Liquid ejecting apparatus, liquid ejecting head, and method for controlling liquid ejecting apparatus

Abstract

The invention relates to a liquid ejecting apparatus, a liquid ejecting head, and a control method of the liquid ejecting apparatus. A detection signal is made to have a suitable amplitude. A liquid ejecting apparatus includes: an ejecting portion including a piezoelectric element driven by a drive signal, a pressure chamber filled with a liquid and having a volume that changes according to the driving of the piezoelectric element, and a nozzle that ejects the liquid in the pressure chamber according to the change of the volume of the pressure chamber; a detection unit that detects a vibration signal indicating a potential of the piezoelectric element that varies in accordance with vibration remaining in the ejection unit after driving of the piezoelectric element, and generates a detection signal on the basis of the detected vibration signal; and a setting unit that sets a signal amplification factor on the basis of liquid characteristic information relating to characteristics of the liquid ejected by the ejection unit and element characteristic information relating to characteristics of the piezoelectric element, and the detection unit generates the detection signal by amplifying the vibration signal in accordance with the signal amplification factor set by the setting unit.

Description

Technical Field

[0001] The present invention relates to a liquid ejection device, a liquid ejection head and a control method of the liquid ejection device. Background Art

[0002] Liquid ejection devices such as inkjet printers drive a piezoelectric element provided in an ejection portion of a liquid ejection head to eject liquid such as ink filled in a pressure chamber provided in the ejection portion from a nozzle to form an image on a medium. However, in a liquid ejection device, ejection abnormalities may occur in which liquid cannot be ejected normally from the ejection portion. Therefore, a technology for determining the ejection state in the ejection portion has been proposed in the past. For example, Patent Document 1 discloses the following technology: determining the ejection state in the ejection portion based on a detection signal obtained by amplifying a vibration signal, the vibration signal indicating the vibration remaining in the ejection portion after the piezoelectric element is driven.

[0003] Patent Document 1: Japanese Patent Application Publication No. 2020-044771

[0004] However, the amplitude of the vibration remaining in the ejection part after the piezoelectric element is driven varies according to the characteristics of the liquid ejected from the ejection part and the characteristics of the piezoelectric element. Therefore, when the ejection state in the ejection part is determined based on the detection signal obtained by amplifying the vibration signal representing the vibration remaining in the ejection part at a certain amplification factor, the ejection state may be determined inaccurately because the detection signal has an inappropriate amplitude. Summary of the invention

[0005] In order to solve the above technical problems, the liquid ejection device involved in the present invention is characterized in that it comprises: an ejection part, comprising a piezoelectric element driven by a driving signal, a pressure chamber filled with liquid and whose volume changes according to the driving of the piezoelectric element, and a nozzle that ejects the liquid in the pressure chamber according to the change in the volume of the pressure chamber; a detection part, which detects a vibration signal and generates a detection signal based on the detected vibration signal, wherein the vibration signal represents the potential of the piezoelectric element that changes according to the vibration remaining in the ejection part after the driving of the piezoelectric element; and a setting part, which sets a signal amplification factor based on liquid characteristic information associated with the characteristics of the liquid ejected by the ejection part and element characteristic information associated with the characteristics of the piezoelectric element, and the detection part generates the detection signal by amplifying the vibration signal according to the signal amplification factor set by the setting part.

[0006] In addition, the liquid ejection head involved in the present invention is characterized in that it comprises: an ejection portion, comprising a piezoelectric element driven by a driving signal, a pressure chamber filled with liquid and whose volume changes according to the driving of the piezoelectric element, and a nozzle that ejects the liquid in the pressure chamber according to the change in the volume of the pressure chamber; and a detection portion, which detects a vibration signal representing the potential of the piezoelectric element that changes according to the vibration remaining in the ejection portion after the driving of the piezoelectric element, and generates a detection signal based on the detected vibration signal, and the detection portion generates the detection signal by amplifying the vibration signal according to a signal amplification factor set based on liquid characteristic information associated with the characteristics of the liquid ejected from the ejection portion and element characteristic information associated with the characteristics of the piezoelectric element.

[0007] In addition, the control method of the liquid ejection device involved in the present invention is characterized in that the liquid device includes a ejection part, the ejection part includes a piezoelectric element driven by a driving signal, a pressure chamber filled with liquid and the volume of which changes according to the driving of the piezoelectric element, and a nozzle that ejects the liquid in the pressure chamber according to the change in the volume of the pressure chamber. In the control method of the liquid ejection device, a vibration signal representing the potential of the piezoelectric element that changes according to the vibration remaining in the ejection part after the driving of the piezoelectric element is detected, a signal amplification factor is set based on liquid characteristic information associated with the characteristics of the liquid ejected from the ejection part and element characteristic information associated with the characteristics of the piezoelectric element, and a detection signal is generated by amplifying the vibration signal according to the signal amplification factor. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 It is a block diagram showing an example of the configuration of the inkjet printer 1 according to the embodiment of the present invention.

[0009] Figure 2 It is a perspective view showing an example of a schematic structure of the inkjet printer 1 .

[0010] Figure 3 It is a cross-sectional view for explaining an example of the structure of the ejection portion D[m].

[0011] Figure 4 It is a block diagram showing an example of the configuration of the head unit 3 .

[0012] Figure 5 It is a timing chart for explaining an example of a signal supplied to the head unit 3 .

[0013] Figure 6 This is an explanatory diagram for explaining an example of the individual designation signal Sd[m].

[0014] Figure 7 This is an explanatory diagram for explaining an example of the individual designation signal Sd[m].

[0015] Figure 8 SK[m] is a timing chart for explaining an example of the detection signal SK[m].

[0016] Fig. 9 This is an explanatory diagram for explaining an example of the discharge state determination process.

[0017] Fig.10 This is a flowchart for explaining an example of the magnification setting process.

[0018] Fig.11 This is an explanatory diagram for explaining an example of the ink corresponding enlargement information QGT.

[0019] Fig.12 It is an explanatory diagram for explaining an example of the piezoelectric corresponding amplification information QGP.

[0020] Fig.13 It is an explanatory diagram for explaining an example of the magnification enhancement information QGC.

[0021] Fig.14 This is a block diagram showing an example of the configuration of an inkjet printer 1B according to Modification 1 of the present invention.

[0022] Fig.15 This is a flowchart for explaining an example of the magnification setting process according to the first modification.

[0023] Fig.16 It is an explanatory diagram for explaining an example of the ink corresponding amplitude information QKT.

[0024] Fig.17 It is an explanatory diagram for explaining an example of the piezoelectric corresponding amplitude information QKP.

[0025] Description of Reference Numerals

[0026] 1: inkjet printer; 2: control unit; 3: head unit; 4: drive signal generating unit; 5: determination unit; 6: storage unit; 7: conveying unit; 21: drive control unit; 22: ejection control unit; 23: determination management unit; 24: magnification setting unit; 25: conveying control unit; 31: supply circuit; 32: recording head; 33: detection circuit; 35: temperature sensor. DETAILED DESCRIPTION

[0027] The following is a description of the method for implementing the present invention with reference to the accompanying drawings. However, in each figure, the size and scale of each part are appropriately different from the actual one. In addition, the embodiments described below are suitable specific examples of the present invention, so various technically preferred limitations are added. However, as long as there is no special description in the following description to limit the meaning of the present invention, the scope of the present invention is not limited to these methods.

[0028] A. Implementation Method

[0029] In this embodiment, the liquid ejecting device is described by taking an inkjet printer that ejects ink to form an image on recording paper PP as an example.

[0030] 1. Overview of inkjet printers

[0031] Refer to the following Figures 1 to 3 , an example of the structure of the inkjet printer 1 involved in this embodiment is described.

[0032] Figure 1 1 is a functional block diagram showing an example of the configuration of the inkjet printer 1 .

[0033] like Figure 1 As shown, print data Img representing an image to be formed by the inkjet printer 1 is supplied from a host computer such as a personal computer or a digital camera to the inkjet printer 1. The inkjet printer 1 executes a print process to form an image represented by the print data Img supplied from the host computer on recording paper PP.

[0034] like Figure 1 As shown, the inkjet printer 1 includes a control unit 2 for controlling each unit of the inkjet printer 1, a head unit 3 provided with a discharge unit D for discharging ink, a drive signal generating unit 4 for generating a drive signal Com for driving the discharge unit D, a determination unit 5 for determining the discharge state of the ink in the discharge unit D, a storage unit 6 for storing various information, and a conveying unit 7 for changing the relative position of the recording paper PP and the head unit 3.

[0035] It should be noted that, in the present embodiment, the inkjet printer 1 is an example of a “liquid ejection device”, the head unit 3 is an example of a “liquid ejection head”, the ink is an example of a “liquid”, the drive signal generating unit 4 is an example of a “drive signal generating unit”, and the determination unit 5 is an example of a “determination unit”.

[0036] In this embodiment, it is assumed that the inkjet printer 1 has one or more head units 3, one or more drive signal generating units 4 corresponding to the one or more head units 3, and one or more determination units 5 corresponding to the one or more head units 3. Specifically, in this embodiment, it is assumed that the inkjet printer 1 has four head units 3, four drive signal generating units 4 corresponding to the four head units 3, and four determination units 5 corresponding to the four head units 3. However, in the following, for the convenience of explanation, Figure 1As shown, the description will focus on one head unit 3 among the four head units 3, one drive signal generating unit 4 among the four drive signal generating units 4 provided corresponding to the one head unit 3, and one determination unit 5 among the four drive signal generating units 4 provided corresponding to the one head unit 3.

[0037] The control unit 2 is configured to include one or more CPUs (Central Processing Units). However, the control unit 2 may also be a unit having a programmable logic device such as an FPGA (field-programmable gate array) instead of a CPU, or the control unit 2 may also be a unit having a programmable logic device such as an FPGA in addition to a CPU.

[0038] The storage unit 6 is configured to include one or both of a volatile memory such as a RAM (Random Access Memory) and a nonvolatile memory such as a ROM (Read Only Memory), an EEPROM (Electrically Erasable Programmable Read-Only Memory) or a PROM (Programmable ROM). Although described in detail later, the storage unit 6 stores the control program PRG of the inkjet printer 1, the ink corresponding magnification information QGT, the piezoelectric corresponding magnification information QGP, and the magnification enhancement information QGC.

[0039] The control unit 2 executes the control program PRG stored in the storage unit 6 and operates according to the control program PRG to function as a drive control unit 21, a discharge control unit 22, a determination management unit 23, an amplification factor setting unit 24, and a transport control unit 25.

[0040] The drive control unit 21 generates a waveform designation signal dCom, and supplies the generated waveform designation signal dCom to the drive signal generation unit 4. Here, the waveform designation signal dCom is a digital signal that specifies the waveform of the drive signal Com. The drive signal Com is an analog signal for driving the ejection unit D. The drive signal generation unit 4 generates a drive signal Com having a waveform specified by the waveform designation signal dCom, and supplies the generated drive signal Com to the head unit 3.

[0041] The ejection control unit 22 generates a designation signal SI and supplies the generated designation signal SI to the head unit 3. Here, the designation signal SI is a digital signal that designates the type of operation of the ejection unit D. Specifically, the designation signal SI is a signal that designates the type of operation of the ejection unit D by designating whether to supply the drive signal Com to the ejection unit D.

[0042] The head unit 3 includes a supply circuit 31 , a recording head 32 , a detection circuit 33 , and a temperature sensor 35 .

[0043] The recording head 32 has M ejection parts D. Here, the value M is a natural number satisfying "M ≥ 2". It should be noted that, hereinafter, the m-th ejection part D among the M ejection parts D provided in the recording head 32 is sometimes referred to as ejection part D[m]. Here, the variable m is a natural number satisfying "1 ≤ m ≤ M". In addition, hereinafter, when a component or signal of the inkjet printer 1 corresponds to an ejection part D[m] among the M ejection parts D, a footnote [m] is sometimes added to the reference numeral used to represent the component or signal.

[0044] The supply circuit 31 switches whether to supply the drive signal Com to the discharge unit D[m] based on the designation signal SI. Hereinafter, the drive signal Com supplied to the discharge unit D[m] among the drive signals Com may be referred to as a supply drive signal Vin[m].

[0045] The supply circuit 31 switches whether to supply a vibration signal VX[m] to the detection circuit 33 based on the designated signal SI. The vibration signal VX[m] indicates the potential of the upper electrode Zu[m] of the piezoelectric element PZ[m] provided in the ejection part D[m]. In the following, when the vibration signal VX[m] is supplied from the ejection part D[m] to the detection circuit 33, the ejection part D[m] is sometimes referred to as the ejection part DH to be determined. It should be noted that, regarding the piezoelectric element PZ[m] and the upper electrode Zu[m], Figure 3 To be described later.

[0046] The detection circuit 33 generates the detection signal SK[m] based on the vibration signal VX[m] supplied from the ejection portion D[m] set as the ejection portion DH to be determined via the supply circuit 31. Specifically, the detection circuit 33 generates the detection signal SK[m] by amplifying the vibration signal VX[m]. It should be noted that in the present embodiment, the detection circuit 33 is an example of a "detection unit".

[0047] The temperature sensor 35 measures the temperature AT of the head unit 3, and outputs a temperature signal ST indicating the measurement result. It should be noted that the temperature of the ink ejected from the ejection unit D[m] has a temperature corresponding to the temperature AT indicated by the temperature signal ST. In addition, the viscosity of the ink ejected from the ejection unit D[m] has a temperature corresponding to the temperature AT indicated by the temperature signal ST. In other words, the temperature signal ST indicates the temperature AT corresponding to the temperature and viscosity of the ink ejected from the ejection unit D[m]. It should be noted that, in the present embodiment, the temperature of the ink ejected from the ejection unit D[m] is an example of "characteristics of the liquid ejected from the ejection unit", and the viscosity of the ink ejected from the ejection unit D[m] is another example of "characteristics of the liquid ejected from the ejection unit". In addition, in the present embodiment, the information indicated by the temperature signal ST is an example of "liquid characteristic information".

[0048] The amplification factor setting unit 24 generates an amplification factor designation signal SG based on the temperature signal ST and the designation signal SI. Here, the amplification factor designation signal SG is a signal for designating the amplification factor AG[m] of the vibration signal VX[m] in the detection circuit 33. It should be noted that in the present embodiment, the amplification factor AG[m] is an example of a "signal amplification factor". In addition, hereinafter, the process of generating the amplification factor designation signal SG by the amplification factor setting unit 24 is sometimes referred to as an amplification factor setting process.

[0049] Specifically, in the amplification setting process, the amplification setting unit 24 first generates the piezoelectric drive count information SP based on the designated signal SI. Here, the piezoelectric drive count information SP is information indicating the piezoelectric drive counts AP[1] to AP[M] corresponding to the ejection units D[1] to D[M]. Among them, the piezoelectric drive count AP[m] is the number of times the piezoelectric element PZ[m] provided in the ejection unit D[m] has been driven from the time when the inkjet printer 1 product was shipped to the present. It should be noted that, in the present embodiment, the number of times the piezoelectric element PZ[m] has been driven is an example of the "characteristics of the piezoelectric element". In addition, in the present embodiment, the piezoelectric drive count information SP is an example of the "element characteristic information".

[0050] Then, in the amplification setting process, the amplification setting unit 24 sets the amplification AG[m] based on the temperature signal ST and the piezoelectric drive number information SP, and generates an amplification designation signal SG indicating the amplification AG[m]. Next, the amplification setting unit 24 supplies the amplification designation signal SG to the detection circuit 33. The detection circuit 33 generates the detection signal SK[m] by amplifying the vibration signal VX[m] according to the amplification AG[m] indicated by the amplification designation signal SG.

[0051] It should be noted that in the present embodiment, the amplification factor setting unit 24 is an example of a “setting unit”.

[0052] In addition, the amplification factor setting unit 24 generates a drive waveform correction signal SC based on the temperature signal ST and the designation signal SI in the amplification factor setting process. Here, the drive waveform correction signal SC is a signal indicating the waveform of the corrected drive signal Com, and is a signal indicating the amplitude AC of the corrected drive signal Com. When the drive waveform correction signal SC is supplied from the amplification factor setting unit 24, the drive control unit 21 corrects the waveform designation signal dCom so that the amplitude of the drive signal Com becomes the amplitude AC indicated by the drive waveform correction signal SC.

[0053] The determination unit 5 determines the ejection state of the ink in the ejection unit D[m] based on the detection signal SK[m]. In other words, the determination unit 5 determines whether an ejection abnormality has not occurred in the ejection unit D[m] based on the detection signal SK[m]. Here, the ejection abnormality is a general term for a state in which the nozzle N provided in the ejection unit D[m] cannot eject the ink normally. For example, the ejection abnormality includes a state in which the ink cannot be ejected from the ejection unit D[m], a state in which the ejection unit D[m] ejects an amount of ink different from the ejection amount of the ink specified by the drive signal Com, and a state in which the ejection unit D[m] ejects the ink at a speed different from the ejection speed of the ink specified by the drive signal Com.

[0054] It should be noted that, hereinafter, the process of determining the discharge state in the discharge portion D[m] based on the detection signal SK[m] is referred to as a discharge state determination process.

[0055] In addition, hereinafter, the process of driving the discharge portion D[m] as the determination target discharge portion DH and detecting the vibration signal VX[m] from the discharge portion D[m] is referred to as determination target drive process.

[0056] The determination unit 5 generates result information SH based on the result of determining the ink ejection state, and supplies the generated result information SH to the determination management unit 23. Then, the determination management unit 23 manages the result information SH supplied from the determination unit 5. Here, the result information SH includes determination result information SH1[m] indicating the result of determining the ink ejection state in the ejection unit D[m] and amplitude information SH2[m] indicating the amplitude AK[m] of the detection signal SK[m].

[0057] It should be noted that, as described above, the inkjet printer 1 performs a printing process. When performing the printing process, the ejection control unit 22 generates a signal such as a designated signal SI for controlling the head unit 3 based on the printing data Img. In addition, the drive control unit 21 generates a signal such as a waveform designated signal dCom for controlling the drive signal generating unit 4. In addition, the conveying control unit 25 generates a conveying control signal MH for controlling the conveying unit 7. Thus, during the printing process, the control unit 2 controls the conveying unit 7 to change the relative position between the recording paper PP and the head unit 3, adjusts whether or not ink is ejected from the ejection unit D[m], the ejection amount of ink, the ejection timing of ink, etc., and controls each part of the inkjet printer 1 so that an image corresponding to the printing data Img is formed on the recording paper PP.

[0058] Hereinafter, the printing process and the determination target driving process may be collectively referred to as the ejection unit driving process.

[0059] Figure 2 This is a perspective view showing an example of a schematic internal structure of the inkjet printer 1 .

[0060] like Figure 2 As shown, in this embodiment, it is assumed that the inkjet printer 1 is a serial printer. Specifically, when the inkjet printer 1 performs printing processing, the recording paper PP is conveyed in the X1 direction, and the head unit 3 is reciprocated in the Y1 direction intersecting the X1 direction and the Y2 direction which is the opposite direction of the Y1 direction, so that the ink is ejected from the ejection part D[m], thereby forming dots Dt corresponding to the print data Img on the recording paper PP.

[0061] Hereinafter, the X1 direction and the X2 direction as its opposite direction are collectively referred to as the "X-axis direction", the Y1 direction intersecting the X-axis direction and the Y2 direction as its opposite direction are collectively referred to as the "Y-axis direction", and the Z1 direction intersecting the X-axis direction and the Y-axis direction and the Z2 direction as its opposite direction are collectively referred to as the "Z-axis direction". In the present embodiment, as an example, it is assumed that the X-axis direction, the Y-axis direction and the Z-axis direction are orthogonal to each other for illustration. However, the present invention is not limited to such a form. The X-axis direction, the Y-axis direction and the Z-axis direction only need to intersect each other. It should be noted that in the present embodiment, the Z1 direction is set as the direction in which ink is ejected from the ejection portion D[m].

[0062] like Figure 2 As shown, the inkjet printer 1 according to the present embodiment includes a housing 100 and a carriage 110 that can reciprocate in the Y-axis direction in the housing 100 and that carries four head units 3 .

[0063] In this embodiment, if Figure 2As shown, it is assumed that the carriage 110 stores four ink cartridges 120 corresponding to the four colors of ink, cyan, magenta, yellow, and black. In addition, in the present embodiment, as described above, it is assumed that the inkjet printer 1 has four head units 3 corresponding to the four ink cartridges 120. Each ejection portion D[m] receives the supply of ink from the ink cartridge 120 corresponding to the head unit 3 provided with the ejection portion D[m]. Thus, each ejection portion D[m] can fill the supplied ink inside and eject the filled ink from the nozzle N. It should be noted that the ink cartridge 120 may also be provided outside the carriage 110.

[0064] In addition, as described above, the inkjet printer 1 according to the present embodiment includes the conveying unit 7. The conveying unit 7 includes the carriage conveying mechanism 71 for reciprocating the carriage 110 in the Y-axis direction, the carriage guide shaft 76 for supporting the carriage 110 so as to freely reciprocate in the Y-axis direction, the medium conveying mechanism 73 for conveying the recording paper PP, and the platen 75 provided in the Z1 direction of the carriage 110. Therefore, when the printing process is executed, the conveying unit 7 causes the head unit 3 to reciprocate along the carriage guide shaft 76 in the Y-axis direction together with the carriage 110 through the carriage conveying mechanism 71, and conveys the recording paper PP on the platen 75 in the X1 direction through the medium conveying mechanism 73, thereby changing the relative position of the recording paper PP and the head unit 3, and making it possible to drop ink on the entire recording paper PP.

[0065] Figure 3 It is a partial schematic cross-sectional view of the recording head 32 obtained by cutting the recording head 32 including the discharge portion D[m].

[0066] like Figure 3As shown, the ejection unit D[m] includes a piezoelectric element PZ[m], a cavity CV[m] filled with ink, a nozzle N[m] communicating with the cavity CV[m], and a vibration plate 321. The ejection unit D[m] is driven by the piezoelectric element PZ[m] by supplying a driving signal Vin[m], so that the ink in the cavity CV[m] is ejected from the nozzle N[m]. The cavity CV[m] is a space defined by a cavity plate 324, a nozzle plate 323 formed with the nozzle N[m], and the vibration plate 321. The cavity CV[m] is communicated with a reservoir 325 via an ink supply port 326. The reservoir 325 is communicated with an ink cartridge 120 corresponding to the ejection unit D[m] via an ink inlet 327. The piezoelectric element PZ[m] includes an upper electrode Zu[m], a lower electrode Zd[m], and a piezoelectric body Zm[m] provided between the upper electrode Zu[m] and the lower electrode Zd[m]. The lower electrode Zd[m] is electrically connected to a power supply line Lv set to a predetermined potential VBS. In addition, when a supply drive signal Vin[m] is supplied to the upper electrode Zu[m] and a voltage is applied between the upper electrode Zu[m] and the lower electrode Zd[m], the piezoelectric element PZ[m] is displaced in the Z1 direction or the Z2 direction according to the applied voltage, and as a result, the piezoelectric element PZ[m] vibrates. The lower electrode Zd[m] is bonded to the vibration plate 321. Therefore, when the piezoelectric element PZ[m] is driven to vibrate by supplying the drive signal Vin[m], the vibration plate 321 also vibrates. Then, due to the vibration of the vibration plate 321, the volume of the cavity CV[m] and the pressure in the cavity CV[m] change, and the ink filled in the cavity CV[m] is ejected from the nozzle N[m]. It should be noted that, in the present embodiment, the piezoelectric element PZ[m] is an example of a “piezoelectric element”, and the cavity CV[m] is an example of a “pressure chamber”.

[0067] 2. Overview of the head unit

[0068] Refer to the following Figures 4 to 7 The outline of the head unit 3 will be described.

[0069] Figure 4 It is a block diagram showing an example of the configuration of the head unit 3 .

[0070] like Figure 4 As shown, the head unit 3 includes a supply circuit 31, a recording head 32, and a detection circuit 33. The head unit 3 also includes a wiring Lc to which the drive signal Com is supplied from the drive signal generating unit 4 and a wiring Ls for supplying the detection circuit 33 with a vibration signal VX[m].

[0071] The supply circuit 31 includes M switches Wc[1] to Wc[M] corresponding one-to-one to the M ejection parts D[1] to D[M], M switches Ws[1] to Ws[M] corresponding one-to-one to the M ejection parts D[1] to D[M], and a connection state designation circuit 34 that designates the connection state of each switch.

[0072] The connection state designation circuit 34 generates a connection state designation signal Rc[m] for designating the on-off state of the switch Wc[m] and a connection state designation signal Rs[m] for designating the on-off state of the switch Ws[m] based on the designation signal SI, latch signal LAT, change signal CH and period designation signal Tsig supplied from the control unit 2.

[0073] The switch Wc[m] switches the connection and non-conduction between the wiring Lc and the upper electrode Zu[m] of the piezoelectric element PZ[m] based on the connection state designation signal Rc[m]. In the present embodiment, the switch Wc[m] is turned on when the connection state designation signal Rc[m] is at a high level, and is turned off when the connection state designation signal Rc[m] is at a low level. When the switch Wc[m] is turned on, the drive signal Com supplied to the wiring Lc is supplied as the supply drive signal Vin[m] to the upper electrode Zu[m] of the ejection portion D[m].

[0074] The switch Ws[m] switches the connection and non-conduction between the wiring Ls and the upper electrode Zu[m] of the piezoelectric element PZ[m] based on the connection state designation signal Rs[m]. In the present embodiment, the switch Ws[m] is turned on when the connection state designation signal Rs[m] is at a high level, and is turned off when the connection state designation signal Rs[m] is at a low level. When the switch Ws[m] is turned on, the vibration signal VX[m] indicating the potential of the upper electrode Zu[m] provided in the ejection portion D[m] is supplied from the upper electrode Zu[m] to the detection circuit 33 through the wiring Ls.

[0075] The detection circuit 33 generates a detection signal SK[m] having a waveform corresponding to the waveform of the vibration signal VX[m] based on the vibration signal VX[m] supplied from the wiring Ls and the amplification factor designation signal SG supplied from the amplification factor setting unit 24. Specifically, the detection circuit 33 generates the detection signal SK[m] by amplifying the vibration signal VX[m] according to the amplification factor AG[m] indicated by the amplification factor designation signal SG.

[0076] In this embodiment, when the inkjet printer 1 performs a printing process or a discharge state determination process, one or more unit periods TP are set as the operation period of the inkjet printer 1. In order to perform a discharge unit drive process including a printing process or a determination target drive process, the inkjet printer 1 can drive each discharge unit D[m] within each unit period TP.

[0077] Figure 5 1 is a timing chart showing an example of various signals such as the drive signal Com supplied to the head unit 3 within the unit period TP.

[0078] like Figure 5 As shown, the control unit 2 outputs the latch signal LAT having the pulse PLL. Thus, the control unit 2 defines the unit period TP as a period from the rising edge of the pulse PLL to the rising edge of the next pulse PLL.

[0079] In addition, the control unit 2 outputs the change signal CH having the pulse PLC in the unit period TP. Then, the control unit 2 divides the unit period TP into a driving period TQ1 from the rising edge of the pulse PLL to the rising edge of the pulse PLC and a driving period TQ2 from the rising edge of the pulse PLC to the rising edge of the pulse PLL.

[0080] In addition, the control unit 2 outputs a period designation signal Tsig having a pulse PLT1 and a pulse PLT2 within the unit period TP. Then, the control unit 2 divides the unit period TP into a control period TS1 from the rising edge of the pulse PLL to the rising edge of the pulse PLT1, a control period TS2 from the rising edge of the pulse PLT1 to the rising edge of the pulse PLT2, and a control period TS3 from the rising edge of the pulse PLT2 to the rising edge of the pulse PLL.

[0081] like Figure 5 As shown, the designation signal SI includes M individual designation signals Sd[1] to Sd[M] corresponding one-to-one to the M ejection units D[1] to D[M]. The individual designation signal Sd[m] designates the driving form of the ejection unit D[m] within each unit period TP when the inkjet printer 1 performs a printing process or an ejection state determination process. Before each unit period TP, the control unit 2 synchronizes the designation signal SI including the M individual designation signals Sd[1] to Sd[M] with the lock signal CL and supplies it to the connection state designation circuit 34. Then, the connection state designation circuit 34 generates a connection state designation signal Rc[m] and a connection state designation signal Rs[m] based on the individual designation signal Sd[m] within the unit period TP.

[0082] It should be noted that in this embodiment, the following situation is assumed: when the inkjet printer 1 performs printing processing or judgment object driving processing, the ejection unit D[m] is able to form any point Dt, which is a large dot composed of ink with an ink amount ξ1 and a small dot composed of ink with an ink amount ξ2 which is less than the ink amount ξ1.

[0083] Figure 6 and Figure 7 This is an explanatory diagram for explaining an example of the individual designation signal Sd[m].

[0084] like Figure 6 and Figure 7 As shown, in the present embodiment, the separate designated signal Sd[m] represents any one of the following four values: a value "1" which designates the ejection unit D[m] as the large dot forming ejection unit DP-1 within the unit period TP, a value "2" which designates the ejection unit D[m] as the small dot forming ejection unit DP-2 within the unit period TP, a value "3" which designates the ejection unit D[m] as the non-driven ejection unit DP-3 within the unit period TP, and a value "4" which designates the ejection unit D[m] as the judgment object ejection unit DH within the unit period TP.

[0085] Here, the large dot forming ejection portion DP-1 is an ejection portion D that forms a large dot within the unit period TP. The small dot forming ejection portion DP-2 is an ejection portion D that forms a small dot within the unit period TP. The non-driven ejection portion DP-3 is an ejection portion D that is not driven by the drive signal Com within the unit period TP. The determination target ejection portion DH is an ejection portion D that becomes the target of the ejection state determination process within the unit period TP.

[0086] return Figure 5 Provide explanation.

[0087] like Figure 5 As shown, in the present embodiment, the driving signal Com has a waveform PA1 provided in the driving period TQ1 and a waveform PA2 provided in the driving period TQ2.

[0088] The waveform PA1 is a waveform that returns to the reference potential V0 from the reference potential V0 through the potential VL1 lower than the reference potential V0 and the potential VH1 higher than the reference potential V0 during the control period TS1 in the driving period TQ1, and maintains the reference potential V0 during the control period TS2 and the control period TS3 in the driving period TQ1. When the supply drive signal Vin[m] having the waveform PA1 is supplied to the ejection portion D[m], the waveform PA1 is determined so that the ink corresponding to the ink amount ξ1 is ejected from the ejection portion D[m].

[0089] In addition, the waveform PA2 is a waveform that returns to the reference potential V0 from the reference potential V0 through the potential VL2 having a potential lower than the reference potential V0 and the potential VH2 having a potential higher than the reference potential V0 during the driving period TQ2. When the supply drive signal Vin[m] having the waveform PA2 is supplied to the ejection portion D[m], the waveform PA2 is determined so that the ink corresponding to the ink amount ξ2 is ejected from the ejection portion D[m].

[0090] It should be noted that in the present embodiment, as an example, the following case is assumed: when the potential of the supply drive signal Vin[m] supplied to the ejection portion D[m] is high, the volume of the cavity CV[m] provided to the ejection portion D[m] becomes smaller than when the potential of the supply drive signal Vin[m] supplied to the ejection portion D[m] is low. Therefore, when the ejection portion D[m] is driven by the supply drive signal Vin[m] having the waveform PA1, etc., the potential of the supply drive signal Vin[m] changes from low potential to high potential, so that the ink in the ejection portion D[m] is ejected from the nozzle N[m].

[0091] Next, refer to Figure 6 and Figure 7 , the operation of the ejection portion D[m] designated by the individual designation signal Sd[m] will be described.

[0092] like Figure 6 As shown in FIG. 1 , when the individual designation signal Sd[m] indicates a value of "1" that designates the ejection unit D[m] as the large dot forming ejection unit DP-1 in the unit period TP, the connection state designation circuit 34 sets the connection state designation signal Rc[m] to a high level in the driving period TQ1. In this case, the switch Wc[m] is turned on in the driving period TQ1. Therefore, the ejection unit D[m] is driven by the supply drive signal Vin[m] having the waveform PA1 in the unit period TP, and ejects ink corresponding to the ink amount ξ1 of the large dot.

[0093] In addition, when the individual designation signal Sd[m] indicates the value "2" for designating the ejection unit D[m] as the dot-forming ejection unit DP-2 in the unit period TP, the connection state designation circuit 34 sets the connection state designation signal Rc[m] to a high level in the driving period TQ2. In this case, the switch Wc[m] is turned on in the driving period TQ2. Therefore, the ejection unit D[m] is driven by the supply drive signal Vin[m] having the waveform PA2 in the unit period TP, and ejects ink corresponding to the ink amount ξ2 of the dot.

[0094] In addition, when the individual designation signal Sd[m] indicates a value "3" for designating the ejection unit D[m] as the non-driven ejection unit DP-3 within the unit period TP, the connection state designation circuit 34 sets the connection state designation signal Rc[m] and the connection state designation signal Rs[m] to a low level throughout the unit period TP. In this case, the switch Wc[m] and the switch Ws[m] are disconnected throughout the unit period TP. Therefore, the ejection unit D[m] is not driven by the drive signal Com within the unit period TP, and does not eject ink.

[0095] like Figure 7As shown, when the individual designation signal Sd[m] indicates the value "4" for designating the ejection unit D[m] as the ejection unit DH to be determined within the unit period TP, the connection state designation circuit 34 sets the connection state designation signal Rc[m] to a high level within the control period TS1, and sets the connection state designation signal Rs[m] to a high level within the control period TS2. In this case, the switch Wc[m] is turned on within the control period TS1, and the switch Ws[m] is turned on within the control period TS2. Therefore, as a result of the ejection unit D[m] designated as the ejection unit DH to be determined being driven by the supply drive signal Vin[m] having the waveform PA1 within the control period TS1, the vibration occurring in the ejection unit D[m] remains within the control period TS2. Then, within the control period TS2, the potential of the upper electrode Zu[m] provided at the ejection unit D[m] changes according to the vibration remaining in the ejection unit D[m]. Then, the detection circuit 33 detects the potential of the upper electrode Zu[m] that changes according to the vibration remaining in the discharge portion D[m] as a vibration signal VX[m] via the switch Ws[m] during the control period TS2.

[0096] That is, the waveform of the vibration signal VX[m] detected from the ejection portion D[m] during the control period TS2 represents the waveform of the vibration remaining in the ejection portion D[m] during the control period TS2. In addition, the waveform of the detection signal SK[m] generated based on the vibration signal VX[m] detected from the ejection portion D[m] during the control period TS2 represents the waveform of the vibration remaining in the ejection portion D[m] during the control period TS2.

[0097] 3. Overview of the judgment unit

[0098] Refer to the following Figure 8 and Fig. 9 The outline of the determination unit 5 will be described.

[0099] As described above, the determination unit 5 executes the discharge state determination processing of determining the discharge state of ink in the discharge portion D[m] designated as the determination target discharge portion DH based on the detection signal SK[m] supplied from the detection circuit 33 .

[0100] Figure 8 1 is a timing diagram for explaining an example of the detection signal SK[m] supplied by the detection circuit 33 to the determination unit 5. It should be noted that the detection signal SK[m] output by the detection circuit 33 during the control period TS2 represents a waveform based on the vibration remaining in the ejection portion D[m] during the control period TS2.

[0101] like Figure 8As shown, hereinafter, the period from the timing when the potential of the detection signal SK[m] matches the reference potential VK0 set near the amplitude center of the detection signal SK[m] to the timing when it next matches the reference potential VK0 is referred to as the period NTC[m]. In addition, hereinafter, the time length of the period NTC[m] is referred to as the period TC[m] of the detection signal SK[m]. In the present embodiment, the period TC[m] is an example of a “feature quantity represented by the detection signal SK[m]”.

[0102] In addition, in this embodiment, it is assumed that the potential difference between the highest potential VKH[m] of the detection signal SK[m] and the lowest potential VKL[m] of the detection signal SK[m] within the cycle period NTC[m] is regarded as the amplitude AK[m] of the detection signal SK[m].

[0103] In the present embodiment, the determination unit 5 measures the period TC[m] and the amplitude AK[m] of the detection signal SK[m]. Then, the determination unit 5 performs the ejection state determination process based on the period TC[m], in which the ejection state of the ink in the ejection portion D[m] is determined, and generates determination result information SH1[m] indicating the result of the determination. Next, the determination unit 5 generates result information SH including the determination result information SH1[m] and the amplitude information SH2[m] indicating the amplitude AK[m], and supplies the generated result information SH to the control unit 2.

[0104] Fig. 9 This is an explanatory diagram for explaining an example of the determination result information SH1 [m] generated by the determination unit 5 in the discharge state determination process.

[0105] like Fig. 9 As shown, in the ejection state determination process, the determination unit 5 determines the ejection state of the ink in the ejection portion D[m] by comparing the period TC[m] with a part or all of the threshold values ​​Tth1, Tth2 and Tth3, and generates determination result information SH1[m] indicating the result of the determination.

[0106] The threshold value Tth1 is a fixed value used to represent the boundary between the period TC[m] of the residual vibration occurring in the ejection part D[m] when the ejection state of the ejection part D[m] is normal and the period TC[m] of the residual vibration occurring in the ejection part D[m] when bubbles are mixed into the cavity CV[m] of the ejection part D[m].

[0107] Threshold value Tth2 is a value larger than threshold value Tth1, and is a fixed value used to represent the boundary between period TC[m] of residual vibration occurring in ejection portion D[m] when the ejection state of ejection portion D[m] is normal and period TC[m] of residual vibration occurring in ejection portion D[m] when foreign matter is attached near nozzle N[m] of ejection portion D[m].

[0108] Threshold value Tth3 is a value larger than threshold value Tth2, and is a fixed value used to represent the boundary between period TC[m] of residual vibration occurring in ejection portion D[m] when foreign matter adheres to the vicinity of nozzle N[m] of ejection portion D[m] and period TC[m] of residual vibration occurring in ejection portion D[m] after ink viscosity increases in cavity CV[m] of ejection portion D[m].

[0109] It should be noted that, in the present embodiment, the threshold value Tth1 , the threshold value Tth2 , and the threshold value Tth3 are examples of “fixed reference values”.

[0110] In this embodiment, in the ejection status determination process, when the period TC[m] satisfies "Tth1≤TC[m]≤Tth2", the determination unit 5 regards the ejection status of the ink in the ejection portion D[m] as normal, and sets the value "1" indicating that the ejection status of the ink in the ejection portion D[m] is normal to the determination result information SH1[m].

[0111] In addition, in the ejection state determination process, when the period TC[m] satisfies "TC[m]<Tth1", the determination unit 5 regards that an ejection abnormality caused by bubbles has occurred in the ejection section D[m], and sets the value "2" indicating that an ejection abnormality caused by bubbles has occurred in the ejection section D[m] to the determination result information SH1[m].

[0112] In addition, in the ejection state determination process, when the period TC[m] satisfies "Tth2<TC[m]≤Tth3", the determination unit 5 regards that an ejection abnormality caused by foreign matter attachment has occurred in the ejection portion D[m], and sets the value "3" indicating that an ejection abnormality caused by foreign matter attachment has occurred in the ejection portion D[m] to the determination result information SH1[m].

[0113] In addition, in the ejection state determination process, when the period TC[m] satisfies "Tth3<TC[m]", the determination unit 5 regards that an ejection abnormality caused by thickening has occurred in the ejection portion D[m], and sets the value "4" indicating that an ejection abnormality caused by thickening has occurred in the ejection portion D[m] to the determination result information SH1[m].

[0114] It should be noted that, in this embodiment, the case where the determination unit 5 can compare the period TC[m] with the three thresholds Tth1, Tth2, and Tth3 is exemplified, but the present invention is not limited to such a form. It is sufficient as long as the determination unit 5 can compare the period TC[m] with one or more of the three thresholds Tth1, Tth2, and Tth3.

[0115] In summary, the determination unit 5 generates result information SH including determination result information SH1[m] indicating the result of determining the ejection state of ink in the ejection portion D[m] and amplitude information SH2[m] indicating the amplitude AK[m] of the detection signal SK[m] based on the detection signal SK[m].

[0116] It should be noted that, generally, the amplitude of the vibration signal VX[m] varies according to the temperature and viscosity of the ink ejected from the ejection unit D[m]. Therefore, the amplitude AK[m] of the detection signal SK[m] also varies according to the temperature and viscosity of the ink ejected from the ejection unit D[m]. In addition, generally, the amplitude of the vibration signal VX[m] varies according to the degree of deterioration of the piezoelectric element PZ[m] of the ejection unit D[m]. Therefore, the amplitude AK[m] of the detection signal SK[m] also varies according to the degree of deterioration of the piezoelectric element PZ[m] of the ejection unit D[m].

[0117] Therefore, as in the past, the detection circuit 33 generates the detection signal SK[m] by amplifying the vibration signal VX[m] at a certain amplification factor. When the determination unit 5 performs the ejection state determination process with the ejection portion D[m] as the object based on the detection signal SK[m], the amplitude AK[m] of the detection signal SK[m] becomes an amplitude that is not suitable for the ejection state determination process. Specifically, as in the past, when the detection circuit 33 amplifies the vibration signal VX[m] at a certain amplification factor, the amplitude AK[m] of the detection signal SK[m] becomes larger than the predetermined upper limit amplitude AK1, and the accuracy of the ejection state determination process based on the detection signal SK[m] decreases. In addition, as in the past, when the detection circuit 33 amplifies the vibration signal VX[m] at a certain amplification factor, the amplitude AK[m] of the detection signal SK[m] becomes smaller than the predetermined lower limit amplitude AK2, making it difficult to measure the period TC[m] of the detection signal SK[m] and to perform the ejection state determination process based on the detection signal SK[m].

[0118] In contrast, according to the present embodiment, as described above, the amplification factor setting unit 24 sets the amplification factor AG[m] based on the designated signal SI and the temperature signal ST. In addition, according to the present embodiment, as described above, the detection circuit 33 generates the detection signal SK[m] by amplifying the vibration signal VX[m] according to the amplification factor AG[m]. Therefore, according to the present embodiment, the amplitude AK[m] of the detection signal SK[m] can be set in such a manner that the amplitude AK[m] of the detection signal SK[m] is within a predetermined amplitude range including a reference amplitude AK0 suitable for the ejection state determination process and being greater than the lower limit amplitude AK2 and less than the upper limit amplitude AK1. Therefore, according to the present embodiment, compared with the case where the detection circuit 33 amplifies the vibration signal VX[m] at a certain amplification factor as in the past, the accuracy of the amplification factor setting process based on the detection signal SK[m] can be improved.

[0119] 4. Magnification setting process

[0120] Refer to the following Figures 10 to 13 The outline of the magnification setting process is described.

[0121] Fig.10 This is a flowchart showing an example of the operation of the control unit 2 when executing the magnification setting process.

[0122] like Fig.10 As shown, when the amplification factor setting process starts, the amplification factor setting unit 24 acquires the temperature signal ST from the temperature sensor 35 ( S101 ).

[0123] Furthermore, the amplification factor setting unit 24 acquires the designation signal SI from the discharge control unit 22 ( S103 ).

[0124] Next, the amplification factor setting unit 24 generates piezoelectric drive count information SP indicating the piezoelectric drive count AP[m] based on the designation signal SI acquired in step S103 ( S105 ).

[0125] Specifically, the amplification setting unit 24 causes the storage unit 6 to store the piezoelectric drive count information SP generated in step S105 in one amplification setting process. Then, the amplification setting unit 24 acquires the piezoelectric drive count information SP stored in the storage unit 6 in step S105 of another amplification setting process executed after the one amplification setting process. Next, the amplification setting unit 24 updates the piezoelectric drive count AP[m] by adding the drive count of the ejection unit D[m] indicated by the designated signal SI acquired in step S103 of the other amplification setting process to the piezoelectric drive count information SP acquired from the storage unit 6 in step S105 of the other amplification setting process, and generates the piezoelectric drive count information SP indicating the updated piezoelectric drive count AP[m].

[0126] like Fig.10 As shown, the amplification factor setting unit 24 sets the provisional amplification factor AGT[m] based on the temperature signal ST acquired in step S101 and the ink corresponding amplification information QGT stored in the storage unit 6 ( S107 ).

[0127] Fig.11 This is an explanatory diagram for explaining an example of the ink corresponding enlargement information QGT.

[0128] like Fig.11 As shown, the ink corresponding amplification information QGT is information showing a curve LGT0 representing a combination of the amplification factor AG[m] and the temperature AT for maintaining the amplitude AK[m] of the detection signal SK[m] at the reference amplitude AK0 in the graph G-GT in which the horizontal axis represents the temperature coordinate value ATx corresponding to the temperature AT and the vertical axis represents the amplification factor coordinate value AGy corresponding to the amplification factor AG[m]. Specifically, the ink corresponding amplification information QGT is information showing the coordinates of each of the plurality of points on the curve LGT0 in the graph G-GT. For example, Fig.11 In the curve LGT0, the point where the temperature coordinate value ATx is the reference temperature AT0 and the amplification factor coordinate value AGy is the reference amplification factor AGT0 is a point on the curve LGT0. Therefore, when the temperature AT is the reference temperature AT0 and the amplification factor AG[m] is the reference amplification factor AGT0, the amplitude AK[m] of the detection signal SK[m] is the reference amplitude AK0.

[0129] The ink corresponding amplification information QGT is information showing a curve LGT1 representing a combination of the amplification factor AG[m] and the temperature AT for maintaining the amplitude AK[m] of the detection signal SK[m] at the upper limit amplitude AK1. Specifically, the ink corresponding amplification information QGT is information on the coordinates of each of the plurality of points on the curve LGT1 in the graph G-GT.

[0130] In addition, the ink corresponding amplification information QGT is information showing a curve LGT2 representing a combination of the amplification factor AG[m] and the temperature AT for maintaining the amplitude AK[m] of the detection signal SK[m] at the lower limit amplitude AK2. Specifically, the ink corresponding amplification information QGT is information showing the coordinates of each of the plurality of points on the curve LGT2 in the graph G-GT.

[0131] In step S107 of the amplification setting process, the amplification setting unit 24 determines a point on the curve LGT0 having the temperature AT represented by the temperature signal ST acquired in step S101 as the temperature coordinate value ATx by referring to the ink corresponding amplification information QGT. Then, in the present embodiment, the amplification setting unit 24 sets the amplification coordinate value AGy corresponding to the determined point on the curve LGT0 as the provisional amplification AGT[m]. It should be noted that, in the present embodiment, when the temperature AT represented by the temperature signal ST is low, the amplification setting unit 24 sets the provisional amplification AGT[m] to a larger value than when the temperature AT represented by the temperature signal ST is high.

[0132] It should be noted that, in the present embodiment, the case where the amplification factor coordinate value AGy corresponding to the point on the curve LGT0 is set as the provisional amplification factor AGT[m] is exemplified, but the present invention is not limited to such a form. For example, the amplification factor setting unit 24 may set the amplification factor coordinate value AGy in the range of greater than the amplification factor coordinate value AGy corresponding to the point on the curve LGT2 having the temperature AT represented by the temperature signal ST acquired in step S101 and having the temperature coordinate value ATx as the temperature coordinate value and less than the amplification factor coordinate value AGy corresponding to the point on the curve LGT1 having the temperature AT represented by the temperature signal ST acquired in step S101 and having the temperature coordinate value ATx as the temperature coordinate value as the provisional amplification factor AGT[m] in step S107.

[0133] It should be noted that, in the present embodiment, the ink-corresponding enlargement information QGT is an example of “first enlargement information”.

[0134] like Fig.10 As shown, the amplification factor setting unit 24 sets the provisional amplification factor AGP[m] based on the piezoelectric drive frequency information SP generated in step S105 and the piezoelectric corresponding amplification information QGP stored in the storage unit 6 ( S109 ).

[0135] Fig.12 It is an explanatory diagram for explaining an example of the piezoelectric corresponding amplification information QGP.

[0136] like Fig.12As shown, the piezoelectric corresponding amplification information QGP is information showing a curve LGP0 representing a combination of the amplification factor AG[m] and the piezoelectric driving number AP[m] for maintaining the amplitude AK[m] of the detection signal SK[m] at the reference amplitude AK0, in a graph G-GP in which the horizontal axis represents the driving number coordinate value APx corresponding to the piezoelectric driving number AP[m] and the vertical axis represents the amplification factor coordinate value AGy corresponding to the amplification factor AG[m]. Specifically, the piezoelectric corresponding amplification information QGP is information representing the coordinates of each of the plurality of points on the curve LGP0 in the graph G-GP. For example, Fig.12 In the curve LGP0, the point where the drive number coordinate value APx is the reference piezoelectric drive number AP0 and the amplification factor coordinate value AGy is the reference amplification factor AGP0 is a point on the curve LGP0. Therefore, when the piezoelectric drive number AP[m] is the reference piezoelectric drive number AP0 and the amplification factor AG[m] is the reference amplification factor AGP0, the amplitude AK[m] of the detection signal SK[m] is the reference amplitude AK0.

[0137] In addition, the piezoelectric corresponding amplification information QGP is information of a curve LGP1 representing a combination of an amplification factor AG[m] and a piezoelectric drive number AP[m] for maintaining the amplitude AK[m] of the detection signal SK[m] at the upper limit amplitude AK1. Specifically, the piezoelectric corresponding amplification information QGP is information showing the coordinates of each of a plurality of points on the curve LGP1 in the graph G-GP.

[0138] In addition, the piezoelectric corresponding amplification information QGP is information showing a curve LGP2 representing a combination of an amplification factor AG[m] and a piezoelectric drive number AP[m] for maintaining the amplitude AK[m] of the detection signal SK[m] at the lower limit amplitude AK2. Specifically, the piezoelectric corresponding amplification information QGP is information showing the coordinates of each of a plurality of points on the curve LGP2 in the graph G-GP.

[0139] In step S109, the amplification setting unit 24 determines a point on the curve LGP0 having the piezoelectric drive count AP[m] indicated by the piezoelectric drive count information SP generated in step S105 as the drive count coordinate value APx by referring to the piezoelectric corresponding amplification information QGP. In addition, in the present embodiment, the amplification setting unit 24 sets the amplification coordinate value AGy corresponding to the determined point on the curve LGP0 as the provisional amplification AGP[m]. It should be noted that in the present embodiment, when the piezoelectric drive count AP[m] indicated by the piezoelectric drive count information SP is a large value, the amplification setting unit 24 sets the provisional amplification AGP[m] to a large value by comparing it with the piezoelectric drive count AP[m] indicated by the piezoelectric drive count information SP being a small value.

[0140] It should be noted that, in the present embodiment, the case where the magnification coordinate value AGy corresponding to the point on the curve LGP0 is set as the provisional magnification AGP[m] is exemplified, but the present invention is not limited to such a form. For example, in step S109, the magnification setting unit 24 may set the magnification coordinate value AGy in the range of greater than the magnification coordinate value AGy corresponding to the point on the curve LGP2 having the piezoelectric drive number AP[m] indicated by the piezoelectric drive number information SP generated in step S105 and having the drive number coordinate value APx as the drive number coordinate value and less than the magnification coordinate value AGy corresponding to the point on the curve LGP1 having the piezoelectric drive number AP[m] indicated by the piezoelectric drive number information SP generated in step S105 and having the drive number coordinate value APx as the drive number coordinate value as the provisional magnification AGP[m].

[0141] It should be noted that, in the present embodiment, the piezoelectricity corresponding amplification information QGP is an example of “second amplification information”.

[0142] like Fig.10 As shown, the amplification ratio setting unit 24 sets the amplification ratio AG[m] based on the temporary amplification ratio AGT[m] set in step S107 and the temporary amplification ratio AGP[m] set in step S109 ( S111 ).

[0143] Specifically, the amplification ratio setting unit 24 sets the amplification ratio AG[m] based on the difference between the provisional amplification ratio AGT[m] and the reference amplification ratio AGT0 and the difference between the provisional amplification ratio AGP[m] and the reference amplification ratio AGP0 in step S111. In addition, in step S111, when the provisional amplification ratio AGT[m] is larger than the reference amplification ratio AGT0, the amplification ratio setting unit 24 sets the amplification ratio AG[m] to a larger value by comparison with the provisional amplification ratio AGT[m] being smaller than the reference amplification ratio AGT0, and when the provisional amplification ratio AGP[m] is larger than the reference amplification ratio AGP0, the amplification ratio setting unit 24 sets the amplification ratio AG[m] to a larger value by comparison with the provisional amplification ratio AGP[m] being smaller than the reference amplification ratio AGP0. In the present embodiment, as an example, the amplification ratio setting unit 24 sets the amplification ratio AG[m] based on the ratio of the provisional amplification ratio AGT[m] to the reference amplification ratio AGT0 and the ratio of the provisional amplification ratio AGP[m] to the reference amplification ratio AGP0 in step S111. That is, in the present embodiment, as an example, the amplification ratio setting unit 24 sets the amplification ratio AG[m] based on the following formula (1) in step S111.

[0144] AG[m]=AG0×{AGT[m]÷AGT0}×{AGP[m]÷AGP0}…(1)

[0145] It should be noted that, when the temperature AT is the reference temperature AT0, the piezoelectric drive number AP[m] is the reference piezoelectric drive number AP0, and the amplification factor AG[m] is the reference amplification factor AG0, the reference amplification factor AG0 shown in formula (1) is AG[m] such that the amplitude AK[m] of the detection signal SK[m] is the reference amplitude AK0. In addition, hereinafter, the right side of formula (1) "AG0×{AGT[m]÷AGT0}×{AGP[m]÷AGP0}" is referred to as the target amplification factor AGM[m].

[0146] It should be noted that, in the present embodiment, it is assumed that the detection circuit 33 can amplify the vibration signal VX[m] at an amplification factor AG[m] that is greater than the minimum amplification factor AG-min and less than the maximum amplification factor AG-max. Therefore, in step S111, when the following equation (2) holds true, the amplification factor setting unit 24 sets the amplification factor AG[m] to the minimum amplification factor AG-min; when the following equation (3) holds true, the amplification factor setting unit 24 sets the amplification factor AG[m] to the maximum amplification factor AG-max; when neither the following equation (2) nor the equation (3) holds true, the amplification factor setting unit 24 sets the amplification factor AG[m] to the target amplification factor AGM[m].

[0147] AGM[m]<AG-min…(2)

[0148] AG-max<AGM[m]…(3)

[0149] Next, the amplification factor setting unit 24 generates an amplification factor designation signal SG indicating the amplification factor AG[m], and supplies the generated amplification factor designation signal SG to the detection circuit 33 ( S113 ).

[0150] Next, the amplification factor setting unit 24 determines whether the amplitude AK[m] of the detection signal SK[m] obtained when the detection circuit 33 amplifies the vibration signal VX[m] is included in the predetermined amplitude range based on the amplification factor AG[m] indicated by the amplification factor designation signal SG supplied in step S113 (S115). Specifically, the amplification factor setting unit 24 determines in step S115 whether the amplification factor AG[m] set in step S111 is the target amplification factor AGM[m]. For example, the amplification factor setting unit 24 may also determine in step S115 whether the following formula (4) holds.

[0151] AG-min≤AGM[m]≤AG-max…(4)

[0152] When the determination result in step S115 is affirmative, the magnification ratio setting section 24 ends the magnification ratio setting process.

[0153] If the result of determination in step S115 is negative, the amplification factor setting unit 24 sets the amplitude AC based on the amplification factor enhancement information QGC ( S117 ). In the present embodiment, the amplitude AC is the potential difference between the potential VH1 and the potential VL1 .

[0154] Fig.13 It is an explanatory diagram for explaining an example of the magnification enhancement information QGC.

[0155] like Fig.13 As shown, the amplification enhancement information QGC is information showing a curve LGC0 showing a combination of the amplification factor AG[m] and the amplitude AC for maintaining the amplitude AK[m] of the detection signal SK[m] at the reference amplitude AK0 in a graph G-GC in which the horizontal axis shows the amplitude coordinate value ACx corresponding to the amplitude AC and the vertical axis shows the amplification factor coordinate value AGy corresponding to the amplification factor AG[m]. Specifically, the amplification enhancement information QGC is information showing the coordinates of each of the plurality of points on the curve LGC0 in the graph G-GC. For example, Fig.13 In the graph, the point where the amplitude coordinate value ACx is the reference amplitude AC0 and the amplification factor coordinate value AGy is the reference amplification factor AG0 is on the curve LGC0. Therefore, when the amplitude AC is the reference amplitude AC0 and the amplification factor AG[m] is the reference amplification factor AG0, the amplitude AK[m] of the detection signal SK[m] is the reference amplitude AK0.

[0156] The amplification enhancement information QGC is information showing a curve LGC1 representing a combination of the amplification AG[m] and the amplitude AC for maintaining the amplitude AK[m] of the detection signal SK[m] at the upper limit amplitude AK1. Specifically, the amplification enhancement information QGC is information showing the coordinates of each of the plurality of points on the curve LGC1 in the graph G-GC.

[0157] The amplification enhancement information QGC is information showing a curve LGC2 showing a combination of the amplification AG[m] and the amplitude AC for maintaining the amplitude AK[m] of the detection signal SK[m] at the lower limit amplitude AK2. Specifically, the amplification enhancement information QGC is information showing the coordinates of each of the plurality of points on the curve LGC2 in the graph G-GC.

[0158] In step S117, the amplification factor setting unit 24 determines a point on the curve LGC0 having the amplification factor AG[m] set in step S111 as the amplification factor coordinate value AGy. Then, the amplification factor setting unit 24 sets the amplitude coordinate value ACx corresponding to the determined point on the curve LGC0 as the amplitude AC. It should be noted that in the present embodiment, when the amplification factor AG[m] indicated by the amplification factor designation signal SG is a small value, the amplification factor setting unit 24 sets the amplitude AC to a large value by comparing the amplification factor AG[m] indicated by the amplification factor designation signal SG to a large value.

[0159] It should be noted that, in the present embodiment, the case where the amplitude coordinate value ACx corresponding to the point on the curve LGC0 is set as the amplitude AC is exemplified, but the present invention is not limited to such a form. For example, in step S117, the amplification factor setting unit 24 may set the amplitude coordinate value ACx in the range of being greater than the amplitude coordinate value ACx corresponding to the point on the curve LGC2 having the amplification factor AG[m] set in step S111 as the amplification factor coordinate value AGy and less than the amplitude coordinate value ACx corresponding to the point on the curve LGC1 having the amplification factor AG[m] set in step S111 as the amplification factor coordinate value AGy as the amplitude AC.

[0160] like Fig.10 As shown, the amplification factor setting unit 24 generates the drive waveform correction signal SC indicating the amplitude AC set in step S117 and supplies the generated drive waveform correction signal SC to the drive control unit 21 ( S119 ), and then ends the amplification factor setting process.

[0161] 5. Summary of implementation methods

[0162] In summary, the inkjet printer 1 involved in this embodiment is characterized by comprising: a discharge unit D[m] including a piezoelectric element PZ[m] driven by a drive signal Com, a cavity CV[m] filled with ink and whose volume changes according to the driving of the piezoelectric element PZ[m], and a nozzle N[m] for discharging the liquid in the cavity CV[m] according to the change in the volume of the cavity CV[m]; a detection circuit 33 for detecting the piezoelectric element PZ[m] that changes according to the vibration remaining in the discharge unit D[m] after the driving of the piezoelectric element PZ[m]. ] and generates a detection signal SK[m] based on the detected vibration signal VX[m]; and an amplification setting unit 24 sets the amplification AG[m] based on the temperature signal ST indicating a value associated with the temperature of the ink ejected by the ejection unit D[m] and the piezoelectric drive number information SP indicating a value associated with the drive number of the piezoelectric element PZ[m]. The detection circuit 33 generates a detection signal SK[m] by amplifying the vibration signal VX[m] according to the amplification AG[m] set by the amplification setting unit 24.

[0163] As can be seen from the above, according to the present embodiment, the detection circuit 33 generates the detection signal SK[m] by amplifying the vibration signal VX[m] according to the amplification factor AG[m] set by the amplification factor setting unit 24 based on the temperature signal ST and the piezoelectric drive number information SP. Therefore, according to the present embodiment, compared with the case where the detection circuit 33 amplifies the vibration signal VX[m] at a certain amplification factor, it is possible to generate the detection signal SK[m] suitable for determining the ejection state of the ink in the ejection portion D[m].

[0164] In addition, the inkjet printer 1 involved in this embodiment is characterized in that the inkjet printer 1 has a judgment unit 5, which judges whether the ejection state of the ink in the ejection part D[m] is normal by comparing the period TC[m] represented by the detection signal SK[m] with a part or all of the threshold value Tth1, the threshold value Tth2 and the threshold value Tth3, and the threshold value Tth1, the threshold value Tth2 and the threshold value Tth3 include a fixed reference value, and the value of the fixed reference value does not change even if the temperature of the ink represented by the temperature signal ST changes, and the value of the fixed reference value does not change even if the driving number of the piezoelectric element PZ[m] represented by the piezoelectric driving number information SP changes.

[0165] It can be seen that according to the present embodiment, since the threshold values ​​Tth1, Tth2 and Tth3 are fixed reference values, the ejection state determination process can be simplified compared to a method in which the threshold values ​​Tth1, Tth2 and Tth3 are changed corresponding to the temperature AT indicated by the temperature signal ST or a method in which the threshold values ​​Tth1, Tth2 and Tth3 are changed corresponding to the piezoelectric drive number AP[m] indicated by the piezoelectric drive number information SP.

[0166] In addition, in the inkjet printer 1 involved in this embodiment, it is characterized in that when the temperature AT of the ink represented by the temperature signal ST changes, the amplification factor setting unit 24 sets the amplification factor AG[m] based on the ink corresponding amplification information QGT representing the amplification factor AG[m] of the vibration signal VX[m] required to keep the amplitude AK[m] of the detection signal SK[m] within a predetermined amplitude range.

[0167] Therefore, according to the present embodiment, it is possible to generate the detection signal SK[m] suitable for the discharge state determination process.

[0168] In addition, in the inkjet printer 1 involved in this embodiment, it is characterized in that when the piezoelectric drive number AP[m] represented by the piezoelectric drive number information SP changes, the amplification factor setting unit 24 sets the amplification factor AG[m] based on the piezoelectric corresponding amplification information QGP representing the amplification factor AG[m] of the vibration signal VX[m] required to keep the amplitude AK[m] of the detection signal SK[m] within a predetermined amplitude range.

[0169] Therefore, according to the present embodiment, it is possible to generate the detection signal SK[m] suitable for the discharge state determination process.

[0170] In addition, the inkjet printer 1 involved in this embodiment is characterized in that the inkjet printer 1 has a drive signal generating unit 4 for generating a drive signal Com. Even if the detection circuit 33 amplifies the vibration signal VX[m], the amplitude AK[m] of the detection signal SK[m] cannot be kept within a predetermined amplitude range. The drive signal generating unit 4 corrects the amplitude AC of the drive signal Com to keep the amplitude AK[m] of the detection signal SK[m] within a predetermined amplitude range.

[0171] Therefore, according to the present embodiment, it is possible to generate the detection signal SK[m] suitable for the discharge state determination process.

[0172] In addition, in the inkjet printer 1 involved in this embodiment, it is characterized in that the temperature signal ST represents the temperature AT corresponding to the temperature of the ink ejected from the ejection part D[m]. When the temperature AT represented by the temperature signal ST is low, the amplification factor AG[m] is set to a large value by comparison with when the temperature AT represented by the temperature signal ST is high.

[0173] Therefore, according to the present embodiment, even when the temperature of the ink ejected from the ejection portion D[m] becomes lower and the viscosity of the ink ejected from the ejection portion D[m] becomes higher, the amplitude AK[m] of the detection signal SK[m] can be suppressed from decreasing, and a detection signal SK[m] suitable for ejection state determination processing can be generated.

[0174] B. Modification

[0175] The above methods can be transformed into various forms. Specific deformation methods are illustrated below. Two or more methods arbitrarily selected from the following examples can be appropriately combined within the scope of non-contradiction. It should be noted that in the deformation examples illustrated below, for elements with the same effects and functions as the implementation method, the figure marks referenced in the above description will be used to appropriately omit the corresponding detailed description.

[0176] Modification 1

[0177] In the above embodiment, the amplification factor setting unit 24 sets the amplification factor AG[m] without using the result information SH and the detection signal SK[m]. However, the present invention is not limited to such a form. The amplification factor setting unit 24 may set the amplification factor AG[m] based on the amplitude information SH2[m] included in the result information SH or the detection signal SK[m].

[0178] Fig.14 It is a functional block diagram showing an example of the configuration of an inkjet printer 1B according to this modification.

[0179] like Fig.14 As shown, the inkjet printer 1B differs from the inkjet printer 1 according to the embodiment in that it includes a control unit 2B instead of the control unit 2 and a storage unit 6B instead of the storage unit 6 .

[0180] The storage unit 6B stores the ink corresponding amplitude information QKT, the piezoelectric corresponding amplitude information QKP, and the control program PRG-B.

[0181] The control unit 2B executes the control program PRG-B stored in the storage unit 6B and operates according to the control program PRG-B, thereby functioning as the drive control unit 21, the discharge control unit 22, the determination management unit 23, the amplification factor setting unit 24B, and the conveyance control unit 25. That is, the control unit 2B is different from the control unit 2 according to the embodiment in that the control unit 2B includes an amplification factor setting unit 24B instead of the amplification factor setting unit 24.

[0182] Fig.15 This is a flowchart showing an example of the operation of the control unit 2B when executing the magnification setting process according to this modification.

[0183] like Fig.15 As shown, when the amplification setting process starts, the amplification setting unit 24B obtains the result information SH from the determination unit 5, and determines the amplitude AK[m] indicated by the amplitude information SH2[m] included in the result information SH (S201). It should be noted that the amplification setting unit 24B may also obtain the detection signal SK[m] instead of the amplitude information SH2[m] in step S201, and determine the amplitude AK[m] based on the detection signal SK[m]. Hereinafter, the amplitude AK[m] determined by the amplification setting unit 24B in step S201 is referred to as the current amplitude AKr[m].

[0184] Next, the amplification factor setting unit 24B determines whether the current amplitude AKr[m] determined in step S201 is included in a predetermined amplitude range (S203). That is, the amplification factor setting unit 24B determines in step S203 whether the following equation (5) holds.

[0185] AK2≤AKr[m]≤AK1…(5)

[0186] When the result of the determination in step S203 is affirmative, the magnification ratio setting unit 24B ends the magnification ratio setting process.

[0187] When the result of the determination in step S203 is negative, the amplification factor setting unit 24B acquires the temperature signal ST from the temperature sensor 35 (S205). Hereinafter, the temperature AT indicated by the temperature signal ST acquired by the amplification factor setting unit 24B in step S205 is referred to as the current temperature ATr.

[0188] In addition, the amplification factor setting unit 24B acquires the designation signal SI from the discharge control unit 22 ( S207 ).

[0189] Then, the amplification setting unit 24B generates piezoelectric drive count information SP (S209) indicating the piezoelectric drive count AP[m] based on the designated signal SI acquired in step S207. Hereinafter, the piezoelectric drive count AP[m] indicated by the piezoelectric drive count information SP generated by the amplification setting unit 24B in step S207 is referred to as the current piezoelectric drive count APr[m].

[0190] Next, the amplification factor setting unit 24B determines the provisional amplitude AKT[m] and the provisional amplitude AKP[m] that satisfy the following equation (6) ( S211 ).

[0191] AK0=AKr[m]×{AKT[m]÷AKr[m]}×{AKP[m]÷AKr[m]}…(6)

[0192] It should be noted that, in step S211, the amplification factor setting unit 24B may select any one of the multiple combinations of the provisional amplitude AKT[m] and the provisional amplitude AKP[m] when there are multiple combinations of the provisional amplitude AKT[m] and the provisional amplitude AKP[m]. For example, in step S211, the amplification factor setting unit 24B may select a combination that minimizes the evaluation value VL expressed by the following formula (7) among the multiple combinations of the provisional amplitude AKT[m] and the provisional amplitude AKP[m].

[0193] VL={AKT[m]} 2 +{AKP[m]} 2 …(7)

[0194] Next, the amplification factor setting unit 24B determines the provisional amplification factor AGKT[m] corresponding to the provisional amplitude AKT[m] based on the ink corresponding amplitude information QKT ( S213 ).

[0195] Fig.16 It is an explanatory diagram for explaining an example of the ink corresponding amplitude information QKT.

[0196] like Fig.16 As shown, the ink corresponding amplitude information QKT is information showing the curved surface CKT indicating the amplitude AK[m] corresponding to the temperature AT indicated by the temperature signal ST and the amplification AG[m] indicated by the amplification designation signal SG in a three-dimensional graph G-KT in which the first axis indicates the temperature coordinate value ATx corresponding to the temperature AT, the second axis indicates the amplification coordinate value AGy corresponding to the amplification AG[m], and the third axis indicates the amplitude coordinate value AKz corresponding to the amplitude AK[m]. Specifically, the ink corresponding amplitude information QKT is information showing the coordinates of each of the plurality of points on the curved surface CKT in the graph G-KT.

[0197] For example, in Fig.16In the figure, the magnification coordinate value AGy of the point on the curved surface CKT whose temperature coordinate value ATx is the current temperature ATr and whose amplitude AK[m] is the current amplitude AKr[m] is the initial magnification AGr.

[0198] In step S213, the amplification factor setting unit 24B determines the amplification factor coordinate value AGy of the point on the curved surface CKT whose temperature coordinate value ATx is the current temperature ATr and whose amplitude AK[m] is the provisional amplitude AKT[m] as the provisional amplification factor AGKT[m].

[0199] Furthermore, the amplification factor setting unit 24B determines the provisional amplification factor AGKP[m] corresponding to the provisional amplitude AKP[m] based on the piezoelectric corresponding amplitude information QKP ( S215 ).

[0200] Fig.17 It is an explanatory diagram for explaining an example of the piezoelectric corresponding amplitude information QKP.

[0201] like Fig.17 As shown, the piezoelectric corresponding amplitude information QKP is information showing a curved surface CKP showing the amplitude AK[m] corresponding to the piezoelectric driving number AP[m] indicated by the piezoelectric driving number information SP and the amplification AG[m] indicated by the amplification designation signal SG in a three-dimensional graph G-KP in which the first axis shows the driving number coordinate value APx corresponding to the piezoelectric driving number AP[m], the second axis shows the amplification coordinate value AGy corresponding to the amplification AG[m], and the third axis shows the amplitude coordinate value AKz corresponding to the amplitude AK[m]. Specifically, the piezoelectric corresponding amplitude information QKP is information showing the coordinates of each of a plurality of points on the curved surface CKP in the graph G-KP.

[0202] For example, in Fig.17 In the figure, the magnification coordinate value AGy of the point on the curved surface CKP whose drive order coordinate value APx is the current piezoelectric drive order APr[m] and whose amplitude AK[m] is the current amplitude AKr[m] is the initial magnification AGr.

[0203] In step S215, the amplification factor setting unit 24B determines the amplification factor coordinate value AGy of the point on the curved surface CKP whose drive order coordinate value APx is the current piezoelectric drive order APr[m] and whose amplitude AK[m] is the provisional amplitude AKP[m] as the provisional amplification factor AGKP[m].

[0204] Next, the amplification ratio setting unit 24B sets the amplification ratio AG[m] based on the tentative amplification ratio AGKT[m] determined in step S213 and the tentative amplification ratio AGKP[m] determined in step S215 ( S217 ).

[0205] Specifically, in step S217, the amplification rate setting unit 24B may set the amplification rate AG[m] based on the degree of difference between the provisional amplification rate AGKT[m] and the reference amplification rate AGT0 and the degree of difference between the provisional amplification rate AGKP[m] and the reference amplification rate AGP0. In addition, in step S217, when the provisional amplification rate AGKT[m] is larger than the reference amplification rate AGT0, the amplification rate setting unit 24B may set the amplification rate AG[m] to a larger value by comparing the provisional amplification rate AGKT[m] with the provisional amplification rate AGT0 being smaller than the reference amplification rate AGT0, and when the provisional amplification rate AGKP[m] is larger than the reference amplification rate AGP0, the amplification rate setting unit 24B may set the amplification rate AG[m] to a larger value by comparing the provisional amplification rate AGKP[m] with the provisional amplification rate AGP0 being smaller than the reference amplification rate AGP0. In this modification, the amplification ratio setting unit 24B sets the amplification ratio AG[m] based on the ratio of the provisional amplification ratio AGKT[m] to the reference amplification ratio AGT0 and the ratio of the provisional amplification ratio AGKP[m] to the reference amplification ratio AGP0 in step S217. That is, in this modification, the amplification ratio setting unit 24B sets the amplification ratio AG[m] based on the following equation (8) in step S217.

[0206] AG[m]=AG0×{AGKT[m]÷AGT0}×{AGKP[m]÷AGP0}…(8)

[0207] Next, the amplification factor setting unit 24B generates an amplification factor designation signal SG indicating the amplification factor AG[m], supplies the generated amplification factor designation signal SG to the detection circuit 33 (S113), and ends the amplification factor setting process.

[0208] In summary, according to this modification, the detection circuit 33 generates the detection signal SK[m] by amplifying the vibration signal VX[m] according to the amplification factor AG[m] set by the amplification factor setting unit 24B based on the temperature signal ST, the piezoelectric drive number information SP, and the amplitude information SH2[m]. Therefore, according to this modification, compared with the case where the detection circuit 33 amplifies the vibration signal VX[m] at a certain amplification factor, it is possible to generate the detection signal SK[m] suitable for determining the ejection state of the ink in the ejection portion D[m].

[0209] Modification 2

[0210] In the above-mentioned embodiment and modification 1, the head unit 3 is configured to include the supply circuit 31, the recording head 32, the detection circuit 33, and the temperature sensor 35, but the present invention is not limited to such a form. The head unit 3 may also be configured to include components other than the supply circuit 31, the recording head 32, the detection circuit 33, and the temperature sensor 35. For example, the head unit 3 may also be configured to include the determination unit 5.

[0211] Modification 3

[0212] In the above-mentioned embodiment and modification examples 1 and 2, it is assumed that the inkjet printer 1 has four head units 3, but the present invention is not limited to such a form. The inkjet printer 1 may be a printer having more than one and less than three head units 3, and the inkjet printer 1 may be a printer having five or more head units 3.

[0213] Modification 4

[0214] In the above-mentioned embodiment and Modifications 1 to 3, the case where the inkjet printer 1 is a serial printer is exemplified, but the present invention is not limited to such a form. The inkjet printer 1 may also be a so-called line printer in which a plurality of nozzles N are provided in a head unit 3 so as to extend in a range wider than the width of the recording paper PP.

Claims

1. A liquid ejection device, characterized in that: have: A discharge unit including a piezoelectric element driven by a driving signal, a pressure chamber filled with a liquid and having a volume changed according to the driving of the piezoelectric element, and a nozzle for discharging the liquid in the pressure chamber according to the change in the volume of the pressure chamber; a detection unit that detects a vibration signal and generates a detection signal based on the detected vibration signal, wherein the vibration signal indicates a potential of the piezoelectric element that varies according to the vibration remaining in the ejection unit after the piezoelectric element is driven; as well as The setting unit sets a signal amplification factor based on liquid characteristic information associated with the characteristics of the liquid ejected by the ejection unit and element characteristic information associated with the characteristics of the piezoelectric element. The detection unit generates the detection signal by amplifying the vibration signal according to the signal amplification factor set by the setting unit.

2. The liquid ejection device according to claim 1, characterized in that: The liquid ejection device includes a determination unit for determining whether the ejection state of the liquid in the ejection unit is normal by comparing the feature quantity represented by the detection signal with one or more reference values. The one or more reference values ​​include a fixed reference value, and the value of the fixed reference value does not change even if the characteristics of the liquid represented by the liquid characteristic information change, and the value of the fixed reference value does not change even if the characteristics of the piezoelectric element represented by the element characteristic information change.

3. The liquid ejection device according to claim 1, characterized in that: When the characteristics of the liquid indicated by the liquid characteristic information vary, the setting unit sets the signal amplification factor based on first amplification information indicating an amplification factor of the vibration signal required to keep the amplitude of the detection signal within a predetermined amplitude range.

4. The liquid ejection device according to claim 1, characterized in that: When the characteristics of the piezoelectric element indicated by the element characteristic information vary, the setting unit sets the signal amplification factor based on second amplification information indicating the amplification factor of the vibration signal required to keep the amplitude of the detection signal within a predetermined amplitude range.

5. The liquid ejection device according to claim 1, characterized in that: The liquid ejection device includes a drive signal generating unit for generating the drive signal. When the amplitude of the detection signal cannot be kept within a predetermined amplitude range even if the detection unit amplifies the vibration signal, the drive signal generation unit corrects the waveform of the drive signal so as to keep the amplitude of the detection signal within the predetermined amplitude range.

6. The liquid ejection device according to claim 1, characterized in that: The liquid characteristic information indicates a temperature corresponding to the temperature of the liquid ejected from the ejection portion, When the temperature indicated by the liquid characteristic information is low, the signal amplification factor is set to a larger value than when the temperature indicated by the liquid characteristic information is high.

7. A liquid ejection head, characterized in that: have: a discharge unit including a piezoelectric element driven by a driving signal, a pressure chamber filled with a liquid and having a volume changed according to the driving of the piezoelectric element, and a nozzle for discharging the liquid in the pressure chamber according to the change in the volume of the pressure chamber; as well as a detection unit that detects a vibration signal indicating a potential of the piezoelectric element that changes according to vibration remaining in the ejection unit after the piezoelectric element is driven, and generates a detection signal based on the detected vibration signal, The detection unit generates the detection signal by amplifying the vibration signal according to a signal amplification factor set based on liquid characteristic information associated with characteristics of the liquid ejected by the ejection unit and element characteristic information associated with characteristics of the piezoelectric element.

8. A method for controlling a liquid ejection device, characterized in that: The liquid ejection device comprises an ejection unit, wherein the ejection unit comprises a piezoelectric element driven by a driving signal, a pressure chamber filled with liquid and whose volume changes according to the driving of the piezoelectric element, and a nozzle for ejecting the liquid in the pressure chamber according to the change in the volume of the pressure chamber. In the control method of the liquid ejection device, detecting a vibration signal indicating a potential of the piezoelectric element that changes according to vibration remaining in the ejection portion after the piezoelectric element is driven, The signal amplification factor is set based on liquid characteristic information associated with the characteristics of the liquid ejected by the ejection unit and element characteristic information associated with the characteristics of the piezoelectric element. A detection signal is generated by amplifying the vibration signal according to the signal amplification rate.

9. The control method of the liquid ejection device according to claim 8, characterized in that: By comparing the characteristic quantity represented by the detection signal with one or more reference values, it is determined whether the ejection state of the liquid in the ejection part is normal. The one or more reference values ​​include a fixed reference value, and the value of the fixed reference value does not change even if the characteristics of the liquid represented by the liquid characteristic information change, and the value of the fixed reference value does not change even if the characteristics of the piezoelectric element represented by the element characteristic information change.

10. The control method of the liquid ejection device according to claim 8, characterized in that: When the characteristics of the liquid indicated by the liquid characteristic information vary, the signal amplification factor is set based on first amplification information indicating the amplification factor of the vibration signal required to keep the amplitude of the detection signal within a predetermined amplitude range.

11. The control method of the liquid ejection device according to claim 8, characterized in that: When the characteristics of the piezoelectric element indicated by the element characteristic information vary, the signal amplification factor is set based on second amplification information indicating the amplification factor of the vibration signal required to keep the amplitude of the detection signal within a predetermined amplitude range.

12. The control method of the liquid ejection device according to claim 8, characterized in that: In the case where the amplitude of the detection signal cannot be kept within a predetermined amplitude range even if the vibration signal is amplified, The waveform of the drive signal is corrected to keep the amplitude of the detection signal within the predetermined amplitude range.

13. The control method of the liquid ejection device according to claim 8, characterized in that: The liquid characteristic information indicates a temperature corresponding to the temperature of the liquid ejected from the ejection portion, When the temperature indicated by the liquid characteristic information is low, the signal amplification factor is set to a larger value compared to when the temperature indicated by the liquid characteristic information is high.

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