Liquid ejection apparatus, method for controlling liquid ejection apparatus, and control program product

Abstract

The invention provides a liquid ejecting apparatus, a control method of the liquid ejecting apparatus, and a control program product. The liquid ejecting apparatus appropriately adjusts pressure near a nozzle. The liquid ejecting apparatus includes a piezoelectric element; a plurality of independent flow channels each including a nozzle and a pressure chamber; a common flow channel which is in common communication with the plurality of independent flow channels and supplies ink to the plurality of independent flow channels; the common flow channel is communicated with the plurality of independent flow channels, and the ink is discharged from the plurality of independent flow channels; a pump (63) for applying, to the common flow path, a pressure (Pin) for supplying the ink to the common flow path; a pump (64) for applying, to the common flow path, a pressure (Pout) for discharging the ink from the common flow path; a detection circuit that detects residual vibration in the pressure chamber after a voltage is applied to the piezoelectric element; and a cycle control unit that determines the pressure (Pin) and the pressure (Pout) on the basis of the residual vibration detected by the detection circuit.

Description

Technical Field

[0001] The present invention relates to a liquid ejection device, a control method for a liquid ejection device, and a control program for a liquid ejection device. Background Art

[0002] In a liquid ejection device such as an inkjet printer, after a liquid such as ink is filled in a liquid ejection head, the liquid is ejected from the liquid ejection head. In such a liquid ejection head, in order to prevent the retention of bubbles in the liquid or the thickening of the liquid, a technique of circulating the liquid in a flow path provided in the liquid ejection head has been proposed. For example, in Patent Document 1, a liquid ejection device having a circulation mechanism that circulates the ink discharged from the liquid ejection head in the liquid ejection head is disclosed.

[0003] However, in a liquid ejection device that circulates a liquid in a flow path provided in a liquid ejection head, in order to make the ejection characteristics of the liquid ejection head into desired characteristics, it is necessary to appropriately adjust the pressure near the nozzle.

[0004] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2021-24082 Summary of the Invention

[0005] In order to solve the above problems, the liquid ejection device according to the present invention includes: a piezoelectric element; a plurality of independent flow paths, each of which includes a nozzle and a pressure chamber; a common supply flow path that is commonly connected to the plurality of independent flow paths and supplies liquid to the plurality of independent flow paths; a common discharge flow path that is commonly connected to the plurality of independent flow paths and discharges liquid from the plurality of independent flow paths; a first pressure applying unit that applies a first pressure for supplying liquid to the common supply flow path to the common supply flow path; a second pressure applying unit that applies a second pressure for discharging liquid from the common discharge flow path to the common discharge flow path; a detection unit that detects residual vibration in the pressure chamber after a voltage is applied to the piezoelectric element; and a pressure determination unit that determines the first pressure and the second pressure respectively based on the residual vibration detected by the detection unit.

[0006] In addition, in the control method of the liquid ejection device according to the present invention, the liquid ejection device includes: a piezoelectric element; a plurality of independent flow paths each including a nozzle and a pressure chamber; a common supply flow path that communicates with the plurality of independent flow paths in common and supplies liquid to the plurality of independent flow paths; a common discharge flow path that communicates with the plurality of independent flow paths in common and discharges liquid from the plurality of independent flow paths; a first pressure applying unit that applies a first pressure for supplying liquid to the common supply flow path to the common supply flow path; a second pressure applying unit that applies a second pressure for discharging liquid from the common discharge flow path to the common discharge flow path; a detection unit that detects residual vibration in the pressure chamber after a voltage is applied to the piezoelectric element. In the control method of the liquid ejection device, the first pressure and the second pressure are respectively determined based on the residual vibration detected by the detection unit.

[0007] In addition, in the control program product of the liquid ejection device according to the present invention, the liquid ejection device includes: a piezoelectric element; a plurality of independent flow paths each including a nozzle and a pressure chamber; a common supply flow path that communicates with the plurality of independent flow paths in common and supplies liquid to the plurality of independent flow paths; a common discharge flow path that communicates with the plurality of independent flow paths in common and discharges liquid from the plurality of independent flow paths; a first pressure applying unit that applies a first pressure for supplying liquid to the common supply flow path to the common supply flow path; a second pressure applying unit that applies a second pressure for discharging liquid from the common discharge flow path to the common discharge flow path; a detection unit that detects residual vibration in the pressure chamber after a voltage is applied to the piezoelectric element. The control program product of the liquid ejection device causes a computer to function as a pressure determination unit, and the pressure determination unit respectively determines the first pressure and the second pressure based on the residual vibration detected by the detection unit. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 A block diagram showing an example of the structure of the liquid ejection device according to the embodiment of the present invention.

[0009] Figure 2 A schematic diagram showing the structure of the liquid ejection device.

[0010] Figure 3 An exploded perspective view showing an example of the structure of the liquid ejection head.

[0011] Figure 4 A cross-sectional view showing an example of the structure of the liquid ejection head.

[0012] Figure 5An explanatory diagram for explaining the flow of ink.

[0013] Figure 6 A block diagram showing an example of the structure of a liquid ejection head.

[0014] Figure 7 A timing chart showing an example of the operation of a liquid ejection device during a unit period.

[0015] Figure 8 An explanatory diagram for explaining the outline of the operation of a circulation control unit.

[0016] Figure 9 A flowchart showing an example of the operation of a liquid ejection device.

[0017] Figure 10 An exploded perspective view showing an example of the structure of a liquid ejection head according to a first modification.

[0018] Figure 11 For showing Figure 10 A cross-sectional view showing an example of the structure of the liquid ejection head shown.

[0019] Figure 12 An explanatory diagram for explaining the flow of ink in the first modification. Detailed implementation mode

[0020] Hereinafter, the mode for implementing the present invention will be described with reference to the drawings. However, in each drawing, the dimensions and scales of each part are appropriately different from the actual situation. In addition, since the following described embodiments are preferred specific examples of the present invention, various technically preferred limitations are added. However, for the scope of the present invention, as long as there is no description of the gist of specifically limiting the present invention in the following description, it is not limited to these modes.

[0021] 1. Embodiment

[0022] First, while referring to Figure 1 The outline of the liquid ejection device 100 according to the present embodiment will be described. In the present embodiment, as an example, it is assumed that the liquid ejection device 100 is an inkjet printer that ejects ink onto a medium PP to form an image. In the present embodiment, as the medium PP, the recording paper shown later is assumed. Figure 2 shown.

[0023] Figure 1 A block diagram showing an example of the structure of the liquid ejection device 100 according to the embodiment of the present invention.

[0024] In the liquid ejecting apparatus 100, print data IMG representing an image to be formed by the liquid ejecting apparatus 100 is supplied from a host device such as a personal computer or a digital camera. The liquid ejecting apparatus 100 performs a printing process of forming an image represented by the print data IMG supplied from the host device on a medium PP.

[0025] The liquid ejecting apparatus 100 includes a liquid ejecting head 1 provided with an ejecting portion D including nozzles N for ejecting ink, a drive signal generation unit 2 that generates a plurality of drive signals COM for driving the ejecting portion D, and a viscosity estimation unit 3 that estimates the viscosity of the ink in the ejecting portion D. Regarding the nozzles N, a description will be given later in Figure 3 and Figure 4 The liquid ejecting apparatus 100 further includes a control unit 4 that controls each unit of the liquid ejecting apparatus 100, and a storage unit 5 that stores various information such as the print data IMG and a control program PG of the liquid ejecting apparatus 100. Further, the liquid ejecting apparatus 100 also includes a circulation mechanism 6 that circulates the ink, a maintenance unit 7 that performs a maintenance process on the liquid ejecting head 1, a medium conveyance mechanism 8 that conveys the medium PP, and a carriage conveyance mechanism 9 that reciprocates a carriage 91. Regarding the carriage 91, a description will be given later in Figure 2 In the following.

[0026] In the present embodiment, it is assumed that the liquid ejecting head 1 and the drive signal generation unit 2 correspond to each other, the liquid ejecting head 1 and the viscosity estimation unit 3 correspond to each other, and the liquid ejecting head 1 and the circulation mechanism 6 correspond to each other. For example, the liquid ejecting apparatus 100 may include a plurality of liquid ejecting heads 1, a plurality of drive signal generation units 2, a plurality of viscosity estimation units 3, and a plurality of circulation mechanisms 6. In this case, for example, the plurality of drive signal generation units 2 correspond one-to-one with the plurality of liquid ejecting heads 1, the plurality of viscosity estimation units 3 correspond one-to-one with the plurality of liquid ejecting heads 1, and the plurality of circulation mechanisms 6 correspond one-to-one with the plurality of liquid ejecting heads 1. Alternatively, the liquid ejecting apparatus 100 may include one liquid ejecting head 1, one drive signal generation unit 2 corresponding to the liquid ejecting head 1, one viscosity estimation unit 3 corresponding to the liquid ejecting head 1, and one circulation mechanism 6 corresponding to the liquid ejecting head 1.

[0027] In the present embodiment, it is assumed that the liquid ejecting apparatus 100 includes four liquid ejecting heads 1 corresponding to four types of inks: cyan, magenta, yellow, and black. That is, in the present embodiment, it is assumed that the liquid ejecting apparatus 100 includes four liquid ejecting heads 1, four drive signal generation units 2, four viscosity estimation units 3, and four circulation mechanisms 6. However, hereinafter, for the sake of convenience of explanation, as Figure 1As illustrated, sometimes, one of the four liquid ejection heads 1, one drive signal generation unit 2 corresponding to the one liquid ejection head 1, one viscosity estimation unit 3, and one circulation mechanism 6 are taken as examples for explanation.

[0028] First, before explaining the liquid ejection head 1, the control unit 4, the drive signal generation unit 2, and the storage unit 5 are explained.

[0029] The control unit 4 is configured to include one or more CPUs (Central Processing Unit). In addition, the control unit 4 may be configured to include programmable logic devices such as FPGAs (field-programmable gate arrays) instead of CPUs or in addition to CPUs. Further, for example, the control unit 4 operates by following the control program PG stored in the storage unit 5 to generate signals such as a printing signal SI and a waveform specification signal dCOM for controlling the operations of the respective parts of the liquid ejection device 100.

[0030] Here, the waveform specification signal dCOM is a digital signal that specifies the waveforms of the respective drive signals COM. In addition, each drive signal COM is an analog signal for driving the ejection unit D. In the present embodiment, as described later Figure 6 and the like, it is assumed that the plurality of drive signals COM include drive signals COMa and COMb. Further, the printing signal SI is a digital signal for specifying the type of operation of the ejection unit D. Specifically, the printing signal SI is a signal for specifying the type of operation of the ejection unit D by specifying whether each drive signal COM is supplied to the ejection unit D.

[0031] In addition, in the present embodiment, the control unit 4 operates by following the control program PG stored in the storage unit 5 to function as a circulation control unit 40 for controlling the circulation mechanism 6. For example, the circulation control unit 40 generates a control signal Ctr for controlling the operation of the circulation mechanism 6 and outputs the generated control signal Ctr to the circulation mechanism 6. The control unit 4 is an example of a "computer", and the circulation control unit 40 is an example of a "pressure determination unit". In addition, the detailed content of the operation of the circulation control unit 40 will be described in Figure 8 and Figure 9 will be described.

[0032] The drive signal generation unit 2 includes, for example, a DAC (Digital Analog Converter), and generates a plurality of drive signals COM based on the waveform specifying signal dCOM supplied from the control unit 4. For example, each of the plurality of drive signals COM generated by the drive signal generation unit 2 includes a waveform specified by the waveform specifying signal dCOM. The drive signal generation unit 2 outputs the plurality of drive signals COM generated based on the waveform specifying signal dCOM to the switching circuit 18 included in the liquid ejection head 1.

[0033] The storage unit 5 is configured to include one or both of a volatile memory such as a RAM (Random Access Memory) and a non-volatile memory such as a ROM (Read Only Memory), an EEPROM (Electrically Erasable Programmable Read-Only Memory), or a PROM (Programmable ROM). Additionally, the storage unit 5 may be included in the control unit 4.

[0034] The liquid ejection head 1 has a switching circuit 18, a recording head 10, and a detection circuit 19.

[0035] The recording head 10 has M ejection portions D. Additionally, the value M is a natural number of 1 or more. Hereinafter, the j-th ejection portion D among the M ejection portions D provided in the recording head 10 may be referred to as the ejection portion D[j]. Here, the variable j is a natural number satisfying "1 ≤ j ≤ M". Further, hereinafter, when a structural element or signal of the liquid ejection device 100 corresponds to the ejection portion D[j] among the M ejection portions D, a suffix [j] may be added to the symbol used to represent the structural element or signal.

[0036] The switching circuit 18 switches whether to supply each drive signal COM to the ejection portion D[j] based on the printing signal SI. Additionally, hereinafter, as described later Figure 6As shown, etc., sometimes, among multiple drive signals COM, the drive signal COM supplied to the ejection unit D[j] is referred to as an independent drive signal Vin[j]. In addition, the switching circuit 18 switches whether to electrically connect the ejection unit D[j] and the detection circuit 19 based on the printing signal SI. When the ejection unit D[j] and the detection circuit 19 are electrically connected, for example, the detection signal Vout[j] detected from the ejection unit D[j] is supplied to the detection circuit 19 via the switching circuit 18. The detection signal Vout[j] represents, for example, the waveform of the residual vibration remaining in the ejection unit D[j] after being driven by the independent drive signal Vin[j].

[0037] The detection circuit 19 generates a residual vibration signal Vd[j] based on the detection signal Vout[j]. For example, the detection circuit 19 shapes the detection signal Vout[j] into a waveform suitable for processing in the viscosity inference unit 3 by amplifying the amplitude of the detection signal Vout[j] or removing the noise components included in the detection signal Vout[j]. Thereby, the residual vibration signal Vd[j] is generated. For example, the detection circuit 19 may also have a structure including a negative feedback type amplifier for amplifying the detection signal Vout[j], a low-pass filter for attenuating the high-frequency components of the detection signal Vout[j], and a voltage follower for converting the impedance and outputting the residual vibration signal Vd[j] with a low impedance, etc.

[0038] The detection circuit 19 outputs the residual vibration signal Vd[j] generated based on the detection signal Vout[j] to the viscosity inference unit 3. In addition, the detection circuit 19 is an example of a "detection unit".

[0039] The viscosity inference unit 3 infers the viscosity of the ink in the ejection unit D[j] based on the residual vibration signal Vd[j], for example. In addition, for example, since the residual vibration signal Vd[j] used in the inference of the ink viscosity in the ejection unit D[j] is generated based on the detection signal Vout[j], it represents the waveform of the residual vibration of the ejection unit D[j] after being driven by the independent drive signal Vin[j].

[0040] For example, the viscosity inference unit 3 may also detect the relative viscosity with respect to a specified viscosity by comparing characteristic quantities such as the amplitude and period of the residual vibration signal Vd[j] with the reference characteristic quantities of the residual vibration signal when the ink viscosity is the specified viscosity. Or, the viscosity inference unit 3 may calculate the attenuation rate of the residual vibration based on the attenuation rate of the amplitude of the residual vibration signal Vd[j], and infer the viscosity of the ink based on the calculated attenuation rate of the residual vibration.

[0041] In addition, for example, the viscosity inference unit 3 generates viscosity information Vinf indicating the viscosity of the ink inferred based on the residual vibration, and outputs the generated viscosity information Vinf to the control unit 4. Additionally, the viscosity inference unit 3 may be included in the control unit 4. For example, the control unit 4 may also function as the viscosity inference unit 3 by operating in accordance with the control program PG stored in the storage unit 5. Furthermore, the elements including the viscosity inference unit 3 and the circulation control unit 40 may be understood as a "pressure determination unit".

[0042] Moreover, in the present embodiment, as described above, the maintenance unit 7 performs the maintenance process. For example, the maintenance unit 7 performs the maintenance process under the control of the control unit 4. The maintenance process includes, for example, a flushing process of discharging the ink from the ejection unit D, a wiping process of wiping foreign substances such as ink adhering near the nozzle N of the ejection unit D using a wiper, and a suction process of sucking the ink inside the ejection unit D using a tube pump or the like.

[0043] The maintenance unit 7 has a discharged ink receiving portion for receiving the discharged ink when the ink inside the ejection unit D is discharged during the flushing process, a wiper for wiping foreign substances such as ink adhering near the nozzle N of the ejection unit D, and a tube pump for sucking the ink or air bubbles inside the ejection unit D. Additionally, the discharged ink receiving portion, the wiper, and the tube pump are not shown in the figure.

[0044] Furthermore, the structure of the liquid ejection device 100 is not limited to Figure 1 the example shown. For example, the viscosity inference unit 3 may also have a function of judging the ejection state of the nozzle N included in the ejection unit D[j] based on the residual vibration signal Vd[j]. In this case, for example, the viscosity inference unit 3 may judge the ejection state of the nozzle N by comparing the detected values such as the amplitude and period of the residual vibration signal Vd[j] with the reference values when the ejection state of the nozzle N is normal.

[0045] Next, while referring to Figure 2 the following, the overall structure of the outline of the liquid ejection device 100 will be described.

[0046] Figure 2 is a schematic structural diagram showing the liquid ejection device 100. In Figure 2 the following, the description will be centered around the circulation mechanism 6, the medium conveyance mechanism 8, and the carriage conveyance mechanism 9.

[0047] The circulation mechanism 6 supplies the ink stored in the circulation mechanism 6 to the liquid ejection head 1 based on the control signal Ctr supplied from the control unit 4. In addition, the circulation mechanism 6 recovers the ink from the liquid ejection head 1 based on the control signal Ctr supplied from the control unit 4, and causes the recovered ink to flow back into the liquid ejection head 1.

[0048] For example, the circulation mechanism 6 includes an ink container 60 for storing ink, a pump 63 connected to a supply flow path 61 for supplying ink to the liquid ejection head 1, and a pump 64 connected to a recovery flow path 62 for recovering the ink discharged from the liquid ejection head 1. As the ink container 60, for example, a cartridge detachable from the liquid ejection device 100, a bag-shaped ink bag formed of a flexible film, or an ink tank that can be replenished with ink can be used. In addition, the type of ink stored in the ink container 60 is not particularly limited and is arbitrary. In addition, the pump 63 is an example of the "first pressure applying unit", and the pump 64 is an example of the "second pressure applying unit".

[0049] The pump 63 and the pump 64 are controlled by the control unit 4. For example, the pump 63 supplies the ink stored in the ink container 60 to the liquid ejection head 1 via the supply flow path 61 based on the control signal Ctr supplied from the control unit 4. In addition, for example, the pump 64 recovers the ink from the liquid ejection head 1 via the recovery flow path 62 based on the control signal Ctr supplied from the control unit 4, and supplies the recovered ink to the ink container 60.

[0050] In addition, the circulation mechanism 6 may be defined as not including the ink container 60, or may be defined as including the supply flow path 61 and the recovery flow path 62.

[0051] The medium conveyance mechanism 8 conveys the medium PP in the Y1 direction along the Y axis under the control implemented by the control unit 4. Hereinafter, the Y1 direction and the Y2 direction opposite to the Y1 direction are collectively referred to as the Y-axis direction. In addition, hereinafter, the X1 direction along the X axis intersecting the Y axis and the X2 direction opposite to the X1 direction are collectively referred to as the X-axis direction. In addition, hereinafter, the Z1 direction along the Z axis intersecting the X axis and the Y axis and the Z2 direction opposite to the Z1 direction are collectively referred to as the Z-axis direction. In the present embodiment, as an example, a case where the X axis, the Y axis, and the Z axis are orthogonal to each other is assumed for description. However, the present invention is not limited to such a manner. The X axis, the Y axis, and the Z axis only need to intersect each other.

[0052] The carriage conveyance mechanism 9 reciprocally moves the plurality of liquid ejection heads 1 in the X1 direction and the X2 direction under the control implemented by the control unit 4. As Figure 2As shown, the carriage conveyance mechanism 9 has a substantially box-shaped carriage 91 that houses a plurality of liquid ejection heads 1, and a seamless belt 92 to which the carriage 91 is fixed. Additionally, the circulation mechanism 6 and the liquid ejection head 1 may also be housed on the carriage 91.

[0053] The liquid ejection head 1 is driven by a drive signal COM under the control of a printing signal SI, so that ink is ejected from a part or all of a plurality of nozzles N provided on the liquid ejection head 1 in the Z1 direction. That is, the liquid ejection head 1 ejects ink from a part or all of the plurality of nozzles N in a manner linked to the conveyance of the medium PP by the medium conveyance mechanism 8 and the reciprocating movement of the liquid ejection head 1 by the carriage conveyance mechanism 9, and causes the ejected ink to be sprayed onto the surface of the medium PP, thereby forming a desired image on the surface of the medium PP.

[0054] Next, while referring to Figure 3 and Figure 4 the schematic structure of the liquid ejection head 1 will be described.

[0055] Figure 3 FIG. is an exploded perspective view showing an example of the structure of the liquid ejection head 1. Figure 4 FIG. is a cross-sectional view showing an example of the structure of the liquid ejection head 1. Figure 4 The cross-sectional view shown in Figure 3 is a cross-sectional view taken along line II-II shown in Figure 4 The cross-section of line II-II is parallel to the XZ plane and passes through the connection ports H1 and H2 described later. In addition, in

[0056] As Figure 3 and Figure 4 shown, the liquid ejection head 1 has a nozzle substrate 11, a communication board 12, a pressure chamber substrate 13, a diaphragm 14, a flow path forming substrate 16, and a wiring substrate 17 on which electronic components EC are mounted. The electronic components EC include circuits such as a switching circuit 18 and a detection circuit 19, for example. For example, the recording head 10 is electrically connected to the switching circuit 18, the detection circuit 19, etc. via the wiring substrate 17.

[0057] As Figure 3As shown, the nozzle substrate 11 is a plate-shaped member that is long in the Y-axis direction and extends substantially parallel to the XY plane. Here, the so-called "substantially parallel" includes the concept that, in addition to the case of being completely parallel, it also includes the case where it is regarded as parallel when considering errors. In the present embodiment, the so-called "substantially parallel" is defined as including the concept that it is regarded as parallel when considering an error of about 10%. Although the nozzle substrate 11 is manufactured by processing a single-crystal silicon substrate using semiconductor manufacturing techniques such as etching, known materials and manufacturing methods can be arbitrarily adopted in the manufacturing of the nozzle substrate 11.

[0058] On the nozzle substrate 11, M nozzles N are formed. Here, the so-called nozzle N is a through-hole provided on the nozzle substrate 11. The surface NP in the Z1 direction of the nozzle substrate 11 corresponds to the nozzle surface. In the present embodiment, it is assumed that the M nozzles N are arranged on the nozzle substrate 11 so as to extend in the Y-axis direction. Hereinafter, the M nozzles N extending in the Y-axis direction may be referred to as a nozzle row Ln.

[0059] As Figure 3 and Figure 4 shown, a communication plate 12 is provided at a position in the Z2 direction with respect to the nozzle substrate 11. The communication plate 12 is a plate-shaped member that is long in the Y-axis direction and extends substantially parallel to the XY plane. Although the communication plate 12 is manufactured by processing a single-crystal silicon substrate using semiconductor manufacturing techniques, known materials and manufacturing methods can be arbitrarily adopted in the manufacturing of the communication plate 12.

[0060] As Figure 3 and Figure 4 shown, a pressure chamber substrate 13 is provided at a position in the Z2 direction with respect to the communication plate 12. The pressure chamber substrate 13 is a plate-shaped member that is long in the Y-axis direction and extends substantially parallel to the XY plane. The pressure chamber substrate 13 is manufactured by processing a single-crystal silicon substrate using semiconductor manufacturing techniques, for example, but known materials and manufacturing methods can also be adopted in the manufacturing of the pressure chamber substrate 13.

[0061] In the communication plate 12 and the pressure chamber substrate 13, flow paths for ink are formed. Specifically, in the communication plate 12 and the pressure chamber substrate 13, a common flow path BA1 provided so as to extend in the Y-axis direction and a common flow path BA2 provided so as to extend in the Y-axis direction are formed. In addition, the common flow path BA2 is located at a position in the X1 direction with respect to the common flow path BA1.

[0062] In addition, on the communication plate 12 and the pressure chamber substrate 13, M connection channels BR1 corresponding to the M nozzles N are formed. In addition, in the communication plate 12 and the pressure chamber substrate 13, M connection channels BR2 corresponding to the M nozzles N are formed. In addition, in the communication plate 12, M nozzle channels BN corresponding to the M nozzles N are formed. In addition, in the pressure chamber substrate 13, M pressure chambers CV corresponding to the M nozzles N are formed.

[0063] The connection channel BR1 is arranged in a manner extending in the X-axis direction at a position in the X1 direction with respect to the common channel BA1 and is in communication with the common channel BA1. The connection channel BR2 is arranged in a manner extending in the X-axis direction at a position in the X2 direction with respect to the common channel BA2 and is in communication with the common channel BA2. The pressure chamber CV is located between the connection channel BR1 and the connection channel BR2 and is in communication with the connection channel BR1 and the connection channel BR2. Further, the pressure chamber CV is in communication with the nozzle channel BN. In addition, the nozzle channel BN is arranged at a position in the Z1 direction with respect to the pressure chamber CV and is in communication with the nozzle N.

[0064] In addition, hereinafter, the common channel BA1 and the common channel BA2 may be collectively referred to as the common channel BA, and the connection channel BR1 and the connection channel BR2 may be collectively referred to as the connection channel BR.

[0065] In addition, hereinafter, the connection channel BR1, the pressure chamber CV in communication with the connection channel BR1, and the connection channel BR2 in communication with the pressure chamber CV may be referred to as an independent channel RK. In addition, hereinafter, the independent channel RK corresponding to the j-th nozzle N among the M nozzles N may be referred to as the independent channel RK[j]. In addition, in the present embodiment, the independent channel RK[j] is defined to include the j-th nozzle N among the M nozzles N. That is, in the present embodiment, the independent channel RK[j] has the j-th nozzle N and the pressure chamber CV corresponding to the j-th nozzle N. In addition, in the present embodiment, the M independent channels RK[1] to RK[M] corresponding to the M nozzles N are arranged along the Y-axis direction. In addition, in the present embodiment, each independent channel RK extends in the X-axis direction.

[0066] In addition, although in Figure 4 it is exemplified that the wall surface of the independent channel RK includes the surfaces SL1d, SL1u, SL2d, and SL2u inclined with respect to the YZ plane, the wall surface of the independent channel RK is not limited to Figure 4The shape shown. For example, the surfaces SL1d, SL1u, SL2d, and SL2u may also be substantially parallel to the YZ plane. In addition, although in this embodiment, an example is assumed where the wall surface defining the end in the Z1 direction in the independent flow path RK is constituted by the connection plate 12, the end in the Z1 direction in the independent flow path RK may also be constituted by the nozzle substrate 11.

[0067] As Figure 3 and Figure 4 shown, a diaphragm 14 is provided at a position in the Z2 direction with respect to the pressure chamber substrate 13. The diaphragm 14 has a diaphragm CPZ, a vibration absorption plate CP1, and a vibration absorption plate CP2. The diaphragm CPZ, the vibration absorption plate CP1, and the vibration absorption plate CP2 are each plate-like members that are long in the Y-axis direction and extend substantially parallel to the XY plane, and are members that can vibrate elastically. The diaphragm CPZ, the vibration absorption plate CP1, and the vibration absorption plate CP2 each have, for example, an elastic film made of silicon oxide and an insulator film made of zirconia. In addition, the elastic film possessed by each of the diaphragm CPZ, the vibration absorption plate CP1, and the vibration absorption plate CP2 is not limited to the elastic film made of silicon oxide. Similarly, the insulator film possessed by each of the diaphragm CPZ, the vibration absorption plate CP1, and the vibration absorption plate CP2 is not limited to the insulator film made of zirconia.

[0068] The diaphragm CPZ is provided at a position in the Z2 direction with respect to the pressure chamber CV. On the surface of the diaphragm CPZ in the Z2 direction, M piezoelectric elements PZ corresponding to the M pressure chambers CV are provided. Here, the surface in the first direction of the first element is the surface of the first element that is substantially perpendicular to the first direction and is visible when observing the first element from the first direction to the second direction. In addition, the second direction is the direction opposite to the first direction. In addition, in this specification, the expression "the second element is formed on the surface of the first element" does not have the main idea of limiting the structure in which the first element and the second element are in direct contact. That is, even in a structure in which a third element is formed on the surface of the first element and the second element is formed on the surface of the third element, as long as at least a part of the first element and the second element overlap in a top view, it is also included in the concept of "the second element is formed on the surface of the first element".

[0069] For the piezoelectric element PZ, although not shown in Figure 3 and Figure 4 it is as shown in Figure 6As shown, it has a common electrode Zd supplied with a predetermined bias potential VBS, an independent electrode Zu supplied with an independent drive signal Vin, and a piezoelectric layer Zm disposed between the independent electrode Zu and the common electrode Zd. For example, the common electrode Zd, the piezoelectric layer Zm, and the independent electrode Zu are disposed in this order along the Z2 direction on the surface of the diaphragm CPZ in the Z2 direction. In addition, although in this embodiment, the common electrode Zd is a so-called lower electrode and the independent electrode Zu is a so-called upper electrode, it is also possible that the common electrode Zd is an upper electrode and the independent electrode Zu is a lower electrode.

[0070] The piezoelectric element PZ is a passive element that deforms according to the potential change of the drive signal COM supplied to the independent electrode Zu as the independent drive signal Vin. Specifically, the piezoelectric element PZ is driven and deformed according to the potential change of the drive signal COM.

[0071] As described above, since the piezoelectric element PZ is disposed on the surface of the diaphragm CPZ in the Z2 direction, the diaphragm CPZ vibrates in a manner linked to the deformation of the piezoelectric element PZ. When the diaphragm CPZ vibrates, the pressure in the pressure chamber CV changes. Then, due to the change in the pressure in the pressure chamber CV, the ink filled inside the pressure chamber CV is ejected from the nozzle N in the Z1 direction through the nozzle flow path BN.

[0072] The vibration absorption plate CP1 is disposed at a position in the Z2 direction with respect to the common flow path BA1. When the ink flowing in the common flow path BA1 vibrates according to the pressure change in the pressure chamber CV, the vibration absorption plate CP1 absorbs the vibration. The vibration absorption plate CP2 is disposed at a position in the Z2 direction with respect to the common flow path BA2. When the ink flowing in the common flow path BA2 vibrates according to the pressure change in the pressure chamber CV, the vibration absorption plate CP2 absorbs the vibration. Hereinafter, the vibration absorption plate CP1 and the vibration absorption plate CP2 may be collectively referred to as the vibration absorption plate CP.

[0073] As Figure 3 and Figure 4 As shown, a flow path forming substrate 16 is disposed at a position in the Z2 direction with respect to the pressure chamber substrate 13. The flow path forming substrate 16 is a plate-like member that is long in the Y-axis direction and extends substantially parallel to the XY plane. Although the flow path forming substrate 16 is formed by, for example, injection molding of a resin material, known materials and manufacturing methods can be arbitrarily adopted in the manufacture of the flow path forming substrate 16.

[0074] In the flow path forming substrate 16, flow paths for ink are formed. Specifically, as Figure 4As shown, in the flow channel forming substrate 16, a common flow channel BB1 and a common flow channel BB2 are formed. The common flow channel BB1 is arranged in a position in the Z2 direction relative to the common flow channel BA1 and extends in the Y-axis direction, and is in communication with the common flow channel BA1. The common flow channel BB2 is arranged in a position in the Z2 direction relative to the common flow channel BA2 and in a position in the X1 direction relative to the common flow channel BB1 and extends in the Y-axis direction, and is in communication with the common flow channel BA2. Additionally, hereinafter, the common flow channel BB1 and the common flow channel BB2 may be collectively referred to as the common flow channel BB.

[0075] Hereinafter, the common flow channel BA1 and the common flow channel BB1 in communication with the common flow channel BA1 may be referred to as the common flow channel RC1. Further, hereinafter, the common flow channel BA2 and the common flow channel BB2 in communication with the common flow channel BA2 may be referred to as the common flow channel RC2. Additionally, hereinafter, the common flow channel RC1 and the common flow channel RC2 may be collectively referred to as the common flow channel RC. Moreover, the common flow channel RC1 is an example of a "common supply flow channel", and the common flow channel RC2 is an example of a "common discharge flow channel".

[0076] On the flow channel forming substrate 16, a connection port H1 in communication with the common flow channel BB1 and a connection port H2 in communication with the common flow channel BB2 are provided. A supply flow channel 61 is connected to the connection port H1, and a recovery flow channel 62 is connected to the connection port H2. For example, a pump 63 supplies ink from an ink container 60 to the common flow channel RC1 including the common flow channel BB1 via the supply flow channel 61 and the connection port H1. In this case, the pressure Pin applied to the common flow channel RC1 becomes a positive pressure that is higher than the atmospheric pressure, for example. Additionally, a part of the ink supplied to the common flow channel RC1 is filled into the pressure chamber CV via a connection flow channel BR1. Then, when the piezoelectric element PZ is driven by a drive signal COM, a part of the ink filled in the pressure chamber CV is ejected from the nozzle N via a nozzle flow channel BN. Moreover, a part of the ink filled in the pressure chamber CV is discharged to the common flow channel RC2 via a connection flow channel BR2.

[0077] For example, the pump 64 recovers a part of the ink stored in the common flow path RC2 including the common flow path BB2 via the recovery flow path 62 and the connection port H2, and supplies the recovered ink to the ink container 60. In this case, the pressure Pout applied to the common flow path RC2 becomes a negative pressure, for example, a pressure lower than the atmospheric pressure. Thus, the pressure Pin is the pressure for supplying ink to the common flow path RC1, and the pressure Pout is the pressure for discharging ink from the common flow path RC2. In addition, the pressure Pout only needs to be less than the pressure Pin, and it can also be above the atmospheric pressure. The pressure Pin is an example of the "first pressure", and the pressure Pout is an example of the "second pressure".

[0078] Hereinafter, an increase in the pressure Pin means, for example, an increase in the pressure of the ink stored in the common flow path RC1 toward the pressure chamber CV, that is, the force for supplying ink to the common flow path RC1. In addition, a decrease in the pressure Pout means an increase in the difference from the pressure Pin, that is, an increase in the pressure reduction amount of the pressure applied to the common flow path RC2. Therefore, a decrease in the pressure Pout means an increase in the pressure for discharging the ink stored in the common flow path RC2 from the connection port H2, that is, the force for discharging ink from the common flow path RC2. In addition, when the pressure Pout is a negative pressure, a decrease in the pressure Pout means an increase in the absolute value of the pressure Pout, and an increase in the pressure Pout means a decrease in the absolute value of the pressure Pout. For example, the pump 63 functions as a pressurizing mechanism for pressurizing the pressure Pin, and the pump 64 functions as a pressure reducing mechanism for reducing the pressure Pout.

[0079] Here, for example, when the pressure Pout is greater than an appropriate pressure with respect to the pressure Pin, ink may leak from the nozzle N, and when the pressure Pout is less than an appropriate pressure with respect to the pressure Pin, the ink may not be ejected from the nozzle N properly. Therefore, the pressure Pin and the pressure Pout are adjusted so that the ejection state of the ink becomes a normal state.

[0080] On the flow path forming substrate 16, a through hole 16h is provided. The through hole 16h is a hole that is located between the common flow path BB1 and the common flow path BB2 when observing the flow path forming substrate 16 from the Z1 direction and penetrates from the surface in the Z1 direction of the flow path forming substrate 16 to the surface in the Z2 direction of the flow path forming substrate 16. A wiring substrate 17 is inserted through the through hole 16h.

[0081] As Figure 3 and Figure 4As shown, a wiring substrate 17 is mounted on the surface of the pressure chamber substrate 13 in the Z2 direction. The wiring substrate 17 is a component for electrically connecting the liquid ejection head 1 and the control unit 4. As the wiring substrate 17, for example, a flexible wiring substrate such as an FPC (Flexible Printed Circuit) or an FFC (Flexible Flat Cable) can be preferably used. As described above, electronic components EC including a switching circuit 18 and a detection circuit 19 are mounted on the wiring substrate 17.

[0082] As Figure 3 and Figure 4 shown, a filter FL is formed in the pressure chamber substrate 13. The filter FL is a structure for capturing air bubbles in the ink in the common flow path BA1. For example, the filter FL is composed of a plurality of protrusions FT arranged in the Y-axis direction. And the filter FL captures the air bubbles floating in the Z2 direction due to buoyancy in the ink flowing in the common flow path BA1 through two protrusions FT adjacent to each other in the Y-axis direction among the plurality of protrusions FT. In addition, in the present embodiment, as an example, it is assumed that the plurality of protrusions FT are formed by the pressure chamber substrate 13. Further, in the present embodiment, as an example, it is assumed that the plurality of protrusions FT are mounted on the surface of the flow path forming substrate 16 in the Z1 direction.

[0083] In the present embodiment, as described above, since the filter FL is provided in the common flow path BA1, it is possible to suppress the situation where foreign matter is mixed into the ink ejected from the nozzle N. In addition, in the present embodiment, since the ink is recovered from the common flow path RC2 by the pump 64, it is possible to suppress the backflow of the ink from the common flow path BA2 to the nozzle N. Therefore, in the present embodiment, even if the structure is such that the filter FL is not provided in the common flow path BA2, it is possible to suppress the situation where foreign matter is mixed into the ink to be ejected from the nozzle N. Further, by adopting the structure in which the filter FL is not provided in the common flow path BA2, it is possible to avoid the situation where the filter FL controls the flow velocity of the ink in the common flow path BA2. In addition, the filter FL is not limited to being composed of a plurality of protrusions FT arranged in the Y-axis direction.

[0084] Thus, in the present embodiment, the filter FL is provided only in one of the first flow path between the pump 63 and the plurality of independent flow paths RK and the second flow path between the pump 64 and the plurality of independent flow paths RK. For example, the first flow path includes the common flow path RC1 and the supply flow path 61, and the second flow path includes the common flow path RC2 and the recovery flow path 62.

[0085] Here, as Figure 4As shown, ejection unit D includes piezoelectric element PZ, pressure chamber CV, and nozzle N. Further, more specifically, the residual vibration of the above-described ejection unit D[j] is the vibration remaining in pressure chamber CV included in ejection unit D[j].

[0086] Next, while referring to Figure 5 the flow of the ink will be described.

[0087] Figure 5 is an explanatory diagram for explaining the flow of the ink. Additionally, Figure 5 shows the flow of the ink in common flow path RC and individual flow paths RK when liquid ejection head 1 is viewed from above in the Z1 direction. However, although in Figure 5 it is described for the sake of illustration that supply flow path 61 and recovery flow path 62 extend in the X-axis direction, supply flow path 61 and recovery flow path 62 are not limited to extending in the X-axis direction. Further, in Figure 5 it is assumed as an example that the value of M is "8". Additionally, in Figure 5 it is assumed that connection port H1 and connection port H2 are respectively located between individual flow paths RK[4] and RK[5] in the Y-axis direction.

[0088] When circulating the ink, supply flow path 61 supplies the ink to common flow path RC1, and recovery flow path 62 recovers the ink from common flow path RC2. For example, in common flow path RC1, as indicated by arrow marks AR11 and AR12, the ink flows from connection port H1 toward the Y1 direction and the Y2 direction. The ink flowing from connection port H1 toward the Y1 direction is supplied to individual flow paths RK[5] to RK[8], and the ink flowing from connection port H1 toward the Y2 direction is supplied to individual flow paths RK[1] to RK[4].

[0089] Further, in individual flow path RK[j], as indicated by arrow mark FA[j], the ink flows in the X1 direction from common flow path RC1 toward common flow path RC2. Thereby, for example, the ink is filled into pressure chamber CV included in individual flow path RK[j].

[0090] In addition, for example, in the common flow path RC2, as indicated by the arrow marks AR21 and AR22, the ink flows in the Y1 direction from the independent flow paths RK[1] to RK[4], and the ink flows in the Y2 direction from the independent flow paths RK[5] to RK[8]. That is, the ink discharged from the independent flow paths RK[1] to RK[4] flows in the Y1 direction and is recovered into the recovery flow path 62 via the connection port H2. In addition, the ink discharged from the independent flow paths RK[5] to RK[8] flows in the Y2 direction and is recovered into the recovery flow path 62 via the connection port H2. Hereinafter, the portion between the common flow path RC1 and the nozzle N in the independent flow path RK[j] may be referred to as the independent flow path RKin[j], and the portion between the nozzle N and the common flow path RC2 may be referred to as the independent flow path RKout[j].

[0091] In this way, the common flow path RC1 communicates with the plurality of independent flow paths RK in common and supplies ink to the plurality of independent flow paths RK. In addition, the common flow path RC2 communicates with the plurality of independent flow paths RK in common and discharges ink from the plurality of independent flow paths RK. Further, in the present embodiment, the following situation is assumed, that is, in the recovery process of returning the ejection state of the nozzle N to the normal state and in the printing process of forming the image represented by the print data IMG on the medium, the ink circulation as Figure 5 shown is performed.

[0092] In addition, in the present embodiment, as described above, the connection port H1 is provided between the independent flow path RK[4] and the independent flow path RK[5] in the Y-axis direction. That is, in the present embodiment, the connection port H1 is provided between the independent flow path RK[1] and the independent flow path RK[M] in the Y-axis direction. Therefore, in the present embodiment, compared with the manner in which the connection port H1 is provided in the Y2 direction relative to the independent flow path RK[1] and the manner in which the connection port H1 is provided in the Y1 direction relative to the independent flow path RK[M], the pressure Pin required to supply ink from the connection port H1 to the M independent flow paths RK can be reduced. As a result, in the present embodiment, the power related to the driving of the circulation mechanism 6 can be reduced.

[0093] In addition, in the present embodiment, in the Y-axis direction, a connection port H1 is provided between the independent flow path RK[1] and the independent flow path RK[M], and a connection port H2 is provided between the independent flow path RK[1] and the independent flow path RK[M]. Therefore, in the present embodiment, multiple connection ports H1 connected to the common flow path RC1 are not provided, thereby suppressing the retention of ink in the common flow path RC1, and multiple connection ports H2 connected to the common flow path RC2 are not provided, thereby suppressing the retention of ink in the common flow path RC2. Thus, in the present embodiment, compared with the method of providing multiple connection ports H1 connected to the common flow path RC1 and the method of providing multiple connection ports H2 connected to the common flow path RC2, the retention of ink in the common flow path RC1 and the common flow path RC2 can be suppressed by a simpler structure.

[0094] Next, while referring to Figure 6 FIG., a general outline of the liquid ejection head 1 will be described.

[0095] Figure 6 FIG. is a block diagram showing an example of the structure of the liquid ejection head 1.

[0096] As described in Figure 1 FIG., the liquid ejection head 1 includes a recording head 10, a switching circuit 18, and a detection circuit 19. In addition, the liquid ejection head 1 has a wiring La to which a drive signal COMa is supplied from the drive signal generation unit 2, a wiring Lb to which a drive signal COMb is supplied from the drive signal generation unit 2, and a wiring Ls for supplying a detection signal Vout to the detection circuit 19. Further, the liquid ejection head 1 has a wiring Li[j] for supplying an independent drive signal Vin[j] to the ejection unit D[j], and a wiring Ld for supplying a bias potential VBS.

[0097] The switching circuit 18 has M switches SWa[1] to SWa[M] corresponding one-to-one to the M ejection units D[1] to D[M], M switches SWb[1] to SWb[M] corresponding one-to-one to the M ejection units D[1] to D[M], and M switches SWs[1] to SWs[M] corresponding one-to-one to the M ejection units D[1] to D[M]. Further, the switching circuit 18 has a connection state specifying circuit CSC. The connection state specifying circuit CSC specifies the respective connection states of the M switches SWa, the M switches SWb, and the M switches SWs. For example, the connection state specifying circuit CSC generates connection state specifying signals Qa[j], Qb[j], and Qs[j] based on at least a part of the signals among the printing signal SI, the latch signal LAT, the conversion signal CH, and the period specifying signal Tsig supplied from the control unit 4. The connection state specifying signal Qa[j] is a signal for specifying the on / off of the switch SWa[j], the connection state specifying signal Qb[j] is a signal for specifying the on / off of the switch SWb[j], and the connection state specifying signal Qs[j] is a signal for specifying the on / off of the switch SWs[j].

[0098] Based on the connection state specifying signal Qa[j], the switch SWa[j] switches the conduction and non-conduction between the wiring La and the independent electrode Zu[j] of the piezoelectric element PZ[j] provided in the ejection unit D[j]. That is, based on the connection state specifying signal Qa[j], the switch SWa[j] switches the conduction and non-conduction between the wiring La and the wiring Li[j] connected to the independent electrode Zu[j]. In the present embodiment, the switch SWa[j] is turned on when the connection state specifying signal Qa[j] is at a high level and turned off when at a low level. When the switch SWa[j] is turned on, the drive signal COMa supplied to the wiring La is supplied as the independent drive signal Vin[j] to the independent electrode Zu[j] of the ejection unit D[j] via the wiring Li[j].

[0099] Based on the connection state specifying signal Qb[j], the switch SWb[j] switches the conduction and non-conduction between the wiring Lb and the independent electrode Zu[j] of the piezoelectric element PZ[j] provided in the ejection unit D[j]. That is, based on the connection state specifying signal Qb[j], the switch SWb[j] switches the conduction and non-conduction between the wiring Lb and the wiring Li[j] connected to the independent electrode Zu[j]. In the present embodiment, the switch SWb[j] is turned on when the connection state specifying signal Qb[j] is at a high level and turned off when at a low level. When the switch SWb[j] is turned on, the drive signal COMb supplied to the wiring Lb is supplied as the independent drive signal Vin[j] to the independent electrode Zu[j] of the ejection unit D[j] via the wiring Li[j].

[0100] The switch SWs[j] designates the connection state specifying signal Qs[j], thereby switching the conduction and non-conduction between the wiring Ls and the independent electrode Zu[j] of the piezoelectric element PZ[j] provided in the ejection unit D[j]. That is, the switch SWs[j] designates the connection state specifying signal Qs[j], thereby switching the conduction and non-conduction between the wiring Ls and the wiring Li[j] connected to the independent electrode Zu[j]. In the present embodiment, the switch SWs[j] is turned on when the connection state specifying signal Qs[j] is at a high level and turned off when it is at a low level.

[0101] For example, when detecting the residual vibration of the pressure chamber CV of the ejection unit D[j], the connection state specifying signal Qs[j] becomes a high level. Hereinafter, the pressure chamber CV that is the detection target of the residual vibration may be simply referred to as the detection target pressure chamber CV. In addition, hereinafter, the ejection unit D including the pressure chamber CV that is the detection target may be simply referred to as the detection target ejection unit D.

[0102] When the connection state specifying signal Qs[j] becomes a high level, the switch SWs[j] is turned on, indicating that the detection signal Vout[j] representing the potential of the independent electrode Zu[j] of the detection target ejection unit D[j] is supplied to the detection circuit 19 via the wiring Li[j] and the wiring Ls. The detection circuit 19 generates a residual vibration signal Vd[j] based on the detection signal Vout[j].

[0103] In addition, as described above, the independent drive signal Vin[j] is the signal among the drive signals COMa and COMb that is supplied to the piezoelectric element PZ[j] of the ejection unit D[j] via the switch SWa[j] or SWb[j].

[0104] Next, while referring to Figure 7 the operation of the liquid ejection device 100 in the unit period Tu will be described.

[0105] Figure 7 FIG. is a timing chart showing an example of the operation of the liquid ejection device 100 in the unit period Tu. In the present embodiment, when the liquid ejection device 100 performs a printing process, a printing process period including one or more unit periods Tu is set as the operation period of the liquid ejection device 100. The liquid ejection device 100 according to the present embodiment can drive each ejection unit D for the printing process within each unit period Tu. In addition, the liquid ejection device 100 according to the present embodiment can drive the ejection unit D that is the detection target and detect the detection signal Vout[j] from the ejection unit D that is the detection target within each unit period Tu.

[0106] The control unit 4 outputs a latch signal LAT having a pulse PlsL and a conversion signal CH having a pulse PlsC. Thus, the control unit 4 defines the unit period Tu as the period from the rising edge of the pulse PlsL to the rising edge of the next pulse PlsL. In addition, the control unit 4 divides the unit period Tu into two control periods Tu1 and Tu2 by the pulse PlsC.

[0107] The printing signal SI includes, for example, M independent designation signals Sd[1] to Sd[M] corresponding one-to-one to M ejection units D[1] to D[M]. The independent designation signal Sd[j] designates the driving manner of the ejection unit D[j] within each unit period Tu when the liquid ejection device 100 performs a printing process.

[0108] Before each unit period Tu in which the printing process is performed, the control unit 4 supplies the printing signal SI including the independent designation signals Sd[1] to Sd[M] to the connection state designation circuit CSC in synchronization with the clock signal CL. Then, within the unit period Tu, the connection state designation circuit CSC generates connection state designation signals Qa[j], Qb[j], and Qs[j] based on the independent designation signal Sd[j].

[0109] In addition, in the present embodiment, it is assumed that the ejection unit D[j] can form any one of a large dot, a midpoint smaller than the large dot, and a small dot smaller than the midpoint within the unit period Tu. Hereinafter, the ink having an amount equivalent to the large dot may be referred to as ink having a large-degree amount, the ink having an amount equivalent to the midpoint may be referred to as ink having a medium-degree amount, and the ink having an amount equivalent to the small dot may be referred to as ink having a small-degree amount.

[0110] For example, the independent designation signal Sd[j] is a signal that designates any one of the five driving manners of ejection of ink having a large-degree amount, ejection of ink having a medium-degree amount, ejection of ink having a small-degree amount, non-ejection of ink, and driving of the ejection unit D as the detection object for the ejection unit D[j] within each unit period Tu. For example, when the independent designation signal Sd[j] is a 3-bit digital signal, one driving manner among the five driving manners can be designated by the independent designation signal Sd[j]. In addition, the independent designation signal Sd[j] may also be a digital signal of 4 bits or more.

[0111] As Figure 7As shown, the drive signal generation unit 2 outputs a drive signal COMa having a pulse PX and a pulse PY. Further, the waveform of the drive signal COMa during the control period Tu1 corresponds to the pulse PX, and the waveform of the drive signal COMa during the control period Tu2 corresponds to the pulse PY.

[0112] In the present embodiment, the pulse PX and the pulse PY are defined such that the potential difference between the highest potential VHx and the lowest potential VLx of the pulse PX is greater than the potential difference between the highest potential VHy and the lowest potential VLy of the pulse PY. Specifically, when driving the ejection unit D[j] with the drive signal COMa having the pulse PX, the waveform of the pulse PX is defined such that a medium amount of ink is ejected from the ejection unit D[j]. Further, when driving the ejection unit D[j] with the drive signal COMa having the pulse PY, the waveform of the pulse PY is defined such that a small amount of ink is ejected from the ejection unit D[j]. In addition, the potentials at the start and end of the pulse PX and the pulse PY are set to the reference potential V0.

[0113] Further, when the independent designation signal Sd[j] designates the formation of a large dot for the ejection unit D[j], the connection state designation circuit CSC sets the connection state designation signal Qa[j] to high level during the control periods Tu1 and Tu2, and sets the connection state designation signals Qb[j] and Qs[j] to low level during the unit period Tu. In this case, the ejection unit D[j] is driven by the pulse PX of the drive signal COMa during the control period Tu1 to eject a medium amount of ink, and is driven by the pulse PY of the drive signal COMa during the control period Tu2 to eject a small amount of ink. Thereby, the ejection unit D[j] ejects a total large amount of ink during the unit period Tu, and thus forms a large dot on the medium PP.

[0114] In addition, when the independent designation signal Sd[j] designates the formation of a medium dot for the ejection unit D[j], the connection state designation circuit CSC sets the connection state designation signal Qa[j] to high level during the control period Tu1 and to low level during the control period Tu2, and sets the connection state designation signals Qb[j] and Qs[j] to low level during the unit period Tu. In this case, the ejection unit D[j] ejects a medium amount of ink during the unit period Tu, and thus forms a medium dot on the medium PP.

[0115] In addition, when the independent designation signal Sd[j] designates the formation of small dots for the ejection unit D[j], the connection state designation circuit CSC sets the connection state designation signal Qa[j] to a low level within the control period Tu1, sets it to a high level within the control period Tu2, and sets the connection state designation signals Qb[j] and Qs[j] to a low level within the unit period Tu. In this case, the ejection unit D[j] ejects a small amount of ink within the unit period Tu, thereby forming small dots on the medium PP.

[0116] In addition, when the independent designation signal Sd[j] designates non-ejection of ink for the ejection unit D[j], the connection state designation circuit CSC sets the connection state designation signals Qa[j], Qb[j], and Qs[j] to a low level within the unit period Tu. In this case, the ejection unit D[j] does not eject ink within the unit period Tu and does not form dots on the medium PP.

[0117] In addition, the drive signal generation unit 2 outputs a drive signal COMb having a pulse PS. Additionally, the waveform of the drive signal COMb in the unit period Tu corresponds to the pulse PS. In the present embodiment, the pulse PS is defined such that the potential difference between the highest potential VHs and the lowest potential VLs of the pulse PS is smaller than the potential difference between the highest potential VHy and the lowest potential VLy of the pulse PY. Specifically, when the drive signal COMb having the pulse PS is supplied to the ejection unit D[j], the waveform of the pulse PS is defined such that the ejection unit D[j] is driven to a degree where ink is not ejected from the ejection unit D[j]. Additionally, the potentials at the start and end of the pulse PS are set to the reference potential V0.

[0118] In addition, the control unit 4 outputs a period designation signal Tsig having a pulse PlsT1 and a pulse PlsT2. Thereby, the control unit 4 divides the unit period Tu into a control period TSS1 from the start of the pulse PlsL to the start of the pulse PlsT1, a control period TSS2 from the start of the pulse PlsT1 to the start of the pulse PlsT2, and a control period TSS3 from the start of the pulse PlsT2 to the start of the next pulse PlsL.

[0119] Also, when the independent designation signal Sd[j] designates the ejection unit D[j] as the ejection unit D to be detected, the connection state designation circuit CSC sets the connection state designation signal Qa[j] to a low level within the unit period Tu, sets the connection state designation signal Qb[j] to a high level within the control periods TSS1 and TSS3 respectively, sets it to a low level within the control period TSS2, sets the connection state designation signal Qs[j] to a low level within the control periods TSS1 and TSS3 respectively, and sets it to a high level within the control period TSS2.

[0120] In this case, the ejection unit D to be detected is driven by the pulse PS of the drive signal COMb within the control period TSS1. Specifically, the piezoelectric element PZ of the ejection unit D to be detected is displaced by the pulse PS of the drive signal COMb within the control period TSS1. As a result, vibration is generated in the ejection unit D to be detected. Regarding the vibration generated within the control period TSS1, it remains even within the control period TSS2. And within the control period TSS2, the potential of the independent electrode Zu of the piezoelectric element PZ of the ejection unit D to be detected changes according to the remaining vibration generated in the ejection unit D to be detected. That is, within the control period TSS2, the potential of the independent electrode Zu of the piezoelectric element PZ of the ejection unit D to be detected becomes a potential corresponding to the electromotive force of the piezoelectric element PZ caused by the remaining vibration generated in the ejection unit D to be detected. And the potential of this independent electrode Zu is detected as the detection signal Vout within the control period TSS2.

[0121] In addition, although in Figure 7 an example is shown where the detection signal Vout representing the remaining vibration of the ejection unit D to be detected is generated during the printing process, the detection signal Vout representing the remaining vibration of the ejection unit D to be detected can also be generated during a period different from the printing process. That is, the process of detecting the remaining vibration of the ejection unit D to be detected can also be performed during a period different from the printing process.

[0122] In addition, the operation of the liquid ejection device 100 is not limited to Figure 7 the example shown. For example, although in Figure 7In the example, the sizes of the dots that can be formed on the medium PP are of three types: large, medium, and small. However, the sizes of the dots that can be formed on the medium PP are not limited to three types. Specifically, the sizes of the dots that can be formed on the medium PP can be one type or two types. In addition, among the plurality of drive signals COM, drive signals COM other than the drive signals COMa and COMb can also be included. For example, a drive signal COM having a micro-vibration waveform for imparting micro-vibrations to the ink inside the ejection unit D to prevent thickening of the ink can also be included in the plurality of drive signals COM.

[0123] Next, while referring to Figure 8 the outline of the operation of the loop control unit 40 will be described.

[0124] Figure 8 FIG. is an explanatory diagram for explaining the outline of the operation of the loop control unit 40. In Figure 8 a graph showing the relationship between the ink flow rate and the flow path resistance and an equivalent circuit diagram equivalent to the flow path provided in the liquid ejection head 1 are shown. Figure 8 The arrow mark of the dashed line of the equivalent circuit of FIG. indicates the flow of the ink. In addition, in the graph of Figure 8 the horizontal axis represents the ink flow rate and the vertical axis represents the flow path resistance. The flow path resistance Rin is, for example, the flow path resistance of the flow path from the connection port H1 to the M nozzles N. The flow path from the connection port H1 to the nozzle N includes, for example, a common flow path RC1 and an independent flow path RKin. In addition, the flow path resistance Rout is, for example, the flow path resistance of the flow path from the nozzle N to the connection port H2. The flow path from the nozzle N to the connection port H2 includes, for example, a common flow path RC1 and an independent flow path RKout. The independent flow path RKin is, as described in Figure 5 the part between the common flow path RC1 and the nozzle N in the independent flow path RK. In addition, the independent flow path RKin is the part between the nozzle N and the common flow path RC2 in the independent flow path RK.

[0125] The loop control unit 40 controls the pumps 63 and 64 to adjust the pressure Pn near the nozzle N to an appropriate pressure. However, in the present embodiment, as described above, since the filter FL is provided only in the common flow path RC1 among the common flow paths RC1 and RC2, in order to adjust the pressure Pn to an appropriate pressure, it is necessary to consider the flow path resistances Rin and Rout.

[0126] Generally, the flow path resistance R is expressed by Equation (1) using a constant A and a constant B defined by the shape of the flow path, the ink viscosity μ, the mass m of the ink, and the ink flow rate F. In addition, the "*" in Equation (1) represents multiplication, and the "^" in Equation (1) represents exponentiation.

[0127] R = A * μ * F + B * m * F^2…(1)

[0128] In the flow channel resistance R, "A * μ * F" in formula (1) corresponds to the resistance specified according to the ink viscosity μ, that is, the viscous resistance. In addition, in the flow channel resistance R, "B * m * F^2" in formula (1) corresponds to the resistance depending on the shape of the flow channel, that is, the inertial resistance.

[0129] Here, since a filter FL is provided in the common flow channel RC1, in the flow channel resistance Rin of the flow channel including the common flow channel RC1, the viscous resistance is dominant compared to the inertial resistance. Therefore, in formula (1), the inertial resistance can be ignored and the flow channel resistance Rin can be approximated. That is, the flow channel resistance Rin can be expressed by formula (2) using, for example, a constant Ain specified by the shape of the flow channel from the connection port H1 to the nozzle N, the ink viscosity μ, and the ink flow rate F.

[0130] Rin = Ain * μ * F…(2)

[0131] On the other hand, since no filter FL is provided in the common flow channel RC2, both the viscous resistance and the inertial resistance act in the flow channel resistance Rout of the flow channel including the common flow channel RC2. Therefore, the flow channel resistance Rout can be expressed by formula (3) using, for example, a constant Aout and a constant Bout specified by the shape of the flow channel from the nozzle N to the connection port H2, the ink viscosity μ, the ink mass m, and the ink flow rate F.

[0132] Rout = Aout * μ * F + Bout * m * F^2…(3)

[0133] From formula (2) and formula (3), it can be seen that the values of the flow channel resistances Rin and Rout and the balance of the flow channel resistances Rin and Rout change according to the flow rate F. The balance of the flow channel resistances Rin and Rout is, for example, the ratio or difference of the flow channel resistances Rin and Rout. As Figure 8 shown in the curve graph, for example, the balance of the flow channel resistances Rin1 and Rout1 when the flow rate F is F1 is different from the balance of the flow channel resistances Rin2 and Rout2 when the flow rate F is F2.

[0134] Thus, in the present embodiment, in one of the flow channel resistances R in the common flow channels RC1 and RC2, for example, the flow channel resistance Rin, the viscous resistance is greater than the inertial resistance, and in the other flow channel resistance R in the common flow channels RC1 and RC2, for example, the flow channel resistance Rout, the inertial resistance is greater than the viscous resistance.

[0135] In addition, as shown in the equivalent circuit of Figure 8 the pressure Pn near the nozzle N can be expressed using the flow path resistances Rin and Rout and the pressures Pin and Pout. For example, the flow velocity of the ink can be expressed by Equation (4) using the flow path resistances Rin and Rout and the pressures Pin, Pout, and Pn. And Equation (5) representing the pressure Pn can be derived from Equation (4).

[0136] Flow velocity = (Pin - Pn) / Rin = (Pn - Pout) / Rout …(4)

[0137] Pn = (Pin*Rout + Pout*Rin) / (Rin + Rout)…(5)

[0138] Here, for example, in the flow paths from the connection port H1 to the nozzle N and from the connection port H2 to the nozzle N, when the same filter FL is provided in both flow paths, or when no filter FL is provided in both flow paths and the shapes of the flow paths are the same, ideally, the flow path resistances Rin and Rout are equal to each other. In this case, when “Rin = Rout” is substituted into Equation (5), since “Rin” and “Rout” disappear from Equation (5), the pressure Pn can be expressed as “(Pin + Pout) / 2”. Therefore, in the above example where the flow path resistances Rin and Rout are equal to each other, the pressures Pin and Pout that make the pressure Pn an appropriate pressure can be determined based on the equation “Pn = (Pin + Pout) / 2”, that is, an equation that does not include the flow path resistances Rin and Rout.

[0139] However, in the present embodiment, since the filter FL is provided only in the common flow path RC1 among the common flow paths RC1 and RC2, the change in the flow path resistance R corresponding to the ink viscosity μ is different between the common flow path RC1 and the common flow path RC2. Specifically, when focusing on the flow rate F, as shown in Equations (2) and (3), the flow path resistance Rin becomes a linear equation, and the flow path resistance Rout becomes a quadratic equation. Therefore, “Rin” and “Rout” in Equation (5) do not disappear from Equation (5). Therefore, in the structure of the present embodiment, it is difficult to adjust the pressure Pn near the nozzle N to an appropriate pressure without considering the flow path resistances Rin and Rout when adjusting the pressures Pin and Pout. Therefore, in the present embodiment, the circulation control unit 40 adjusts the pressures Pin and Pout by considering the flow path resistances Rin and Rout, thereby adjusting the pressure Pn to an appropriate pressure.

[0140] For example, since the constant A and the constant B in the expression (1) representing the flow path resistance R are constants determined by the shape of the flow path, they are known values at the head manufacturer that manufactures the liquid ejection head 1. In addition, since the mass m of the ink is determined by the ink used, it is a coefficient whose value can be known in advance by the manufacturer using the liquid ejection head 1 or the like. In addition, since the flow rate F of the ink can be adjusted using a flow meter or the like, it can be adjusted to a desired value. Therefore, when the flow rate F of the ink is adjusted to a desired value, the only variable in the expression (1) representing the flow path resistance R becomes the ink viscosity μ. That is, by specifically specifying the ink viscosity μ, the flow path resistances Rin and Rout can be calculated according to expressions (2) and (3). In addition, by using the flow path resistances Rin and Rout calculated based on the ink viscosity μ, the pressures Pin and Pout for making the pressure Pn near the nozzle N an appropriate pressure can be calculated according to expression (5).

[0141] In the present embodiment, the circulation control unit 40 uses, for example, the flow path resistances Rin and Rout calculated based on the viscosity μ inferred by the viscosity inference unit 3 to respectively determine the pressures Pin and Pout for making the pressure Pn near the nozzle N an appropriate pressure. In addition, since the viscosity μ is inferred based on the residual vibration, using the flow path resistances Rin and Rout calculated based on the viscosity μ to respectively determine the pressures Pin and Pout is equivalent to respectively determining the pressures Pin and Pout based on the residual vibration.

[0142] Next, while referring to Figure 9 the operation of the liquid ejection device 100 will be described.

[0143] Figure 9 FIG. is a flowchart showing an example of the operation of the liquid ejection device 100. In addition, in Figure 9 the operation of the circulation control unit 40 that respectively determines the pressures Pin and Pout will be mainly described.

[0144] First, in step S100, the control unit 4 functions as the circulation control unit 40 to cause the detection circuit 19 to detect the residual vibration. Specifically, the circulation control unit 40 outputs an independent designation signal Sd designating any one of the M ejection units D as the detection target to the connection state designation circuit CSC. Thereby, the detection circuit 19 acquires a detection signal Vout representing the residual vibration of the ejection unit D as the detection target, and outputs a residual vibration signal Vd generated based on the detection signal Vout to the viscosity inference unit 3.

[0145] Next, in step S120, the control unit 4 functions as a circulation control unit 40, and thereby acquires viscosity information Vinf indicating the viscosity μ of the ink from the viscosity inference unit 3. For example, the viscosity inference unit 3 infers the ink viscosity μ based on the residual vibration signal Vd supplied from the detection circuit 19 through the process of step S100. Then, the viscosity inference unit 3 outputs the viscosity information Vinf indicating the viscosity of the ink inferred based on the residual vibration signal Vd to the control unit 4. Thereby, the circulation control unit 40 acquires the viscosity information Vinf indicating the viscosity of the ink inferred based on the residual vibration signal Vd.

[0146] Next, in step S140, the control unit 4 functions as a circulation control unit 40, and thereby determines the pressure Pin for supplying the ink to the common flow path RC1 and the pressure Pout for discharging the ink from the common flow path RC2 based on the viscosity information Vinf. Specifically, the circulation control unit 40 determines the respective pressure values of the pressure Pin and Pout for making the pressure Pn near the nozzle N an appropriate pressure based on the viscosity μ represented by the viscosity information Vinf, the above-described expressions (2), (3), and (5). In addition, the determination of the pressure Pin and the pressure Pout is not limited to determining the pressure values themselves. For example, determining how much the pressure Pin and the pressure Pout increase or decrease from the pressure at the current time point is also included in the determination of the pressure Pin and the pressure Pout.

[0147] Furthermore, in a case where there are a plurality of candidates for combinations of the pressure Pin and the pressure Pout calculated based on the viscosity μ represented by the viscosity information Vinf, the above-described expressions (2), (3), and (5), the circulation control unit 40 selects one candidate from among the plurality of candidates. For example, assume the following case, that is, a case where "Pn = C * Pin + D * Pout" and "C = 1, D = 2" can be derived from the viscosity μ represented by the viscosity information Vinf, the above-described expressions (2), (3), and (5). Further, assume a case where the pressure Pn is set to 10. In this case, a plurality of candidates such as "(Pin, Pout) = (30, -10)", "(Pin, Pout) = (50, -20)", and "(Pin, Pout) = (2, 4)" can be calculated.

[0148] Normally, the pressure Pin is a positive pressure and the pressure Pout is a negative pressure. Thus, for example, the cycle control unit 40 does not adopt the candidate of "(Pin, Pout) = (2, 4)". Further, since both "(Pin, Pout) = (30, -10)" and "(Pin, Pout) = (50, -20)" are combinations of positive pressure and negative pressure, the cycle control unit 40 determines the combination of the pressure Pin and the pressure Pout based on, for example, whether to increase the flow rate of the ink or the like.

[0149] For example, in the case of "(Pin, Pout) = (30, -10)", the difference between the pressure Pin and the pressure Pout is 40, and in the case of "(Pin, Pout) = (50, -20)", the difference between the pressure Pin and the pressure Pout is 70. When the difference between the pressure Pin and the pressure Pout is large, the flow rate of the ink is larger than when the difference between the pressure Pin and the pressure Pout is small. When it is desired to suppress an increase in the circulation flow rate of the ink, the cycle control unit 40 selects the combination of "(Pin, Pout) = (30, -10)". Further, compared with the combination of "(Pin, Pout) = (50, -20)", the combination of "(Pin, Pout) = (30, -10)" can reduce the loads on the pumps 63 and 64 because both the absolute value of the pressure Pin and the absolute value of the pressure Pout are small. In addition, when importance is attached to eliminating the thickening of the ink by circulation, the cycle control unit 40 increases the circulation flow rate of the ink by selecting the combination of "(Pin, Pout) = (50, -20)".

[0150] In addition, the loop control unit 40 may also prompt the user with multiple candidates for the combination of the pressures Pin and Pout, and obtain selection information indicating the candidate selected by the user from among the candidates prompted to the user. Also, the loop control unit 40 may select the candidate indicated by the selection information from among the multiple candidates as the combination of the pressures Pin and Pout. Further, the loop control unit 40 may also prompt the user with a part of the multiple candidates for the combination of the pressures Pin and Pout. For example, when the multiple candidates include candidates where the pressure Pout is a positive pressure or the pressure Pin is a negative pressure, the loop control unit 40 may prompt the user with candidates other than those where the pressure Pout is a positive pressure or the pressure Pin is a negative pressure among the multiple candidates. In the above example, the loop control unit 40 may prompt the user with candidates other than "(Pin, Pout) = (2, 4)", i.e., "(Pin, Pout) = (50, -20)" and "(Pin, Pout) = (30, -10)" among the three candidates. In addition, although the loop control unit 40 prompts all three candidates to the user, it may also prompt them in a way that recommends "(Pin, Pout) = (50, -20)". Further, although the prompting described here may appropriately employ any method that can convey the candidates to the user, as an example, it refers to a case where information indicating the candidates is displayed in a visually confirmable manner on the display of the user's computer and the like.

[0151] Thus, in the present embodiment, the loop control unit 40 determines the pressure Pin and the pressure Pout for making the pressure Pn an appropriate pressure respectively based on the ink viscosity μ inferred from the residual vibration detected by the detection circuit 19. Accordingly, in the present embodiment, compared with a comparative example in which the pressure Pin and the pressure Pout are determined without using the residual vibration, the pressure Pn can be appropriately adjusted. The comparative example in which the pressure Pin and the pressure Pout are determined without using the residual vibration is, for example, a method of determining the pressure Pin and the pressure Pout based on the above-mentioned formula "Pn = (Pin + Pout) / 2", that is, a formula that does not include the flow path resistances Rin and Rout.

[0152] As described above, in the present embodiment, the liquid ejecting device 100 includes: a piezoelectric element PZ; a plurality of independent flow paths RK each including a nozzle N and a pressure chamber CV; a common flow path RC1 that communicates with the plurality of independent flow paths RK in common and supplies ink to the plurality of independent flow paths RK; a common flow path RC2 that communicates with the plurality of independent flow paths RK in common and discharges ink from the plurality of independent flow paths RK; a pump 63 that applies a pressure Pin for supplying ink to the common flow path RC1 to the common flow path RC1; a pump 64 that applies a pressure Pout for discharging ink from the common flow path RC2 to the common flow path RC2; a detection circuit 19 that detects residual vibration in the pressure chamber CV after a voltage is applied to the piezoelectric element PZ; and a circulation control unit 40 that determines the pressure Pin and the pressure Pout respectively based on the residual vibration detected by the detection circuit 19. For example, the control program PG of the liquid ejecting device 100 causes the control unit 4 to function as the circulation control unit 40.

[0153] As described above, in the present embodiment, the circulation control unit 40 determines the pressure Pin and the pressure Pout respectively based on the residual vibration detected by the detection circuit 19. Thus, in the present embodiment, compared with a comparative example in which the pressure Pin and the pressure Pout are determined without using the residual vibration, the pressure Pin and the pressure Pout for making the pressure Pn near the nozzle N an appropriate pressure can be determined with high accuracy. As a result, in the present embodiment, the pressure Pn near the nozzle N can be appropriately adjusted.

[0154] In addition, in the present embodiment, in the common flow path RC1 and the common flow path RC2, the change in the flow path resistance R corresponding to the viscosity μ of the ink is different. Even in this case, in the present embodiment, since the pressure Pin and the pressure Pout are determined respectively based on the residual vibration, the pressure Pn near the nozzle N can be appropriately adjusted. That is, in the present embodiment, even for the liquid ejection head 1 in which the change in the flow path resistance R corresponding to the viscosity μ of the ink is different between the common flow path RC1 and the common flow path RC2, the pressure Pn near the nozzle N can be appropriately adjusted.

[0155] In addition, in the present embodiment, in the flow path resistance R of one of the common flow paths RC1 and RC2, the viscous resistance is greater than the inertial resistance, and in the flow path resistance R of the other of the common flow paths RC1 and RC2, the inertial resistance is greater than the viscous resistance. Even in such a case, in the present embodiment, since the pressures Pin and Pout are determined separately based on the residual vibration, the pressure Pn near the nozzle N can be appropriately adjusted. That is, in the present embodiment, even for the liquid ejection head 1 in which the viscous resistance is greater than the inertial resistance in the flow path resistance R of one of the common flow paths RC1 and RC2 and the inertial resistance is greater than the viscous resistance in the flow path resistance R of the other, the pressure Pn near the nozzle N can be appropriately adjusted.

[0156] In addition, in the present embodiment, the filter FL is provided only in one of the first flow path between the pump 63 and the plurality of independent flow paths RK and the second flow path between the pump 64 and the plurality of independent flow paths RK. The first flow path includes the common flow path RC1, and the second flow path includes the common flow path RC2. Even in the case where the filter FL is provided only in one of the first flow path and the second flow path, since the pressures Pin and Pout are determined separately based on the residual vibration in the present embodiment, the pressure Pn near the nozzle N can be appropriately adjusted. That is, in the present embodiment, even for the liquid ejection head 1 in which the filter FL is provided only in one of the first flow path and the second flow path, the pressure Pn near the nozzle N can be appropriately adjusted.

[0157] In addition, in the present embodiment, the flow paths connecting the common flow path RC1 and the common flow path RC2 are only the plurality of independent flow paths RK. In this case, since the flow paths connecting the common flow path RC1 and the common flow path RC2 do not exist outside the plurality of independent flow paths RK, it is possible to suppress the complexity of the calculation of the flow path resistances Rin and Rout corresponding to the viscosity μ.

[0158] In addition, in the present embodiment, the cycle control unit 40 may also calculate candidates for combinations of the pressure Pin and the pressure Pout based on the residual vibration detected by the detection circuit 19, and present the candidates to the user. Further, the cycle control unit 40 may also acquire selection information indicating the candidate selected by the user from among the candidates presented to the user, and determine the pressure Pin and the pressure Pout respectively based on the selection information. In this case, since the user can select a combination of the pressure Pin and the pressure Pout, it is possible to appropriately determine the combination of the pressure Pin and the pressure Pout for making the pressure Pn near the nozzle N an appropriate pressure. In addition, the user only needs to select one candidate from the candidates presented by the cycle control unit 40. Therefore, for example, the operation of the user for adjusting the pressure Pn to an appropriate pressure can be simplified.

[0159] In addition, in the present embodiment, when presenting candidates to the user, the cycle control unit 40 may also recommend (suggest) a part of the candidates. In this case, the candidates to be recommended refer to the candidates for combinations of the pressure Pin and the pressure Pout determined based on the residual vibration and are also realistic candidates for other reasons. Conversely, the non-recommended candidates are candidates for combinations of the pressure Pin and the pressure Pout determined based on the residual vibration but are unrealistic candidates for other reasons. As a result, it is possible to suppress a situation where an unrealistic combination of the pressure Pin and the pressure Pout is selected by the user. As candidates for unrealistic combinations of the pressure Pin and the pressure Pout, for example, candidates where the pressure Pout is a positive pressure or the pressure Pin is a negative pressure, and candidates where the pressure Pin exceeds the capacity of the pump 63 or the pressure Pout exceeds the capacity of the pump 64 can be cited. In addition, the recommendation here means a presentation method in which, for a part of the candidates, compared with the other parts of the candidates, it is preferentially selected. For example, emphasis display such as changing the display color of the candidates to be recommended or increasing the display size may be implemented to make it easier for the user to visually confirm. Further, for example, in a case where a screen is presented on the user's display in such a way that the user can select a plurality of candidates by moving a cursor or the like, the default (initial) position of the cursor or the like may be set at the candidate to be recommended.

[0160] 2. Modification

[0161] The above-described various modes can be variously modified. Specific modification modes are exemplified below. Two or more modes arbitrarily selected from the following examples can be appropriately combined within a non-contradictory range. In addition, in the modification examples exemplified below, for elements having the same functions and actions as those in the embodiment, the reference symbols referred to in the above description are used, and the respective detailed descriptions are appropriately omitted.

[0162] First Modification Example

[0163] Although in the above-described embodiment, it is exemplified that the flow paths connecting between the common flow path RC1 and the common flow path RC2 are only the plurality of independent flow paths RK, the present invention is not limited to such a mode. For example, as Figure 10 shown, the liquid ejecting device 100 further includes bypass flow paths BP1 and BP2. The bypass flow paths BP1 and BP2 are flow paths different from the plurality of independent flow paths RK, and connect between the common flow path RC1 and the common flow path RC2.

[0164] Figure 10 FIG. is an exploded perspective view showing an example of the structure of the liquid ejecting head 1 according to the first modification example. Figure 11 FIG. is showing Figure 10 a cross-sectional view showing an example of the structure of the liquid ejecting head 1 shown in FIG. Figure 11 The cross-sectional view shown in FIG. is Figure 10 a cross-sectional view taken along line III-III shown in FIG. The cross-section of line III-III is parallel to the XZ plane and passes through the bypass flow path BP1 described later. For elements identical to those described in Figures 1 to 9 , the same reference numerals are given, and detailed description thereof is omitted. The liquid ejecting head 1 according to this mode is the same as the liquid ejecting head 1 according to the above-described embodiment except that the bypass flow paths BP1 and BP2 are provided. In Figure 10 and Figure 11 , description will be made centering on the bypass flow paths BP1 and BP2.

[0165] As Figure 10 and Figure 11 shown, in the connection plate 12, one bypass flow path BP1 connecting the common flow path BA1 and the common flow path BA2, and one bypass flow path BP2 connecting the common flow path BA1 and the common flow path BA2 at a position in the Y1 direction with respect to the bypass flow path BP1 are formed. The bypass flow path BP1 and the bypass flow path BP2 each extend in the X-axis direction. Hereinafter, the bypass flow path BP1 and the bypass flow path BP2 may be collectively referred to as the bypass flow path BP. In addition, one or both of the bypass flow path BP1 and the bypass flow path BP2 are an example of a "bypass flow path".

[0166] In this mode, as Figure 11As shown, the walls of the bypass flow path BP in the Z2 direction and the Z1 direction are formed into flat shapes. However, the walls of the bypass flow path BP may also include surfaces inclined with respect to the YZ plane, similar to the walls of the independent flow path RK. Alternatively, the walls of the bypass flow path BP may also include surfaces substantially parallel to the XZ plane. Further, although in this embodiment, as an example, it is assumed that the wall defining the end in the Z1 direction in the bypass flow path BP is constituted by the connection plate 12, the end in the Z1 direction in the bypass flow path BP may also be constituted by the nozzle substrate 11. Further, in this embodiment, nozzles N are not provided on the bypass flow path BP.

[0167] Next, while referring to Figure 12 the ink flow in the first modification will be described.

[0168] Figure 12 FIG. is an explanatory diagram for explaining the ink flow in the first modification. Additionally, Figure 12 shows the ink flow in the common flow path RC and the independent flow path RK when the liquid ejection head 1 is viewed from above in the Z1 direction. Similar to Figure 5 even in Figure 12 it is assumed that the value M is "8", and it is also assumed that the connection port H1 and the connection port H2 are respectively located between the independent flow paths RK[4] and RK[5] in the Y-axis direction.

[0169] Even in this embodiment, when the ink is circulated, the supply flow path 61 supplies ink to the common flow path RC1, and the recovery flow path 62 recovers ink from the common flow path RC2. For example, in the common flow path RC1, as indicated by the arrow marks AR11 and AR12, the ink flows from the connection port H1 toward the Y1 direction and the Y2 direction. The ink flowing from the connection port H1 toward the Y1 direction is supplied to the independent flow paths RK[5] to RK[8] and the bypass flow path BP2, and the ink flowing from the connection port H1 toward the Y2 direction is supplied to the independent flow paths RK[1] to RK[4] and the bypass flow path BP1.

[0170] Further, in the independent flow path RK[j], as indicated by the arrow mark FA[j], the ink flows from the common flow path RC1 to the common flow path RC2 toward the X1 direction. Thus, for example, the ink is filled in the pressure chamber CV provided in the independent flow path RK[j]. Further, in the bypass flow path BP, as indicated by the arrow marks FB1 and FB2, the ink flows from the common flow path RC1 to the common flow path RC2 toward the X1 direction.

[0171] In addition, for example, in the common flow path RC2, as indicated by the arrow marks AR21 and AR22, the ink flows in the Y1 direction from the independent flow paths RK[1] to RK[4] and the bypass flow path BP1, and the ink flows in the Y2 direction from the independent flow paths RK[5] to RK[8] and the bypass flow path BP2. That is, the ink discharged from the independent flow paths RK[1] to RK[4] and the bypass flow path BP1 flows in the Y1 direction and is recovered into the recovery flow path 62 via the connection port H2. In addition, the ink discharged from the independent flow paths RK[5] to RK[8] and the bypass flow path BP2 flows in the Y2 direction and is recovered into the recovery flow path 62 via the connection port H2.

[0172] Hereinafter, as Figure 12 shown, the interval between the bypass flow path BP and the independent flow path RK adjacent to the bypass flow path BP in the Y-axis direction is referred to as the interval dYB, and the interval between one independent flow path RK among the M independent flow paths RK and another independent flow path RK adjacent to the one independent flow path RK in the Y-axis direction is referred to as the interval dYK. More specifically, the interval between the bypass flow path BP1 and the independent flow path RK[1], and the interval between the bypass flow path BP2 and the independent flow path RK[M] are referred to as the interval dYB, and the interval between the independent flow path RK[j1] and the independent flow path RK[j2] is referred to as the interval dYK. Here, the variables j1 and j2 are natural numbers that satisfy "1 ≤ j1 < j2 ≤ M" and "1 + j1 = j2".

[0173] And, in this embodiment, as Figure 12 shown, the bypass flow path BP and the independent flow path RK are arranged such that the interval dYB and the interval dYK satisfy "dYB > dYK". Therefore, according to this embodiment, compared with the case where the interval dYB is smaller than the interval dYK, the influence of vibrations and other noises generated by the ink flowing in the bypass flow path BP on the ink flowing in the independent flow path RK can be reduced. Thus, according to this embodiment, compared with the case where the interval dYB is smaller than the interval dYK, the deviation of the ejection characteristics of the ink ejected from the M nozzles N provided in the liquid ejection head 1 can be reduced. However, the present invention is not limited to the manner of arranging the bypass flow path BP such that the interval dYB is greater than the interval dYK. That is, the bypass flow path BP may be arranged such that the interval dYB is less than or equal to the interval dYK. Even in this case, in addition to the effects obtained when the bypass flow path BP is arranged such that the interval dYB is greater than the interval dYK, the same effects as those of the above-described embodiment can be obtained.

[0174] In addition, in this embodiment, as Figure 12As shown, M independent flow channels RK are provided between the bypass flow channel BP1 and the bypass flow channel BP2. Therefore, according to this method, compared with the method in which one or both of the bypass flow channel BP1 and the bypass flow channel BP2 are provided between two independent flow channels RK among the M independent flow channels RK, the possibility of ink remaining at the ends of the common flow channel RC1 and the common flow channel RC2 can be reduced. Thus, according to this method, the possibility of ink thickening and the retention of air bubbles in the ink at the ends of the common flow channel RC1 and the common flow channel RC2 can be reduced.

[0175] Here, preferably, the flow resistance R of the bypass flow channel BP, that is, the combined flow resistance obtained by combining the flow resistance R of the bypass flow channel BP1 and the flow resistance R of the bypass flow channel BP2, is more than one-third times the combined flow resistance obtained by combining the flow resistances R of the multiple independent flow channels RK. In this modified example, it is assumed that the flow resistance R of the bypass flow channel BP is more than one-third times the combined flow resistance obtained by combining the flow resistances R of the multiple independent flow channels RK. In this case, the amount of ink passing through the bypass flow channel BP is less than the amount of ink passing through the multiple independent flow channels RK. Therefore, in this modified example, even if the amount of ink passing through the bypass flow channel BP is ignored, the flow resistances Rin and Rout corresponding to the viscosity μ of the ink can be calculated with high precision. In other words, since when the amount of ink passing through the bypass flow channel BP is large, the amount of ink passing through the bypass flow channel BP cannot be ignored when calculating the flow resistances Rin and Rout corresponding to the viscosity μ of the ink, the calculation of the flow resistances Rin and Rout becomes complicated. That is, in this modified example, while suppressing the complication of the calculation of the flow resistances Rin and Rout, the possibility of ink thickening and the retention of air bubbles in the ink can be reduced. As a result, in this modified example, while reducing the possibility of ink thickening and the retention of air bubbles in the ink, the pressure Pn near the nozzle N can be appropriately adjusted.

[0176] In addition, although in Figures 10 to 12 the example shown, the case where the bypass flow channel BP is formed on the communication plate 12 is illustrated, the present invention is not limited to such a method. For example, the bypass flow channel BP can also be formed on the communication plate 12 and the pressure chamber substrate 13. Or, the bypass flow channel BP can also be formed at a location different from the communication plate 12 and the pressure chamber substrate 13, for example, at a location in the Z2 direction with respect to the pressure chamber substrate 13. Further, even in the above example or in the case of adopting a known bypass flow channel BP, it is preferable to form the bypass flow channel BP in such a way that the amount of ink passing through the bypass flow channel BP does not exceed an amount that cannot be ignored when calculating the flow resistance R corresponding to the viscosity μ of the ink.

[0177] As described above, in this modification example, the liquid ejection device 100 further includes a bypass flow path BP, which is a flow path different from the plurality of independent flow paths RK and connects the common flow path RC1 and the common flow path RC2. The flow path resistance R of the bypass flow path is more than one-third of the combined flow path resistance obtained by combining the flow path resistances R of the plurality of independent flow paths RK. Even in this modification example, the same effects as those of the above-described embodiment can be obtained. Further, in this modification example, since the bypass flow path BP is provided, the possibility of ink thickening and the retention of air bubbles in the ink can be reduced.

[0178] Second Modification Example

[0179] In the above-described embodiment and modification example, the flow path including the common flow path RC1 and the independent flow path RKin, and the flow path including the common flow path RC2 and the independent flow path RKout may be provided symmetrically with respect to Figure 4 the reference plane SF shown. That is, the cross-sectional area in the common flow path RC1 with respect to the ink flow direction and the cross-sectional area in the common flow path RC2 with respect to the ink flow direction may be the same at positions symmetric with respect to the reference plane SF. In addition, the reference plane SF is, for example, a plane parallel to the YZ plane and passing through the nozzle N. That is, the reference plane SF is a plane having the ink flow direction in the plurality of independent flow paths RK as the normal direction and passing through the nozzle N.

[0180] Thus, in this modification example, the cross-sectional area in the common flow path RC1 with respect to the ink flow direction and the cross-sectional area in the common flow path RC2 with respect to the ink flow direction are the same at positions symmetric with respect to the plane having the ink flow direction in the plurality of independent flow paths RK as the normal direction and passing through the nozzle N. Even in this modification example, for example, depending on the presence or absence of the filter FL, the change in the flow path resistance R corresponding to the ink viscosity μ in the common flow path RC1 and the common flow path RC2 is different. Therefore, even in this modification example, compared with the comparative example in which the residual vibration is not used to determine the pressure Pin and the pressure Pout, the pressure Pn near the nozzle N can be appropriately adjusted.

[0181] Third Modification Example

[0182] Although in the above-described embodiments and modifications, the case where the filter FL is provided only in the common flow path RC1 among the common flow paths RC1 and RC2 has been illustrated, the present invention is not limited to such a mode. For example, the filter FL may be provided only in the common flow path RC2 among the common flow paths RC1 and RC2. In this case, in one of the flow path resistances R of the common flow paths RC1 and RC2, for example, the flow path resistance Rout, the viscous resistance is greater than the inertial resistance, and in the other flow path resistance R of the common flow paths RC1 and RC2, for example, the flow path resistance Rin, the inertial resistance is greater than the viscous resistance.

[0183] In addition, the filter FL may be provided in both of the common flow paths RC1 and RC2, or may not be provided in both of the common flow paths RC1 and RC2. Further, the main reason for the difference in the change of the flow path resistance R corresponding to the viscosity μ of the ink in the common flow path RC1 and the common flow path RC2 is not limited to the presence or absence of the filter FL. For example, there may be a case where the change in the flow path resistance R corresponding to the viscosity μ of the ink in the common flow path RC1 and the common flow path RC2 is different due to manufacturing errors or the like. Therefore, even for a structure in which the filter FL is provided in both of the common flow paths RC1 and RC2, compared with a comparative example in which the residual vibration is not used to determine the pressure Pin and the pressure Pout, the pressure Pn near the nozzle N can be appropriately adjusted. Similarly, even for a structure in which the filter FL is not provided in both of the common flow paths RC1 and RC2, compared with a comparative example in which the residual vibration is not used to determine the pressure Pin and the pressure Pout, the pressure Pn near the nozzle N can be appropriately adjusted.

[0184] In addition, the filter FL may be provided in one or both of the supply flow path 61 and the recovery flow path 62. When the filter FL is provided in one or both of the supply flow path 61 and the recovery flow path 62, the filter FL may be provided in at least one of the common flow paths RC1 and RC2, or may not be provided in both of the common flow paths RC1 and RC2.

[0185] As described above, even in this modification, the same effects as those of the above-described embodiments and modifications can be obtained.

[0186] Fourth Modification

[0187] While the above-described embodiment and variations illustrate the case where the vibration-absorbing plate CP1 and the vibration-absorbing plate CP2 are provided separately from each other, the present invention is not limited to this configuration. For example, the vibration-absorbing plate CP1 and the vibration-absorbing plate CP2 may be formed integrally. As described above, even in this variation, the same effects as those of the above-described embodiment and variations can be achieved.

[0188] Modification 5

[0189] In the above-mentioned embodiment and modification, a flexible sheet for absorbing the pressure fluctuation of the ink in the common flow channel BA may be provided. For example, the nozzle substrate 11 may be provided with a flexible sheet for absorbing the pressure fluctuation of the ink in the common flow channel BA. Figure 3 The nozzle substrate 11 shown is formed so as to be shorter than its length in the X-axis direction and is positioned between two flexible sheets. Specifically, one of the two flexible sheets can be configured to close the common flow channel BA1 at a position relative to the connecting plate 12 in the Z1 direction and at a position relative to the nozzle substrate 11 in the X2 direction. Furthermore, the other of the two flexible sheets can be configured to close the common flow channel BA2 at a position relative to the connecting plate 12 in the Z1 direction and at a position relative to the nozzle substrate 11 in the X1 direction. As described above, even in this modified example, the same effects as those of the aforementioned embodiment and modified examples can be achieved.

[0190] Modification 6

[0191] While the above-described embodiment and modified examples illustrate a serial-type liquid ejection device 100 in which the carriage 91 carrying the liquid ejection head 1 reciprocates in the X-axis direction, the present invention is not limited to this configuration. For example, the liquid ejection device 100 may also be a row-type liquid ejection device in which multiple nozzles N are distributed across the entire width of the medium PP. As described above, even in this modified example, the same effects as those of the above-described embodiment and modified examples can be achieved.

[0192] Modification 7

[0193] While the above-described embodiment and modified examples illustrate a case where one piezoelectric element PZ, one pressure chamber CV, and one nozzle N are provided for one discharge portion D, the present invention is not limited to this configuration. For example, one discharge portion D may include two piezoelectric elements PZ, two pressure chambers CV, and one nozzle N. As described above, even in this modified example, the same effects as those of the above-described embodiment and modified examples can be achieved.

[0194] Modification 8

[0195] In addition to equipment dedicated to printing, the liquid ejection device 100 exemplified in the above-described embodiments and modified examples can also be adopted by various devices such as a facsimile machine or a copying machine. Of course, the use of the liquid ejection device of the present invention is not limited to printing. For example, a liquid ejection device that ejects a solution of a color material can be used as a manufacturing device for forming a color filter of a liquid crystal display device. In addition, a liquid ejection device that ejects a solution of a conductive material can be used as a manufacturing device for forming wirings or electrodes of a wiring substrate. As described above, even in this modified example, the same effects as those of the above-described embodiments and modified examples can be obtained.

[0196] 3. Supplementary Note

[0197] According to the manner exemplified above, the following structure can be grasped, for example.

[0198] The liquid ejection device according to Mode 1, which is a preferred mode, includes: a piezoelectric element; a plurality of independent flow paths, each of which includes a nozzle and a pressure chamber; a common supply flow path that communicates with the plurality of independent flow paths in common and supplies liquid to the plurality of independent flow paths; a common discharge flow path that communicates with the plurality of independent flow paths in common and discharges liquid from the plurality of independent flow paths; a first pressure applying unit that applies a first pressure for supplying liquid to the common supply flow path to the common supply flow path; a second pressure applying unit that applies a second pressure for discharging liquid from the common discharge flow path to the common discharge flow path; a detection unit that detects residual vibration in the pressure chamber after a voltage is applied to the piezoelectric element; and a pressure determination unit that determines the first pressure and the second pressure respectively based on the residual vibration detected by the detection unit.

[0199] According to Mode 1, the first pressure and the second pressure for making the pressure near the nozzle an appropriate pressure can be determined with high precision. As a result, according to Mode 1, the pressure near the nozzle can be appropriately adjusted.

[0200] In the liquid ejection device according to Mode 2, which is a specific example of Mode 1, the change in flow path resistance corresponding to the viscosity of the liquid is different between the common supply flow path and the common discharge flow path.

[0201] According to Mode 2, even for a liquid ejection device in which the change in flow path resistance corresponding to the viscosity of the liquid is different between the common supply flow path and the common discharge flow path, the first pressure and the second pressure for making the pressure near the nozzle an appropriate pressure can be determined with high precision.

[0202] In the liquid ejection device according to Mode 3, which is a specific example of Mode 1 or 2, among the flow resistances of one of the common supply channel and the common discharge channel, the viscous resistance is greater than the inertial resistance, and among the flow resistances of the other of the common supply channel and the common discharge channel, the inertial resistance is greater than the viscous resistance.

[0203] According to Mode 3, even for a liquid ejection device in which the viscous resistance is greater than the inertial resistance among the flow resistances of one of the common supply channel and the common discharge channel, and the inertial resistance is greater than the viscous resistance among the flow resistances of the other of the common supply channel and the common discharge channel, the first pressure and the second pressure for making the pressure near the nozzle an appropriate pressure can be determined with high precision.

[0204] In the liquid ejection device according to Mode 4, which is a specific example of any one of Modes 1 to 3, a filter is provided only in one of the first channel between the first pressure applying portion and the plurality of independent channels and the second channel between the second pressure applying portion and the plurality of independent channels. The first channel includes the common supply channel, and the second channel includes the common discharge channel.

[0205] According to Mode 4, even for a liquid ejection device in which a filter is provided only in one of the first channel and the second channel, the first pressure and the second pressure for making the pressure near the nozzle an appropriate pressure can be determined with high precision.

[0206] In the liquid ejection device according to Mode 5, which is a specific example of any one of Modes 1 to 4, the cross-sectional area of the common supply channel with respect to the liquid flow direction and the cross-sectional area of the common discharge channel with respect to the liquid flow direction are the same at positions symmetric with respect to the plane normal to the liquid flow direction in the plurality of independent channels and passing through the nozzle.

[0207] Even in Mode 5, the first pressure and the second pressure for making the pressure near the nozzle an appropriate pressure can be determined with high precision.

[0208] In the liquid ejection device according to Mode 6, which is a specific example of any one of Modes 1 to 5, the channels connecting the common supply channel and the common discharge channel are only the plurality of independent channels.

[0209] According to Mode 6, it is possible to suppress the complexity of the process of separately determining the first pressure and the second pressure based on residual vibration.

[0210] In the liquid ejection device according to Mode 7, which is a specific example of any one of Modes 1 to 5, there is also a bypass flow path that is different from the plurality of independent flow paths and connects the common supply flow path and the common discharge flow path. The flow path resistance of the bypass flow path is more than one-third times the combined flow path resistance obtained by combining the flow path resistances of the plurality of independent flow paths.

[0211] According to Mode 7, it is possible to reduce the likelihood of ink thickening and the retention of air bubbles in the ink, and to accurately determine the first pressure and the second pressure for making the pressure near the nozzle appropriate.

[0212] In the liquid ejection device according to Mode 8, which is a specific example of any one of Modes 1 to 7, the pressure determination unit calculates candidates for combinations of the first pressure and the second pressure based on the residual vibration detected by the detection unit, presents the candidates to the user, obtains selection information indicating the candidate selected by the user from among the candidates presented to the user, and determines the first pressure and the second pressure respectively based on the selection information.

[0213] According to Mode 8, it is possible to appropriately determine the combination of the first pressure and the second pressure for making the pressure near the nozzle appropriate.

[0214] In the liquid ejection device according to Mode 9, which is a specific example of Mode 8, when presenting the candidates to the user, the pressure determination unit recommends a part of the candidates.

[0215] According to Mode 9, it is possible to suppress the situation where candidates for combinations of unrealistic first and second pressures are presented to the user. As a result, it is possible to suppress the situation where the user selects a combination of unrealistic first and second pressures.

[0216] In addition, in the control method of the liquid ejection device according to Preferred Mode 10, the liquid ejection device includes: a piezoelectric element; a plurality of independent flow paths each including a nozzle and a pressure chamber; a common supply flow path that communicates with the plurality of independent flow paths in common and supplies liquid to the plurality of independent flow paths; a common discharge flow path that communicates with the plurality of independent flow paths in common and discharges liquid from the plurality of independent flow paths; a first pressure applying unit that applies a first pressure for supplying liquid to the common supply flow path to the common supply flow path; a second pressure applying unit that applies a second pressure for discharging liquid from the common discharge flow path to the common discharge flow path; and a detection unit that detects residual vibration in the pressure chamber after a voltage is applied to the piezoelectric element. In the control method of the liquid ejection device, the first pressure and the second pressure are respectively determined based on the residual vibration detected by the detection unit.

[0217] Even in Preferred Mode 10, it is possible to accurately determine the first pressure and the second pressure for making the pressure near the nozzle an appropriate pressure.

[0218] In addition, in the control program product of the liquid ejection device according to Preferred Mode 11, the liquid ejection device includes: a piezoelectric element; a plurality of independent flow paths each including a nozzle and a pressure chamber; a common supply flow path that communicates with the plurality of independent flow paths in common and supplies liquid to the plurality of independent flow paths; a common discharge flow path that communicates with the plurality of independent flow paths in common and discharges liquid from the plurality of independent flow paths; a first pressure applying unit that applies a first pressure for supplying liquid to the common supply flow path to the common supply flow path; a second pressure applying unit that applies a second pressure for discharging liquid from the common discharge flow path to the common discharge flow path; and a detection unit that detects residual vibration in the pressure chamber after a voltage is applied to the piezoelectric element. The control program product of the liquid ejection device causes a computer to function as a pressure determination unit, and the pressure determination unit respectively determines the first pressure and the second pressure based on the residual vibration detected by the detection unit.

[0219] Even in Preferred Mode 11, it is possible to accurately determine the first pressure and the second pressure for making the pressure near the nozzle an appropriate pressure.

[0220] Symbol Explanation

[0221] 1... Liquid ejection head; 2... Driving signal generation unit; 3... Viscosity inference unit; 4... Control unit; 5... Storage unit; 6... Circulation mechanism; 7... Maintenance unit; 8... Medium conveyance mechanism; 9... Carriage conveyance mechanism; 10... Recording head; 18... Switching circuit; 19... Detection circuit; 40... Circulation control unit; 100... Liquid ejection device; CV... Pressure chamber; D... Ejection part; N... Nozzle; PG... Control program; PP... Medium; PZ... Piezoelectric element.

Claims

1. A liquid ejection device, characterized in that, Comprising: A piezoelectric element; A plurality of independent flow channels, each of which includes a nozzle and a pressure chamber; A common supply flow channel that communicates with the plurality of independent flow channels and supplies liquid to the plurality of independent flow channels; A common discharge flow channel that communicates with the plurality of independent flow channels and discharges liquid from the plurality of independent flow channels; A first pressure applying unit that applies a first pressure for supplying liquid to the common supply flow channel to the common supply flow channel; A second pressure applying unit that applies a second pressure for discharging liquid from the common discharge flow channel to the common discharge flow channel; A detection unit that detects residual vibration in the pressure chamber after a voltage is applied to the piezoelectric element; A pressure determination unit that determines the first pressure and the second pressure respectively based on the residual vibration detected by the detection unit.

2. The liquid ejection device according to claim 1, wherein: The change in flow channel resistance corresponding to the viscosity of the liquid is different in the common supply flow channel and the common discharge flow channel.

3. The liquid ejection device according to claim 2, wherein: In the flow channel resistance of one of the common supply flow channel and the common discharge flow channel, the viscous resistance is greater than the inertial resistance, In the flow channel resistance of the other of the common supply flow channel and the common discharge flow channel, the inertial resistance is greater than the viscous resistance.

4. The liquid ejection device according to any one of claims 1 to 3, wherein: A filter is provided only in one of a first flow channel between the first pressure applying unit and the plurality of independent flow channels and a second flow channel between the second pressure applying unit and the plurality of independent flow channels, The first flow channel includes the common supply flow channel, The second flow channel includes the common discharge flow channel.

5. The liquid ejection device according to claim 4, wherein: The cross-sectional area of the common supply flow channel with respect to the flow direction of the liquid and the cross-sectional area of the common discharge flow channel with respect to the flow direction of the liquid are the same at positions symmetric with respect to a plane that is normal to the flow direction of the liquid in the plurality of independent flow channels and passes through the nozzle.

6. The liquid ejection device according to any one of claims 1 to 3, wherein: The flow channels that connect the common supply flow channel and the common discharge flow channel are only the plurality of independent flow channels.

7. The liquid ejection device according to any one of claims 1 to 3, wherein: It further has a bypass flow channel, the bypass flow channel is a flow channel different from the plurality of independent flow channels and connects the common supply flow channel and the common discharge flow channel, The flow channel resistance of the bypass flow channel is more than one-third times the combined flow channel resistance obtained by combining the flow channel resistances of the plurality of independent flow channels.

8. The liquid ejection device according to any one of claims 1 to 3, wherein: The pressure determination unit calculates candidates for combinations of the first pressure and the second pressure based on the residual vibration detected by the detection unit, presents the candidates to the user, obtains selection information indicating the candidate selected by the user from among the candidates presented to the user, and determines the first pressure and the second pressure respectively based on the selection information.

9. The liquid ejection device according to claim 8, wherein: When presenting the candidates to the user, the pressure determination unit recommends a part of the candidates.

10. A control method for a liquid ejection device, wherein: The liquid ejection device includes: A piezoelectric element; A plurality of independent flow paths, each including a nozzle and a pressure chamber; A common supply flow path that communicates with the plurality of independent flow paths in common and supplies liquid to the plurality of independent flow paths; A common discharge flow path that communicates with the plurality of independent flow paths in common and discharges liquid from the plurality of independent flow paths; A first pressure application unit that applies a first pressure for supplying liquid to the common supply flow path to the common supply flow path; A second pressure application unit that applies a second pressure for discharging liquid from the common discharge flow path to the common discharge flow path; A detection unit that detects residual vibration in the pressure chamber after a voltage is applied to the piezoelectric element, In the control method of the liquid ejection device, The first pressure and the second pressure are determined respectively based on the residual vibration detected by the detection unit.

11. A control program product for a liquid ejection device, wherein: The liquid ejection device includes: A piezoelectric element; A plurality of independent flow paths, each including a nozzle and a pressure chamber; A common supply flow path that communicates with the plurality of independent flow paths in common and supplies liquid to the plurality of independent flow paths; A common discharge flow path that communicates with the plurality of independent flow paths in common and discharges liquid from the plurality of independent flow paths; A first pressure application unit that applies a first pressure for supplying liquid to the common supply flow path to the common supply flow path; A second pressure application unit that applies a second pressure for discharging liquid from the common discharge flow path to the common discharge flow path; A detection unit that detects residual vibration in the pressure chamber after a voltage is applied to the piezoelectric element, The control program product of the liquid ejection device causes a computer to function as a pressure determination unit, and the pressure determination unit determines the first pressure and the second pressure respectively based on the residual vibration detected by the detection unit.

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