejection and the residual vibration of the vibration plate 14 caused by discontinuous ejection.

[0112] As described above, the residual vibration signal VR indicates a waveform corresponding to the residual vibration occurring in the ejection portion D to be detected, i.e., the residual vibration of the diaphragm 14. Specifically, the residual vibration signal VR indicates an amplitude corresponding to the amplitude of the residual vibration of the diaphragm 14, a period corresponding to the period of the residual vibration of the diaphragm 14, and a phase corresponding to the phase of the residual vibration of the diaphragm 14. Note that in FIG. 7, the same number as the number added to the end of the symbol of each element of the residual vibration signal VR, such as the amplitude, is added. For example, the amplitude λA0 indicates the amplitude λA of the first peak of the waveform of the residual vibration signal VR0, the amplitude λA1 indicates the amplitude λA of the first peak of the waveform of the residual vibration signal VR1, and the amplitude λA2 indicates the amplitude λA of the first peak of the waveform of the residual vibration signal VR2.

[0113] 7, the analysis unit 3 identifies the amplitude λA of the first peak of the residual vibration signal VR as the amplitude of the first peak of the residual vibration of the diaphragm 14, and identifies the amplitude λB of the second peak of the residual vibration signal VR as the amplitude of the second peak of the residual vibration of the diaphragm 14. Specifically, the analysis unit 3 identifies the amplitude λA0 of the first peak and the amplitude λB0 of the second peak of the residual vibration signal VR0 as the amplitude of the first peak and the amplitude of the second peak of the residual vibration of the diaphragm 14 caused by continuous ejection, respectively. Similarly, the analysis unit 3 identifies the amplitude λA1 of the first peak and the amplitude λB1 of the second peak of the residual vibration signal VR1 as the amplitude of the first peak and the amplitude of the second peak of the residual vibration of the diaphragm 14 caused by discontinuous ejection using the first drive signal COMb, respectively. In addition, the analysis unit 3 identifies the amplitude λA2 of the first peak and the amplitude λB2 of the second peak of the residual vibration signal VR2 as the amplitude of the first peak and the amplitude of the second peak of the residual vibration of the vibration plate 14 caused by the discontinuous ejection using the second drive signal COMb, respectively.

[0114] The method for determining the amplitude of the residual vibration signal VR is not particularly limited, and any known method can be used. The analysis unit 3 may also determine the amplitude λC0 of the third peak of the residual vibration signal VR0 as the amplitude of the third peak of the residual vibration of the vibration plate 14 resulting from continuous ejection. Similarly, the analysis unit 3 may also determine the amplitude λC1 of the third peak of the residual vibration signal VR1 as the amplitude of the third peak of the residual vibration of the vibration plate 14 resulting from discontinuous ejection using the first drive signal COMb. The analysis unit 3 may also determine the amplitude λC2 of the third peak of the residual vibration signal VR2 as the amplitude of the third peak of the residual vibration of the vibration plate 14 resulting from discontinuous ejection using the second drive signal COMb.

[0115] Furthermore, for example, the analysis unit 3 identifies the phase of the residual vibration signal VR as the phase of the residual vibration of the diaphragm 14. In this embodiment, for example, it is assumed that the time TA from the start of the unit period TU to the first peak of the residual vibration signal VR is identified as the first phase of the residual vibration signal VR. Furthermore, in this embodiment, it is assumed that the time TB from the start of the unit period TU to the second peak of the residual vibration signal VR is identified as the second phase of the residual vibration signal VR. Note that, for example, if the periods of multiple residual vibration signals VR are considered to be the same, the difference between the time TA of one residual vibration signal VR and the time TA of another residual vibration signal VR can be considered to be the shift amount of the other residual vibration signal VR relative to the one residual vibration signal VR.

[0116] Therefore, for example, the analysis unit 3 identifies times TA0 and TB0 of the residual vibration signal VR0 as the first and second phases, respectively, of the residual vibration of the diaphragm 14 resulting from continuous ejection. Similarly, the analysis unit 3 identifies times TA1 and TB1 of the residual vibration signal VR1 as the first and second phases, respectively, of the residual vibration of the diaphragm 14 resulting from discontinuous ejection using the first drive signal COMb. Furthermore, the analysis unit 3 identifies times TA2 and TB2 of the residual vibration signal VR2 as the first and second phases, respectively, of the residual vibration of the diaphragm 14 resulting from discontinuous ejection using the second drive signal COMb.

[0117] The method for identifying the phase of the residual vibration signal VR is not particularly limited, and any known method can be used.

[0118] The analysis section 3 outputs to the control unit 4, for example, residual vibration information Vinf indicating the amplitudes λA and λB of the residual vibration signal VR and the times TA and TB identified as the phase of the residual vibration signal VR.

[0119] The analysis unit 3 may, for example, identify the period of the residual vibration signal VR as the period of the residual vibration of the diaphragm 14. For example, the analysis unit 3 may identify the time from the first peak to the third peak of the residual vibration signal VR0 as the period of the residual vibration of the diaphragm 14 resulting from continuous ejection. Similarly, the analysis unit 3 may identify the time from the first peak to the third peak of the residual vibration signal VR1 as the period of the residual vibration of the diaphragm 14 resulting from discontinuous ejection using the first drive signal COMb. Furthermore, the analysis unit 3 may identify the time from the first peak to the third peak of the residual vibration signal VR2 as the period of the residual vibration of the diaphragm 14 resulting from discontinuous ejection using the second drive signal COMb. The method for identifying the period of the residual vibration signal VR is not particularly limited, and any known method may be employed. For example, when the analysis unit 3 identifies the period of the residual vibration signal VR, the analysis unit 3 outputs residual vibration information Vinf including information indicating the period of the residual vibration signal VR to the control unit 4.

[0120] Next, with reference to FIG. 8, an example of the drive signal COMb used to evaluate the variation in the ejection characteristics of the nozzles N will be described.

[0121] Fig. 8 is an explanatory diagram illustrating an example of a drive signal COMb used to evaluate variations in the ejection characteristics of the nozzle N. In the example shown in Fig. 8, residual vibration of the ejection section D[m] to be detected is detected in the third unit period TU3 of three consecutive unit periods TU.

[0122] As shown in Figure 8, in continuous ejection, in each of the first unit period TU1 and the second unit period TU2 of three consecutive unit periods TU, a drive signal COMa including a vibration pulse PA is supplied to the ejection section D[m] as an individual drive signal Vin[m].

[0123] In the discontinuous ejection, the drive signal COMb including the minute vibration pulse PB is supplied to the ejection unit D[m] as the individual drive signal Vin[m] in the unit period TU1, and the drive signal COMa including the vibration pulse PA is supplied to the ejection unit D[m] as the individual drive signal Vin[m] in the unit period TU2.

[0124] 8, the explanation will be centered on the drive signal COMb, i.e., the micro-vibration pulse PB, supplied to the discharge section D[m] as the individual drive signal Vin[m] in the unit period TU1. In the example shown in FIG. 8, five types of drive signals COMb are shown, from the first example to the fifth example. In FIG. 8, to make the explanation easier to understand, one of the numbers "1", "2", "3", "4", and "5" is added to the end of the symbols of the micro-vibration pulses PB in the first example to the fifth example.

[0125] 8, a drive signal COMb including a minute vibration pulse PB1 is supplied to the discharge section D[m] as an individual drive signal Vin[m]. The minute vibration pulse PB1 is a pulse with an amplitude A1 and a pulse width W1, and is applied to the piezoelectric element PZ of the discharge section D[m] at timing T1 within the unit period TU1.

[0126] In the second example, a drive signal COMb including a minute vibration pulse PB2 is supplied to the discharge section D[m] as an individual drive signal Vin[m]. The minute vibration pulse PB2 is a pulse with an amplitude A1 and a pulse width W2, and is applied to the piezoelectric element PZ of the discharge section D[m] at timing T1 within the unit period TU1. That is, in the second example, a minute vibration pulse PB2 with a pulse width W2 different from the pulse width W1 of the minute vibration pulse PB1 is applied to the piezoelectric element PZ of the discharge section D[m].

[0127] In the third example, a drive signal COMb including a micro-vibration pulse PB3 is supplied to the discharge section D[m] as an individual drive signal Vin[m]. The micro-vibration pulse PB3 is a pulse with an amplitude A2 and a pulse width W1, and is applied to the piezoelectric element PZ of the discharge section D[m] at timing T1 within the unit period TU1. That is, in the third example, a micro-vibration pulse PB3 with an amplitude A2 different from the amplitude A1 of the micro-vibration pulse PB1 is applied to the piezoelectric element PZ of the discharge section D[m].

[0128] In the fourth example, a drive signal COMb including a minute vibration pulse PB4 is supplied to the discharge section D[m] as an individual drive signal Vin[m]. The minute vibration pulse PB4 is a pulse with an amplitude A1 and a pulse width W1, and is applied to the piezoelectric element PZ of the discharge section D[m] at timing T2 within the unit period TU1. That is, in the fourth example, the minute vibration pulse PB4 is applied to the piezoelectric element PZ of the discharge section D[m] at timing T2, which is different from timing T1.

[0129] In the fifth example, a drive signal COMb including a minute vibration pulse PB5 is supplied to the discharge section D[m] as an individual drive signal Vin[m]. The minute vibration pulse PB5 includes two pulses PL1 and PL2 with an amplitude A1 and a pulse width W1. Hereinafter, the pulses PL1 and PL2 will also be referred to as pulses PL without any particular distinction. In the fifth example, a minute vibration pulse PB5 including a number of pulses PL different from the number of pulses included in the minute vibration pulse PB1 is applied to the piezoelectric element PZ of the discharge section D[m].

[0130] Here, the micro-vibration pulse PB1 is an example of a “first micro-vibration pulse”, and each of the micro-vibration pulses PB2, PB3, and PB5 is an example of a “second micro-vibration pulse”. Furthermore, the timing T1 is an example of a “first timing”, and the timing T2 is an example of a “second timing”.

[0131] Note that the drive signal COMb used to evaluate the variation in the ejection characteristics of the nozzles N, i.e., the candidates for the drive signal COMb, are not limited to the example shown in FIG. 8. For example, the drive signal COMb may include a micro-vibration pulse PB having a pulse width W2 different from the pulse width W1 of the micro-vibration pulse PB1, and an amplitude A2 different from the amplitude A1 of the micro-vibration pulse PB1. Also, for example, in the fifth example, one or both of the amplitude A1 and the pulse width W1 may be different between the two pulses Pb. Also, for example, in the fifth example, the micro-vibration pulse PB5 may include three or more pulses Pb. Also, for example, the micro-vibration pulse PB of the drive signal COMb may have a waveform in which the potential of the drive signal COMb changes from a potential VC to a potential lower than the potential VC and then returns to the potential VC.

[0132] Next, with reference to FIG. 9, the operation of the liquid ejection device 100 when evaluating variations in the ejection characteristics of the nozzles N will be described.

[0133] 9 is a flowchart showing an example of the operation of the liquid ejection device 100 when evaluating the variation in the ejection characteristics of the nozzles N. The timing at which the operation shown in FIG. 9 is performed is not particularly limited, but it is preferable that the operation be 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.

[0134] The operation shown in Fig. 9 is performed for each of the plurality of liquid ejection heads 1, for example. Furthermore, the nozzle N to be detected when evaluating the variation in the ejection characteristics of the nozzles N is a nozzle N that represents the M nozzles N. The nozzle N that represents the M nozzles N may be one nozzle N of the M nozzles N, or may be multiple nozzles N. When the nozzle N that represents the M nozzles N is multiple nozzles N, the operation shown in Fig. 9 is performed for each of the multiple nozzles N. In Figs. 9 and 10, the operation of the liquid ejection device 100 will be described assuming that the nozzle N that represents the M nozzles N is one nozzle N of the M nozzles N.

[0135] The control unit 4 functions as the evaluation control unit 40 in each of steps S100 to S152 shown in FIG. 9 and in step S200. The process of step S100 is executed, for example, in a state where the pressure chambers CV are 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 chambers CV are filled with ink to be used by the user. The process of filling the pressure chambers CV with ink may be executed by the evaluation control unit 40, or may be executed by a processing unit other than the evaluation control unit 40. The user is, for example, a user of the liquid ejection device 100. Furthermore, if 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.

[0136] First, in step S100, the evaluation control unit 40 executes continuous ejection in which ejection driving is continuous by the drive signal COMa that causes ink to be ejected from the nozzles N. For example, the evaluation control unit 40 controls the liquid ejection head 1 so that the piezoelectric element PZ of the ejection section D to be detected is driven by the drive signal COMa in each of the continuous unit periods TU. As a result, ejection driving is continuously executed by the drive signal COMa.

[0137] Next, in step S110, the evaluation control unit 40 detects the residual vibration of the ejection unit D to be detected immediately after the continuous ejection in step S100 is performed. For example, the evaluation control unit 40 causes the detection circuit 19 to detect the residual vibration from the piezoelectric element PZ of the ejection unit D to be detected in the unit period TU next to two consecutive unit periods TU in which the ejection drive was performed. As a result, the residual vibration of the diaphragm 14 caused by the continuous execution of the ejection drive is detected by the detection circuit 19. The residual vibration detected by the detection circuit 19 is then analyzed by the analysis unit 3. As a result, for example, the amplitudes λA0 and λB0 of the residual vibration signal VR0 and the times TA0 and TB0 indicating the phase of the residual vibration signal VR0 are identified as the analysis result of the residual vibration of the diaphragm 14 caused by the continuous execution of the ejection drive. The evaluation control unit 40 then acquires residual vibration information Vinf from the analysis unit 3 indicating the analysis result of the residual vibration detected by the detection circuit 19. The residual vibration detected in step S110 is an example of a “first residual vibration.”

[0138] Next, in step S120, the evaluation control unit 40 sets the variable i to 1. After executing the process of step S120, the evaluation control unit 40 moves the process to step S130.

[0139] In step S130, the evaluation control unit 40 performs discontinuous ejection using the i-th candidate micro-vibration pulse PB of the drive signal COMb. For example, the evaluation control unit 40 controls the liquid ejection head 1 so that the piezoelectric element PZ of the ejection portion D to be detected is driven by the i-th candidate micro-vibration pulse PB of the drive signal COMb in the first unit period TU of two consecutive unit periods TU. Then, the evaluation control unit 40 controls the liquid ejection head 1 so that the piezoelectric element PZ of the ejection portion D to be detected is driven by the drive signal COMa in the second unit period TU of the above-mentioned two consecutive unit periods TU. As a result, non-ejection driving by the i-th candidate of the drive signal COMb and ejection driving by the drive signal COMa are performed consecutively in this order.

[0140] Next, in step S140, the evaluation control unit 40 detects the residual vibration of the ejection unit D to be detected immediately after the discontinuous ejection in step S130 is performed. For example, the evaluation control unit 40 causes the detection circuit 19 to detect the residual vibration from the piezoelectric element PZ of the ejection unit D to be detected in the unit period TU following the second of the two consecutive unit periods TU described in step S130. As a result, the residual vibration of the diaphragm 14 resulting from the non-ejection drive and the ejection drive being performed consecutively in this order is detected by the detection circuit 19. The residual vibration detected by the detection circuit 19 is then analyzed by the analysis unit 3. As a result, for example, the amplitudes λAi and λBi of the residual vibration signal VRi and the times TAi and TBi indicating the phase of the residual vibration signal VRi are identified as the analysis results of the residual vibration of the diaphragm 14 resulting from the non-ejection drive and the ejection drive being performed consecutively in this order. The "i" at the end of each symbol for the residual vibration signal VRi, amplitudes λAi and λBi, and times TAi and TBi indicates that the residual vibration signal VR and the element of the residual vibration signal VR correspond to the i-th candidate for the drive signal COMb. The evaluation control 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. The residual vibration detected in step S140 is an example of a "second residual vibration."

[0141] Next, in step S150, the evaluation control unit 40 determines whether the variable i is at its final value. The final value of the variable i is, for example, the number of candidates for the drive signal COMb prepared in advance. That is, the evaluation control unit 40 determines whether residual vibration of the diaphragm 14 caused by discontinuous ejection has been detected for all of the drive signals COMb prepared in advance as candidates for the drive signal COMb.

[0142] If the result of the determination in step S150 is negative, the evaluation control unit 40 adds "1" to the variable i in step S152, and then returns the process to step S130. On the other hand, if the result of the determination in step S150 is positive, the evaluation control unit 40 moves the process to step S200.

[0143] In step S200, the evaluation control unit 40 performs a residual vibration comparison process. For example, for each candidate for the drive signal COMb, the evaluation control unit 40 compares the residual vibration of the diaphragm 14 caused by the continuous ejection detected in step S110 with the residual vibration of the diaphragm 14 caused by the discontinuous ejection detected in step S140. By performing the process of step S120, it is determined for each candidate for the drive signal COMb whether or not variations in the ejection characteristics of the nozzles N will occur, and the operation shown in FIG. 9 is then completed.

[0144] Next, the residual vibration comparison process executed in step S200 will be described with reference to FIG.

[0145] Fig. 10 is a flowchart showing an example of the comparison process of residual vibration shown in Fig. 9. A series of processes from step S210 to step S272 shown in Fig. 10 corresponds to the process of step S200 shown in Fig. 9. The control unit 4 functions as the evaluation control unit 40 in each of steps S210 to S272 shown in Fig. 10. The process of step S210 is executed when the result of the determination in step S150 shown in Fig. 9 is positive.

[0146] The operation shown in FIG. 10 uses the times TA0, TB0, TAi, and TBi and the amplitudes λA0, λB0, λAi, and λBi determined by the series of processes from step S100 to step S152 shown in FIG. 9. The time TA0, time TB0, amplitude λA0, and amplitude λB0 represent the first phase, second phase, first peak amplitude, and second peak amplitude of the residual vibration of the vibration plate 14 resulting from continuous ejection, respectively, and are determined by the process of step S110 shown in FIG. 9. The time TAi, time TBi, amplitude λAi, and amplitude λBi represent the first phase, second phase, first peak amplitude, and second peak amplitude of the residual vibration of the vibration plate 14 resulting from discontinuous ejection using the i-th candidate of the drive signal COMb, respectively. For example, the time TAi, time TBi, amplitude λAi, and amplitude λBi are determined by the process of step S140 shown in FIG. 9.

[0147] First, in step S210, the evaluation control unit 40 sets the variable i to 1. After executing the process of step S210, the evaluation control unit 40 moves the process to step S220.

[0148] In step S220, the evaluation control unit 40 determines whether the time TAi is 0.6 to 1.4 times the time TA0. The range of 0.6 to 1.4 times the time TA0 is an example of a "range based on the phase of the first residual vibration." That is, the evaluation control unit 40 determines whether the first phase of the residual vibration of the diaphragm 14 resulting from discontinuous ejection using the i-th candidate of the drive signal COMb is within a first phase range identified based on the first phase of the residual vibration of the diaphragm 14 resulting from continuous ejection. Note that the first phase range is not limited to the above example and may be appropriately set based on data obtained through experiments, etc. Furthermore, for example, the first phase range may be a range obtained by adding or subtracting a predetermined value from or to the time TA0. However, the determination in step S220 is preferably a determination of whether the time TA0 and the time TAi are relatively close to each other.

[0149] If the result of the determination in step S220 is negative, i.e., if the first phase of the residual vibration of the diaphragm 14 caused by discontinuous ejection is not included in the first phase range, the evaluation control unit 40 determines that there is variation in the ejection characteristics of the nozzle N, and proceeds to step S262. In step S262, the evaluation control unit 40 decides not to adopt the i-th candidate micro-vibration pulse PB of the drive signal COMb, and then proceeds to step S270. In this way, the evaluation control unit 40 evaluates the variation in the ejection characteristics of the nozzle N based on the first phase of the residual vibration of the diaphragm 14 caused by discontinuous ejection using the i-th candidate of the drive signal COMb, and the first phase of the residual vibration of the diaphragm 14 caused by continuous ejection.

[0150] On the other hand, if the result of the determination in step S220 is positive, that is, if the first phase of the residual vibration of the diaphragm 14 caused by discontinuous ejection is included in the first phase range, the evaluation control unit 40 proceeds to step S230.

[0151] In step S230, the evaluation control unit 40 determines whether the time TBi is 0.8 to 1.2 times the time TB0. The range of 0.8 to 1.2 times the time TB0 is another example of the "range based on the phase of the first residual vibration." That is, the evaluation control unit 40 determines whether the second phase of the residual vibration of the diaphragm 14 resulting from discontinuous ejection using the i-th candidate of the drive signal COMb is included in a second phase range determined based on the second phase of the residual vibration of the diaphragm 14 resulting from continuous ejection. Note that the second phase range is not limited to the above example and may be appropriately set based on data obtained through experiments, etc. Also, for example, the second phase range may be a range obtained by adding or subtracting a predetermined value from or to the time TB0. However, the determination in step S230 is preferably a determination of whether the time TB0 and the time TBi are relatively close to each other.

[0152] If the result of the determination in step S230 is negative, i.e., if the second phase of the residual vibration of the diaphragm 14 caused by discontinuous ejection is not included in the second phase range, the evaluation control unit 40 determines that there is variation in the ejection characteristics of the nozzle N, and proceeds to step S262. In this way, the evaluation control unit 40 evaluates the variation in the ejection characteristics of the nozzle N based on the second phase of the residual vibration of the diaphragm 14 caused by discontinuous ejection using the i-th candidate for the drive signal COMb, and the second phase of the residual vibration of the diaphragm 14 caused by continuous ejection.

[0153] On the other hand, if the result of the determination in step S230 is positive, that is, if the second phase of the residual vibration of the diaphragm 14 caused by discontinuous ejection is included in the second phase range, the evaluation control unit 40 proceeds to step S240.

[0154] In step S240, the evaluation control unit 40 determines whether the amplitude λAi is 0.5 to 1.5 times the amplitude λA0. The range of 0.5 to 1.5 times the amplitude λA0 is an example of a "first range." That is, the evaluation control unit 40 determines whether the amplitude of the first peak of the residual vibration of the diaphragm 14 resulting from discontinuous ejection using the i-th candidate of the drive signal COMb is within a first range specified based on the amplitude of the first peak of the residual vibration of the diaphragm 14 resulting from continuous ejection. Note that the first range is not limited to the above example and may be appropriately set based on data obtained through experiments, etc. Also, for example, the first range may be a range obtained by subtracting or adding a predetermined value from or to the amplitude λA0. However, it is preferable that the determination in step S240 be a determination of whether the amplitude λA0 and the amplitude λAi are relatively close in value.

[0155] If the result of the determination in step S240 is negative, i.e., if the amplitude of the first peak of the residual vibration of the diaphragm 14 caused by discontinuous ejection is not within the first range, the evaluation control unit 40 determines that there is variation in the ejection characteristics of the nozzle N, and proceeds to step S262. In this way, the evaluation control unit 40 evaluates the variation in the ejection characteristics of the nozzle N based on the amplitude of the first peak of the residual vibration of the diaphragm 14 caused by discontinuous ejection using the i-th candidate of the drive signal COMb, and the amplitude of the first peak of the residual vibration of the diaphragm 14 caused by continuous ejection.

[0156] On the other hand, if the result of the determination in step S240 is positive, that is, if the amplitude of the first peak of the residual vibration of the diaphragm 14 caused by discontinuous ejection is included in the first range, the evaluation control unit 40 proceeds to step S250.

[0157] In step S250, the evaluation control unit 40 determines whether the amplitude λBi is 0.7 to 1.3 times the amplitude λB0. The range of 0.7 to 1.3 times the amplitude λB0 is an example of a "second range." That is, the evaluation control unit 40 determines whether the amplitude of the second peak of the residual vibration of the diaphragm 14 resulting from discontinuous ejection using the i-th candidate of the drive signal COMb is within a second range specified based on the amplitude of the second peak of the residual vibration of the diaphragm 14 resulting from continuous ejection. Note that the second range is not limited to the above example and may be appropriately set based on data obtained through experiments, etc. Also, for example, the second range may be a range obtained by adding or subtracting a predetermined value from or to the amplitude λB0. However, it is preferable that the determination in step S250 be a determination of "whether the amplitude λB0 and the amplitude λBi are relatively close in value."

[0158] If the result of the determination in step S250 is negative, i.e., if the amplitude of the second peak of the residual vibration of the diaphragm 14 caused by discontinuous ejection is not within the second range, the evaluation control unit 40 determines that there is variation in the ejection characteristics of the nozzle N, and proceeds to step S262. In this way, the evaluation control unit 40 evaluates the variation in the ejection characteristics of the nozzle N based on the amplitude of the second peak of the residual vibration of the diaphragm 14 caused by discontinuous ejection using the i-th candidate of the drive signal COMb, and the amplitude of the second peak of the residual vibration of the diaphragm 14 caused by continuous ejection.

[0159] On the other hand, if the result of the judgment in step S250 is positive, that is, if the amplitude of the second peak of the residual vibration of the diaphragm 14 caused by discontinuous ejection is included in the second range, the evaluation control unit 40 judges that there is no variation in the ejection characteristics of the nozzle N, and proceeds to step S260.

[0160] In step S260, the evaluation control unit 40 determines the micro-vibration pulse PB of the i-th candidate for the drive signal COMb as the adopted candidate. That is, the evaluation control unit 40 determines the i-th candidate for the drive signal COMb as the adopted candidate if the waveform of the residual vibration of the diaphragm 14 caused by non-continuous ejection using the i-th candidate for the drive signal COMb matches or is similar to the waveform of the residual vibration of the diaphragm 14 caused by continuous ejection. After executing the process of step S260, the evaluation control unit 40 proceeds to step S270.

[0161] In step S270, the evaluation control unit 40 determines whether the variable i is the final value or not. That is, the evaluation control unit 40 determines whether the comparison of the residual vibrations detected by the series of processes from step S100 to step S152 shown in FIG. 9 has ended.

[0162] If the result of the determination in step S270 is negative, the evaluation control unit 40 adds "1" to the variable i in step S272, and then returns the process to step S220. On the other hand, if the result of the determination in step S270 is positive, the evaluation control unit 40 ends the operations shown in FIGS. 9 and 10.

[0163] In the evaluation of the variation in the ejection characteristics of nozzle N shown in FIG. 10, the first range is the range obtained by subtracting or adding the value obtained by multiplying the amplitude λA0 by the first coefficient "0.5" from or to the amplitude λA0. The second range is the range obtained by multiplying the amplitude λB0 by the second coefficient "0.3" from or to the amplitude λB0. The second coefficient is smaller than the first coefficient. Because the residual vibration decays, the amplitudes of the latter peaks of the residual vibration signal VR tend to be smaller than the amplitudes of the first peaks. When the actual data values ​​obtained as the peak amplitudes are large, the deviation in the measurement value when some measurement error occurs is larger than when the actual data values ​​obtained as the peak amplitudes are small. Therefore, by making the first coefficient larger than the second coefficient and allowing for a larger deviation in the first half of the peaks where the amplitudes of the peaks are large, the variation in the ejection characteristics of nozzle N can be evaluated with high accuracy. However, the relationship between the first coefficient and the second coefficient is not limited to the example described above. For example, the first coefficient and the second coefficient may be the same value.

[0164] It should be noted that the operation of the liquid ejection device 100 when evaluating the variation in the ejection characteristics of the nozzles N is not limited to the examples shown in Figures 9 and 10. For example, the process of step S120 shown in Figure 9 may be executed before the process of step S100.

[0165] Furthermore, for example, one, two, or three of the processes of steps S220, S230, S240, and S250 may be omitted. Alternatively, the evaluation control unit 40 may evaluate the variation in the ejection characteristics of the nozzles N based on the period of the residual vibration of the diaphragm 14 resulting from discontinuous ejection and the period of the residual vibration of the diaphragm 14 resulting from continuous ejection. When the process of evaluating the variation in the ejection characteristics of the nozzles N based on the period of the residual vibration is executed, some or all of the processes of steps S220, S230, S240, and S250 may be omitted.

[0166] Furthermore, for example, the evaluation control unit 40 may determine the waveform of the drive signal COMb, i.e., the waveform of the micro-vibration pulse PB, based on the results of evaluating the variations in the ejection characteristics of the nozzles N. For example, the evaluation control unit 40 may adopt the candidate for the drive signal COMb determined as the adopted candidate in the process shown in FIG. 10 as the drive signal COMb to be used in the actual printing process. That is, the evaluation control unit 40 may determine the waveform of the drive signal COMb, i.e., the waveform of the micro-vibration pulse PB, based on the residual vibration of the diaphragm 14 caused by continuous ejection and the residual vibration of the diaphragm 14 caused by discontinuous ejection. Furthermore, for example, when there are multiple candidates for the drive signal COMb determined as the adopted candidates, the evaluation control unit 40 may adopt one of the multiple adopted candidates as the drive signal COMb to be used in the actual printing process. Specifically, the evaluation control unit 40 may adopt, from among the multiple adopted candidates, the adopted candidate in which the waveform of the residual vibration of the diaphragm 14 caused by discontinuous ejection matches or is most similar to the waveform of the residual vibration of the diaphragm 14 caused by continuous ejection as the drive signal COMb. In this way, in this embodiment, by determining the waveform of the drive signal COMb based on the evaluation results of the variation in the ejection characteristics of the nozzle N, it is possible to easily suppress the occurrence of variation in the ejection characteristics between continuous ejection and discontinuous ejection.

[0167] As described above, in this embodiment, the liquid ejection device 100 comprises a liquid ejection head 1 including a nozzle N that ejects ink, a piezoelectric element PZ corresponding to the nozzle N, a vibration plate 14 that vibrates when the piezoelectric element PZ is driven, and a detection circuit 19 that detects residual vibration of the vibration plate 14 caused by the driving of the piezoelectric element PZ, and an evaluation control unit 40. The evaluation control unit 40 is capable of performing non-ejection drive, which drives the piezoelectric element PZ with a micro-vibration pulse PB that does not cause ink to be ejected from the nozzle N, and ejection drive, which drives the piezoelectric element PZ with a vibration pulse PA that generates in the vibration plate 14 a vibration greater than the vibration of the vibration plate 14 caused by the non-ejection drive, and causes the detection circuit 19 to detect residual vibration resulting from consecutively executing the ejection drives as a first residual vibration, and causes the detection circuit 19 to detect residual vibration resulting from consecutively driving the piezoelectric element PZ in the order of non-ejection drive and ejection drive as a second residual vibration, and evaluates the variation in the ejection characteristics of the nozzle N between the case where the ejection drives are consecutive and the case where the ejection drives are not consecutive, based on the first residual vibration and the second residual vibration detected by the detection circuit 19. The evaluation control unit 40 may also determine the waveform of the micro-vibration pulse PB based on the first residual vibration and the second residual vibration detected by the detection circuit 19.

[0168] As described above, in this embodiment, the evaluation control unit 40 evaluates the variation in the ejection characteristics of the nozzle N based on the first residual vibration resulting from consecutively executing the ejection drive and the second residual vibration resulting from consecutively driving the piezoelectric element PZ in the order of non-ejection drive and ejection drive. Therefore, in this embodiment, it is possible to appropriately and easily evaluate the variation in the ejection characteristics of the nozzle N between consecutive ejection drives and non-consecutive ejection drives. Furthermore, in this embodiment, the evaluation control unit 40 determines the waveform of the micro-vibration pulse PB based on the first residual vibration and the second residual vibration, thereby appropriately and easily determining the waveform of the drive signal COMb that drives the piezoelectric element PZ so as not to eject ink from the nozzle N. For example, in this embodiment, the evaluation control unit 40 determines the waveform of the drive signal COMb based on the evaluation result of the variation in the ejection characteristics of the nozzle N, thereby appropriately and easily determining the waveform of the drive signal COMb that does not cause the nozzle N to eject ink.

[0169] Furthermore, in this embodiment, the evaluation control unit 40 may evaluate the variation in the ejection characteristics of the nozzles N based on the phase of the first residual vibration and the phase of the second residual vibration. In this aspect as well, the evaluation of the variation in the ejection characteristics of the nozzles N can be performed appropriately and easily.

[0170] Furthermore, in this embodiment, the evaluation control unit 40 may determine that the ejection characteristics of the nozzle N vary when the phase of the second residual vibration is not included in a range based on the phase of the first residual vibration. In this aspect as well, it is possible to appropriately and easily perform evaluation of the variation in the ejection characteristics of the nozzle N. Furthermore, in this aspect, for example, by not adopting the micro-vibration pulse PB for which it has been determined that the ejection characteristics of the nozzle N vary as the micro-vibration pulse PB of the actual drive signal COMb, it is possible to appropriately and easily determine the waveform of the drive signal COMb.

[0171] Furthermore, in this embodiment, the evaluation control unit 40 may evaluate the variation in the ejection characteristics of the nozzles N based on the amplitude of the first residual vibration and the amplitude of the second residual vibration. In this aspect as well, the evaluation of the variation in the ejection characteristics of the nozzles N can be performed appropriately and easily.

[0172] Furthermore, in this embodiment, the evaluation control unit 40 may determine that the ejection characteristics of the nozzle N vary if the amplitude at the first peak of the second residual vibration is not included in a first range based on the amplitude at the first peak of the first residual vibration. In this aspect as well, it is possible to appropriately and easily evaluate the variation in the ejection characteristics of the nozzle N. Furthermore, in this aspect as well, by not adopting the micro-vibration pulse PB for which it has been determined that the ejection characteristics of the nozzle N vary as the micro-vibration pulse PB of the actual drive signal COMb, it is possible to appropriately and easily determine the waveform of the drive signal COMb.

[0173] Furthermore, in this embodiment, the evaluation control unit 40 may determine that the ejection characteristics of the nozzle N vary if the amplitude at the second peak of the second residual vibration is not included in a second range based on the amplitude at the second peak of the first residual vibration. In this aspect as well, it is possible to appropriately and easily evaluate the variation in the ejection characteristics of the nozzle N.

[0174] Furthermore, in this embodiment, the first range may be a range obtained by multiplying the amplitude at the first peak of the first residual vibration by a first coefficient, and then subtracting or adding the result to or from the amplitude at the first peak of the first residual vibration. The second range may be a range obtained by multiplying the amplitude at the second peak of the first residual vibration by a second coefficient, and then subtracting or adding the result to or from the amplitude at the second peak of the first residual vibration. The second coefficient is smaller than the first coefficient. In this aspect, too, it is possible to appropriately and easily evaluate the variation in the ejection characteristics of nozzle N. Furthermore, in this aspect, because the second coefficient is smaller than the first coefficient, it is possible to accurately evaluate the presence or absence of variation in the ejection characteristics of nozzle N.

[0175] Furthermore, in this embodiment, the evaluation control unit 40 may evaluate the variation in the ejection characteristics of the nozzle N using the micro-vibration pulse PB1 as the micro-vibration pulse PB, and may further evaluate the variation in the ejection characteristics of the nozzle N using the micro-vibration pulse PB2 having a pulse width W2 different from the pulse width W1 of the micro-vibration pulse PB1 as the micro-vibration pulse PB. In this aspect as well, the evaluation of the variation in the ejection characteristics of the nozzle N can be performed appropriately and easily. Furthermore, in this aspect, it is possible to easily determine whether it is better to adopt the micro-vibration pulse PB1 or the micro-vibration pulse PB2 as the micro-vibration pulse PB.

[0176] Furthermore, in this embodiment, the evaluation control unit 40 may evaluate the variation in the ejection characteristics of the nozzle N using the micro-vibration pulse PB1 as the micro-vibration pulse PB, and may further evaluate the variation in the ejection characteristics of the nozzle N using the micro-vibration pulse PB3 having an amplitude A2 different from the amplitude A1 of the micro-vibration pulse PB1 as the micro-vibration pulse PB. In this aspect as well, the evaluation of the variation in the ejection characteristics of the nozzle N can be performed appropriately and easily. Furthermore, in this aspect, it is possible to easily determine whether it is better to adopt the micro-vibration pulse PB1 or the micro-vibration pulse PB3 as the micro-vibration pulse PB.

[0177] Furthermore, in this embodiment, the evaluation control unit 40 performs non-ejection driving by applying the micro-vibration pulse PB to the piezoelectric element PZ at timing T1 within the unit period TU for driving the piezoelectric element PZ, thereby evaluating the variation in the ejection characteristics of the nozzle N, and further performs non-ejection driving by applying the micro-vibration pulse PB to the piezoelectric element PZ at timing T2 different from timing T1 within the unit period TU, thereby evaluating the variation in the ejection characteristics of the nozzle N. In this aspect as well, it is possible to appropriately and easily evaluate the variation in the ejection characteristics of the nozzle N. Furthermore, in this aspect, it is possible to easily determine whether it is better to apply the micro-vibration pulse PB to the piezoelectric element PZ at timing T1 or to apply the micro-vibration pulse PB to the piezoelectric element PZ at timing T2.

[0178] Furthermore, in this embodiment, the evaluation control unit 40 may evaluate the variation in the ejection characteristics of the nozzle N using the micro-vibration pulse PB1 including at least one pulse as the micro-vibration pulse PB, and may further evaluate the variation in the ejection characteristics of the nozzle N using the micro-vibration pulse PB5 including a number of pulses Pb different from the number of pulses included in the micro-vibration pulse PB1 as the micro-vibration pulse PB. In this aspect as well, the evaluation of the variation in the ejection characteristics of the nozzle N can be performed appropriately and easily. Furthermore, in this aspect, it is possible to easily determine whether it is better to adopt the micro-vibration pulse PB1 or the micro-vibration pulse PB5 as the micro-vibration pulse PB.

[0179] Furthermore, in this embodiment, the vibration pulse PA is a pulse that causes ink to be ejected from the nozzle N. In this aspect as well, it is possible to appropriately and easily evaluate the variation in the ejection characteristics of the nozzle N. Furthermore, in this aspect, because the vibration pulse PA is a pulse that causes ink to be ejected from the nozzle N, it is possible to evaluate the variation in the ejection characteristics of the nozzle N under conditions that are close to actual ejection conditions. As a result, in this aspect, it is possible to accurately evaluate whether or not there is variation in the ejection characteristics of the nozzle N.

[0180] [2. Modifications] Each of the above embodiments can be modified in various ways. Specific modified embodiments are exemplified below. Two or more embodiments arbitrarily selected from the following examples can be combined as appropriate within a range that does not contradict each other. In the modified examples exemplified below, elements whose actions and functions are equivalent to those of the embodiments will be designated by the same reference numerals as in the above description, and detailed descriptions of each will be omitted as appropriate.

[0181] [First Modification] In the above-described embodiment, a case was illustrated in which residual vibration resulting from consecutively executing ejection driving is detected as the first residual vibration, but the present invention is not limited to this example. For example, the evaluation control unit 40 may cause the detection circuit 19 to detect, as the first residual vibration, residual vibration resulting from consecutively executing vibration driving in which the piezoelectric element PZ is driven with a vibration pulse that does not cause ink to be ejected from the nozzle N. Note that the vibration pulse described above is a pulse that generates in the vibration plate 14 a vibration that is greater than the vibration of the vibration plate 14 caused by non-ejection driving in which the piezoelectric element PZ is driven with a minute vibration pulse PB. This modification can also achieve the same effects as the above-described embodiment. Furthermore, in this modification, ink is not ejected from the nozzle N when evaluating the variation in the ejection characteristics of the nozzle N, so the amount of ink consumed in evaluating the variation in the ejection characteristics of the nozzle N can be reduced.

[0182] [Second Modification] In the above-described embodiment, an example was given of a case in which the variation in the ejection characteristics of the nozzle N is evaluated based on the first residual vibration and the second residual vibration detected by the detection circuit 19, but the present invention is not limited to this form.

[0183] For example, in this modified example, the evaluation control unit 40 causes the detection circuit 19 to detect the residual vibration resulting from three consecutive executions of the ejection drive as the first residual vibration. Specifically, for example, in the continuous ejection shown in Fig. 8, the evaluation control unit 40 supplies the drive signal COMa including the vibration pulse PA as the individual drive signal Vin[m] to the ejection unit D[m] in the unit period TU immediately preceding the unit period TU1. As a result, in the unit period TU3 shown in Fig. 8, the residual vibration resulting from three consecutive executions of the ejection drive is detected as the first residual vibration.

[0184] Furthermore, the evaluation control unit 40 causes the detection circuit 19 to detect, as the second residual vibration, the residual vibration resulting from driving the piezoelectric element PZ consecutively in the order of non-ejection drive, non-ejection drive, and ejection drive. Specifically, for example, in the discontinuous ejection shown in Fig. 8, the evaluation control unit 40 supplies the drive signal COMb including the micro-vibration pulse PB as the individual drive signal Vin[m] to the ejection unit D[m] in the unit period TU immediately before the unit period TU1. As a result, in the unit period TU3 shown in Fig. 8, the residual vibration resulting from consecutively executing non-ejection drive, non-ejection drive, and ejection drive in this order is detected as the second residual vibration.

[0185] Furthermore, the evaluation control unit 40 causes the detection circuit 19 to detect, as the third residual vibration, the residual vibration resulting from successively driving the piezoelectric element PZ in the order of non-ejection drive, ejection drive, and ejection drive. Specifically, for example, in the continuous ejection shown in Fig. 8, the evaluation control unit 40 supplies the drive signal COMb including the micro-vibration pulse PB as the individual drive signal Vin[m] to the ejection unit D[m] in the unit period TU immediately before the unit period TU1. As a result, in the unit period TU3 shown in Fig. 8, the residual vibration resulting from successively executing non-ejection drive, ejection drive, and ejection drive in this order is detected as the third residual vibration.

[0186] The evaluation control unit 40 then evaluates the variation in the ejection characteristics of the nozzle N based on the first residual vibration, the second residual vibration, and the third residual vibration detected by the detection circuit 19. Note that in this modified example, as in the first modified example described above, vibration driving that does not cause ink to be ejected from the nozzle N may also be performed instead of ejection driving.

[0187] As described above, in this modification, the same effects as those of the above-described embodiment and modification can be obtained.

[0188] [Third Modification] In the above-described embodiment, the drive signal COM for detecting an ejection abnormality in the nozzle N may be supplied from the drive signal generation unit 2 to the liquid ejection head 1.

[0189] Fig. 11 is a block diagram showing an example of the configuration of a liquid ejection head 1 according to a third modified example. The liquid ejection head 1 shown in Fig. 11 is similar to the liquid ejection head 1 shown in Fig. 5, except that a drive signal COMc for detecting ejection abnormalities in a nozzle N is supplied from a drive signal generation unit 2. Specifically, the liquid ejection head 1 shown in Fig. 11 is similar to the liquid ejection head 1 shown in Fig. 5, except that it has a switching circuit 18A instead of the switching circuit 18 shown in Fig. 5.

[0190] 5, except that a wiring Lc to which a drive signal COMc is supplied from the drive signal generating unit 2 and M switches SWc[1] to SWb[M] corresponding one-to-one to the M discharge sections D[1] to D[M] are added to the switching circuit 18. However, the connection state specifying circuit CSC generates connection state specifying signals Qa[m], Qb[m], Qc[m], and Qs[m] based on at least some of the print signal SI, latch signal LAT, and period specifying signal Tsig supplied from the control unit 4.

[0191] The switch SWc[m] switches between conduction and non-conduction between the wiring Lc and the individual electrode Za[m] of the piezoelectric element PZ[m] provided in the discharge section D[m] based on the connection state designation signal Qc[m]. That is, the switch SWc[m] switches between conduction and non-conduction between the wiring Lc and the wiring Li[m] connected to the individual electrode Za[m] based on the connection state designation signal Qc[m]. In this modified example, the switch SWc[m] is turned on when the connection state designation signal Qc[m] is at a high level and turned off when it is at a low level. When the switch SWc[m] is turned on, the drive signal COMc supplied to the wiring Lc is supplied as an individual drive signal Vin[m] to the individual electrode Za[m] of the discharge section D[m] via the wiring Li[m].

[0192] Next, the operation of the liquid ejection device 100 according to the third modified example will be described with reference to FIG.

[0193] Fig. 12 is a timing chart showing an example of the operation of the liquid ejection device 100 according to the third modified example. The operation of the connection state specification circuit CSC and the like when the drive mode of the ejection unit D that forms dots, the ejection unit D that does not form dots, and the ejection unit D that is the detection target when evaluating variations in the ejection characteristics of the nozzle N is specified by the individual specification signal Sd[m] is the same as the operation described in Fig. 6. For this reason, Fig. 12 describes the operation of the connection state specification circuit CSC and the like when the drive mode of the ejection unit D that is the detection target for ejection abnormalities of the nozzle N is specified by the individual specification signal Sd[m].

[0194] For example, the drive signal generation unit 2 outputs a drive signal COMc having a pulse PS. The pulse PS has a waveform in which the potential of the drive signal COMc changes from a potential VC to a potential VLs lower than the potential VC, passes through a potential VHs higher than the potential VC, and returns to the potential VC. In this modification, the pulse PS is determined so that the potential difference between the potential VHs, which is the highest potential of the pulse PS, and the potential VLs, which is the lowest potential, is smaller than the potential difference between the potential VHa, which is the highest potential of the vibration pulse PA, and the potential VLa, which is the lowest potential. Specifically, when the drive signal COMc having the pulse PS is supplied to the ejection section D[m], the waveform of the pulse PS is determined so that the ejection section D[m] is driven to such an extent that ink is not ejected from the ejection section D[m]. As described above, the start and end potentials of the pulse PS are set to the potential VC.

[0195] The control unit 4 also outputs a period defining signal Tsig having a pulse PLSt1 and a pulse PLSt2, thereby dividing the unit period TU into a control period TSS1 from the start of the pulse PlsL to the start of the pulse PLSt1, a control period TSS2 from the start of the pulse PLSt1 to the start of the pulse PLSt2, and a control period TSS3 from the start of the pulse PLSt2 to the start of the next pulse PlsL.

[0196] For example, when the individual designation signal Sd[m] designates the discharge section D[m] as the discharge section D for which discharge abnormalities are to be detected, the connection state designation circuit CSC sets the connection state designation signals Qa[m] and Qb[m] to a low level during the unit period TU. The connection state designation circuit CSC also sets the connection state designation signal Qc[m] to a high level during the control periods TSS1 and TSS3, and to a low level during the control period TSS2. The connection state designation circuit CSC also sets the connection state designation signal Qs[m] to a low level during the control periods TSS1 and TSS3, and to a high level during the control period TSS2.

[0197] In this case, the piezoelectric element PZ[m] of the discharge section D[m] to be detected for discharge abnormalities is driven by the pulse PS of the drive signal COMc during the control period TSS1. Specifically, the piezoelectric element PZ[m] is displaced by the pulse PS of the drive signal COMc during the control period TSS1. As a result, vibration occurs in the discharge section D[m] to be detected. The vibration generated during the control period TSS1 remains during the control period TSS2. Then, during the control period TSS2, the potential of the individual electrode Za[m] of the piezoelectric element PZ[m] of the discharge section D[m] to be detected changes depending on the residual vibration generated in the discharge section D[m]. That is, during the control period TSS2, the potential of the individual electrode Za of the piezoelectric element PZ of the discharge section D to be detected becomes a potential corresponding to the electromotive force of the piezoelectric element PZ caused by the residual vibration generated in the discharge section D to be detected. Then, the potential of the individual electrode Za is detected as the detection signal Vout during the control period TSS2.

[0198] 12 illustrates an example in which the detection signal Vout indicating the residual vibration of the ejection section D that is the target of ejection abnormality detection is generated during the printing process period, but the detection signal Vout may be generated during a period other than the printing process period. In other words, the process of detecting the residual vibration of the ejection section D that is the target of ejection abnormality detection may be executed during a period other than the printing process period.

[0199] As described above, this modification can also achieve the same effects as the above-described embodiment. Furthermore, this modification can detect ejection abnormalities in the nozzle N based on the residual vibration detected using the drive signal COMc.

[0200] [Fourth Modification] In the above-described embodiment and modified examples, waveform information indicating candidates for drive signal COMb 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 candidates for drive signal COMb 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 candidates for drive signal COMb prepared by the head manufacturer is read from a storage unit 5 or the like in which waveform information indicating candidates for drive signal COMb is stored when the operation shown in FIG. 9 is performed.

[0201] As described above, in this modified example, the same effects as those of the above-described embodiment can be obtained.

[0202] [Fifth 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 determines the phase and amplitude of the residual vibration of the diaphragm 14 resulting from continuous ejection and the phase and amplitude of the residual vibration of the diaphragm 14 resulting from discontinuous ejection. The control unit of the external server then compares the residual vibration of the diaphragm 14 resulting from continuous ejection with the residual vibration of the diaphragm 14 resulting from discontinuous ejection based on the identification result. The control unit of the external server determines whether or not there is variation in the ejection characteristics of the nozzle N based on the comparison result between the residual vibration of the diaphragm 14 resulting from continuous ejection and the residual vibration of the diaphragm 14 resulting from discontinuous ejection. The control unit of the external server may then transmit to the liquid ejection device 100 an analysis result indicating the presence or absence of variation in the ejection characteristics of the nozzle N. Alternatively, the control unit of the external server may identify which drive signal COMb should be used to suppress the occurrence of variation in the ejection characteristics of the nozzle N based on the comparison result between the residual vibration of the diaphragm 14 resulting from continuous ejection and the residual vibration of the diaphragm 14 resulting from discontinuous ejection. The control unit of the external server may then transmit information indicating the identification result to the liquid ejection device 100.

[0203] As described above, in this modified example, the same effects as those of the above-described embodiment can be obtained.

[0204] [Sixth 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[m] changes from low to high, but the present invention is not limited to this example. 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[m] changes from high to low. In this case, for example, the potential of the drive signal COM changes from low to high in the portion corresponding to the expansion element, and from high to low in the portion corresponding to the contraction element. This modified example can also achieve the same effects as the above-described embodiment and modified example.

[0205] [Seventh Modification] In the above-described embodiment and modified example, one piezoelectric element PZ, one pressure chamber CV, and one nozzle N are provided for one discharge portion D, but the present invention is not limited to this. For example, one discharge portion D may have two piezoelectric elements PZ, two pressure chambers CV, and one nozzle N. As described above, in this modified example, the same effects as those of the above-described embodiment and modified example can be obtained.

[0206] [Eighth 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 N 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.

[0207] [Ninth Variation] 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.

[0208] [3. Notes] From the above-described exemplary embodiments, the following configurations can be understood, for example.

[0209] A liquid ejection device according to a preferred aspect, aspect 1, comprises a liquid ejection head including a nozzle for ejecting liquid, a piezoelectric element corresponding to the nozzle, a vibration plate that vibrates when the piezoelectric element is driven, and a detection unit that detects residual vibration of the vibration plate caused by driving the piezoelectric element; and a control unit, wherein the control unit is capable of performing micro-vibration drive, which drives the piezoelectric element with a micro-vibration pulse that does not cause liquid to be ejected from the nozzle, and vibration drive, which drives the piezoelectric element with a vibration pulse that generates a vibration in the vibration plate that is greater than the vibration of the vibration plate caused by the micro-vibration drive, and causes the detection unit to detect the residual vibration caused by continuously performing the vibration drive as a first residual vibration, and causes the detection unit to detect the residual vibration caused by continuously driving the piezoelectric element in the order of the micro-vibration drive and the vibration drive as a second residual vibration, and evaluates the variation in the ejection characteristics of the nozzle between when the vibration drive is continuous and when the vibration drive is not continuous based on the first residual vibration and the second residual vibration detected by the detection unit. According to the first aspect, it is possible to appropriately and easily evaluate the variations in the ejection characteristics of the nozzles.

[0210] In the liquid ejection device according to Aspect 2, which is a specific example of Aspect 1, the control unit evaluates the variation in the ejection characteristics of the nozzles based on the phase of the first residual vibration and the phase of the second residual vibration. In the second aspect as well, the variation in the ejection characteristics of the nozzles N can be evaluated appropriately and easily.

[0211] In a liquid ejection device according to aspect 3, which is a specific example of aspect 2, the control unit determines that the ejection characteristics of the nozzle vary when the phase of the second residual vibration is not included in a range based on the phase of the first residual vibration. In the third aspect as well, it is possible to appropriately and easily evaluate the variations in the ejection characteristics of the nozzles.

[0212] In a liquid ejection device according to aspect 4, which is a specific example of any one of aspects 1 to 3, the control unit evaluates the variation in the ejection characteristics of the nozzle based on the amplitude of the first residual vibration and the amplitude of the second residual vibration. In the fourth aspect as well, the variation in the ejection characteristics of the nozzles N can be appropriately and easily evaluated.

[0213] In a liquid ejection device according to aspect 5, which is a specific example of aspect 4, the control unit determines that the ejection characteristics of the nozzle vary if the amplitude at the first peak of the second residual vibration is not within a first range based on the amplitude at the first peak of the first residual vibration. In the fifth aspect as well, it is possible to appropriately and easily evaluate the variations in the ejection characteristics of the nozzles.

[0214] In a liquid ejection device according to aspect 6, which is a specific example of aspect 5, the control unit determines that the ejection characteristics of the nozzle vary if the amplitude at the second peak of the second residual vibration is not within a second range based on the amplitude at the second peak of the first residual vibration. In the sixth aspect as well, it is possible to appropriately and easily evaluate the variations in the ejection characteristics of the nozzles.

[0215] In a liquid ejection device according to aspect 7, which is a specific example of aspect 6, the first range is a range obtained by subtracting or adding the value obtained by multiplying the amplitude at the first peak of the first residual vibration by a first coefficient to the amplitude at the first peak of the first residual vibration, and the second range is a range obtained by multiplying the value obtained by multiplying the amplitude at the second peak of the first residual vibration by a second coefficient to the amplitude at the second peak of the first residual vibration, and the second coefficient is smaller than the first coefficient. Also in aspect 7, it is possible to appropriately and easily evaluate the variation in the ejection characteristics of the nozzles. Furthermore, in this aspect, since the second coefficient is smaller than the first coefficient, it is possible to accurately evaluate whether or not there is variation in the ejection characteristics of the nozzles.

[0216] In a liquid ejection device according to aspect 8, which is a specific example of any one of aspects 1 to 7, the control unit evaluates the variation in the ejection characteristics of the nozzle using a first micro-vibration pulse as the micro-vibration pulse, and further evaluates the variation in the ejection characteristics of the nozzle using a second micro-vibration pulse having a pulse width different from the pulse width of the first micro-vibration pulse as the micro-vibration pulse. Also in the eighth aspect, it is possible to appropriately and easily evaluate the variation in the ejection characteristics of the nozzles. Furthermore, in this aspect, it is possible to easily determine whether it is better to adopt the first vibration pulse as the vibration pulse or the second vibration pulse as the vibration pulse.

[0217] In a liquid ejection device according to aspect 9, which is a specific example of any one of aspects 1 to 8, the control unit evaluates the variation in the ejection characteristics of the nozzle using a first micro-vibration pulse as the micro-vibration pulse, and further evaluates the variation in the ejection characteristics of the nozzle using a third micro-vibration pulse having an amplitude different from that of the first micro-vibration pulse as the micro-vibration pulse. Also in the ninth aspect, it is possible to appropriately and easily evaluate the variation in the ejection characteristics of the nozzles. Also, in this aspect, it is possible to easily determine whether it is better to adopt the first vibration pulse as the vibration pulse or the third vibration pulse as the vibration pulse.

[0218] In a liquid ejection device according to aspect 10, which is a specific example of any one of aspects 1 to 9, the control unit performs the micro-vibration drive by applying the micro-vibration pulse to the piezoelectric element at a first timing within a unit period for driving the piezoelectric element, thereby evaluating the variation in the ejection characteristics of the nozzle, and further performs the micro-vibration drive by applying the micro-vibration pulse to the piezoelectric element at a second timing different from the first timing within the unit period, thereby evaluating the variation in the ejection characteristics of the nozzle. In aspect 10, it is also possible to appropriately and easily evaluate the variation in the ejection characteristics of the nozzles. Furthermore, in this aspect, it is possible to easily determine whether it is better to apply the micro-vibration pulse to the piezoelectric element at the first timing or the second timing.

[0219] In a liquid ejection device according to aspect 11, which is a specific example of any one of aspects 1 to 10, the control unit evaluates the variation in the ejection characteristics of the nozzle using a fourth micro-vibration pulse including at least one pulse as the micro-vibration pulse, and further evaluates the variation in the ejection characteristics of the nozzle using a fifth micro-vibration pulse including a number of pulses different from the number of pulses included in the fourth micro-vibration pulse as the micro-vibration pulse. Also in the eleventh aspect, it is possible to appropriately and easily evaluate the variation in the ejection characteristics of the nozzles. Also, in this aspect, it is possible to easily determine whether it is better to adopt the fourth vibration pulse as the vibration pulse or the fifth vibration pulse as the vibration pulse.

[0220] In the liquid ejection device according to aspect 12, which is a specific example of any one of aspects 1 to 11, the control unit causes the detection unit to detect the residual vibration resulting from performing the vibration drive three times in succession as the first residual vibration, causes the detection unit to detect the residual vibration resulting from driving the piezoelectric element in succession in the order of the micro-vibration drive, the micro-vibration drive, and the vibration drive as the second residual vibration, causes the detection unit to detect the residual vibration resulting from driving the piezoelectric element in succession in the order of the micro-vibration drive, the vibration drive, and the vibration drive as the third residual vibration, and evaluates the variation in the ejection characteristics of the nozzle based on the first residual vibration, the second residual vibration, and the third residual vibration detected by the detection unit. In the twelfth aspect as well, it is possible to appropriately and easily evaluate the variations in the ejection characteristics of the nozzles.

[0221] In a liquid ejection device according to Aspect 13, which is a specific example of any one of Aspects 1 to 12, the vibration pulse is a pulse that ejects liquid from the nozzle. Aspect 13 also makes it possible to appropriately and easily evaluate the variation in the nozzle ejection characteristics. Furthermore, in this aspect, the variation in the nozzle ejection characteristics can be evaluated under conditions that are close to the actual ejection conditions, making it possible to accurately evaluate whether or not there is variation in the nozzle ejection characteristics.

[0222] Furthermore, a liquid ejection device according to aspect 14, which is another preferred aspect, comprises a liquid ejection head including a nozzle for ejecting liquid, a piezoelectric element corresponding to the nozzle, a vibration plate that vibrates when the piezoelectric element is driven, and a detection unit that detects residual vibration of the vibration plate caused by driving the piezoelectric element, and a control unit, wherein the control unit is capable of performing micro-vibration drive, which drives the piezoelectric element with a micro-vibration pulse that does not cause liquid to be ejected from the nozzle, and vibration drive, which drives the piezoelectric element with a vibration pulse that generates a vibration in the vibration plate that is greater than the vibration of the vibration plate caused by the micro-vibration drive, and causes the detection unit to detect the residual vibration caused by consecutively performing the vibration drive as a first residual vibration, and causes the detection unit to detect the residual vibration caused by consecutively driving the piezoelectric element in the order of the micro-vibration drive and the vibration drive as a second residual vibration, and determines the waveform of the micro-vibration pulse based on the first residual vibration and the second residual vibration detected by the detection unit. According to the fourteenth aspect, it is possible to appropriately and easily determine the waveform of the minute vibration pulse that drives the piezoelectric element so as not to eject liquid from the nozzle.

[0223] Furthermore, a control method for a liquid ejection device according to aspect 15, which is a preferred aspect, is a control method for a liquid ejection device having a liquid ejection head including a nozzle that ejects liquid, a piezoelectric element corresponding to the nozzle, a vibration plate that vibrates when the piezoelectric element is driven, and a detection unit that detects residual vibration of the vibration plate caused by driving the piezoelectric element, and is capable of performing micro-vibration drive that drives the piezoelectric element with a micro-vibration pulse that does not cause liquid to be ejected from the nozzle, and vibration drive that drives the piezoelectric element with a vibration pulse that generates a vibration in the vibration plate that is greater than the vibration of the vibration plate caused by the micro-vibration drive, and the detection unit detects the residual vibration caused by continuously performing the vibration drive as a first residual vibration, and detects the residual vibration caused by continuously driving the piezoelectric element in the order of the micro-vibration drive and the vibration drive as a second residual vibration, and evaluates the variation in the ejection characteristics of the nozzle between when the vibration drive is continuous and when the vibration drive is not continuous based on the first residual vibration and the second residual vibration detected by the detection unit. In the fifteenth aspect as well, it is possible to appropriately and easily evaluate the variations in the ejection characteristics of the nozzles.

[0224] Furthermore, a control method for a liquid ejection device according to aspect 16, which is another preferred aspect, is a control method for a liquid ejection device having a liquid ejection head including a nozzle that ejects liquid, a piezoelectric element corresponding to the nozzle, a vibration plate that vibrates when the piezoelectric element is driven, and a detection unit that detects residual vibration of the vibration plate caused by driving the piezoelectric element, and is capable of performing micro-vibration drive that drives the piezoelectric element with a micro-vibration pulse that does not cause liquid to be ejected from the nozzle, and vibration drive that drives the piezoelectric element with a vibration pulse that generates a vibration in the vibration plate that is greater than the vibration of the vibration plate caused by the micro-vibration drive, and the detection unit detects the residual vibration caused by continuously performing the vibration drives as a first residual vibration, and detects the residual vibration caused by continuously driving the piezoelectric element in the order of the micro-vibration drive and the vibration drive as a second residual vibration, and determines the waveform of the micro-vibration pulse based on the first residual vibration and the second residual vibration detected by the detection unit. In the sixteenth aspect as well, it is possible to appropriately and easily determine the waveform of the minute vibration pulse that drives the piezoelectric element so as not to eject liquid from the nozzle. [Explanation of symbols]

[0225] 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...evaluation control unit, 60...ink container, 100...liquid ejection device, CV...pressure chamber, D...ejection unit, N...nozzle, PP...medium, PZ...piezoelectric element.

Claims

1. a liquid ejection head including a nozzle for ejecting a liquid, a piezoelectric element corresponding to the nozzle, a vibration plate that vibrates when the piezoelectric element is driven, and a detection unit that detects residual vibration of the vibration plate caused by the driving of the piezoelectric element; A control unit; Equipped with The control unit micro-vibration driving is capable of driving the piezoelectric element with a micro-vibration pulse that does not cause liquid to be ejected from the nozzle, and vibration driving is capable of driving the piezoelectric element with a vibration pulse that generates in the vibration plate a vibration that is greater than the vibration of the vibration plate caused by the micro-vibration driving, causing the detection unit to detect the residual vibration resulting from continuous execution of the vibration driving as a first residual vibration; the residual vibration resulting from successively driving the piezoelectric element in the order of the micro-vibration driving and the vibration driving is detected by the detection unit as a second residual vibration; evaluating a variation in the ejection characteristics of the nozzle between a case where the vibration driving is continuous and a case where the vibration driving is not continuous, based on the first residual vibration and the second residual vibration detected by the detection unit; A liquid ejection device characterized by:

2. The control unit evaluating the variation in the ejection characteristics of the nozzles based on the phase of the first residual vibration and the phase of the second residual vibration; The liquid ejection device according to claim 1 .

3. The control unit If the phase of the second residual vibration is not included in a range based on the phase of the first residual vibration, it is determined that the ejection characteristics of the nozzle vary.

3. The liquid ejection device according to claim 2.

4. The control unit evaluating the variation in the ejection characteristics of the nozzles based on the amplitude of the first residual vibration and the amplitude of the second residual vibration; The liquid ejection device according to claim 1 .

5. The control unit determining that the ejection characteristics of the nozzle vary when the amplitude at the first peak of the second residual vibration is not included in a first range based on the amplitude at the first peak of the first residual vibration; 5. The liquid ejection device according to claim 4.

6. The control unit determining that the ejection characteristics of the nozzle vary when the amplitude at the second peak of the second residual vibration is not included in a second range based on the amplitude at the second peak of the first residual vibration; 6. The liquid ejection device according to claim 5.

7. the first range is a range obtained by multiplying the amplitude of the first residual vibration at a first peak by a first coefficient, and then adding or subtracting the product from or to the amplitude of the first residual vibration at a first peak, the second range is a range obtained by multiplying the amplitude of the second peak of the first residual vibration by a second coefficient, and adding or subtracting the product from or to the amplitude of the second peak of the first residual vibration, The second coefficient is smaller than the first coefficient.

7. The liquid ejection device according to claim 6.

8. The control unit Using the first micro-vibration pulse as the micro-vibration pulse, the variation in the ejection characteristics of the nozzles is evaluated; Furthermore, a second micro-vibration pulse having a pulse width different from the pulse width of the first micro-vibration pulse is used as the micro-vibration pulse, and the variation in the ejection characteristics of the nozzles is evaluated. The liquid ejection device according to claim 1 .

9. The control unit Using the first micro-vibration pulse as the micro-vibration pulse, the variation in the ejection characteristics of the nozzles is evaluated; Furthermore, a second vibration pulse having an amplitude different from that of the first vibration pulse is used as the vibration pulse, and the variation in the ejection characteristics of the nozzle is evaluated. The liquid ejection device according to claim 1 .

10. The control unit applying the micro-vibration pulse to the piezoelectric element at a first timing within a unit period for driving the piezoelectric element, thereby performing the micro-vibration drive, and evaluating variations in the ejection characteristics of the nozzles; further, the micro-vibration driving is performed by applying the micro-vibration pulse to the piezoelectric element at a second timing different from the first timing within the unit period, and the variation in the ejection characteristics of the nozzles is evaluated. The liquid ejection device according to claim 1 .

11. The control unit a first vibration pulse including at least one pulse is used as the vibration pulse, and a variation in the ejection characteristics of the nozzle is evaluated; Furthermore, a second vibration pulse including a number of pulses different from the number of pulses included in the first vibration pulse is used as the vibration pulse, and the variation in the ejection characteristics of the nozzle is evaluated. The liquid ejection device according to claim 1 .

12. The control unit causing the detection unit to detect the residual vibration resulting from three consecutive executions of the vibration driving as the first residual vibration; the residual vibration resulting from successively driving the piezoelectric element in the order of the micro-vibration driving, the micro-vibration driving, and the vibration driving is detected by the detection unit as the second residual vibration; causing the detection unit to detect the residual vibration resulting from successively driving the piezoelectric element in the order of the micro-vibration driving, the vibration driving, and the vibration driving as a third residual vibration; evaluating variations in the ejection characteristics of the nozzles based on the first residual vibration, the second residual vibration, and the third residual vibration detected by the detection unit; The liquid ejection device according to claim 1 .

13. the vibration pulse is a pulse that causes liquid to be ejected from the nozzle; The liquid ejection device according to claim 1 .

14. a liquid ejection head including a nozzle for ejecting a liquid, a piezoelectric element corresponding to the nozzle, a vibration plate that vibrates when the piezoelectric element is driven, and a detection unit that detects residual vibration of the vibration plate caused by the driving of the piezoelectric element; A control unit; Equipped with The control unit micro-vibration driving is capable of driving the piezoelectric element with a micro-vibration pulse that does not cause liquid to be ejected from the nozzle, and vibration driving is capable of driving the piezoelectric element with a vibration pulse that generates in the vibration plate a vibration that is greater than the vibration of the vibration plate caused by the micro-vibration driving, causing the detection unit to detect the residual vibration resulting from continuous execution of the vibration driving as a first residual vibration; the residual vibration resulting from successively driving the piezoelectric element in the order of the micro-vibration driving and the vibration driving is detected by the detection unit as a second residual vibration; determining a waveform of the micro-vibration pulse based on the first residual vibration and the second residual vibration detected by the detection unit; A liquid ejection device characterized by:

15. A control method for a liquid ejection device having a liquid ejection head including nozzles that eject liquid, piezoelectric elements corresponding to the nozzles, a vibration plate that vibrates when the piezoelectric elements are driven, and a detection unit that detects residual vibration of the vibration plate caused by the driving of the piezoelectric elements, micro-vibration driving is capable of driving the piezoelectric element with a micro-vibration pulse that does not cause liquid to be ejected from the nozzle, and vibration driving is capable of driving the piezoelectric element with a vibration pulse that generates in the vibration plate a vibration that is greater than the vibration of the vibration plate caused by the micro-vibration driving, causing the detection unit to detect the residual vibration resulting from continuous execution of the vibration driving as a first residual vibration; the residual vibration resulting from successively driving the piezoelectric element in the order of the micro-vibration driving and the vibration driving is detected by the detection unit as a second residual vibration; evaluating a variation in the ejection characteristics of the nozzle between a case where the vibration driving is continuous and a case where the vibration driving is not continuous, based on the first residual vibration and the second residual vibration detected by the detection unit; A method for controlling a liquid ejection device.

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