Liquid discharge apparatus

Abstract

To provide a liquid discharge apparatus capable of suppressing occurrence of meniscus collapse and a failure to eliminate thickening of liquid in a nozzle.SOLUTION: A liquid discharge apparatus includes: a liquid discharge head including individual flow paths including pressure chambers and nozzles, a common supplying flow path, a common discharging flow path, and piezoelectric elements provided corresponding to the pressure chambers; and a drive control unit for performing discharge control and micro-vibration control, where the nozzles are configured by coupling a first nozzle portion and a second nozzle portion in a height direction, the second nozzle portion being provided closer to the individual flow paths than the first nozzle portion and having a larger diameter than the first nozzle portion, and where the drive control unit is configured to perform the micro-vibration control so as to satisfy (C4B4) / (DA4)×0.052≤M≤(C4B4) / (DA4)×0.365 when A is a diameter of the first nozzle portion, B is a diameter of the second nozzle portion, C is a height of the first nozzle portion, D is a height of the second nozzle portion, and M is a maximum pull-in amount of meniscuses of liquid at the time of the micro-vibration control by the drive control unit.SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] The present disclosure relates to a liquid ejection device.

Background Art

[0002] Liquid ejection devices that eject a liquid such as ink onto a medium such as printing paper have been conventionally proposed. For example, the liquid ejection device described in Patent Document 1 includes a pressure chamber filled with a liquid, a piezoelectric element that causes a pressure change in the liquid in the pressure generation chamber, and a nozzle that ejects the liquid in the pressure chamber in accordance with the pressure change.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Since the liquid at the nozzle opening is in contact with the atmosphere, evaporation of moisture occurs. Then, the liquid at the nozzle opening thickens because the solvent component decreases. As a result, there is a risk of nozzle clogging or poor ejection, which may adversely affect the ejection characteristics of the droplets. In order to solve this problem, an operation of ejecting a large amount of liquid, so-called flushing, may be performed before the recording operation on the medium by the ejection of the liquid. However, flushing has the drawback of consuming the liquid.

[0005] In order to solve the above problems, it is known to perform a circulation operation and a micro-vibration operation. The circulation operation is an operation of supplying and discharging liquid to an individual flow path communicating with a nozzle. By this circulation operation, while discharging the liquid that can become highly viscous due to evaporation at the nozzle opening from the individual flow path, new liquid can be supplied into the individual flow path. Therefore, thickening of the liquid in the nozzle can be suppressed. The micro-vibration operation is an operation of applying a micro-vibration waveform to a piezoelectric element to cause meniscus vibration of the liquid at the nozzle opening to such an extent that the liquid is not discharged, and stirring the liquid in the nozzle. By this micro-vibration operation, local thickening in the nozzle can be eliminated.

[0006] Normally, thickening of the ink can be sufficiently suppressed by performing either the circulation operation or the micro-vibration operation. However, there are cases where both the circulation operation and the micro-vibration operation must be performed simultaneously, such as in the liquid ejection device of Patent Document 1. If the nozzle has a straight pipe structure without a step, there is no particular problem in using the circulation operation and the micro-vibration operation in combination. However, when using a so-called two-stage nozzle divided into an upper nozzle and a lower nozzle, it has been found that when the circulation operation and the micro-vibration operation are used in combination, there are problems such as meniscus breakdown or poor elimination of thickening of the liquid in the nozzle.

[0007] As a result of the inventors' studies, it has been found that there is a correlation between the respective diameters and heights of the upper nozzle and the lower nozzle and the height of meniscus drawing-in in the lower nozzle, and by setting this correlation value within a predetermined range, the problems occurring in the case of a two-stage nozzle can be solved.

Means for Solving the Problem

[0008] A liquid ejection device according to one aspect of the present disclosure includes an individual flow path including a pressure chamber and a nozzle, a common supply flow path communicating with the plurality of individual flow paths and supplying liquid to the plurality of individual flow paths, a common discharge flow path communicating with the plurality of individual flow paths and discharging liquid from the plurality of individual flow paths, and a liquid ejection head including a piezoelectric element provided corresponding to the pressure chamber, and a drive control unit that performs ejection control for driving the piezoelectric element to eject liquid and micro-vibration control for driving the piezoelectric element to micro-vibrate the liquid in the nozzle. In the liquid ejection device, the nozzle is configured by connecting a first nozzle portion and a second nozzle portion provided on the individual flow path side with respect to the first nozzle portion and having a diameter larger than that of the first nozzle portion in the height direction. When the diameter of the first nozzle portion is A, the diameter of the second nozzle portion is B, the height of the first nozzle portion is C, the height of the second nozzle portion is D, and the maximum drawing amount of the liquid meniscus during the micro-vibration control by the drive control unit is M, the drive control unit performs the micro-vibration control so as to satisfy (C 2 B 4 ) / (DA 4 )×0.052≦M≦(C 2 B 4 ) / (DA 4 )×0.365.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Best Mode for Carrying Out the Invention

[0010] Hereinafter, preferred embodiments according to the present disclosure will be described with reference to the accompanying drawings. Note that the dimensions and scales of each part in the drawings are appropriately different from the actual ones, and there are also some parts schematically shown for easy understanding. Further, the scope of the present disclosure is not limited to these embodiments unless otherwise specified in the following description.

[0011] The following description will be made using the X-axis, Y-axis, and Z-axis that intersect each other as appropriate. Further, in the following, one direction along the X-axis is the X1 direction, and the direction opposite to the X1 direction is the X2 direction. Similarly, the directions opposite to each other along the Y-axis are the Y1 direction and the Y2 direction. The directions opposite to each other along the Z-axis are the Z1 direction and the Z2 direction. Typically, the Z-axis is a vertical axis, and the Z2 direction corresponds to the downward direction in the vertical direction. However, the Z-axis does not have to be a vertical axis. Further, the X-axis, Y-axis, and Z-axis typically intersect at right angles to each other, but are not limited thereto, and may intersect at an angle within the range of 80° or more and 100° or less, for example.

[0012] A: Embodiment A1: Overall Configuration of Liquid Discharge Device FIG. 1 is a schematic diagram showing a configuration example of a liquid discharge device 100 according to an embodiment. The liquid discharge device 100 is an inkjet printing device that discharges a liquid such as ink as droplets onto a medium 90. The medium 90 is, for example, printing paper. Note that the medium 90 is not limited to printing paper, and may be a printing target of any material such as a resin film or fabric, for example.

[0013] As shown in FIG. 1, the liquid discharge device 100 includes a liquid container 10, a drive control unit 20, a transport mechanism 30, a movement mechanism 40, a liquid discharge head 50, and a circulation mechanism 60.

[0014] The liquid container 10 stores ink. Specific examples of the liquid container 10 include, for example, a cartridge that is detachable from the liquid ejection device 100, a bag-shaped ink pack composed of a flexible film, and an ink tank that can be refilled with ink. Note that the type of ink stored in the liquid container 10 is arbitrary.

[0015] The drive control unit 20 controls the operations of the respective elements of the liquid ejection device 100. The drive control unit 20 includes, for example, one or more processing circuits such as a CPU (Central Processing Unit) or an FPGA (Field Programmable Gate Array), and one or more storage circuits such as a semiconductor memory.

[0016] The conveyance mechanism 30 conveys the medium 90 in the Y1 direction under the control of the drive control unit 20. The movement mechanism 40 reciprocates the liquid ejection head 50 along the X-axis under the control of the drive control unit 20. The movement mechanism 40 includes a substantially box-shaped carriage 41 that houses the liquid ejection head 50, and an endless conveyor belt 42 to which the carriage 41 is fixed. Note that the number of liquid ejection heads 50 mounted on the carriage 41 is not limited to one, and may be a plurality. In addition to the liquid ejection head 50, the aforementioned liquid container 10 may be mounted on the carriage 41.

[0017] The liquid ejection head 50 ejects the ink supplied from the liquid container 10 from each of a plurality of nozzles onto the medium 90 under the control of the drive control unit 20 based on the print data Img. By performing this ejection in parallel with the conveyance of the medium 90 by the conveyance mechanism 30 and the reciprocating movement of the liquid ejection head 50 by the movement mechanism 40, an image corresponding to the print data Img with ink is formed on the surface of the medium 90.

[0018] A liquid ejection head 50 is connected to a liquid container 10 via a circulation mechanism 60. The circulation mechanism 60 is a mechanism that supplies ink to the liquid ejection head 50 and collects the ink discharged from the liquid ejection head 50 for resupply to the liquid ejection head 50 under the control of a drive control unit 20. By the operation of the circulation mechanism 60, it is possible to suppress an increase in the viscosity of the ink and reduce the retention of air bubbles in the ink.

[0019] A2: Electrical configuration of the liquid ejection device 100 FIG. 2 is a diagram showing the electrical configuration of the liquid ejection device 100 according to the embodiment. As shown in FIG. 2, the liquid ejection head 50 includes a head chip 51 and a supply circuit 52. The head chip 51 has a plurality of piezoelectric elements 51e. As will be described later, for example, two piezoelectric elements 51e are provided for one nozzle. Note that one piezoelectric element 51e may be provided for one nozzle N.

[0020] The supply circuit 52 switches whether to supply the drive signal Com output from the drive control unit 20 as a supply signal Vin to each of the plurality of piezoelectric elements 51e under the control of the drive control unit 20.

[0021] As shown in FIG. 2, the drive control unit 20 includes a control circuit 21, a storage circuit 22, a power supply circuit 23, and a drive signal generation unit 24.

[0022] The control circuit 21 has a function of controlling the operations of each part of the liquid ejection device 100 and a function of processing various data. The control circuit 21 includes, for example, one or more processors such as a CPU (Central Processing Unit). Note that the control circuit 21 may include a programmable logic device such as an FPGA (field-programmable gate array) instead of or in addition to the CPU. Also, when the control circuit 21 is composed of a plurality of processors, the plurality of processors may be mounted on different substrates or the like. Note that the control circuit 21 may be regarded as the "drive control unit".

[0023] The memory circuit 22 stores various programs executed by the control circuit 21 and various data such as print data Img processed by the control circuit 21. The memory circuit 22 includes, for example, one or both semiconductor memories of a volatile memory such as a RAM (Random Access Memory) and a non-volatile memory such as a ROM (Read Only Memory), an EEPROM (Electrically Erasable Programmable Read-Only Memory), or a PROM (Programmable ROM). The print data Img is supplied from an external device 200 such as a personal computer or a digital camera. Note that the memory circuit 22 may be configured as a part of the control circuit 21.

[0024] The power supply circuit 23 receives power supply from a commercial power supply (not shown) and generates various predetermined potentials. The generated various potentials are appropriately supplied to each part of the liquid ejection device 100. For example, the power supply circuit 23 generates a power supply potential VHV and an offset potential VBS. The offset potential VBS is supplied to the liquid ejection head 50. The power supply potential VHV is supplied to the drive signal generation unit 24.

[0025] The drive signal generation unit 24 is a circuit that repeatedly generates a drive signal Com for driving each piezoelectric element 51e. Specifically, the drive signal generation unit 24 includes, for example, a DA conversion circuit and an amplifier circuit. In the drive signal generation unit 24, the DA conversion circuit converts the waveform designation signal dCom from the control circuit 21 from a digital signal to an analog signal. The amplifier circuit amplifies the analog signal using the power supply potential VHV from the power supply circuit 23 to generate the drive signal Com. The signal of the waveform actually supplied to each piezoelectric element 51e among the waveforms included in the drive signal Com is the aforementioned supply signal Vin. The waveform designation signal dCom is a digital signal for defining the waveform of the drive signal Com.

[0026] The control circuit 21 controls the operations of each part of the liquid ejection device 100 by executing a program stored in the memory circuit 22. Here, the control circuit 21 generates a control signal Sk1, a control signal Sk2, a print data signal SI, a waveform designation signal dCom, a latch signal LAT, a change signal CNG, and a clock signal CLK as signals for controlling the operations of each part of the liquid ejection device 100 when executing the program.

[0027] The control signal Sk1 is a signal for controlling the drive of the conveyance mechanism 30. The control signal Sk2 is a signal for controlling the drive of the moving mechanism 40. The print data signal SI is a digital signal for designating the operating state of each piezoelectric element 51e. The latch signal LAT and the change signal CNG are timing signals that are used in combination with the print data signal SI and define the ink ejection timing from each nozzle. These timing signals are generated based on, for example, the output of an encoder that detects the position of the carriage 41 described above.

[0028] A3: Flow path of the liquid ejection head 50 FIG. 3 is a schematic diagram for explaining the circulation flow path of the liquid ejection head 50. As shown in FIG. 3, the liquid ejection head 50 is provided with a plurality of individual flow paths IP, a common supply flow path R1, and a common discharge flow path R2. A circulation mechanism 60 is connected to the common supply flow path R1 and the common discharge flow path R2. The plurality of individual flow paths IP, the common supply flow path R1, and the common discharge flow path R2 constitute the circulation flow path.

[0029] Each individual flow path IP has a nozzle N, a pressure chamber C1a, a pressure chamber C1b, a communication flow path Nf, an individual supply flow path Ra1, and an individual discharge flow path Ra2.

[0030] The plurality of nozzles N are arranged along the Y-axis. Each of the plurality of nozzles N ejects ink in the Z2 direction. The set of the plurality of nozzles N constitutes a nozzle row L0. Also, the plurality of nozzles N are arranged at equal intervals.

[0031] Each nozzle N communicates with an individual flow path IP. Each of the plurality of individual flow paths IP extends along the X-axis and communicates with different nozzles N. Further, the plurality of individual flow paths IP are arranged along the Y-axis. Each individual flow path IP supplies ink to the pressure chamber C1a and discharges ink from the pressure chamber C1b.

[0032] Each of the pressure chamber C1a and the pressure chamber C1b extends along the X-axis and is a space for storing ink discharged from the nozzle N communicating with the individual flow path IP. In the example shown in FIG. 3, the plurality of pressure chambers C1a are arranged along the Y-axis. Similarly, the plurality of pressure chambers C1b are arranged along the Y-axis. Note that in each individual flow path IP, the positions of the pressure chamber C1a and the pressure chamber C1b in the direction along the Y-axis are the same as each other in the example shown in FIG. 3, but may be different from each other. Further, hereinafter, when the pressure chamber C1a and the pressure chamber C1b are not particularly distinguished, they are also simply referred to as "pressure chamber C1".

[0033] A communication flow path Nf is arranged between the pressure chamber C1a and the pressure chamber C1b in each individual flow path IP. In each individual flow path IP, the communication flow path Nf is a flow path that communicates the pressure chamber C1a and the pressure chamber C1b. Further, the plurality of communication flow paths Nf are arranged along the Y-axis at intervals from each other. A nozzle N is provided in each communication flow path Nf. In each communication flow path Nf, ink is discharged from the nozzle N due to the pressure fluctuations in the pressure chamber C1a and the pressure chamber C1b described above.

[0034] An individual supply flow path Ra1 is provided between the pressure chamber C1a and the common supply flow path R1 in each individual flow path IP. The individual supply flow path Ra1 is a flow path that communicates the pressure chamber C1a and the common supply flow path R1. Similarly, an individual discharge flow path Ra2 is provided between the pressure chamber C1b and the common discharge flow path R2 in each individual flow path IP. The individual discharge flow path Ra2 is a flow path that communicates the pressure chamber C1b and the common discharge flow path R2.

[0035] Each of the plurality of individual flow paths IP communicates with a common supply flow path R1 and a common discharge flow path R2, respectively, which are common to them. Each of the common supply flow path R1 and the common discharge flow path R2 is a space extending along the Y-axis over the entire range where the plurality of nozzles N are distributed. When viewed in the direction along the Z-axis, a plurality of individual flow paths IP are located between the common supply flow path R1 and the common discharge flow path R2.

[0036] The common supply flow path R1 is connected to an end portion E1 in the X2 direction of each individual flow path IP. The common supply flow path R1 communicates with the plurality of individual flow paths IP and supplies ink to the plurality of individual flow paths IP. Further, ink for supplying each individual flow path IP is stored in the common supply flow path R1. On the other hand, the common discharge flow path R2 is connected to an end portion E2 in the X1 direction of each individual flow path IP. The common discharge flow path R2 communicates with the plurality of individual flow paths IP and discharges ink from the plurality of individual flow paths IP. Further, ink discharged from each individual flow path IP is stored in the common discharge flow path R2.

[0037] A circulation mechanism 60 is connected to the common supply flow path R1 and the common discharge flow path R2. The circulation mechanism 60 supplies ink to the common supply flow path R1 and collects the ink discharged from the common discharge flow path R2 for re-supplying it to the common supply flow path R1. The circulation mechanism 60 includes a first supply pump 61, a second supply pump 62, a storage container 63, a recovery flow path 64, and a supply flow path 65.

[0038] The first supply pump 61 is a pump that supplies the ink stored in the liquid container 10 to the storage container 63. The storage container 63 is a sub-tank that temporarily stores the ink supplied from the liquid container 10. The recovery channel 64 connects the common discharge channel R2 and the storage container 63, and is a channel for recovering the ink from the common discharge channel R2 to the storage container 63. In addition to the ink stored in the liquid container 10 being supplied from the first supply pump 61 to the storage container 63, the ink discharged from each individual channel IP to the common discharge channel R2 is also supplied to the storage container 63 via the recovery channel 64. The second supply pump 62 is a pump that sends out the ink stored in the storage container 63. The supply channel 65 connects the common supply channel R1 and the storage container 63, and is a channel for supplying the ink from the storage container 63 to the common supply channel R1.

[0039] A4: Specific Structure of the Head Chip 51 FIG. 4 is a view corresponding to the cross-section taken along the line A1 - A1 in FIG. 3. In FIG. 4, a cross-section of the head chip 51 cut along a plane perpendicular to the Y-axis along the individual channel IP is shown. The head chip 51 includes a nozzle substrate 51a, a flow path substrate 51b, a pressure chamber substrate 51c, a diaphragm 51d, a plurality of piezoelectric elements 51e, a case 51f, a protective plate 51g, and a wiring substrate 51h.

[0040] The nozzle substrate 51a, the flow path substrate 51b, the pressure chamber substrate 51c, and the diaphragm 51d are laminated in this order in the Z1 direction. These members extend along the Y-axis and are manufactured, for example, by processing a single-crystal silicon substrate using semiconductor processing technology. Also, these members are joined to each other by an adhesive or the like. Note that other layers or substrates such as an adhesive layer may be appropriately interposed between two adjacent members among these members.

[0041] The nozzle substrate 51a is provided with a plurality of nozzles N. Each of the plurality of nozzles N extends along the Z-axis and penetrates the nozzle substrate 51a, and is a through-hole for allowing ink to pass through.

[0042] The flow path substrate 51b is provided with a liquid chamber R1a which is a part of the common supply flow path R1 and a liquid chamber R2a which is a part of the common discharge flow path R2, together with the portions of the plurality of individual flow paths IP described above excluding the pressure chambers C1a and C1b. That is, the flow path substrate 51b is provided with a communication flow path Nf, an individual supply flow path Ra1, an individual discharge flow path Ra2, a liquid chamber R1a, and a liquid chamber R2a.

[0043] Each of the liquid chamber R1a and the liquid chamber R2a is a space penetrating the flow path substrate 51b. An absorber 51i for closing the opening due to the space is installed on the surface of the flow path substrate 51b facing the Z2 direction.

[0044] The absorber 51i is a layered member made of an elastic material. The absorber 51i constitutes a part of the wall surfaces of the common supply flow path R1 and the common discharge flow path R2, and absorbs pressure fluctuations in the common supply flow path R1 and the common discharge flow path R2.

[0045] The communication flow path Nf has a first communication flow path Na1, a second communication flow path Na2, and a nozzle flow path Nfa. Each of the first communication flow path Na1 and the second communication flow path Na2 is a space penetrating the flow path substrate 51b. The first communication flow path Na1 and the second communication flow path Na2 communicate with each other via the nozzle flow path Nfa. The first communication flow path Na1 communicates the pressure chamber C1a and the nozzle flow path Nfa. The second communication flow path Na2 communicates the pressure chamber C1b and the nozzle flow path Nfa. The nozzle flow path Nfa is a space in a groove provided on the surface of the flow path substrate 51b facing the Z2 direction and extends along the X axis. The nozzle substrate 51a constitutes a part of the wall surface of the nozzle flow path Nfa.

[0046] Each of the individual supply channel Ra1 and the individual discharge channel Ra2 is a space penetrating the flow path substrate 51b. The individual supply channel Ra1 connects the common supply channel R1 and the pressure chamber C1a, and supplies ink from the common supply channel R1 to the pressure chamber C1a. One end of the individual supply channel Ra1 opens to the surface of the flow path substrate 51b facing the Z1 direction. On the other hand, the other end of the individual supply channel Ra1 is the upstream end of the individual channel IP, and opens to the wall surface of the common supply channel R1 in the flow path substrate 51b. In contrast, the individual discharge channel Ra2 connects the common discharge channel R2 and the pressure chamber C1b, and discharges ink from the pressure chamber C1b to the common discharge channel R2. One end of the individual discharge channel Ra2 opens to the surface of the flow path substrate 51b facing the Z1 direction. On the other hand, the other end of the individual discharge channel Ra2 is the downstream end of the individual channel IP, and opens to the wall surface of the common discharge channel R2 in the flow path substrate 51b.

[0047] The pressure chamber substrate 51c is provided with the pressure chambers C1a and C1b of a plurality of individual channels IP. Each of the pressure chambers C1a and C1b penetrates the pressure chamber substrate 51c and is a gap between the flow path substrate 51b and the diaphragm 51d. The pressure chamber C1a communicates with the nozzle N via the first communication channel Na1 and the nozzle channel Nfa. The pressure chamber C1b communicates with the nozzle N via the second communication channel Na2 and the nozzle channel Nfa.

[0048] The diaphragm 51d is an elastically vibratable plate-like member. The diaphragm 51d is, for example, a laminate including a first layer made of silicon oxide (SiO 2 ) and a second layer made of zirconium oxide (ZrO 2 ). Another layer such as a metal oxide may be interposed between the first layer and the second layer. Note that part or all of the diaphragm 51d may be integrally formed of the same material as the pressure chamber substrate 51c. For example, the diaphragm 51d and the pressure chamber substrate 51c can be integrally formed by selectively removing a part in the thickness direction of a region corresponding to the pressure chamber C1 in a plate-like member having a predetermined thickness. Further, the diaphragm 51d may be composed of a single material layer.

[0049] On the surface of the diaphragm 51d facing the Z1 direction, a plurality of piezoelectric elements 51e provided corresponding to different pressure chambers C1 are installed. The plurality of piezoelectric elements 51e are provided one-to-one for the plurality of pressure chambers C1. The piezoelectric element 51e gives pressure fluctuations to the ink in the pressure chamber C1 according to the drive signal Com. Each piezoelectric element 51e is composed of, for example, a stack of a first electrode and a second electrode facing each other and a piezoelectric layer disposed between both electrodes. Each piezoelectric element 51e discharges the ink in the pressure chamber C1 from the nozzle N by varying the pressure of the ink in the pressure chamber C1. When the drive signal Com is supplied, the piezoelectric element 51e vibrates the diaphragm 51d as it deforms itself. Along with this vibration, the pressure chamber C1 expands and contracts, so that the pressure of the ink in the pressure chamber C1 fluctuates.

[0050] The case 51f is a case for storing ink. The case 51f is provided with a liquid chamber R1b which is a part other than the liquid chamber R1a of the common supply passage R1, a liquid chamber R2b which is a part other than the liquid chamber R2a of the common discharge passage R2, an inlet R01, and an outlet R02. Each of the liquid chamber R1b and the liquid chamber R2b is a recess provided on the surface of the case 51f facing the Z2 direction. The inlet R01 is a through hole formed by an inner peripheral surface extending between the surface of the case 51f facing the Z1 direction and the wall surface of the liquid chamber R1b. The supply passage 65 of the aforementioned circulation mechanism 60 is connected to the inlet R01. The outlet R02 is a through hole formed by an inner peripheral surface extending between the surface of the case 51f facing the Z1 direction and the wall surface of the liquid chamber R2b. The recovery passage 64 of the aforementioned circulation mechanism 60 is connected to the outlet R02.

[0051] The protective plate 51g is a plate-like member installed on the surface of the diaphragm 51d facing the Z1 direction, protecting the plurality of piezoelectric elements 51e and reinforcing the mechanical strength of the diaphragm 51d. A space for accommodating the plurality of piezoelectric elements 51e is formed between the protective plate 51g and the diaphragm 51d.

[0052] The wiring board 51h is mounted on the surface of the diaphragm 51d facing the Z1 direction, and is a mounting component for electrically connecting the drive control unit 20 and the head chip 51. For example, a flexible wiring board 51h such as an FPC (Flexible Printed Circuit) or an FFC (Flexible Flat Cable) is preferably used. The supply circuit 52 described above is mounted on the wiring board 51h.

[0053] In the head chip 51 with the above configuration, due to the operation of the circulation mechanism 60 described above, the ink flows through the common supply channel R1, the individual supply channel Ra1, the pressure chamber C1a, the communication channel Nf, the pressure chamber C1b, the individual discharge channel Ra2, and the common discharge channel R2 in this order. Also, the piezoelectric elements 51e corresponding to both the pressure chamber C1a and the pressure chamber C1b are simultaneously driven by the supply signal Vin from the supply circuit 52, thereby varying the pressures in the pressure chamber C1a and the pressure chamber C1b, and the ink is ejected from the nozzle N along with the pressure variation.

[0054] A5: Nozzle N FIG. 5 is an enlarged cross-sectional view of the nozzle N. In FIG. 5, a cross-sectional view of a part of the nozzle channel Nfa of the individual channel IP and the nozzle N taken along a plane orthogonal to the Y axis is shown. As shown in FIG. 5, the nozzle N branches from the nozzle channel Nfa of the individual channel IP and extends in a direction different from that of the nozzle channel Nfa. Specifically, while the nozzle channel Nfa extends in the direction along the X axis, the nozzle N extends in the direction along the Z axis.

[0055] The nozzle N is a through hole formed in the nozzle substrate 51a, and includes a discharge-side opening end N1 and a connection portion N2. The discharge-side opening end N1 is the opening end on the surface of the nozzle N facing the Z2 direction of the nozzle substrate 51a. The connection portion N2 is the boundary portion of the nozzle N with the nozzle channel Nfa. The length along the Z axis from the discharge-side opening end N1 to the connection portion N2 is the total length E of the nozzle N.

[0056] The nozzle N has a first nozzle portion NP1 and a second nozzle portion NP2. The nozzle N is a so-called two-stage nozzle. The first nozzle portion NP1 and the second nozzle portion NP2 are arranged in the Z1 direction in this order and are connected in the direction along the Z axis which is the height direction. Each of the first nozzle portion NP1 and the second nozzle portion NP2 extends along the Z axis. The second nozzle portion NP2 is provided on the nozzle flow path Nfa side of the individual flow path IP rather than the first nozzle portion NP1. The nozzle flow path Nfa and the first nozzle portion NP1 communicate with each other via the second nozzle portion NP2. Further, the first nozzle portion NP1 includes a discharge-side opening end N1. The second nozzle portion NP2 includes a connection portion N2.

[0057] The cross-sectional areas of the first nozzle portion NP1 and the second nozzle portion NP2 are circular. The central axis of the first nozzle portion NP1 and the central axis of the second nozzle portion NP2 coincide. Therefore, the first nozzle portion NP1 and the second nozzle portion NP2 are provided coaxially. The central axis of the first nozzle portion NP1 refers to an axis that passes through the center of the first nozzle portion NP1 and extends along the Z-axis direction. The central axis of the second nozzle portion NP2 refers to an axis that passes through the center of the second nozzle portion NP2 and extends along the Z-axis direction. The center mentioned here refers to, for example, a point where the position in the X-axis direction bisects the maximum width in the X-axis direction of each portion equally, and the position in the Y-axis direction bisects the maximum width in the Y-axis direction of each portion equally.

[0058] In the illustrated example, the height C of the first nozzle portion NP1 is smaller than the height D of the second nozzle portion NP2. However, the height C may be equal to the height D or may be larger than the height D. The height C is the length along the Z axis from the discharge-side opening end N1 to the boundary portion between the first nozzle portion NP1 and the second nozzle portion NP2. The height D is the length along the Z axis from the boundary portion between the first nozzle portion NP1 and the second nozzle portion NP2 to the connection portion N2.

[0059] The diameter B of the second nozzle portion NP2 is larger than the diameter A of the first nozzle portion NP1. Therefore, the nozzle N has a shape in which the width gradually increases in the Z1 direction. Also, since the diameter A is smaller than the diameter B, it is possible to eject fine ink droplets and improve the landing accuracy of the ink droplets as compared with the case where the diameter of the nozzle N is constant. Further, it is preferable that the diameter B is smaller than the width of the nozzle flow path Nfa, that is, the length along the Z axis. By the diameter B being smaller than the width of the nozzle flow path Nfa, it is possible to reduce crosstalk between two adjacent second nozzle portions NP2 in the direction along the Y axis.

[0060] At the discharge-side opening end N1 of the nozzle N described above, the ink is in contact with the outside air. For this reason, the solvent component contained in the ink at the discharge-side opening end N1 evaporates, increasing the viscosity of the ink. As a result, there is a risk of nozzle clogging or poor discharge. To suppress this, so-called flushing, which discharges a large amount of ink, is known. However, this flushing has the drawback of consuming a large amount of ink.

[0061] Therefore, in order to suppress nozzle clogging and poor discharge without wasting a large amount of ink, the liquid discharge device 100 performs a circulation operation and a fine vibration operation.

[0062] The liquid discharge device 100 has a circulation mechanism 60. By providing the circulation mechanism 60, it is possible to perform a circulation operation of supplying and discharging ink to the individual flow path IP having the nozzle N. For this reason, even if the viscosity of the ink increases due to evaporation of the ink at the discharge-side opening end N1 of the nozzle N, the ink is discharged to the common discharge flow path R2 through the individual flow path IP, and fresh ink is supplied from the common supply flow path R1. Therefore, it is possible to suppress an increase in the viscosity of the ink at the discharge-side opening end N1.

[0063] Further, the aforementioned drive control unit 20 performs ejection control for driving the piezoelectric element 51e to eject ink and fine vibration control for driving the piezoelectric element 51e to finely vibrate the ink in the nozzle N. The fine vibration control is performed during a non-ejection period when ink is not ejected from the nozzle N. By the fine vibration control, the meniscus MN can be finely vibrated to such an extent that ink is not ejected from the nozzle N. When the fine vibration control is performed, the ink in the nozzle N is agitated during the non-ejection period. Therefore, it is possible to suppress the increase in the viscosity of the ink near the ejection-side opening end N1.

[0064] In a nozzle with a normal constant width, by performing at least one of the aforementioned circulation operation and fine vibration operation, it is possible to suppress the increase in the viscosity of the ink. On the other hand, in the case of a so-called two-stage nozzle, it may be necessary to use both the circulation operation and the fine vibration operation in combination.

[0065] For example, the total length E of the nozzle N, which is a two-stage nozzle, tends to be longer than the total length of a nozzle N with a normal constant width in order to ensure a certain length in the Z-axis direction of each of the first nozzle portion NP1 and the second nozzle portion NP2. Therefore, in a two-stage nozzle, it is difficult for the circulating flow of ink in the individual flow path IP to reach the first nozzle portion NP1. Therefore, in a two-stage nozzle, it is preferable to use both the circulation operation and the fine vibration operation in combination.

[0066] By using the circulation operation and the fine vibration operation in combination, in addition to the generation of an ink flow in the nozzle N due to the fine vibration operation, the action of the circulating flow of ink by the circulation mechanism 60 is combined, and the replacement of ink between the nozzle N and the nozzle flow path Nfa can be smoothly performed. Therefore, it is possible to suppress the thickening of the ink in the nozzle N while avoiding waste of ink due to flushing.

[0067] However, in the two-stage nozzle, when the circulation operation and the fine vibration operation are used in combination, problems that are unlikely to occur in a normal nozzle with a constant width occur. Specifically, in the two-stage nozzle, when the circulation operation and the fine vibration operation are used in combination, problems such as meniscus breakdown or poor resolution of ink thickening in the nozzle N may occur. Meniscus breakdown means that the meniscus MN during fine vibration collides with the circulation flow of the nozzle flow path Nfa into which it has flowed into the nozzle N, resulting in interface breakdown. Due to this meniscus breakdown, the bubbles that may exist in the nozzle N are refined, resulting in deterioration of the ink ejection characteristics.

[0068] As a result of the inventors' intensive study to solve such problems in the two-stage nozzle, it was found that there is a correlation between the flow path resistance ratio R1N / R2N and the ratio M / C of the maximum drawing amount M of the meniscus MN at the height C of the first nozzle portion NP1. Note that the flow path resistance ratio R1N / R2N is the ratio of the flow path resistance R1N of the first nozzle portion NP1 to the flow path resistance R2N of the second nozzle portion NP2. Also, the flow path resistance ratio R1N / R2N is related to the respective sizes of the first nozzle portion NP1 and the second nozzle portion NP2. For this reason, it was found that there is a correlation between the respective sizes of the first nozzle portion NP1 and the second nozzle portion NP2 and the aforementioned ratio M / C. And by setting this correlation value within a predetermined range, it was found that the breakdown of the meniscus MN and the occurrence of poor resolution of ink thickening in the nozzle N can be eliminated.

[0069] The flow path resistance ratio R1N / R2N is obtained as follows. First, the flow path resistance R of a circular flow path is represented by the following formula [2]. R = 128μL / πd 4 …[2] In formula [2], μ is the liquid viscosity. L is the flow path length. d is the flow path diameter.

[0070] Next, the flow path resistance ratio R1N / R2N is obtained using formula [2]. When obtaining the flow path resistance ratio R1N / R2N, since "128μ / π" in formula [2] is a constant that cancels out, hereinafter, for simplicity, "128μ / π" is denoted as "α".

[0071] The flow path resistance R1N of the first nozzle portion NP1 and the flow path resistance R2N of the second nozzle portion NP2 are as follows. R1N = α × C / A 4 R2N = α × D / B 4 Therefore, the flow path resistance ratio R1N / R2N is represented by the following formula [3]. (R1N / R2N) = (C / B 4 ) / (D / A 4 ) …[3]

[0072] As described above, as a result of the inventors' intensive studies, it has been found that there is a correlation between the flow path resistance ratio R1N / R2N and the ratio M / C, specifically, a proportional relationship. That is, the following formula [4] holds. (M / C) ∝ (R1N / R2N) …[4] From formula [3] and formula [4], the following formula [5] holds. M ∝ (C 2 B 4 ) / (D / A 4 ) …[5]

[0073] And, as described above, it has been found that by setting the correlation value shown in this formula [5] within a predetermined range, the breakdown of the meniscus MN and the occurrence of poor dissolution of the thickening of the ink in the nozzle N can be eliminated. Specifically, the drive control unit 20 causes the piezoelectric element 51e to perform micro-vibration control so as to satisfy the following formula [1]. {(C 2 B 4 ) / (D / A 4 )} × 0.052 ≤ M ≤ {(C 2 B 4 ) / (D / A 4 )} × 0.365 …[1] In formula [1], M is the maximum retraction amount of the meniscus MN of the ink during the fine vibration control by the drive control unit 20. The maximum retraction amount M is the state in which the meniscus MN is located most in the Z1 direction within the nozzle N. A is the diameter of the first nozzle portion NP1. B is the diameter of the second nozzle portion NP2. C is the height of the first nozzle portion NP1. D is the height of the second nozzle portion NP2.

[0074] By performing fine vibration control by the drive control unit 20 so as to satisfy formula [1], it is possible to eliminate the breakage of the meniscus MN and the occurrence of poor resolution of ink thickening in the nozzle N. The two-stage nozzle has a more complex configuration than a normal nozzle with a constant width, and the flow path resistance in the nozzle N is significantly different from that of a normal nozzle with a constant width. Simply providing a two-stage nozzle alone will cause meniscus breakage or poor resolution of ink thickening in the nozzle N due to the influence of the flow path resistance in the two-stage nozzle. The numerical values on the right and left sides of the above formula [1] are values obtained from the experiments described later. According to the experiments of the inventors, it was found that by designing a two-stage nozzle that satisfies the above formula [1], both meniscus breakage and poor resolution of ink thickening in the nozzle N can be suppressed.

[0075] Each of FIGS. 6 and 7 is a table showing experimental results. Each of FIGS. 6 and 7 shows an example of the correlation value shown in formula [5]. Specifically, a plurality of examples in which the maximum retraction amount M of the meniscus MN and (C 2 B 4 ) / (DA 4 ) of formula [5] are changed are shown.

[0076] Specifically, in Examples 1, 2, 3, 4, 5, Comparative Examples 1, 2, 3, 4, 5, and 6, (C 2 B 4 ) / (DA 4 ) of formula [1] is the same for each, and the maximum retraction amount M is different for each. In Examples 6, 7, 8, 9, Comparative Examples 7, 8, 9, and 10, (C 2 B 4 ) / (DA 4) are the same as each other, and the maximum draw-in amounts M are different from each other. Examples 10, 11, 12, Comparative Examples 11, 12, and 13 have (C 2 B 4 ) / (DA 4 ) the same as each other, and the maximum draw-in amounts M are different from each other. Examples 13, 14, 15, 16, 17, Comparative Examples 14, 15, 16, 17, 18, and 19 have (C 2 B 4 ) / (DA 4 ) the same as each other, and the maximum draw-in amounts M are different from each other. Examples 18, 19, 20, 21, 22, Comparative Examples 20, 22, 23, 24, and 25 have (C 2 B 4 ) / (DA 4 ) the same as each other, and the maximum draw-in amounts M are different from each other.

[0077] For the examples and comparative examples, the presence or absence of the breakdown of the meniscus MN and the presence or absence of poor thickening resolution of the ink were evaluated. When there is no breakdown of the meniscus MN, "〇" is indicated, and when there is a breakdown of the meniscus MN, it is indicated by "×". Also, when there is no breakdown of the meniscus MN but there is a risk of causing destruction, "△" is indicated. Also, when there is no poor thickening resolution of the ink, "〇" is indicated, and when there is poor thickening resolution of the ink, "×" is indicated. When there is no poor thickening resolution of the ink but there is a risk that the thickening resolution becomes insufficient, "△" is indicated. Note that "△" is inferior to "〇" but superior to "×".

[0078] In each example, there was no breakdown of the meniscus MN and no poor thickening resolution of the ink, and good ejection characteristics were exhibited. On the other hand, in each comparative example, at least one of the breakdown of the meniscus MN and the poor thickening resolution of the ink occurred, and the ejection characteristics were not good.

[0079] Figure 8 is a graph showing the experimental results. The horizontal axis of Figure 8 is (C 2 B 4 ) / (DA 4) and the vertical axis is the maximum drawing amount M. In FIG. 8, each example of FIGS. 6 and 7 is plotted. Also, the group of plots arranged vertically in FIG. 8 are examples where (C 2 B 4 ) / (DA 4 ) is the same.

[0080] Among the plots in FIG. 8, the plots indicated by circles are data that became "○" or "△" in both the presence or absence of the collapse of the meniscus MN and the elimination of thickening in the experimental results shown in FIGS. 6 and 7, and correspond to the data of the examples. On the other hand, the plots indicated by triangles in FIG. 8 are data that became "×" in either the presence or absence of the collapse of the meniscus MN or the elimination of thickening in the experimental results shown in FIGS. 6 and 7, and correspond to the data of the comparative examples. As can be seen from FIG. 8, there is a boundary that satisfies the above formula [1] between the examples with excellent evaluation results and the comparative examples with evaluation results inferior to those of the examples. This indicates that there is a correlation between the maximum drawing amount M and (C 2 B 4 ) / (DA 4 ). That is, there is a correlation between the maximum drawing amount M, the height C and diameter A of the first nozzle portion NP1, and the height D and diameter B of the second nozzle portion NP2. Specifically, as shown by the solid line in the experimental results of FIG. 8, the upper limit value is calculated as M = 0.365×(C 2 B 4 ) / (DA 4 ), and the lower limit value is calculated as M = 0.052×(C 2 B 4 ) / (DA 4 ). The lower limit value, which is the left side of the above formula [1], and the upper limit value, which is the right side, were obtained from the experimental results of this FIG. 8.

[0081] By the maximum drawing amount M being within the range X1 that satisfies the above formula [1], it is possible to prevent both the collapse of the meniscus MN and the occurrence of poor elimination of ink thickening.

[0082] On the one hand, if the maximum drawing amount M is less than the lower limit value of Equation [1], it cannot overcome the flow path resistance, and the maximum drawing amount M of the meniscus MN will become small. For this reason, the thickened ink will stay in the nozzle N. As a result, the problem of poor thickening resolution of the ink cannot be solved, and there is a risk of nozzle clogging. Also, when the maximum drawing amount M exceeds the upper limit value of Equation [1], it is not affected much by the flow path resistance and collides with the circulating flow in the nozzle flow path Nfa, making the meniscus MN more likely to break down. For this reason, the refinement of bubbles that can occur in the nozzle N will occur. As a result, the ejection characteristics of the ink will deteriorate.

[0083] Furthermore, the drive control unit 20 preferably performs fine vibration control so as to satisfy (C 2 B 4 ) / (DA 4 )×0.156 ≦ M. The straight line representing (C2B4) / (DA4)×0.156 is shown by the broken line in FIG. 8. By the maximum drawing amount M being equal to or greater than the above lower limit value, the occurrence of poor thickening resolution of the ink can be more effectively prevented compared to the case where it is less than the lower limit value.

[0084] Also, the drive control unit 20 preferably performs fine vibration control so as to satisfy M ≦ (C 2 B 4 ) / (DA 4 )×0.260. The straight line representing (C 2 B 4 ) / (DA 4 )×0.260 is shown by the broken line in FIG. 7. By the maximum drawing amount M being equal to or less than the above upper limit value, the risk of breakdown of the meniscus MN can be more reliably avoided compared to the case where it exceeds the upper limit value.

[0085] Although not shown separately in FIG. 8, in FIGS. 6 and 7, there are six data points marked with "○" in both the presence or absence of meniscus MN breakdown and thickening resolution. These six examples can be said to be more suitable than other examples. These six examples are such that in FIG. 8, M = 0.156×(C 2 B 4 ) / (DA4 ) to M = 0.260×(C 2 B 4 ) / (DA 4 ) corresponds to six plots included between. The more preferable lower limit value M = 0.156×(C 2 B 4 ) / (DA 4 ) and the more preferable upper limit value M = 0.260×(C 2 B 4 ) / (DA 4 ) are the values obtained in this way.

[0086] Also, each of the heights C and D of the nozzle N is not particularly limited as long as the above formula [1] is satisfied, but the nozzle N preferably satisfies 0.4 ≦ C / D ≦ 0.8. If the height C is too small, there is no margin for the movement width of the meniscus MN in the first nozzle portion NP1, and there is a risk that the fine vibration operation cannot be sufficiently performed. Therefore, if C / D of the nozzle N is less than the above lower limit value, there is a risk that the fine vibration operation cannot be sufficiently performed. Also, when the total length E is constant, if the height C is too large, the height D becomes small, so the meniscus MN is likely to collide with the circulating flow in the individual flow path IP and the meniscus MN is likely to break down. Therefore, if C / D of the nozzle N exceeds the above upper limit value, there is a risk that the meniscus MN is more likely to break down than when it is below the upper limit value.

[0087] The specific numerical values of the height C and the height D are not particularly limited, but for example, they are 10 μm or more and 100 μm or less.

[0088] Further, each of the diameters A and B of the nozzle N is not particularly limited as long as it satisfies the above formula [1], but the nozzle N preferably satisfies 1.1 ≦ B / A ≦ 1.7. If the diameter B is too small, it means that the opening width at the connection portion N2 between the nozzle N and the nozzle flow path Nfa becomes small. When the opening width becomes small, the supply efficiency of the ink to the nozzle N decreases. Therefore, if B / A of the nozzle N is less than the above lower limit value, the supply efficiency of the ink to the nozzle N may decrease. Further, if the diameter B is increased while the diameter A remains constant, the step between the first nozzle portion NP1 and the second nozzle portion NP2 becomes too large, and ink may stay in the nozzle N. Therefore, if B / A of the nozzle N exceeds the above upper limit value, ink may stay in the nozzle N.

[0089] Incidentally, if the diameter B is increased while increasing the diameter A, the step can be reduced, but the width of the entire nozzle N becomes too large, so the straightness of the droplets ejected from the nozzle N deteriorates. Further, the specific numerical values of the diameter A and the diameter B are not particularly limited, but for example, they are 10 μm or more and 100 μm or less.

[0090] Further, the drive control unit 20 preferably performs fine vibration control so as to satisfy M < C. By the maximum retraction amount M being smaller than the height C, it is possible to suppress the circulating flow in the nozzle flow path Nfa from affecting the meniscus MN. Therefore, it is possible to effectively suppress the possibility of meniscus breakdown.

[0091] Further, the drive control unit 20 performs fine vibration control in a state where the ink is supplied from the common supply channel R1 to the individual channels IP and discharged from the individual channels IP to the common discharge channel R2. That is, the drive control unit 20 is performing the circulation operation and the fine vibration operation simultaneously. In the liquid ejection device 100 in which both the circulation operation and the fine vibration operation are performed simultaneously, by satisfying the above formula [1], in the two-stage nozzle, meniscus breakdown and poor dissolution of ink thickening in the nozzle N can be effectively suppressed.

[0092] 2. Modifications Each of the forms exemplified above can be variously modified. Specific forms of modification applicable to each of the above forms are exemplified below. Two or more forms arbitrarily selected from the following examples can be appropriately combined within a range where they do not conflict with each other.

[0093] In the liquid ejection device 100 of the above-described embodiment, by including the circulation mechanism 60, the ink in the individual flow path IP circulated. However, for example, the ink in the individual flow path IP may be circulated by driving two piezoelectric elements 51e provided for one nozzle N. In this case, the circulation mechanism 60 may be omitted.

[0094] In the above-described embodiment, two piezoelectric elements 51e were provided for one nozzle N. However, the liquid ejection device 100 may be configured such that only one piezoelectric element 51e is provided for one nozzle N.

[0095] In the above-described embodiment, the liquid ejection device 100 was a serial method of reciprocating the carriage 41, but it may be a line method in which a plurality of nozzles N are distributed over the entire width of the medium 90.

[0096] The liquid ejection device 100 exemplified in the above form may be adopted in various devices such as a facsimile device and a copying machine in addition to a device dedicated to printing, and the use of the present disclosure is not particularly limited. However, the use of the liquid ejection device is not limited to printing. For example, a liquid ejection device that ejects a solution of a coloring material is used as a manufacturing device for forming a color filter of a display device such as a liquid crystal display panel. Also, a liquid ejection device that ejects a solution of a conductive material is used as a manufacturing device for forming wirings and electrodes on a wiring board. Further, a liquid ejection device that ejects a solution of an organic substance related to a living body is used, for example, as a manufacturing device for manufacturing a biochip.

[0097] Although the present invention has been described based on the preferred embodiments above, the present invention is not limited to the above-described embodiments. Also, the configuration of each part of the present invention can be replaced with any configuration that exhibits the same function as that of the above-described embodiment, and any configuration can be added.

Description of Symbols

[0098] 20... Drive control unit, 50... Liquid ejection head, 51... Head chip, 60... Circulation mechanism, 100... Liquid ejection device, A... Diameter, B... Diameter, C... Height, D... Height, L... Overall length, C1... Pressure chamber, IP... Individual flow path, M... Maximum suction amount, MN... Meniscus, N... Nozzle, N1... Discharge side opening end, N2... Connection part, NP1... First nozzle part, NP2... Second nozzle part, Nf... Communication flow path, Nfa... Nozzle flow path, R1... Common supply flow path, R2... Common discharge flow path.

Claims

1. An individual flow path including a pressure chamber and a nozzle, A common supply flow path communicating with the plurality of individual flow paths and supplying liquid to the plurality of individual flow paths, A common discharge flow path communicating with the plurality of individual flow paths and discharging liquid from the plurality of individual flow paths, and A liquid discharge head provided with a piezoelectric element provided corresponding to the pressure chamber, A liquid discharge apparatus having a drive control unit that performs discharge control for driving the piezoelectric element to discharge liquid and micro-vibration control for driving the piezoelectric element to slightly vibrate the liquid in the nozzle, The nozzle is configured by connecting a first nozzle portion and a second nozzle portion provided on the individual flow path side with respect to the first nozzle portion and having a diameter larger than that of the first nozzle portion in the height direction, Let A be the diameter of the first nozzle portion, Let B be the diameter of the second nozzle portion, Let C be the height of the first nozzle portion, Let D be the height of the second nozzle portion, When the maximum drawing amount of the liquid meniscus during the micro-vibration control by the drive control unit is M, The drive control unit causes the fine vibration control to be performed so as to satisfy (C ２ B ４ ) / (DA ４ ) × 0.052 ≤ M ≤ (C ２ B ４ ) / (DA ４ ) × 0.

365. A liquid ejection device characterized by this is provided.

2. The drive control unit causes the fine vibration control to be performed so as to further satisfy (C ２ B ４ ) / (DA ４ ) × 0.156 ≤ M. The liquid ejection device according to claim 1, characterized in that

3. The drive control unit causes the fine vibration control to be further performed so as to further satisfy M ≦ (C ２ B ４ ) / (DA ４ ) × 0.

260. The liquid ejection device according to claim 1 or 2, characterized in that

4. The liquid discharge apparatus according to claim 1, wherein the nozzle satisfies 0.4 ≦ C / D ≦ 0.

8.

5. The liquid discharge apparatus according to claim 1, wherein the nozzle satisfies 1.1 ≦ B / A ≦ 1.

7.

6. The liquid discharge apparatus according to claim 1, wherein the drive control unit performs the micro-vibration control so as to further satisfy M < C.

7. The liquid discharge apparatus according to claim 1, wherein the drive control unit performs the micro-vibration control in a state where liquid is supplied from the common supply flow path to the individual flow path and discharged from the individual flow path to the common discharge flow path.

8. The liquid discharge apparatus according to claim 1, wherein the nozzle is configured such that the central axis of the first nozzle portion coincides with the central axis of the second nozzle portion.

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