Liquid discharge device and liquid discharge method

Abstract

To provide a liquid discharge device and a liquid discharge method which can suppress finely-vibrated ink droplets from being unstably discharged.SOLUTION: A liquid discharge device comprises: an individual passage; a nozzle, branched from the individual passage, which discharges liquid; a driving element that imparts pressure variation to liquid in a pressure chamber in response to a driving signal; a driving signal generating part that generates a driving signal; and a control part that controls supply of a driving signal to the driving element so that either of a discharge period of time during which the nozzle discharges liquid or a non-discharge period of time during which the nozzle does not discharge liquid is set. In the discharge period of time, the control supplies discharge pulses to the driving element, and in the non-discharge period of time, supplies non-discharge pulses to the driving element. When a length from a discharge-side opening end of the nozzle to a part connected to the individual passage of the nozzle is defined as L and a distance between a position of meniscus of liquid most drawn into the nozzle by supply of the non-discharge pulses to the driving element and a tip of the nozzle is defined as Lm, a relational expression of 0.07≤Lm / L≤0.15 is satisfied.SELECTED DRAWING: Figure 8

Description

[Technical field]

[0001] The present disclosure relates to a liquid ejection device and a liquid ejection method. [Background technology]

[0002] 2. Description of the Related Art Liquid ejection devices equipped with a liquid ejection head that ejects liquid such as ink onto a medium such as printing paper have been proposed.

[0003] The liquid ejection device described in Patent Document 1 includes a pressure chamber, a first flow path that supplies liquid to the pressure chamber, a second flow path that discharges the liquid from the pressure chamber, a nozzle that ejects the liquid from the second flow path, and a drive element that applies pressure fluctuations to the liquid in the pressure chamber in response to a drive signal. In this liquid ejection device, while circulating the liquid in the flow paths including the first flow path and the second flow path, a drive is performed to slightly vibrate the meniscus in the nozzle during a period when the liquid is not ejected from the nozzle. This drive replaces the liquid in the nozzle with the circulating liquid, suppressing thickening of the liquid in the nozzle. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2023-45780 A Summary of the Invention [Problem to be solved by the invention]

[0005] By micro-vibrating the meniscus and drawing it in significantly, the circulating liquid can be replaced with the liquid in the meniscus more efficiently. However, if the meniscus is drawn in significantly, the residual vibration of the micro-vibration becomes large. For this reason, the ejection of ink droplets after the micro-vibration tends to become unstable. [Means for solving the problem]

[0006] A liquid ejection device according to one aspect of the present disclosure includes an individual flow path that supplies liquid to a pressure chamber and further discharges liquid from the pressure chamber, a nozzle branching from the individual flow path and ejecting liquid, a drive element that imparts pressure fluctuations to the liquid in the pressure chamber in response to a drive signal, a drive signal generation unit that generates the drive signal, and a control unit that controls supply of the drive signal to the drive element based on print data so that, for each unit period of a predetermined cycle, a target period is either an ejection period in which liquid is ejected from the nozzle or a non-ejection period in which liquid is not ejected from the nozzle, and a non-ejection pulse that drives the driving element so as to generate a pressure fluctuation in the pressure chamber of a strength that does not cause liquid to be ejected from the nozzle, wherein the control unit supplies the ejection pulse to the driving element when the target period is the ejection period, and supplies the non-ejection pulse to the driving element when the target period is the non-ejection period, such that when the length from the ejection side opening end of the nozzle to the connection part of the nozzle with the individual flow path is L and the distance between the position of the meniscus of liquid that is drawn most into the nozzle by the supply of the non-ejection pulse to the driving element and the tip of the nozzle, the relationship of 0.07≦Lm / L≦0.15 is satisfied.

[0007] A liquid ejection method according to one aspect of the present disclosure is a liquid ejection method executed by a liquid ejection device capable of ejecting liquid, the liquid ejection device comprising: an individual flow path that supplies liquid to a pressure chamber and further discharges liquid from the pressure chamber; a nozzle branching from the individual flow path and ejecting liquid; a drive element that applies pressure fluctuation to the liquid in the pressure chamber in response to a drive signal; a drive signal generation unit that generates the drive signal; and a control unit that controls supply of the drive signal to the drive element based on print data so that a target period is either an ejection period in which liquid is ejected from the nozzle or a non-ejection period in which liquid is not ejected from the nozzle, for each unit period of a predetermined cycle, When the target period is the ejection period, an ejection pulse is supplied to the driving element to drive the driving element so as to generate a pressure fluctuation in the pressure chamber of a strength that causes liquid to be ejected from the nozzle, and when the target period is the non-ejection period, a non-ejection pulse is supplied to the driving element to drive the driving element so as to generate a pressure fluctuation in the pressure chamber of a strength that does not cause liquid to be ejected from the nozzle, and when the length from the ejection side opening end of the nozzle to the connection part with the individual flow path is L and the distance between the position of the meniscus of the liquid that is drawn most into the nozzle by the supply of the non-ejection pulse to the driving element and the tip of the nozzle is Lm, the relationship of 0.07≦Lm / L≦0.15 is satisfied. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a schematic diagram illustrating an example of the configuration of a liquid ejection device according to a first embodiment. [Diagram 2] FIG. 2 is a diagram showing an electrical configuration of the liquid ejection device according to the first embodiment. [Diagram 3] 5A and 5B are schematic diagrams illustrating circulation channels of a liquid ejection head. [Figure 4] 4 is a cross-sectional view taken along the line A1-A1 in FIG. 3. [Diagram 5] FIG. [Figure 6] FIG. 2 is a diagram for explaining a switching circuit. [Figure 7] FIG. 4 is a diagram for explaining a drive signal. [Figure 8]FIG. 4 is a diagram for explaining a meniscus in a nozzle. [Figure 9] 11 is an example showing the results of evaluation of intermittent performance and ejection stability relative to the amount of change in the meniscus. [Figure 10] 11 is an example showing the results of evaluation of intermittent performance and ejection stability relative to the amount of change in the meniscus. [Figure 11] 13A and 13B are schematic diagrams illustrating circulation channels of a liquid ejection head according to a modified example. [Figure 12] 12 is a cross-sectional view taken along line A2-A2 in FIG. 11. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, preferred embodiments of the present disclosure will be described with reference to the accompanying drawings. Note that the dimensions and scale of each part in the drawings may differ from the actual dimensions, and some parts are shown diagrammatically to facilitate understanding. In addition, the scope of the present disclosure is not limited to these forms unless otherwise specified in the following description to the effect that the present disclosure is limited.

[0010] The following description will be given using the mutually intersecting X-axis, Y-axis, and Z-axis as appropriate. In addition, 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 mutually opposite directions along the Y-axis are the Y1 direction and the Y2 direction. The mutually opposite directions 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. In addition, the X-axis, Y-axis, and Z-axis are typically perpendicular to each other, but are not limited to this, and may intersect at an angle within a range of 80° to 100°, for example.

[0011] A: First embodiment A1: Overall configuration of the liquid ejection device 1 is a schematic diagram showing an example of the configuration of a liquid ejection device 100 according to a first embodiment. The liquid ejection device 100 is an inkjet printing device that ejects liquid such as ink as droplets onto a medium M. The medium M is, for example, printing paper. Note that the medium M is not limited to printing paper, and may be a printing target made of any material, such as a resin film or fabric.

[0012] As shown in FIG. 1, the liquid ejection device 100 includes a liquid container 10, a control unit 20, a transport mechanism 30, a moving mechanism 40, a liquid ejection head 50, and a circulation mechanism 60.

[0013] The liquid container 10 stores ink. Specific examples of the liquid container 10 include a cartridge that is detachable from the liquid ejection device 100, a bag-shaped ink pack made of a flexible film, and an ink tank that can be refilled with ink. The type of ink stored in the liquid container 10 is arbitrary.

[0014] The control unit 20 controls the operation of each element of the liquid ejection device 100. The 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.

[0015] The transport mechanism 30 transports the medium M in the Y1 direction under the control of the control unit 20. The movement mechanism 40 reciprocates the liquid ejection head 50 along the X axis under the control of the control unit 20. The movement mechanism 40 has a substantially box-shaped carriage 41 that houses the liquid ejection head 50, and an endless transport belt 42 to which the carriage 41 is fixed. The number of liquid ejection heads 50 mounted on the carriage 41 is not limited to one, and may be multiple. In addition to the liquid ejection head 50, the above-mentioned liquid container 10 may be mounted on the carriage 41.

[0016] Under the control of the control unit 20 based on the print data Img, the liquid ejection head 50 ejects ink supplied from the liquid container 10 from each of the multiple nozzles onto the medium M. This ejection is performed in parallel with the transportation of the medium M by the transport mechanism 30 and the reciprocating movement of the liquid ejection head 50 by the movement mechanism 40, so that an image corresponding to the print data Img is formed in ink on the surface of the medium M.

[0017] The liquid container 10 is connected to the liquid ejection head 50 via a circulation mechanism 60. The circulation mechanism 60 is a mechanism that supplies ink to the liquid ejection head 50 and recovers ink discharged from the liquid ejection head 50 for re-supply to the liquid ejection head 50 under the control of the control unit 20. The operation of the circulation mechanism 60 can suppress an increase in the viscosity of the ink and reduce the retention of air bubbles in the ink.

[0018] A2: Electrical configuration of the liquid ejection device 100 2 is a diagram showing the electrical configuration of the liquid ejection device 100 according to the first embodiment. As shown in FIG.

[0019] Head chip 51 has a plurality of ejection units 510. Drive control unit 52, under the control of control unit 20, switches whether or not to supply drive signal Com output from control unit 20 as supply signal Vin to each of the plurality of ejection units 510 of head chip 51.

[0020] In the example shown in FIG. 2, the head chip 51 has M ejection parts 510. The value M is a natural number equal to or greater than 1. Hereinafter, the m-th ejection part 510 among the M ejection parts 510 may be referred to as ejection part 510m. m is a natural number that satisfies "1≦m≦M". Hereinafter, when a component or signal of the liquid ejection head 50 corresponds to the ejection part 510m among the M ejection parts 510, the subscript m may be added to the symbol representing the component or signal.

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

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

[0023] The memory circuit 22 stores various programs executed by the control unit 21 and various data such as print data Img processed by the control unit 21. The memory circuit 22 includes one or both of semiconductor memories, for example, a volatile memory such as a random access memory (RAM) and a non-volatile memory such as a read only memory (ROM), an electrically erasable programmable read-only memory (EEPROM) or a programmable ROM (PROM). The print data Img is supplied from an external device 200 such as a personal computer or a digital camera. The memory circuit 22 may be configured as a part of the control unit 21.

[0024] The power supply circuit 23 receives power from a commercial power supply (not shown) and generates various predetermined potentials. The generated various potentials are appropriately supplied to each section 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. In addition, the power supply potential VHV is supplied to the drive signal generation section 24.

[0025] The drive signal generating unit 24 is a circuit that repeatedly generates a drive signal Com for driving each drive element 51e included in the discharge unit 510 described later. Specifically, the drive signal generating unit 24 has, for example, a DA conversion circuit and an amplifier circuit. In the drive signal generating unit 24, the DA conversion circuit converts the waveform designation signal dCom from the control unit 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. Of the waveforms included in the drive signal Com, the signal of the waveform that is actually supplied to the drive element 51e is the supply signal Vin described above. The waveform designation signal dCom is a digital signal for defining the waveform of the drive signal Com.

[0026] The control unit 21 executes a program stored in the memory circuit 22 to control the operation of each part of the liquid ejection device 100. Here, the control unit 21 executes the program to generate control signals Sk1 and 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 operation of each part of the liquid ejection device 100.

[0027] The control signal Sk1 is a signal for controlling the driving of the transport mechanism 30. The control signal Sk2 is a signal for controlling the driving of the movement mechanism 40. The print data signal SI is a digital signal for specifying the operating state of the drive element 51e. The latch signal LAT and the change signal CNG are used in conjunction with the print data signal SI and are timing signals that determine the timing of ink ejection from each nozzle of the head chip 51. These timing signals are generated, for example, based on 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 nozzles N, a plurality of individual flow paths IP, a first common liquid chamber R1, and a second common liquid chamber R2. A circulation mechanism 60 is connected to the first common liquid chamber R1 and the second common liquid chamber R2. The individual flow paths IP, the first common liquid chamber R1, and the second common liquid chamber R2 form a circulation flow path.

[0029] The multiple nozzles N are arranged along the Y axis. Each of the multiple nozzles N ejects ink in the Z2 direction. A group of the multiple nozzles N constitutes a nozzle row L. The multiple nozzles N are also arranged at equal intervals.

[0030] An individual flow path IP communicates with each of the plurality of nozzles N. Each of the plurality of individual flow paths IP extends along the X-axis and communicates with a different nozzle N. Furthermore, the plurality of individual flow paths IP are arranged along the Y-axis.

[0031] Each individual flow path IP has a pressure chamber Ca, a pressure chamber Cb, a communication flow path Nf, an individual supply flow path Ra1, and an individual discharge flow path Ra2. The individual flow path IP supplies ink to the pressure chamber C and discharges ink from the pressure chamber C.

[0032] Each of the pressure chambers Ca and pressure chambers Cb in each individual flow path IP extends along the X-axis and is a space in which ink ejected from a nozzle N communicating with the individual flow path IP is stored. In the example shown in FIG. 3, the multiple pressure chambers Ca are arranged along the Y-axis. Similarly, the multiple pressure chambers Cb are arranged along the Y-axis. Note that, in each individual flow path IP, the positions of the pressure chambers Ca and pressure chambers Cb in the direction along the Y-axis are the same in the example shown in FIG. 3, but may be different from each other. In the following, when there is no particular distinction between the pressure chambers Ca and pressure chambers Cb, they are also simply referred to as "pressure chambers C."

[0033] A communication flow path Nf is disposed between the pressure chamber Ca and the pressure chamber Cb 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 Ca and the pressure chamber Cb. Furthermore, the multiple communication flow paths Nf are arranged along the Y axis at intervals from one another. A nozzle N is provided in each communication flow path Nf. In each communication flow path Nf, ink is ejected from the nozzle N due to pressure fluctuations in the pressure chamber Ca and the pressure chamber Cb described above.

[0034] Each individual flow path IP is provided with an individual supply flow path Ra1 between the pressure chamber Ca and the first common liquid chamber R1. The individual supply flow path Ra1 is a flow path that connects the pressure chamber Ca and the first common liquid chamber R1. Similarly, each individual flow path IP is provided with an individual discharge flow path Ra2 between the pressure chamber Cb and the second common liquid chamber R2. The individual discharge flow path Ra2 is a flow path that connects the pressure chamber Cb and the second common liquid chamber R2.

[0035] The individual flow paths IP are commonly connected to a first common liquid chamber R1 and a second common liquid chamber R2. Each of the first common liquid chamber R1 and the second common liquid chamber R2 is a space extending along the Y axis over the entire range in which the nozzles N are distributed. When viewed in the direction along the Z axis, the individual flow paths IP are located between the first common liquid chamber R1 and the second common liquid chamber R2.

[0036] The first common liquid chamber R1 is connected to an end E1 of each individual flow path IP in the X2 direction. Ink to be supplied to each individual flow path IP is stored in the first common liquid chamber R1. Meanwhile, the second common liquid chamber R2 is connected to an end E2 of each individual flow path IP in the X1 direction. Ink that is not ejected and is discharged from each individual flow path IP is stored in the second common liquid chamber R2.

[0037] A circulation mechanism 60 is connected to the first common liquid chamber R1 and the second common liquid chamber R2. The circulation mechanism 60 supplies ink to the first common liquid chamber R1 and recovers ink discharged from the second common liquid chamber R2 for re-supply to the first common liquid chamber R1. The circulation mechanism 60 has 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 flow path 64 communicates the second common liquid chamber R2 with the storage container 63, and is a flow path for recovering the ink from the second common liquid chamber 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 flow path IP to the second common liquid chamber R2 is supplied via the recovery flow path 64. The second supply pump 62 is a pump that sends out the ink stored in the storage container 63. The supply flow path 65 communicates the first common liquid chamber R1 with the storage container 63, and is a flow path for supplying the ink from the storage container 63 to the first common liquid chamber R1.

[0039] A4: Specific structure of head chip 51 Fig. 4 is a cross-sectional view taken along the line A1-A1 in Fig. 3. Fig. 4 shows a cross section of head chip 51 cut along an individual flow path IP at a plane perpendicular to the Y axis. As shown in Fig. 4, head chip 51 has a nozzle substrate 51a, a flow path substrate 51b, a pressure chamber substrate 51c, a vibration plate 51d, a plurality of driving elements 51e, a case 51f, a protection plate 51g, and a wiring substrate 51h.

[0040] The nozzle substrate 51a, the flow path substrate 51b, the pressure chamber substrate 51c, and the vibration plate 51d are stacked in this order toward the Z1 direction. Each of these members extends along the Y axis, and is manufactured, for example, by processing a single crystal silicon substrate using semiconductor processing technology. These members are also bonded to each other with an adhesive or the like. Note that another layer such as an adhesive layer or a substrate 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 that allows ink to pass through.

[0042] The flow path substrate 51b is provided with the above-mentioned portions of the individual flow paths IP excluding the pressure chambers Ca and Cb, a liquid chamber R1a which is a part of the first common liquid chamber R1, and a liquid chamber R2a which is a part of the second common liquid chamber R2. That is, the flow path substrate 51b is provided with the communication flow path Nf, the individual supply flow path Ra1, the individual discharge flow path Ra2, the liquid chamber R1a, and the liquid chamber R2a.

[0043] Each of the liquid chambers R1a and R2a is a space penetrating the flow path substrate 51b. A vibration absorber 51i that closes the opening of the space is provided on the surface of the flow path substrate 51b facing the Z2 direction.

[0044] The vibration absorber 51i is a layered member made of an elastic material. The vibration absorber 51i constitutes a part of the wall surface of each of the first common liquid chamber R1 and the second common liquid chamber R2, and absorbs pressure fluctuations in the first common liquid chamber R1 and the second common liquid chamber 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. The first communication flow path Na1 and the second communication flow path Na2 are each 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 Ca with the nozzle flow path Nfa. The second communication flow path Na2 communicates the pressure chamber Cb with the nozzle flow path Nfa. The nozzle flow path Nfa is a space within a groove provided on a surface of the flow path substrate 51b facing the Z2 direction, and extends along the X axis. The nozzle substrate 51a forms a part of the wall surface of the nozzle flow path Nfa.

[0046] Each of the individual supply flow passages Ra1 and the individual discharge flow passages Ra2 is a space penetrating the flow passage substrate 51b. The individual supply flow passage Ra1 communicates the first common liquid chamber R1 with the pressure chamber Ca, and supplies ink from the first common liquid chamber R1 to the pressure chamber Ca. One end of the individual supply flow passage Ra1 opens to a surface of the flow passage substrate 51b facing the Z1 direction. On the other hand, the other end of the individual supply flow passage Ra1 is an upstream end of the individual flow passage IP, and opens to a wall surface of the first common liquid chamber R1 in the flow passage substrate 51b. On the other hand, the individual discharge flow passage Ra2 communicates the second common liquid chamber R2 with the pressure chamber Cb, and discharges ink from the pressure chamber Cb to the second common liquid chamber R2. One end of the individual discharge flow passage Ra2 opens to a surface of the flow passage substrate 51b facing the Z1 direction. On the other hand, the other end of the individual discharge flow path Ra2 is the downstream end of the individual flow path IP, and opens into the wall surface of the second common liquid chamber R2 in the flow path substrate 51b.

[0047] The pressure chamber substrate 51c is provided with pressure chambers Ca and pressure chambers Cb of a plurality of individual flow paths IP. Each of the pressure chambers Ca and pressure chambers Cb penetrates the pressure chamber substrate 51c and is a gap between the flow path substrate 51b and the vibration plate 51d. The pressure chamber Ca communicates with the nozzle N via the first communication flow path Na1 and the nozzle flow path Nfa. The pressure chamber Cb communicates with the nozzle N via the second communication flow path Na2 and the nozzle flow path Nfa.

[0048] The diaphragm 51d is a plate-like member capable of elastically vibrating. The diaphragm 51d is, for example, a laminate including a first layer made of silicon oxide (SiO2) and a second layer made of zirconium oxide (ZrO2). Another layer such as a metal oxide may be interposed between the first layer and the second layer. A part or all of the diaphragm 51d may be integrally formed with the pressure chamber substrate 51c using the same material. For example, the diaphragm 51d and the pressure chamber substrate 51c can be integrally formed by selectively removing a part in the thickness direction from a region corresponding to the pressure chamber C in a plate-like member of a predetermined thickness. The diaphragm 51d may also be formed from a layer of a single material.

[0049] A plurality of driving elements 51e corresponding to different pressure chambers C are provided on the surface of the vibration plate 51d facing the Z1 direction. The driving elements 51e apply pressure fluctuations to the ink in the pressure chambers C in response to the driving signal Com. Each driving element 51e is formed, for example, by laminating a first electrode and a second electrode facing each other and a piezoelectric layer disposed between the two electrodes. Each driving element 51e ejects the ink in the pressure chambers C from the nozzles N by fluctuating the pressure of the ink in the pressure chambers C. When the driving signal Com is supplied, the driving element 51e vibrates the vibration plate 51d as the driving element itself deforms. As a result of this vibration, the pressure chambers C expand and contract, and the pressure of the ink in the pressure chambers C fluctuates.

[0050] The case 51f is a case for storing ink. The case 51f is provided with a liquid chamber R1b, which is a portion other than the liquid chamber R1a of the first common liquid chamber R1, a liquid chamber R2b, which is a portion other than the liquid chamber R2a of the second common liquid chamber R2, an inlet port R01, and an outlet port R02. The liquid chamber R1b and the liquid chamber R2b are each a recess provided on the surface of the case 51f facing the Z2 direction. The inlet port R01 is a through hole formed by an inner circumferential surface extending from the surface of the case 51f facing the Z1 direction to the wall surface of the liquid chamber R1b. The inlet port R01 is connected to the supply flow path 65 of the circulation mechanism 60 described above. The outlet port R02 is a through hole formed by an inner circumferential surface extending from the surface of the case 51f facing the Z1 direction to the wall surface of the liquid chamber R2b. The outlet port R02 is connected to the recovery flow path 64 of the circulation mechanism 60 described above.

[0051] The protective plate 51g is a plate-like member provided on the surface of the diaphragm 51d facing the Z1 direction, and protects the multiple driving elements 51e and reinforces the mechanical strength of the diaphragm 51d. A space for accommodating the multiple driving 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 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 drive control unit 52 described above is mounted on the wiring board 51h.

[0053] In the head chip 51 configured as above, ink flows through the first common liquid chamber R1, the individual supply flow path Ra1, the pressure chamber Ca, the communication flow path Nf, the pressure chamber Cb, the individual discharge flow path Ra2, and the second common liquid chamber R2 in this order by the operation of the above-mentioned circulation mechanism 60. Also, the drive elements 51e corresponding to both the pressure chamber Ca and the pressure chamber Cb are simultaneously driven by a supply signal Vin from the drive control unit 52, thereby fluctuating the pressure in the pressure chamber Ca and the pressure chamber Cb, and ink is ejected from the nozzle N in accordance with the pressure fluctuation.

[0054] In the head chip 51, the ejection section 510 includes a nozzle N, a pressure chamber C, and a driving element 51e. In this embodiment, the ejection section 510 is configured by the nozzle N, the pressure chamber Ca, the pressure chamber Cb, the individual supply flow path Ra1, the individual discharge flow path Ra2, the communication flow path Nf, the two driving elements 51e, and the vibration plate 51d.

[0055] A5: Nozzle N Fig. 5 is an enlarged cross-sectional view of the nozzle N. Fig. 5 shows a cross section of a part of the nozzle flow path Nfa and the nozzle N perpendicular to the Y-axis. As shown in Fig. 5, the nozzle N branches off from the nozzle flow path Nfa of the individual flow path IP and extends in a direction different from the nozzle flow path Nfa. Specifically, the nozzle flow path Nfa extends in the direction along the X-axis, while the nozzle N extends in the direction along the Z-axis.

[0056] 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 an opening end of the nozzle N on a surface of the nozzle substrate 51a facing the Z2 direction. The connection portion N2 is a boundary portion with the nozzle flow path Nfa of the nozzle N. The length along the Z axis from the discharge side opening end N1 to the connection portion N2 is the length L of the nozzle N.

[0057] 5, the nozzle N has a first portion NP1 and a second portion NP2. The first portion NP1 and the second portion NP2 are arranged in this order in the Z1 direction. The second portion NP2 is provided between the nozzle flow path Nfa and the first portion NP1 of the individual flow path IP. The nozzle flow path Nfa and the first portion NP1 communicate with each other via the second portion NP2.

[0058] Each of the first portion NP1 and the second portion NP2 extends along the Z-axis. The cross-sectional area of ​​each of the first portion NP1 and the second portion NP2 is circular. The first portion NP1 and the second portion NP2 are arranged coaxially. The first portion NP1 includes a discharge-side opening end N1. The second portion NP2 includes a connection portion N2.

[0059] The length L1 of the first portion NP is shorter than the length L2 of the second portion NP2. The length L1 is the length along the Z axis from the discharge side opening end N1 to the boundary between the first portion L1 and the second portion L2. The length L2 is the length along the Z axis from the boundary between the first portion L1 and the second portion L2 to the connection portion N2.

[0060] The cross-sectional area of ​​the first portion NP1 is smaller than the cross-sectional area of ​​the second portion NP2. Therefore, the nozzle N has a shape in which the width gradually decreases in the Z2 direction. The width W1 of the first portion NP1 is smaller than the width W2 of the second portion NP2. By making the width W1 smaller than the width W2, it is possible to eject finer ink droplets and improve the landing accuracy of the ink droplets compared to when the width is constant. In addition, it is preferable that the width W2 is smaller than the width of the nozzle flow path Nfa. By making the width W2 smaller than the width of the nozzle flow path Nfa, it is possible to reduce crosstalk between two second portions NP2 adjacent to each other in the direction along the Y axis.

[0061] Note that width W1 is the length of the first portion NP1 in a direction perpendicular to the Z axis. Width W2 is the length of the second portion NP2 in a direction perpendicular to the Z axis. Since the cross-sectional areas of the first portion NP1 and the second portion NP2 are circular, width W1 corresponds to the diameter of the first portion NP1, and width W2 corresponds to the diameter of the second portion NP2. The width of the nozzle flow path Nfa is the length along the Z axis.

[0062] Furthermore, the specific values ​​of the length L1 are not particularly limited, but are determined appropriately depending on the characteristics such as the ink ejection amount or ejection speed required for the nozzle N. The specific value of the length L2 is determined appropriately depending on the width W2 of the second portion NP2 or the thickness of the nozzle substrate 51a, etc. Furthermore, the specific values ​​of the widths W1 and W2 are not particularly limited, but are determined appropriately depending on the characteristics such as the ink ejection amount or ejection speed required for the nozzle N, for example.

[0063] As described above, the nozzle N extends in a direction intersecting the direction in which the nozzle flow path Nfa extends. Therefore, even if the circulation mechanism 60 described above is operated, the circulating flow of ink generated in the nozzle flow path Nfa by the operation is unlikely to reach the inside of the nozzle N. In particular, in the nozzle N having the first portion NP1 and the second portion NP2 as described above, it is necessary to ensure a certain length in the Z-axis direction for each of the first portion NP1 and the second portion NP2. Therefore, in the nozzle N of this embodiment, the circulating flow is unlikely to reach the first portion NP1 compared to a nozzle of a constant width. Therefore, during the standby period in which the drive element 51e is not operated, the ink is likely to stagnate in the nozzle N. Therefore, if the standby period is prolonged, the ink in the nozzle N may thicken.

[0064] Therefore, in the liquid ejection device 100, during a period when ink is not ejected from the nozzle N, the drive element 51e is driven to slightly vibrate the meniscus MN to such an extent that ink is not ejected from the nozzle N. This slight vibration is smaller than the vibration of the meniscus MN when ink is ejected. This slight vibration agitates the ink in the nozzle N. Therefore, coupled with the action of the circulating flow of ink by the circulation mechanism 60, the replacement of ink is smoothly performed between the nozzle N and the nozzle flow path Nfa. This makes it possible to prevent the ink in the nozzle N from thickening, etc.

[0065] In this embodiment, the nozzle N has two parts, a first part NP1 and a second part NP2, which are different in width. However, the nozzle N may have a constant width as a whole, or may have a shape having two or more different widths. In addition, when the cross-sectional shape of the nozzle N is circular, the width of the nozzle N corresponds to the diameter.

[0066] A6: Driving the liquid ejection head 50 Fig. 6 is a diagram for explaining the drive control unit 52. The drive element 51e is driven by a supply signal Vin from the drive control unit 52. The drive control unit 52 will be explained below with reference to Fig. 6. In the example shown in Fig. 6, the drive signal Com includes a first drive signal Com-A and a second drive signal Com-B.

[0067] As shown in FIG. 6, wirings LHa and LHb are connected to the drive control unit 52. The wiring LHa is a signal line that transmits the first drive signal Com-A. The wiring LHb is a signal line that transmits the second drive signal Com-B. Note that in FIG. 6, one of the first electrode and the second electrode of the drive element 51e described above is shown as an electrode Zd[m], and the other is shown as an electrode Zu[m]. A wiring LHd is connected to the electrode Zd[m]. The wiring LHd is a power supply line to which an offset potential VBS is supplied.

[0068] The drive control unit 52 has M switches SWa (SWa[1] to SWa[M]), M switches SWb (SWb[1] to SWb[M]), and a connection state designation circuit 52a that designates the connection states of these switches.

[0069] The switch SWa[m] is a switch that switches between conduction (on) and non-conduction (off) between the wiring LHa for transmitting the first drive signal Com-A and the electrode Zu[m] of the drive element 51e[m]. The switch SWb[m] is a switch that switches between conduction (on) and non-conduction (off) between the wiring LHb for transmitting the second drive signal Com-B and the electrode Zu[m] of the drive element 51e[m]. Each of these switches is, for example, a transmission gate.

[0070] The connection state designation circuit 52a generates connection state designation signals SLa[1] to SLa[M] that specify the on / off state of switches SWa[1] to SWa[M], and connection state designation signals SLb[1] to SLb[M] that specify the on / off state of switches SWb[1] to SWb[M], based on the clock signal CLK, the print data signal SI, the latch signal LAT, and the change signal CNG supplied from the control unit 21.

[0071] For example, although not shown, the connection state designation circuit 52a has a plurality of transfer circuits, a plurality of latch circuits, and a plurality of decoders so as to correspond one-to-one to the driving elements 51e[1] to 51e[M]. Of these, the print data signal SI is supplied to the transfer circuit. The print data signal SI includes an individual designation signal for each driving element 51e, and the individual designation signal is supplied serially. For example, the print data signal SI includes the individual designation signal that is transferred to the plurality of transfer circuits in sequence in synchronization with the clock signal CLK. Furthermore, the latch circuit latches the individual designation signal supplied to the transfer circuit based on the latch signal LAT. Furthermore, the decoder generates the connection state designation signals SLa[m] and SLb[m] based on the individual designation signal, the latch signal LAT, and the change signal CNG.

[0072] For example, the switch SWa[m] is turned on when the connection state designation signal SLa[m] is at a high level, and turned off when the connection state designation signal SLa[m] is at a low level. For example, the switch SWb[m] is turned on when the connection state designation signal SLb[m] is at a high level, and turned off when the connection state designation signal SLa[m] is at a low level.

[0073] A7: Drive signal Fig. 7 is a diagram for explaining the drive signal Com. As shown in Fig. 7, the latch signal LAT includes a pulse PlsL for defining a unit period Tu. The unit period Tu corresponds to a printing cycle for forming dots of ink from the nozzle N on the medium M. The unit period Tu is defined as, for example, the period from the rising edge of the pulse PlsL to the rising edge of the next pulse PlsL. The unit period Tu is repeated at a predetermined cycle.

[0074] The first drive signal Com-A has an ejection pulse P1. The ejection pulse P1 is a potential pulse that drives the drive element 51e to generate a pressure fluctuation in the pressure chamber C with a strength that causes ink to be ejected from the nozzle N. When the ejection pulse P1 is supplied to the drive element 51e, ink is ejected as an ink droplet from the nozzle N. In the example shown in FIG. 7, the ejection pulse P1 has a waveform that drops from a reference potential to a potential lower than the reference potential, and then rises to a potential higher than the reference potential and then returns to the reference potential. Note that the reference potential is, for example, a potential higher than the offset potential VBS.

[0075] The second drive signal Com-B has a non-ejection pulse P01. The non-ejection pulse P01 is a potential pulse that drives the drive element 51e to generate a pressure fluctuation in the pressure chamber C that is strong enough to prevent ink from being ejected from the nozzle N. When the non-ejection pulse P01 is supplied to the drive element 51e, the meniscus MN of the ink in the nozzle N is slightly vibrated without ejecting ink from the nozzle N. In the example shown in Fig. 7, the non-ejection pulse P01 has a waveform that drops from a reference potential to a potential lower than the reference potential and then returns to the reference potential.

[0076] The above-mentioned ejection pulse P1 and non-ejection pulse P01 are appropriately selected and used for the supply signal Vin. Note that the drive signal Com shown in Fig. 7 is only an example. For example, in order to adjust the amount of ink ejected from the nozzle N, multiple types of ejection pulses other than the ejection pulse P1 may be provided.

[0077] Based on the print data Img, the control unit 21 controls the supply of the drive signals Com to the ejection units 510[1]-[M] for each unit period Tu of a predetermined cycle so that the target period for each of the ejection units 510[1]-[M] is one of an ejection period, a non-ejection period, and a standby period. The target period is a period during which the control unit 21 determines which of the drive signals Com to supply to the ejection unit 510[m]. The ejection period is a unit period Tu during which ink is ejected from the nozzle N[m] of the ejection unit 510[m]. When the target period is the ejection period, the control unit 21 supplies a supply signal Vin including an ejection pulse P1 to the electrode Zu[m] of the ejection unit 510[m]. As a result, ink droplets are ejected from the nozzle N[m] of the ejection unit 510[m] onto the medium M during the target period. The non-ejection period is a unit period Tu during which ink is not ejected from the nozzle N[m] of the ejection unit 510[m]. When the target period is a non-ejection period, the control unit 21 supplies a supply signal Vin including a non-ejection pulse P01 to the electrode Zu[m] of the ejection unit 510[m]. As a result, during the target period, ink is not ejected from the nozzle N[m] of the ejection unit 510[m] and the ink in the nozzle N[m] is slightly vibrated. The standby period is a unit period Tu during which ink is not ejected from the nozzle N[m] of the ejection unit 510[m] without slightly vibrating the ink in the nozzle N[m]. When the target period is a standby period, the control unit 21 supplies a supply signal Vin that maintains a constant potential and does not include a pulse that changes potential including the ejection pulse P1 and the non-ejection pulse P01 to the electrode Zu[m] of the ejection unit 510[m], or does not supply the supply signal Vin.

[0078] By slightly vibrating the meniscus MN in the nozzle N[m] during the non-ejection period, the ink in the nozzle N[m] is replaced with ink circulating through the nozzle flow path Nfa, and thickening of the ink in the nozzle N[m] can be suppressed. Furthermore, even during a period in which the liquid ejection head 50 is not printing an image based on the print data Img, the control unit 21 controls the supply of the drive signal Com to the ejection units 510[1]-[M] for each unit period Tu of a predetermined cycle so that the target period for each of the ejection units 510[1]-[M] is either a non-ejection period or a standby period.

[0079] In the liquid ejection device 100, when the nozzle N is released from the capped state, the meniscus MN, which is the ink surface inside the nozzle N, is exposed to air. The capped state is a state in which the nozzle N is sealed by a sealing member such as a cap (not shown). When the nozzle N is exposed to air, the ink solvent evaporates over time through the meniscus MN, which is the ink surface exposed to the nozzle N, and the ink inside the nozzle N gradually thickens. If the ink thickens further, ejection defects may occur, such as ink not being ejected from the nozzle N or the flight direction of the ink ejected from the nozzle N being curved.

[0080] In the liquid ejection device 100 having the circulation mechanism 60 of this embodiment, in parallel with the circulation of the ink, the ink is slightly vibrated during non-ejection periods to replace the ink in the nozzle N with the ink in the circulation flow path including the nozzle flow path Nfa. This prevents ejection failures due to increased viscosity of the ink in the nozzle N.

[0081] However, if the pressure fluctuation caused by the micro-vibration is too weak, the replacement of the ink in the circulation flow path with the ink in the nozzle N will be insufficient. This will cause the ink in the nozzle N to thicken, which may cause abnormalities in the flight speed or flight direction of the ink droplets ejected in the next ejection period. The characteristic related to the occurrence of abnormalities in the ejection state in the ejection period after this non-ejection period is called intermittent performance. On the other hand, if the pressure fluctuation caused by the micro-vibration is too strong, the residual vibration of the micro-vibration will affect the ejection of ink droplets in the next ejection period. As a result, the ejection of ink after the micro-vibration will become unstable. The characteristic related to the occurrence of abnormalities in the ejection state due to the influence of this residual vibration is called ejection stability.

[0082] Fig. 8 is a diagram for explaining the meniscus MN in the nozzle N. As shown in Fig. 8, the length from the ejection side opening end N1 of the nozzle N to the connection part N2 is defined as L. The distance between the position of the meniscus MN of the ink that is drawn most into the nozzle N by the supply of the non-ejection pulse P01 to the driving element 51e and the ejection side opening end N1, which is the tip of the nozzle N, is defined as Lm. In this case, the length L and the distance Lm satisfy the relationship 0.07≦Lm / L≦0.15.

[0083] By satisfying the above relationship between the length L and the distance Lm, it is possible to suppress the occurrence of abnormalities in the ejection state during the ejection period following the non-ejection period, while suppressing the instability of the ink, compared to when the relationship is not satisfied. In other words, it is possible to improve the intermittent performance and the ejection stability.

[0084] In order to improve the intermittent performance and ejection stability, it is more preferable that the length L and the distance Lm satisfy the relationship 0.09≦Lm / L≦0.14, and it is even more preferable that they satisfy the relationship 0.09≦Lm / L≦0.12.

[0085] 9 and 10 are examples showing the results of evaluation of intermittent performance and ejection stability with respect to the amount of change in the meniscus MN. Fig. 9 is an example in which the length L of the nozzle N is 65 μm and the width W1 of the first portion NP1 of the nozzle N is 20 μm. Fig. 10 is an example in which the length L of the nozzle N is 65 μm and the width W1 of the first portion NP1 of the nozzle N is 29 μm.

[0086] "◯" indicates that the performance is excellent, and "×" indicates that the performance is not excellent. The intermittent performance and ejection stability can be evaluated, for example, by continuing the micro-vibration operation for a predetermined period of time, and then performing a continuous ejection operation, and checking the flight state of ink droplets from the nozzle N.

[0087] When the strength of the micro-vibration is 0 (zero), it means that the ink in the nozzle N is not vibrated. The greater the strength of the micro-vibration, the greater the distance Lm. As the distance Lm increases, Lm / L increases. And when the length L and the distance Lm satisfy the relationship 0.07≦Lm / L≦0.15, as in the embodiment shown in FIG. 9 and FIG. 10, both the intermittent performance and the ejection stability are excellent.

[0088] On the other hand, if the length L and the distance Lm are less than the lower limit, the intermittent performance is degraded. This is because the strength of the micro-vibration is insufficient, so the ink in the nozzle N is not sufficiently agitated, and the ink in the nozzle N is not sufficiently replaced by the ink in the nozzle flow path Nfa. Also, if the length L and the distance Lm exceed the upper limit, the ejection stability is degraded. This is because the strength of the micro-vibration is too large, so the residual vibration of the micro-vibration becomes large, and this residual vibration affects the ejection of ink after the micro-vibration.

[0089] Furthermore, the width W1 of the nozzle N, particularly the width of the ejection side opening end N1, is not particularly limited, but is preferably 10 μm or more and 40 μm or less. Therefore, by having the width W1 within the above range, it is possible to eject smaller ink droplets compared to when the width is outside the range. This makes it possible to perform high-resolution printing.

[0090] In order to achieve the above effects significantly, the width W1 is more preferably 12 μm or more and 35 μm or less, and even more preferably 15 μm or more and 30 μm or less. The cross-sectional shapes of the first portion NP1 and the discharge side opening end N1 are circular. Therefore, the width W1 and the width of the discharge side opening end N1 correspond to the diameter. In addition, since the first portion NP1 has a constant width, the width W1 and the width of the discharge side opening end N1 are equal.

[0091] The nozzle N of this embodiment has a first portion NP1 and a second portion NP2 with different widths. In this manner, when the nozzle N includes portions with different widths, it is preferable that the width at the discharge side opening end N1 satisfies the above range. Similarly, when the entire nozzle N is constant, it is preferable that the width at the discharge side opening end N1 satisfies the above range.

[0092] Furthermore, the length L from the discharge side opening end N1 of the nozzle N to the connection part N2, i.e., the length L of the nozzle N, is not particularly limited, but is preferably 1.5 to 3.5 times the width W1 of the discharge side opening end N1 of the nozzle N. By having the length L within the above range, it is possible to ensure flow path resistance within the nozzle N and hasten the damping of the vibration of the meniscus MN, while efficiently replacing the ink in the nozzle N with the ink in the circulation flow path, compared to when it is outside the range.

[0093] In order to significantly exert the above-mentioned effects, the width W1 is more preferably 12 μm or more and 35 μm or less, and further preferably 15 μm or more and 30 μm or less.

[0094] As described above, the nozzle N includes a first portion NP1 and a second portion NP2. The width W1 of the first portion NP1 is smaller than the width W2 of the second portion NP2. The length L1 of the first portion NP1 is shorter than the length L2 of the second portion NP2. By including the first portion NP1 and the second portion NP2 in the nozzle N, fine ink droplets can be ejected and the landing accuracy of the ink droplets can be improved compared to when the entire area of ​​the nozzle N has a constant width. Furthermore, the flow path resistance in the nozzle N can be secured to hasten the attenuation of the vibration of the meniscus MN, and the ink in the nozzle N can be efficiently replaced with the ink in the circulation flow path.

[0095] The cross-sectional area of ​​the first portion NP1 is preferably 0.25 to 0.60 times the cross-sectional area of ​​the second portion NP2. By having the cross-sectional area of ​​the first portion NP1 within the above range, the ink in the nozzle N can be replaced with the ink in the circulation flow path more efficiently while ensuring the flow path resistance in the nozzle N and hastening the damping of the vibration of the meniscus MN, compared to when the cross-sectional area is outside the range.

[0096] To prominently exhibit the above effect, the cross-sectional area of ​​the first portion NP1 is more preferably 0.30 to 0.55 times, and even more preferably 0.40 to 0.50 times, the cross-sectional area of ​​the second portion NP2.

[0097] Furthermore, it is preferable that the length L1 of the first portion NP1 is 30% or more and 50% or less of the length L of the nozzle N. By having the length L1 within the above range, it is possible to ensure flow path resistance within the nozzle N and hasten the damping of the vibration of the meniscus MN, while efficiently replacing the ink in the nozzle N with the ink in the circulation flow path, compared to when the length L1 is outside the range.

[0098] In order to prominently exhibit the above effect, the length L1 is more preferably 32% or more and 45% or less of the length L of the nozzle N, and further preferably 33% or more and 44% or less.

[0099] As described above, according to the liquid ejection method executed by the liquid ejection device 100 so that the length L and the distance Lm satisfy the relationship 0.07≦Lm / L≦0.15, it is possible to improve the intermittent performance and ejection stability.

[0100] 2. Variations Each of the above-mentioned exemplary embodiments may be modified in various ways. Specific modified embodiments that may be applied to each of the above-mentioned embodiments are illustrated below. Two or more embodiments selected from the following examples may be appropriately combined as long as they are not mutually contradictory.

[0101] Fig. 11 is a schematic diagram for explaining the circulation flow path of a liquid ejection head 50B of a modified example. The liquid ejection head 50B is similar to the liquid ejection head 50 of the first embodiment described above, except that the liquid ejection head 50B has a plurality of individual flow paths IPa and a plurality of individual flow paths IPb instead of the plurality of individual flow paths IP. That is, as shown in Fig. 11, the liquid ejection head 50B is provided with a plurality of nozzles N, a plurality of individual flow paths IPa, a plurality of individual flow paths IPb, a first common liquid chamber R1, and a second common liquid chamber R2, and is connected to a circulation mechanism 60.

[0102] More specifically, the liquid ejection head 50B is provided with a plurality of nozzles Na and a plurality of nozzles Nb. Each of these nozzles is configured similarly to the nozzle N in the above-described embodiment, and ejects ink in the Z2 direction. In the following description, when there is no need to distinguish between the nozzles Na and Nb, they will simply be referred to as "nozzles N."

[0103] The multiple nozzles Na are arranged along the Y axis, and a group of these constitute a first nozzle row La. Similarly, the multiple nozzles Nb are arranged along the Y axis, and a group of these constitute a second nozzle row Lb.

[0104] The first nozzle row La and the second nozzle row Lb are aligned at a predetermined interval along the X-axis. Here, the arrangement pitch of the nozzles Na and the arrangement pitch of the nozzles Nb are equal to each other, but the nozzles Na and the nozzles Nb that are closest to each other are shifted from each other in the Y-axis direction.

[0105] An individual flow path IPa communicates with each of the multiple nozzles Na. Each of the multiple individual flow paths IPa extends along the X-axis and communicates with a different nozzle Na from the other. Similarly, an individual flow path IPb communicates with each of the multiple nozzles Nb. Each of the multiple individual flow paths IPb extends along the X-axis and communicates with a different nozzle Nb from the other. The individual flow paths IPa and the individual flow paths IPb are alternately arranged along the Y-axis.

[0106] The individual flow path IPa is similar to the individual flow path IP of the above embodiment, except that the pressure chamber Cb is omitted. Specifically, the individual flow path IPa includes a first flow path portion Pa1 and a second flow path portion Pa2. The first flow path portion Pa1 in each individual flow path IPa is a flow path between an upstream end E1 of the individual flow path IPa and the nozzle Na. The first flow path portion Pa1 includes a pressure chamber Ca. On the other hand, the second flow path portion Pa2 in each individual flow path IPa is a flow path between a downstream end E2 of the individual flow path IPa and the nozzle Na.

[0107] The individual flow paths IPb are similar to the individual flow paths IP of the above-described embodiment, except that the pressure chamber Ca is omitted. Specifically, the individual flow paths IPb include a third flow path portion Pb1 and a fourth flow path portion Pb2. The third flow path portion Pb1 in each individual flow path IPb is a flow path between an upstream end E1 of the individual flow path IPb and the nozzle Nb. On the other hand, the fourth flow path portion Pb2 in each individual flow path IPb is a flow path between a downstream end E2 of the individual flow path IPb and the nozzle Nb. The fourth flow path portion Pb2 includes a pressure chamber Cb.

[0108] A first common liquid chamber R1 is connected to the upstream end E1 of each of the individual flow paths IPa and IPb, while a second common liquid chamber R2 is connected to the downstream end E2 of each of the individual flow paths IPa and IPb.

[0109] Fig. 12 is a cross-sectional view taken along line A2-A2 in Fig. 12. Fig. 12 shows a cross section of the liquid ejection head 50B cut along an individual flow path IPa by a plane parallel to the X-axis and Z-axis. Below, the configuration of the individual flow path IPa will be representatively described. Note that the individual flow paths IPb are the same as the individual flow paths IPa except that their orientation is different by 180° around the Z-axis, and therefore description thereof will be omitted.

[0110] The individual flow paths IPa are the same as the individual flow paths IP of the first embodiment described above, except that the pressure chambers Cb are replaced with horizontal communication flow paths Cq1. The liquid ejection head 50B is configured in the same manner as the liquid ejection head 50 of the first embodiment described above, except that it includes a nozzle substrate 51aB, a flow path substrate 51bB, and a pressure chamber substrate 51cB instead of the nozzle substrate 51a, the flow path substrate 51b, and the pressure chamber substrate 51c. Note that in the individual flow paths IPa, the driving elements 51e corresponding to the pressure chambers Cb are omitted.

[0111] The nozzle substrate 51aB is provided with a plurality of nozzles Na. The nozzle substrate 51aB is configured similarly to the nozzle substrate 51a described above, except for the arrangement of the nozzles Na. When viewed in the direction along the Z axis, the nozzles Na overlap the pressure chambers Ca.

[0112] The flow path substrate 51bB is provided with the above-mentioned individual flow paths IPa except for the pressure chambers Ca, the liquid chambers R1a and the liquid chambers R2a.

[0113] As shown in Fig. 12, each individual flow path IPa has a communication flow path Nf, a horizontal communication flow path Cq1, an individual supply flow path Ra1, and an individual discharge flow path Ra2 in addition to the pressure chamber Ca. Of these, the communication flow path Nf, the horizontal communication flow path Cq1, the individual supply flow path Ra1, and the individual discharge flow path Ra2 are provided in the flow path substrate 51bB. Here, the first communication flow path Na1 of the communication flow path Nf overlaps with the nozzle Na when viewed in the direction along the Z axis. In addition, the nozzle Na branches off from the first communication flow path Na1 in a direction different from the nozzle flow path Nfa.

[0114] The lateral communication channel Cq1 is a space extending along the X-axis. The lateral communication channel Cq1 communicates the second communication channel Na2 with the individual discharge channel Ra2, and guides ink from the second communication channel Na2 to the individual discharge channel Ra2.

[0115] The pressure chamber substrate 51cB is similar to the pressure chamber substrate 51c of the above-described embodiment, except that the pressure chamber Cb is omitted for the individual flow passage IPa.

[0116] In the modified example shown in Figures 11 and 12, as in the previously described embodiment, the length L and the distance Lm can be made to satisfy the relationship 0.07≦Lm / L≦0.15, thereby improving the intermittent performance and ejection stability.

[0117] In each of the above-described embodiments, the nozzle N has a first portion NP1 and a second portion NP2, but the nozzle N is not limited to this configuration. For example, the nozzle N may have a constant width or may have a shape with three or more steps.

[0118] The driving element that changes the pressure of the ink in the pressure chamber C is not limited to the driving element 51e exemplified in each of the above-mentioned embodiments. For example, a heating element that generates air bubbles inside the pressure chamber C by heating to change the pressure of the ink may be used as the driving element.

[0119] In each of the above-described embodiments, a serial-type liquid ejection device 100 in which a carriage 41 carrying a liquid ejection head 50 is moved back and forth has been exemplified, but the present disclosure can also be applied to a line-type liquid ejection device in which multiple nozzles N are distributed across the entire width of the medium M.

[0120] The liquid ejection device 100 exemplified in the above embodiment may be adopted in various devices such as facsimile machines and copy machines in addition to devices 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 color material is used as a manufacturing device that forms a color filter of a display device such as a liquid crystal display panel. In addition, a liquid ejection device that ejects a solution of a conductive material is used as a manufacturing device that forms wiring and electrodes of a wiring board. In addition, a liquid ejection device that ejects a solution of an organic substance related to a living body is used as a manufacturing device that manufactures, for example, a biochip.

[0121] Although the present invention has been described based on the preferred embodiment, the present invention is not limited to the above embodiment. Furthermore, the configuration of each part of the present invention can be replaced with any configuration that exhibits the same function as the above embodiment, and any configuration can be added. [Explanation of symbols]

[0122] 24...driving signal generating unit, 50...liquid ejection head, 51e...driving element, 52...driving control unit, 60...circulation mechanism, 100...liquid ejection device, 510...ejection unit, C...pressure chamber, Com...driving signal, IP...individual flow path, Img...printing data, Lm...distance, MN...meniscus, N...nozzle, N1...ejection side opening end, N2...connection unit, NP1...first part, NP2...second part, Nf...communicating flow path, Nfa...nozzle flow path, P01...non-ejection pulse, P1...ejection pulse, P2...ejection pulse, PlsL...pulse, Tu...unit period, W1...width.

Claims

1. an individual flow path that supplies liquid to the pressure chamber and discharges liquid from the pressure chamber; A nozzle branching from the individual flow path and discharging a liquid; A drive element that applies a pressure fluctuation to the liquid in the pressure chamber in response to a drive signal; A drive signal generating unit that generates the drive signal; a control unit that controls the supply of the drive signals to the drive elements based on print data so that a target period becomes either an ejection period in which liquid is ejected from the nozzles or a non-ejection period in which liquid is not ejected from the nozzles, for each unit period of a predetermined cycle; Equipped with The drive signal is an ejection pulse for driving the drive element so as to generate a pressure fluctuation in the pressure chamber having a strength for ejecting liquid from the nozzle; a non-ejection pulse for driving the driving element so as to generate a pressure fluctuation in the pressure chamber that is strong enough not to eject liquid from the nozzle; Including, The control unit is If the target period is the ejection period, the ejection pulse is supplied to the drive element; If the target period is the non-ejection period, the non-ejection pulse is supplied to the driving element; Let L be the length from the discharge side opening end of the nozzle to the connection part of the nozzle with the individual flow path, and let Lm be the distance between the position of the meniscus of the liquid that is drawn most into the nozzle by the supply of the non-ejection pulse to the drive element and the tip of the nozzle, The relationship of 0.07≦Lm / L≦0.15 is satisfied. The liquid ejection device is characterized by the above.

2. The diameter of the nozzle is 10 μm or more and 40 μm or less. The liquid ejection device according to claim 1 .

3. a length from the discharge side opening end of the nozzle to a connection portion of the nozzle with the individual flow passage is 1.5 times or more and 3.5 times or less a diameter of the discharge side opening end of the nozzle; The liquid ejection device according to claim 1 .

4. The nozzle has a first portion and a second portion provided between the first portion and the individual flow path, a cross-sectional area of ​​the first portion is smaller than a cross-sectional area of ​​the second portion; The length of the first portion is shorter than the length of the second portion. The liquid ejection device according to claim 1 .

5. The cross-sectional area of ​​the first portion is 0.25 times or more and 0.60 times or less than the cross-sectional area of ​​the second portion. The liquid ejection device according to claim 4 .

6. The length of the first portion is equal to or greater than 30% and equal to or less than 50% of the length of the nozzle. The liquid ejection device according to claim 4 .

7. A liquid ejection method performed by a liquid ejection device capable of ejecting liquid, comprising: The liquid ejection device includes: an individual flow path that supplies liquid to the pressure chamber and discharges liquid from the pressure chamber; A nozzle branching from the individual flow path and discharging a liquid; A drive element that applies a pressure fluctuation to the liquid in the pressure chamber in response to a drive signal; A drive signal generating unit that generates the drive signal; a control unit that controls the supply of the drive signals to the drive elements based on print data so that a target period becomes either an ejection period in which liquid is ejected from the nozzles or a non-ejection period in which liquid is not ejected from the nozzles, for each unit period of a predetermined cycle; Equipped with supplying an ejection pulse to the drive element to drive the drive element so as to generate a pressure fluctuation in the pressure chamber having a strength that causes liquid to be ejected from the nozzle when the target period is the ejection period; If the target period is the non-ejection period, a non-ejection pulse is supplied to the drive element to drive the drive element so as to generate a pressure fluctuation in the pressure chamber that is strong enough to prevent liquid from being ejected from the nozzle; Let L be the length from the discharge side opening end of the nozzle to the connection portion with the individual flow path, and let Lm be the distance between the position of the meniscus of the liquid that is drawn most into the nozzle by the supply of the non-ejection pulse to the drive element and the tip of the nozzle, The relationship of 0.07≦Lm / L≦0.15 is satisfied. A liquid ejection method comprising the steps of:

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