Liquid discharge device, control method, article manufacturing method, program, and recording medium

Abstract

To provide a technique advantageous for shortening the adjustment time of a discharge speed and a discharge amount of liquid droplets discharged from a nozzle.SOLUTION: A control unit of a liquid discharge device applies a first drive signal to a first piezoelectric element to discharge a liquid droplet from a first nozzle, and acquires data of a first discharge speed and a first discharge amount of the discharged liquid droplet. The control unit discharges a plurality of liquid droplets from a second nozzle by keeping a pulse width of a second drive signal applied to the first piezoelectric element or to a second piezoelectric element constant and varying a voltage of the second drive signal, and acquires data of a first rate of change in the discharge speed relative to the discharge amount of the discharged liquid droplets. The control unit discharges the plurality of liquid droplets from the second nozzle by keeping a voltage of the second drive signal constant and varying the pulse width, and acquires data of a second rate of change in the discharge speed relative to the discharge amount of the discharged liquid droplets. The control unit updates settings of the voltage and the pulse width of the first drive signal on the basis of the first rate of change and the second rate of change.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present disclosure relates to a liquid ejection device, a control method, a method for manufacturing an article, a program, and a recording medium. [Background technology]

[0002] Liquid ejection devices such as inkjet printers are configured to use energy-generating elements such as piezoelectric elements to impart kinetic energy to liquid, causing it to be ejected from nozzles. The liquid ejection device includes a liquid ejection head in which multiple piezoelectric elements are arranged in multiple pressure chambers, respectively, to eject droplets from multiple nozzles independently. In such a liquid ejection head, each of the multiple nozzles is individually connected to a single pressure chamber in which a piezoelectric element is arranged. The multiple pressure chambers are connected to a common liquid chamber that stores liquid.

[0003] The dimensions of each pressure chamber vary, and even if a drive signal with the same waveform is applied to each piezoelectric element, variations may occur in at least one of the droplet ejection speed and ejection volume. Such variations may lead to quality degradation, such as uneven concentration or streaks in the liquid when the liquid is supplied to the target object. Patent Document 1 discloses a technology for adjusting the voltage and pulse width of a drive signal applied to each of multiple piezoelectric elements so that the ejection speed and ejection volume of droplets ejected from multiple nozzles fall within target ranges. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2003-127430 Summary of the Invention [Problem to be solved by the invention]

[0005] However, since each of the multiple nozzles is connected to a common liquid chamber via a corresponding one of the multiple pressure chambers, crosstalk occurs in which pressure fluctuations generated in one pressure chamber are propagated to other pressure chambers via the common liquid chamber.

[0006] When droplets are ejected from one of a plurality of nozzles, and the adjustment work of adjusting the droplet ejection speed and ejection volume based on the ejection results is performed on all of the plurality of nozzles, adjusting the droplet ejection speed and ejection volume for one nozzle may change crosstalk, which may change the droplet ejection speed and ejection volume for the other adjusted nozzles.

[0007] In this way, the ejection speed and ejection volume of each nozzle may differ after adjustment, and therefore, even after adjusting the ejection speeds and ejection volumes of all of the multiple nozzles, the same adjustment process must be repeated again until the ejection speed and ejection volume of the liquid from each of the multiple nozzles converges to the target range. Furthermore, each time the ejection speed and ejection volume of droplets ejected from a nozzle are adjusted, the ejection speed and ejection volume of droplets ejected from the other nozzles change, so the number of times the adjustment process must be repeated increases, and the adjustment time becomes longer.

[0008] The present disclosure provides a technique that is advantageous for shortening the time required to adjust the ejection speed and ejection amount of droplets ejected from a nozzle. [Means for solving the problem]

[0009] A first aspect of the present disclosure includes a liquid ejection head having a plurality of nozzles and a plurality of piezoelectric elements including a first piezoelectric element and a second piezoelectric element corresponding to the plurality of nozzles, respectively; and a control unit that controls each of the plurality of piezoelectric elements so that droplets are ejected from each of the plurality of nozzles, wherein the control unit performs a first ejection process of applying a first drive signal of a set voltage and pulse width to a first piezoelectric element of the plurality of piezoelectric elements to eject droplets from a first nozzle of the plurality of nozzles that corresponds to the first piezoelectric element; a first acquisition process of acquiring data on a first ejection speed and a first ejection amount of the droplets ejected in the first ejection process; and a second acquisition process of setting a constant pulse width of a second drive signal to be applied to the first piezoelectric element or the second piezoelectric element of the plurality of piezoelectric elements. a second ejection process that changes the voltage of the second drive signal to eject multiple droplets from a second nozzle among the multiple nozzles that corresponds to the second piezoelectric element; a second acquisition process that acquires data on a first rate of change in the ejection speed with respect to the ejection amount of the multiple droplets ejected in the second ejection process; a third ejection process that keeps the voltage of the second drive signal constant and changes the pulse width to eject multiple droplets from the second nozzle; a third acquisition process that acquires data on a second rate of change in the ejection speed with respect to the ejection amount of the multiple droplets ejected in the third ejection process; and an update process that updates the settings of the voltage and the pulse width of the first drive signal based on the first rate of change and the second rate of change.

[0010] A second aspect of the present disclosure is a control method for a liquid ejection device including a liquid ejection head having a plurality of nozzles and a plurality of piezoelectric elements including a first piezoelectric element and a second piezoelectric element corresponding to the plurality of nozzles, respectively, and a computer that controls each of the plurality of piezoelectric elements so that droplets are ejected from each of the plurality of nozzles, wherein the computer performs a first ejection process of applying a first drive signal of a set voltage and pulse width to a first piezoelectric element of the plurality of piezoelectric elements to eject droplets from a first nozzle of the plurality of nozzles that corresponds to the first piezoelectric element, a first acquisition process of acquiring data on a first ejection speed and a first ejection amount of the droplets ejected in the first ejection process, and a second drive signal to be applied to the first piezoelectric element or the second piezoelectric element of the plurality of piezoelectric elements. a second ejection process for ejecting a plurality of droplets from a second nozzle among the plurality of nozzles that corresponds to the second piezoelectric element by keeping the pulse width of the second drive signal constant and changing the voltage of the second drive signal; a second acquisition process for acquiring data on a first rate of change in the ejection speed with respect to the ejection amount of the plurality of droplets ejected in the second ejection process; a third ejection process for ejecting a plurality of droplets from the second nozzle by keeping the voltage of the second drive signal constant and changing the pulse width; a third acquisition process for acquiring data on a second rate of change in the ejection speed with respect to the ejection amount of the plurality of droplets ejected in the third ejection process; and an update process for updating the settings of the voltage and the pulse width of the first drive signal based on the first rate of change and the second rate of change. [Effects of the Invention]

[0011] According to the present disclosure, a technique is provided that is advantageous for shortening the time required to adjust the ejection speed and ejection amount of droplets ejected from a nozzle. [Brief explanation of the drawings]

[0012] [Figure 1] 1A is a top view schematically illustrating the configuration of a liquid ejection device according to an embodiment, and FIG. 1B is a side view schematically illustrating the configuration of a liquid ejection device according to an embodiment. [Figure 2]1A and 1B are explanatory views of a liquid ejection head according to an embodiment of the present invention; [Figure 3] FIG. 2 is a cross-sectional view of a portion of the liquid ejection head according to the embodiment. [Figure 4] FIG. 2 is a block diagram schematically illustrating the configuration of a control system of the liquid ejection device according to the embodiment. [Figure 5] FIG. 2 is an explanatory diagram of a drive control unit according to the embodiment. [Figure 6] 1A is a schematic waveform diagram of an example of a drive signal according to an embodiment, FIG. 1B is a schematic waveform diagram of another example of a drive signal according to an embodiment, and FIG. 1C is a schematic waveform diagram of yet another example of a drive signal according to an embodiment. [Figure 7] 10 is a flowchart illustrating a method for controlling the liquid ejection device by the control unit according to the embodiment. [Figure 8] 1A is an explanatory diagram showing the correspondence between the nozzle, piezoelectric element, pressure chamber, and drive signal according to an embodiment. 1B is a graph showing the ejection volume of droplets ejected from a used nozzle according to an embodiment. 1C is a graph showing the ejection velocity y of droplets ejected from a used nozzle according to an embodiment. [Figure 9] 1A is a graph showing the droplet ejection speed versus voltage according to an embodiment, FIG. 1B is a graph showing the droplet ejection amount versus voltage according to an embodiment, and FIG. 1C is a graph showing the ejection speed versus ejection amount according to an embodiment. [Figure 10] 1A is a graph showing the droplet ejection speed versus pulse width according to an embodiment, FIG. 1B is a graph showing the droplet ejection amount versus pulse width according to an embodiment, and FIG. 1C is a graph showing the ejection speed versus ejection amount according to an embodiment. [Figure 11] 10A and 10B are graphs showing the ejection speed versus the ejection amount according to an embodiment of the present invention; [Figure 12] 10A is an explanatory diagram of an example of a second region according to the embodiment, and FIG. 10B is an explanatory diagram of another example of a second region according to the embodiment. [Figure 13]1A is an explanatory diagram of an example of calculation processing according to an embodiment, FIG. 1B is an explanatory diagram of an example of calculation processing according to an embodiment, and FIG. 1C is an explanatory diagram of an example of calculation processing according to an embodiment. [Figure 14] 1A and 1B are explanatory diagrams illustrating an example of calculation processing according to an embodiment; [Figure 15] FIG. 10 is an explanatory diagram of an example of a second region according to a modified example. [Figure 16] 10 is a graph showing the discharge speed relative to the discharge amount according to Example 1. [Figure 17] 10 is a graph showing the discharge speed relative to the discharge amount according to Example 1. [Figure 18] 10 is a graph showing the discharge speed relative to the discharge amount according to Example 1. [Figure 19] 10(a) is a graph showing the measurement results of the discharge speed of each used nozzle according to Example 1. FIG. 10(b) is a graph showing the measurement results of the discharge amount of each used nozzle according to Example 1. [Figure 20] 1 is a table showing the experimental conditions and evaluations for Examples 1 to 10 and Comparative Example 1. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, exemplary embodiments and modifications of the present disclosure will be described in detail with reference to the drawings. Note that the embodiments and modifications shown below are merely examples, and those skilled in the art can appropriately modify and implement the detailed configurations, for example, without departing from the spirit of the present invention.

[0014] In the drawings referred to in the following description of the embodiments and examples, elements denoted by the same reference numerals have the same functions unless otherwise specified. When a plurality of identical elements are arranged in a drawing, the reference numerals and their descriptions may be omitted.

[0015] Furthermore, the drawings may be represented schematically for the convenience of illustration and explanation, and the shape, size, arrangement, etc. of elements depicted in the drawings may not necessarily strictly correspond to the actual objects.

[0016] In the following description, directions are indicated using an XYZ coordinate system, which is a Cartesian coordinate system. The X, Y, and Z axes are perpendicular to each other. The direction of the X axis is also referred to as the X direction, the direction of the Y axis as the Y direction, and the direction of the Z axis as the Z direction. For example, the positive direction of the X axis refers to the same direction as the X-axis arrow in the coordinate system shown in the figure, and the negative direction of the X axis refers to the direction 180 degrees opposite to the direction of the X-axis arrow in the coordinate system shown in the figure. Furthermore, when simply referred to as the X direction, it refers to a direction parallel to the X axis, regardless of whether it is in the direction indicated by the X-axis arrow in the figure. The same applies to the Y and Z axes other than the X axis. For example, a plane including the X and Y axes is referred to as the XY plane. The negative direction of the Z axis is also the direction of gravity. The X and Y directions are also horizontal.

[0017] In this specification, the liquid handled by the liquid ejection head may be referred to as "ink," but the ink according to the embodiment is not limited to a liquid containing a recording material for forming characters or images. For example, the ink may be a liquid containing a functional material for forming a functional thin film such as an electrode or an optical filter, or a functional element such as an organic EL element. It may also be a liquid containing an insoluble solid component.

[0018] Furthermore, the act of discharging a liquid onto an object is sometimes referred to as "recording," but the recording referred to here is not necessarily limited to recording information such as characters or images. For example, it also includes applying a liquid to an object to manufacture an article such as a functional thin film, a functional element, or a three-dimensional object. Furthermore, the object onto which the liquid is applied is sometimes referred to as a "recording medium," but this is not limited to a medium for recording information such as characters or images, and includes components (e.g., substrates) that serve as base materials for manufacturing articles such as a functional thin film, a functional element, or a three-dimensional object.

[0019] FIG. 1(a) is a top view schematically illustrating the configuration of a liquid ejection device 1 according to an embodiment, and FIG. 1(b) is a side view schematically illustrating the configuration of the liquid ejection device 1 according to an embodiment. For convenience of illustration, FIGS. 1(a) and 1(b) only show a portion of the configuration of the liquid ejection device 1. The liquid ejection device 1 includes a liquid ejection head 3. FIGS. 2(a) and 2(b) are explanatory diagrams of the liquid ejection head 3 according to an embodiment. FIG. 2(a) is a schematic perspective view of a liquid flow path in the liquid ejection head 3. The liquid flow path is formed by a first member, a second member, and a third member (not shown). Each of the first, second, and third members may be made of one or more base materials. FIG. 2(b) illustrates the liquid flow path divided into the first, second, and third members, with arrows indicating the flow of liquid through the liquid flow path of each member.

[0020] As shown in FIGS. 2(a) and 2(b), the liquid ejection head 3 has one or more nozzle rows 30. In this embodiment, the liquid ejection head 3 has two nozzle rows 30 arranged at an interval in the X direction. Each nozzle row 30 includes two or more nozzles 20 arranged at an interval in the Y direction. In other words, the liquid ejection head 3 has a plurality of nozzles 20. Note that, in FIG. 2(a), two nozzle rows 30 are shown, and each nozzle row 30 has four nozzles 20, but this is not limited to this, and the number of nozzles 20 and the number of nozzle rows 30 are arbitrary.

[0021] As shown in FIGS. 1(a) and 1(b), a recording medium 6, which is an object to be coated with liquid, is set at a predetermined position on a stage 10. The stage 10 is fixed to a base 9. Multiple nozzles 20 of the liquid ejection head 3 are arranged to face the recording medium 6. A main scanning guide rail 5 extends in the X direction, which is the main scanning direction. A sub-scanning guide rail 7 extends in the Y direction, which is the sub-scanning direction, and is supported by a support member 8. The liquid ejection head 3 is fixed to a main scanner 4 and can freely scan within a plane parallel to the XY plane at a height a predetermined distance from the recording medium 6 in the Z direction. Note that, to scan the liquid ejection head 3 across the recording medium 6, the liquid ejection head 3 and the recording medium 6 need only be moved relative to each other; alternatively, the liquid ejection head 3 may be fixed and the recording medium 6 may be moved. Liquid is supplied to the liquid ejection head 3 from a liquid tank 25 through a liquid supply path 11. Liquid not used for ejection is returned from the liquid ejection head 3 to the liquid tank 25 through a liquid discharge path 12. Such liquid supply can be achieved by a pressure supply system or a head supply system.

[0022] As shown in FIGS. 2(a) and 2(b), the liquid supply path 11 is connected to the liquid supply chamber 13 via a liquid supply port 23 formed in the third member. The liquid supply chamber 13 is connected to a supply-side common liquid chamber 15 formed in the second member via an opening 21. The supply-side common liquid chamber 15 is connected to each of a plurality of pressure chambers 19 formed in the first member via individual supply paths 17. Each pressure chamber 19 is an individual liquid chamber. A nozzle 20 formed in the first member is connected to each of the plurality of pressure chambers 19. In addition, an individual discharge path 18 is connected to each of the plurality of pressure chambers 19.

[0023] The multiple pressure chambers 19 are connected to a discharge-side common liquid chamber 16 formed in the second member via corresponding individual discharge paths 18. The discharge-side common liquid chamber 16 is connected to a liquid discharge chamber 14 formed in the third member via an opening 22. The liquid discharge chamber 14 is connected to the liquid discharge path 12 via a liquid discharge port 24.

[0024] The liquid supplied to the liquid supply chamber 13 via the liquid supply path 11 and the liquid supply port 23 is supplied to the supply-side common liquid chamber 15 via the opening 21. The liquid supplied to the supply-side common liquid chamber 15 is then supplied to each of the multiple pressure chambers 19 via the individual supply paths 17.

[0025] A plurality of piezoelectric elements 100 are arranged in each of the plurality of pressure chambers 19. Droplets are ejected from each of the plurality of pressure chambers 19 via a nozzle 20. Liquid that is not used to eject droplets from each of the plurality of pressure chambers 19 is discharged to the discharge-side common liquid chamber 16 via an individual discharge path 18. The liquid discharged to the discharge-side common liquid chamber 16 is discharged to the liquid discharge chamber 14 via an opening 22. The liquid discharged to the liquid discharge chamber 14 is returned to the liquid tank 25 via a liquid discharge port 24 and a liquid discharge path 12.

[0026] FIG. 3 is a cross-sectional view of a portion of a liquid ejection head 3 according to an embodiment. FIG. 3 shows a cross-section of a portion of the liquid ejection head 3 taken along a plane parallel to the XZ plane. The X direction is the longitudinal direction of the pressure chamber 19. A piezoelectric element 100 is disposed above the pressure chamber 19. The piezoelectric element 100 has an electrode 101a and an electrode 101b. A drive signal is applied between the electrodes 101a and 101b, and the piezoelectric element 100 vibrates in accordance with the voltage and pulse width of the drive signal. The vibration of the piezoelectric element 100 causes a minute change in the volume of the pressure chamber 19, and the liquid in the pressure chamber 19 is pressurized by the contraction pressure caused by the volume change of the pressure chamber 19, causing droplets to be ejected from the nozzle 20.

[0027] Fig. 4 is a block diagram showing a schematic configuration of a control system of a liquid ejection device 1 according to an embodiment. Note that the functional elements shown in Fig. 4 are conceptual and do not necessarily have to be physically configured as shown. For example, the specific form of distribution or integration of the functional blocks is not limited to the illustrated example, and all or part of the functional blocks can be functionally or physically distributed or integrated in any unit depending on the usage situation, etc. Each functional block can be configured using hardware or software.

[0028] The control unit 200 is connected to a plurality of sensors and a plurality of controlled elements included in the liquid ejection device 1, but for ease of explanation, only some of the plurality of sensors and a plurality of controlled elements are shown in Fig. 4. The control unit 200 is a computer for controlling the entire liquid ejection device 1. The control unit 200 is configured to control each of the plurality of piezoelectric elements 100 so that droplets are ejected from each of the plurality of nozzles 20. The control unit 200 includes a CPU 201, a ROM 202, a RAM 203, an I / O port 210, etc.

[0029] The CPU 201 is an example of a processor, and executes programs to perform various calculations and processes. The CPU 201 is connected to a ROM 202, an I / O port 210, a RAM 203, a conveying unit 204, a cleaning unit 205, a recording processing unit 206, a drive control unit 207, a discharge amount detection unit 208, and a discharge speed detection unit 209.

[0030] An operation program for the liquid ejection device 1 is stored in the ROM 202, which is a non-volatile storage medium. The program for executing various processes related to the liquid ejection method of this embodiment may be stored in the ROM 202 like other operation programs, or may be loaded into the RAM 203 via a network or a recording medium. The recording medium storing the program loaded into the RAM 203 may be any recording medium as long as it is a non-transitory recording medium readable by a computer. For example, the recording medium may be a hard disk, a flexible disk, an optical disk, a magneto-optical disk, a magnetic tape, a non-volatile memory such as a USB memory, an SSD, or the like.

[0031] The RAM 203, which is a volatile storage medium, can temporarily store data and programs required for the processing executed by the CPU 201, and functions as a work area for executing the processing.

[0032] The I / O port 210, which is an input / output unit, is connected to an external device or a network, and can acquire, for example, data necessary for manufacturing organic EL elements from an input device 211 such as an external computer. The I / O port 210 is also connected to a display device (not shown) and an input device (not shown), and can display information related to the operating state of the liquid ejection device 1 on the display device and can receive commands from an operator via the input device. The display device may be a display device such as a liquid crystal display or an organic EL display, and the input device may be an input device such as a keyboard, a jog dial, a mouse, a pointing device, or a voice input device.

[0033] The recording processing unit 206 performs a process of determining the nozzles 20 that will eject droplets and a process of determining the timing at which droplets will be ejected, in accordance with the array pattern of the organic EL elements to be manufactured or a print pattern such as a recording image pattern. The recording processing unit 206 also performs a process of determining the scanning timing of the main scanner 4 and the main scanning guide rail 5, in accordance with the determined nozzles 20 and droplet ejection timing.

[0034] The drive control unit 207 controls the liquid ejection head 3 to drive the liquid ejection head 3. A drive signal is set by the CPU 201 for the drive control unit 207 to eject droplets from the nozzles 20 determined by the recording processing unit 206. The drive control unit 207 drives the liquid ejection head 3 based on the drive signal.

[0035] Each of the recording processing unit 206 and the drive control unit 207 can be configured by the CPU 201 reading and executing a control program stored in, for example, the ROM 202 or another non-transitory recording medium. Note that a part or all of each of the recording processing unit 206 and the drive control unit 207 may be configured by hardware such as an ASIC provided in the control unit 200.

[0036] The discharge amount detection unit 208 detects the discharge amount (i.e., the volume of the droplets) of the droplets discharged from each of the multiple nozzles 20. The discharge amount detection unit 208 is composed of, for example, an imaging device and an image processing unit that processes images acquired by the imaging device. The imaging device is placed at a position where the droplets discharged from the nozzles 20 and flying are included in the angle of view, and captures an image of the flying droplets. The image processing unit measures the diameter of the droplets using the captured image obtained by the imaging operation of the imaging device, and calculates the discharge amount (i.e., the volume) of the droplets. Note that the means for detecting the discharge amount of the droplets is not limited to this. For example, the discharge amount detection unit 208 may have a laser microscope. The volume of the droplets that have landed on a substrate or the like may be measured using the laser microscope.

[0037] The ejection speed detection unit 209 detects the ejection speed of droplets ejected from each of the multiple nozzles 20 (i.e., the flight speed of the droplets). The ejection speed detection unit 209 is composed of, for example, an imaging device and an image processing unit that processes images acquired by the imaging device. The imaging device is placed at a position where the flying droplets ejected from the nozzles are within the angle of view, and captures images of the flying droplets at multiple different imaging timings. The image processing unit calculates the ejection speed of the droplets based on the position and imaging timing of the droplets in each of the multiple captured images. Note that the means for detecting the ejection speed of the droplets is not limited to this.

[0038] Furthermore, when the discharge amount detection unit 208 and the discharge speed detection unit 209 each have an imaging device, the discharge amount detection unit 208 and the discharge speed detection unit 209 may share the same imaging device, or the discharge amount detection unit 208 and the discharge speed detection unit 209 may each have their own individual imaging device.

[0039] For example, when performing a recording operation by causing the liquid ejection head 3 to eject liquid, the CPU 201 controls the transport section 204 (i.e., the main scanner 4 and the main scanning guide rail 5) to cause the liquid ejection unit 2 to scan the recording medium 6 and eject liquid from the liquid ejection head 3. Furthermore, when cleaning of the liquid ejection head 3 becomes necessary, the CPU 201 operates the cleaning section 205 to perform cleaning processing.

[0040] The CPU 201 can correct the drive signal output by the drive control unit 207 based on the acquired information, and adjust the ejection volume and ejection speed of the droplets ejected from each nozzle 20 of the liquid ejection head 3 .

[0041] Fig. 5 is an explanatory diagram of the drive control unit 207 according to the embodiment. Components of the drive control unit 207 and the liquid ejection head 3 are shown in blocks in Fig. 5. The drive control unit 207 has a data control circuit 301, a waveform generation circuit 302, and a drive circuit 303. The data control circuit 301 generates operation commands such as logic signals according to the print pattern to be recorded and correction data, and the waveform generation circuit 302 outputs a plurality of drive signals S1 to S3 with different waveforms to the drive circuit 303 in accordance with the operation commands from the data control circuit 301.

[0042] The drive circuit 303 supplies any one of the drive signals S1 to S3 obtained from the waveform generation circuit 302 to each piezoelectric element 100 of the liquid ejection head 3, thereby driving each piezoelectric element 100 and ejecting liquid from each nozzle 20. The drive circuit 303 is electrically connected to one (electrode 101a) of the two electrodes 101a and 101b of the piezoelectric element 100. The other (electrode 101b) of the two electrodes 101a and 101b of the piezoelectric element 100 is grounded to a metal housing (not shown) or the like via a common ground line.

[0043] The drive circuit 303 has a plurality of switch units 304 corresponding to the plurality of piezoelectric elements 100, respectively. Each switch unit 304 is provided corresponding to one of the plurality of piezoelectric elements 100, i.e., one of the plurality of nozzles 20. A switch signal is input to each switch unit 304 from a decoder (not shown) corresponding to the piezoelectric element 100. In response to the input switch signal, each switch unit 304 outputs (supplies) one of the drive signals S1 to S3 acquired from the waveform generation circuit 302 to the piezoelectric element 100 of the liquid ejection head 3. Each switch unit 304 has a plurality of switch circuits 304a, 304b, and 304c, and switches between outputting and stopping the output of each of the drive signals S1 to S3 by switching the on / off states of the plurality of switch circuits 304a, 304b, and 304c in response to the switch signal from the decoder. For convenience of explanation, FIG. 5 shows four piezoelectric elements 100, four switch sections 304 corresponding to the four piezoelectric elements 100, and three drive signals S1 to S3 to be selected as an example, but the number of each is not limited to this.

[0044] FIG. 6(a) is a schematic waveform diagram of an example of a drive signal S according to the embodiment. FIG. 6(b) is a schematic waveform diagram of another example of a drive signal S according to the embodiment. FIG. 6(c) is a schematic waveform diagram of yet another example of a drive signal S according to the embodiment. The drive signal S is, for example, any of the drive signals S1 to S3 described above. The drive signal S is generated by the waveform generating circuit 302 of FIG. 5. The drive signal S is then applied between the electrode 101a and the electrode 101b via the drive control unit 207 to drive the piezoelectric element 100. The drive signal S applied to the piezoelectric element 100 is, for example, any of the signals shown in FIG. 6(a), FIG. 6(b), and FIG. 6(c).

[0045] The drive signal S has a rectangular or trapezoidal drive waveform. The drive signal S has a pull-push type or pull-push-pull type drive waveform. FIG. 6(a) shows a trapezoidal drive waveform of the pull-push type drive signal S. FIG. 6(b) shows a rectangular drive waveform of the pull-push type drive signal S. FIG. 6(c) shows a trapezoidal drive waveform of the pull-push-pull type drive signal S.

[0046] The drive waveform of the drive signal S is a pulse waveform having a rising portion where potential V1 rises to another potential V2 (>V1), a subsequent hold portion where potential V2 is held constant, and a subsequent falling portion where potential V2 falls from potential V2 to potential V1. During the rising portion of the drive signal S, a forced displacement is applied to the piezoelectric element 100 in a direction that increases the volume of the pressure chamber 19, generating negative pressure within the pressure chamber 19. After the hold portion of the drive signal S, at the timing when the pressure reverses and increases due to the reaction force, the falling portion of the drive signal S applies a forced displacement to the piezoelectric element 100 in a direction that contracts the volume of the pressure chamber 19, thereby efficiently pressurizing the liquid within the pressure chamber 19. Therefore, if the time width ΔT from the timing T1 when the drive signal S starts to rise to the timing T2 when the drive signal S starts to fall is significantly different from 1 / 2 the resonance period of the pressure chamber 19, droplet ejection will be inefficient and unstable. Therefore, it is preferable that the time width ΔT from timing T1 when the drive signal S starts to rise to timing T2 when it starts to fall be set in the range of ¼ to ¾ of the resonance period of the pressure chamber 19. Here, the resonance period of the pressure chamber 19 is the average value of the components of the resonance period in the X direction, the Y direction, and the Z direction. Furthermore, the drive signal S is a drive signal that has been adjusted by an adjustment process, which will be described later.

[0047] As shown in FIGS. 6(a) to 6(c), the voltage V of the drive signal S is the potential difference (V2-V1). The pulse width p of the drive signal S is the time width of the hold portion of the drive signal S. In the drive signal S having the trapezoidal drive waveform shown in FIGS. 6(a) and 6(c), the pulse width p is smaller than the time width ΔT. In the drive signal S having the rectangular drive waveform shown in FIG. 6(b), the pulse width p is the same as the time width ΔT. Here, the voltage V before adjustment is V0, and the pulse width p before adjustment is p0.

[0048] The potential V1 is a reference potential, such as the ground potential. The potential V2 is the peak potential of the pulse. The voltage V is also the pulse amplitude.

[0049] 2(a) and 2(b), pressure crosstalk occurs between the multiple nozzles 20 included in one nozzle row 30. For example, by driving one piezoelectric element 100, a pressure wave is generated in the liquid in the pressure chamber 19 in which that piezoelectric element 100 is arranged. The pressure wave propagates to the liquid in the other pressure chambers 19 via the liquid in the common liquid chambers 15 and 16, which can cause the pressure of the liquid in the other pressure chambers 19 to fluctuate. This phenomenon is called crosstalk.

[0050] When pressure crosstalk occurs, the ejection volume and ejection speed of droplets ejected from the nozzles 20 corresponding to the other pressure chambers 19 change depending on the pressure propagated to the liquid in the other pressure chambers 19, so the voltage V and pulse width p of the drive signal S are adjusted taking into account the effects of the crosstalk.

[0051] Fig. 7 is a flowchart showing a method for controlling the liquid ejection device 1 by the control unit 200 according to the embodiment. Below, a procedure for adjusting (i.e., correcting) the drive waveform of the drive signal S applied to each piezoelectric element 100 will be described with reference to the flowchart shown in Fig. 7. Fig. 8(a) is an explanatory diagram showing the correspondence between the nozzles 20-1 to 20-N, piezoelectric elements 100-1 to 100-N, pressure chambers 19-1 to 19-N, and drive signals S-1 to SN according to the embodiment.

[0052] In step S101, the CPU 201 receives input information from the input device 211, such as information about the drive waveform of the drive signal S before adjustment, information about the print pattern, information about the target droplet discharge volume Xg, and information about the target droplet discharge speed Yg, and sets some or all of the input information in the drive control unit 207. The print pattern is determined by the N nozzles (used nozzles) 20-1 to 20-N to be used among the multiple (M) nozzles 20 included in the nozzle row 30, and the timing at which droplet discharge starts from the N used nozzles 20-1 to 20-N, etc. N is an integer equal to or greater than 1. M is an integer equal to or greater than N. The multiple (M) piezoelectric elements 100 include N piezoelectric elements (used piezoelectric elements) 100-1 to 100-N corresponding to the N used nozzles 20-1 to 20-N, respectively.

[0053] Here, the "i" (where i is an integer equal to or greater than 1) following the hyphen "-" after the symbol indicates a unique number, and for example, the used nozzle 20-i, pressure chamber 19-i, used piezoelectric element 100-i, and drive signal Si, etc., having the same number "i" correspond to one another. In other words, the used piezoelectric element 100-i is disposed in the pressure chamber 19-i connected to the used nozzle 20-i, and when the drive signal Si is applied to the used piezoelectric element 100-i, droplets are ejected from the used nozzle 20-i. The used nozzle 20-i is an example of a first nozzle, the pressure chamber 19-i is an example of a first pressure chamber, the used piezoelectric element 100-i is an example of a first piezoelectric element, and the drive signal Si is an example of a first drive signal.

[0054] In this embodiment, N is 2 or more, that is, the plurality of nozzles 20 includes two or more active nozzles 20-1 to 20-N, and the plurality of piezoelectric elements 100 includes two or more active piezoelectric elements 100-1 to 100-N. The active nozzles 20-1 to 20-N are included in, for example, one nozzle row 30.

[0055] As described above, the input device 211 is, for example, an external computer. Input information is stored in advance in a storage unit of the input device 211 by a user's input operation, etc. The input information of the input device 211 is then passed to the CPU 201 via the I / O port 210.

[0056] The target discharge amount Xg is a target discharge amount of droplets that is common to the N working nozzles 20-1 to 20-N. The target discharge speed Yg is a target discharge speed of droplets that is common to the N working nozzles 20-1 to 20-N. An upper limit and a lower limit are set for the target discharge amount Xg, and an upper limit and a lower limit are set for the target discharge speed Yg.

[0057] Furthermore, in step S101, a representative nozzle 20-R is also set among the plurality of nozzles 20. Specifically, among the plurality of piezoelectric elements 100, a representative piezoelectric element 100-R corresponding to the representative nozzle 20-R is set.

[0058] Here, the "R" following the hyphen "-" after the reference symbol represents a representative, although not shown in the figures. The representative nozzle 20-R may be any of the used nozzles 20-1 to 20-N, or may be a nozzle 20 other than the used nozzles 20-1 to 20-N. That is, the representative nozzle 20-R may be the same nozzle as the used nozzle 20-i, or a nozzle different from the used nozzle 20-i. The number of representative nozzles 20-R is equal to or less than the number of used nozzles 20-1 to 20-N. For example, the number of used nozzles 20-1 to 20-N is 128, and the number of representative nozzles 20-R is approximately one or two. Similarly, the representative piezoelectric element 100-R may be the same piezoelectric element as the used piezoelectric element 100-i, or may be a piezoelectric element different from the used piezoelectric element 100-i. The representative nozzle 20-R is an example of a second nozzle. The representative piezoelectric element 100-R is an example of a second piezoelectric element.

[0059] The drive waveforms of the drive signals S-1 to SN before adjustment may be set to a waveform that is common to all of the active nozzles 20-1 to 20-N, or may be set individually for each. For example, the drive signals S-1 to SN may have waveforms that have been adjusted in advance based on variations in the characteristics of the pressure chambers 19 and the piezoelectric elements 100. In this embodiment, the drive waveforms of the drive signals S-1 to SN before adjustment will be described as being set to a waveform that is common to all of the active nozzles 20-1 to 20-N. In the drive signals S-1 to SN, the voltage V before adjustment is V0 and the pulse width p before adjustment is p0.

[0060] Furthermore, the timing of ejecting droplets from each of the working nozzles 20-1 to 20-N may be simultaneous, but the ejection timing may be set in advance for each of the working nozzles 20-1 to 20-N, taking into consideration variations in the ejection angle of the droplets.

[0061] In step S102, the drive control unit 207 drives the active piezoelectric elements 100-1 to 100-N in accordance with the input information (information related to the drive waveforms of the drive signals S-1 to SN before adjustment, and information related to the print pattern) input to the input device 211 in step S101, thereby causing droplets to be ejected from each of the active nozzles 20-1 to 20-N. That is, the drive control unit 207 applies a drive signal Si having a pre-adjusted voltage V (= V0) and pulse width p (= p0) to the active piezoelectric element 100-i, causing droplets to be ejected from the active nozzle 20-i corresponding to the active piezoelectric element 100-i (first ejection process: i = 1 to N).

[0062] In step S103, the CPU 201 causes the discharge amount detection unit 208 to detect the discharge amount of droplets discharged from the operating nozzles 20-1 to 20-N, and causes the discharge speed detection unit 209 to detect the discharge speed. FIG. 8(b) is a graph showing the discharge amount x of droplets discharged from the operating nozzles 20-1 to 20-N according to an embodiment, and FIG. 8(c) is a graph showing the discharge speed y of droplets discharged from the operating nozzles 20-1 to 20-N according to an embodiment. In the graph shown in FIG. 8(b), x represents the discharge amounts Xp-1 to Xp-N before adjustment. In the graph shown in FIG. 8(c), y represents the discharge speeds Yp-1 to Yp-N before adjustment. The CPU 201 acquires data on the discharge amounts Xp-1 to Xp-N from the discharge amount detection unit 208 and acquires data on the discharge speeds Yp-1 to Yp-N from the discharge speed detection unit 209. That is, the CPU 201 acquires data on the ejection speed Yp-i and ejection volume Xp-i of droplets ejected from the used nozzle 20-i in step S102 (first acquisition process). The ejection volume Xp-i is an example of a first ejection volume. The ejection speed Yp-i is an example of a first ejection speed.

[0063] In step S104, the drive control unit 207 keeps the pulse width p of the drive signal SR applied to the representative piezoelectric element 100-R constant and changes the voltage V of the drive signal SR to sequentially eject multiple droplets from the representative nozzle 20-R corresponding to the representative piezoelectric element 100-R (second ejection process). In this embodiment, the pulse width p set in step S104 has the same value as the pulse width p0 before adjustment described above. The drive signal SR is an example of a second drive signal.

[0064] In step S105, the CPU 201 causes the discharge amount detection unit 208 to detect the discharge amount of each of the plurality of droplets discharged from the representative nozzle 20-R, and causes the discharge speed detection unit 209 to detect the discharge speed of each of the plurality of droplets. Fig. 9(a) is a graph showing the discharge speed y of a droplet versus the voltage V according to an embodiment, and Fig. 9(b) is a graph showing the discharge amount x of a droplet versus the voltage V according to an embodiment. Fig. 9(c) is a graph showing the discharge speed y versus the discharge amount x according to an embodiment. Fig. 9(c) illustrates a profile Prof1 of the discharge speed y versus the discharge amount x of the plurality of droplets discharged in step S104.

[0065] The CPU 201 acquires data on the ejection volume x of each of the plurality of droplets from the ejection volume detection unit 208, and acquires data on the ejection velocity y of each of the plurality of droplets from the ejection velocity detection unit 209. Then, the CPU 201 calculates a rate of change (first rate of change) a1 of the ejection velocity y with respect to the ejection volume x when the voltage of the drive signal SR applied to the representative piezoelectric element 100-R corresponding to the representative nozzle 20-R is changed, and stores the data of the first rate of change a1 in the RAM 203. That is, the CPU 201 acquires data on the first rate of change a1 of the ejection velocity y with respect to the ejection volume x of the plurality of droplets ejected in step S104 (second acquisition process).

[0066] Here, as shown in FIG. 9(a), the ejection speed y can be approximated by a straight line (a linear function of V) relative to the voltage V. Also, as shown in FIG. 9(b), the ejection volume x can be approximated by a straight line (a linear function of V) relative to the voltage V. Therefore, as shown in FIG. 9(c), the ejection speed y can be approximated by a straight line (a linear function of x) relative to the ejection volume x. The CPU 201 determines the slope of the approximate straight line shown in FIG. 9(c) as the first rate of change a1.

[0067] In this embodiment, a case where the number of representative nozzles 20-R is one will be described, but this is not limiting, and the number of representative nozzles 20-R may be two or more. Furthermore, the representative nozzle 20-R may be a nozzle 20 located at the end of the nozzle row 30, or a nozzle 20 located in the center of the nozzle row 30, and any nozzle can be selected.

[0068] In step S106, the drive control unit 207 keeps the voltage V of the drive signal SR applied to the representative piezoelectric element 100-R constant and varies the pulse width p of the drive signal SR to sequentially eject multiple droplets from the representative nozzle 20-R (third ejection process). In this embodiment, the voltage V set in step S106 has the same value as the voltage V0 before adjustment described above. The drive signal SR is an example of a second drive signal.

[0069] In step S107, the CPU 201 causes the ejection amount detection unit 208 to detect the ejection amount of each of the plurality of droplets ejected from the representative nozzle 20-R, and causes the ejection speed detection unit 209 to detect the ejection speed of each of the plurality of droplets. Fig. 10(a) is a graph showing the ejection speed y of droplets versus the pulse width p according to an embodiment, and Fig. 10(b) is a graph showing the ejection amount x of droplets versus the pulse width p according to an embodiment. Fig. 10(c) is a graph showing the ejection speed y versus the ejection amount x according to an embodiment. Fig. 10(c) illustrates a profile Prof2 of the ejection speed y versus the ejection amount x of the plurality of droplets ejected in step S106.

[0070] The CPU 201 acquires data on the ejection volume x of each of the plurality of droplets from the ejection volume detection unit 208, and acquires data on the ejection velocity y of each of the plurality of droplets from the ejection velocity detection unit 209. Then, the CPU 201 calculates a rate of change (second rate of change) a2 of the ejection velocity y with respect to the ejection volume x when the pulse width p of the drive signal SR applied to the representative piezoelectric element 100-R corresponding to the representative nozzle 20-R is changed, and stores the data of the second rate of change a2 in the RAM 203. That is, the CPU 201 acquires data on the second rate of change a2 of the ejection velocity y with respect to the ejection volume x of the plurality of droplets ejected in step S106 (third acquisition process).

[0071] In step S107, the CPU 201 obtains a profile Prof2 of the ejection speed relative to the ejection amount of the droplets ejected in step S106, and obtains an ejection speed Ym that is a maximum value from the profile Prof2. The ejection speed Ym is an example of a third ejection speed. The ejection amount corresponding to the ejection speed Ym is set to Xm. The ejection amount Xm is an example of the third ejection amount.

[0072] As shown in FIG. 10(a), the ejection velocity y varies with the pulse width p in a quadratic curve. When the pulse width p=pm, the ejection velocity y reaches its maximum value (ejection velocity Ym). The maximum value of the ejection velocity y with respect to the pulse width p (ejection velocity Ym) is determined by the resonance period of the pressure chamber 19. As shown in FIG. 10(b), the ejection volume x varies linearly with respect to the pulse width p and is approximated by a straight line (a linear function of p). Therefore, as shown in FIG. 10(c), the ejection velocity y varies with respect to the ejection volume x in a quadratic curve. Therefore, the second rate of change a2 can be divided into a positive case as shown in FIG. 11(a) and a negative case as shown in FIG. 11(b), with the ejection volume Xm (pulse width pm) at which the ejection velocity y reaches its maximum value, the ejection velocity Ym, as a boundary.

[0073] If the discharge rate Xp before adjustment is greater than the target discharge rate Xg, the discharge rate x of droplets from the used nozzle 20 must be adjusted to be smaller than the discharge rate Xp before adjustment. To adjust the discharge rate x to be smaller than the discharge rate Xp before adjustment, the pulse width p of the drive signal S must be made smaller than the pulse width p0 before adjustment. Therefore, the pulse width p must be corrected within the range below the discharge rate Xm corresponding to the maximum discharge rate Ym, i.e., within the range below the pulse width pm. Therefore, the positive value shown in FIG. 11(a) is used as the second change rate a2. That is, if the discharge rate Xp is greater than the target discharge rate Xg, the CPU 201 calculates the second change rate a2 based on the region of the profile Prof2 below the discharge rate Xm corresponding to the discharge rate Ym. In the example of FIG. 11(a), the discharge rate y is calculated using an approximate straight line that is a linear function of x, and the second change rate a2 is calculated as the slope of the approximate straight line.

[0074] Conversely, if the discharge rate Xp before adjustment is smaller than the target discharge rate Xg, the negative value shown in Figure 11(b) is used as the second change rate a2. That is, if the discharge rate Xp is smaller than the target discharge rate Xg, the CPU 201 calculates the second change rate a2 based on the region of the profile Prof2 that is equal to or greater than the discharge rate Xm corresponding to the discharge rate Ym. In the example of Figure 11(b), the discharge rate y is calculated using an approximate straight line that is a linear function of x, and the second change rate a2 is calculated as the slope of the approximate straight line.

[0075] Next, in steps S108 to S112, the control unit 200 updates the settings of the voltage V and pulse width p of the drive signal Si based on the target discharge speed Yg, the target discharge amount Xg, the discharge speed Yp, the discharge amount Xp, the first change rate a1, and the second change rate a2 (update process). Each of steps S108 to S112 will be specifically described below.

[0076] In step S108, the CPU 201 calculates an area ZA shown in FIG. 12(a) or 12(b) where the ejection amount x and ejection speed y can be adjusted to the target ejection amount Xg and target ejection speed Yg by simply adjusting the pulse width p.

[0077] FIG. 12(a) is an explanatory diagram of an example of the region ZA according to the embodiment. FIG. 12(b) is an explanatory diagram of another example of the region ZA according to the embodiment. FIG. 12(a) illustrates a case where the second change rate a2 is a positive value, and FIG. 12(b) illustrates a case where the second change rate a2 is a negative value. A coordinate space CS1 is defined, with the droplet discharge volume x as the x-axis (first coordinate axis) and the droplet discharge velocity y as the y-axis (second coordinate axis). In the coordinate space CS1, a target region TA indicating the target discharge volume Xg and the target discharge velocity Yg is the region within the bold frame lines shown in FIGS. 12(a) and 12(b). That is, the target region TA is a rectangular region defined by the upper and lower limit values ​​of the target discharge volume Xg and the upper and lower limit values ​​of the target discharge velocity Yg. The target region TA is an example of a first region. The region ZA is an example of a second region. The processing of step S108 will be specifically described below.

[0078] If the second change rate a2 acquired in step S107 is positive, the CPU 201 obtains two lines LA and LB in the coordinate space CS1, with a slope equal to the second change rate a2 (>0), sandwiching the target area TA, as shown in FIG. 12(a). The line LA is a line that passes through the lower limit of the target discharge amount Xg and the upper limit of the target discharge speed Yg. The line LB is a line that passes through the upper limit of the target discharge amount Xg and the lower limit of the target discharge speed Yg. The two lines LA and LB are parallel to each other. The CPU 201 then obtains the area ZA sandwiched between the two lines LA and LB.

[0079] If the second change rate a2 acquired in step S107 is negative, the CPU 201 determines two lines LA' and LB' in the coordinate space CS1, with a slope equal to the second change rate a2 (<0), sandwiching the target area TA, as shown in FIG. 12(b). Line LA' is a line that passes through the upper limit of the target discharge amount Xg and the upper limit of the target discharge speed Yg. Line LB' is a line that passes through the lower limit of the target discharge amount Xg and the lower limit of the target discharge speed Yg. The two lines LA' and LB' are parallel to each other. Then, the CPU 201 determines the area ZA sandwiched between the two lines LA' and LB'.

[0080] If the ejection volume x and ejection speed y can be adjusted within the region ZA, it becomes possible to adjust the ejection speed y to the target ejection speed Yg and the ejection volume x to the target ejection volume Xg simply by changing the pulse width p of the drive signal Si while keeping the voltage V of the drive signal Si fixed, thereby reducing the effects of crosstalk due to voltage fluctuations.

[0081] In steps S109 to S111, the CPU 201 calculates the voltage V and pulse width p of each of all of the drive signals S-1 to SN corresponding to all of the active nozzles 20-1 to 20-N, respectively.

[0082] FIGS. 13(a) to 13(c) are explanatory diagrams of an example of calculation processing according to an embodiment. Steps S109 to S110 will be described below using one active nozzle 20 among the active nozzles 20-1 to 20-N as an example. The description will be given assuming that the second change rate a2 is a positive value. FIG. 13(b) corresponds to FIG. 9(a), and FIG. 13(c) corresponds to FIG. 10(b). In FIG. 13(b), a3 is the slope of the ejection velocity y versus the voltage V. b2 is the intercept. In FIG. 13(c), a4 is the slope of the ejection volume x versus the pulse width p. b3 is the intercept. As shown in FIG. 13(b), the ejection velocity y versus the voltage V is approximated by a straight line y = a3 * V + b2, and as shown in FIG. 13(c), the ejection volume x versus the pulse width p is approximated by a straight line x = a4 * p + b3.

[0083] In steps S109 and S110, the CPU 201 defines a coordinate point P1 (Xp, Yp) in the coordinate space CS1, which is defined by a pair of the discharge amount Xp and the discharge speed Yp. The CPU 201 calculates the voltage V and pulse width p of the drive signal Si so that the coordinate point P1 in the coordinate space CS1 transitions to a coordinate point P2 (Xp', Yp') in the area ZA, preferably in the target area TA.

[0084] That is, in step S109, the CPU 201 calculates the voltage V from the pre-adjustment ejection speed Yp, the pre-adjustment ejection volume Xp, and the first change rate a1 so that the coordinate point P1 falls within the area ZA. In addition, in step S110, the CPU 201 calculates the pulse width p from the ejection speed Y' and ejection volume X' estimated from the voltage V', the target ejection speed Yg, the target ejection volume Xg, and the second change rate a2.

[0085] A specific example will be given. In step S109, the CPU 201 determines, in the coordinate space CS1, an intersection P3(X', Y') between a line y=a1*x+(Yp-a1*Xp) whose slope is the first change rate a1 and a line y=a2*x+(Yg-a2*Xg) whose slope is the second change rate a2. Note that "*" means multiplication.

[0086] The line y=a1*x+(Yp-a1*Xp) is a line that passes through the coordinate point P1. The line y=a2*x+(Yg-a2*Xg) is a line that passes through the coordinate point P2 that is included in the target area TA.

[0087] Here, X' is the estimated discharge amount, and Y' is the estimated discharge speed. X' and Y' can be calculated using the following formulas. X´=1 / (a1-a2)*{(Yg-a2*Xg)-(Yp-a1*Xp)} Y´=a1 / (a1-a2)*{(Yg-a2*Xg)-(Yp-a1*Xp)}+(Yp-a1*Xp)

[0088] When adjusting the voltage so that the coordinate point P1 (Xp, Yp) transitions to the intersection point P3 (X', Y'), the CPU 201 calculates a voltage adjustment amount V' for calculating the adjusted voltage V corresponding to the intersection point P3 (X', Y'). V' is calculated by the following formula. V´=(Y´-Yp) / a3 The slope a3 can be determined from the relationship between the voltage V and the ejection velocity y shown in FIG. 13(b), that is, the relationship of the equation y=a3*V+b2.

[0089] Also, in step S110, when the CPU 201 assumes that the intersection point P3(X´, Y´) transitions to the coordinate point P2 within the target area TA by adjusting the pulse width in the coordinate space CS1, the CPU 201 calculates a pulse width adjustment amount p´ for calculating the adjusted pulse width p corresponding to the coordinate point P2. The pulse width adjustment amount p´ is obtained by the following formula. p´ = (X´ - Xg) / a4 The slope a4 is obtained from the relationship between the pulse width p and the discharge amount x shown in FIG. 13(c), that is, the relationship of the formula x = a4*p + b3.

[0090] In step S111, the CPU 201 determines whether i < N. If i < N (S111: YES), the CPU 201 increments i by 1 (i = i + 1) and returns to the process of step S109. As a result, steps S109 and S110 are repeatedly executed from i = 1 to i = N, and the adjusted voltage V and pulse width p of each of the drive signals S-1 to S-N are calculated.

[0091] In step S112, the CPU 201 collectively updates the settings of the voltage V and pulse width p of each of the drive signals S-1 to S-N in the drive control unit 207 with the adjusted voltage V and pulse width p.

[0092] Thus, in steps S108 to S112, the CPU 201 updates the settings of the voltage V and pulse width p of the drive signal S-i based on the target discharge speed Yg, the target discharge amount Xg, the discharge speed Yp, the discharge amount Xp, the first change rate a1, and the second change rate a2.

[0093] Here, even if the updated drive signal S-i is applied to the piezoelectric element 100-i for use to discharge droplets from the nozzle 20-i for use, the discharge amount x of the droplets does not necessarily become the calculated discharge amount Xp´, and the discharge speed y of the droplets does not necessarily become the calculated discharge speed Yp´. Therefore, first, in step S113, the drive control unit 207 discharges droplets from the nozzle 20-i for use by applying the updated drive signal S-i to the piezoelectric element 100-i for use to drive the piezoelectric element 100-i for use (fourth discharge process: i = 1 to N).

[0094] Then, in step S114, the CPU 201 causes the discharge amount detection unit 208 to detect the discharge amount of droplets discharged from the operating nozzles 20-1 to 20-N, and causes the discharge speed detection unit 209 to detect the discharge speed. That is, the CPU 201 acquires data on the discharge speed Ys-i and discharge amount Xs-i of the droplets discharged in step S113 (fourth acquisition process). The discharge amount Xs-i in step S114 is an example of the second discharge amount, and the discharge speed Ys-i is an example of the second discharge speed.

[0095] In step S115, the CPU 201 determines whether the discharge speed Ys-i is within the range of the target discharge speed Yg and whether the discharge amount Xs-i is within the range of the target discharge amount Xg.

[0096] If the ejection speed Ys-i is outside the range of the target ejection speed Yg and / or the ejection amount Xs-i is outside the range of the target ejection amount Xg (S115: NO), in step S116, the CPU 201 adjusts the setting of the pulse width p of the drive signal Si while keeping the adjusted voltage V of the drive signal Si constant (adjustment process). Note that it is only necessary to adjust the setting of the pulse width p for only those nozzles 20 of the N active nozzles 20-1 to 20-N whose droplet ejection state is outside the target range.

[0097] The adjustment process of step S116 will be described below using a specific example. Figures 14(a) and 14(b) are explanatory diagrams of an example of calculation process according to an embodiment. The ejection amount x detected in step S114 is Xs. Furthermore, the ejection speed y detected in step S114 is Ys.

[0098] The straight line y = a2 * x + (Yg - a2 * Xg) shown in Figure 14(a) is a line that passes through coordinate points included in the target area TA. Also, as shown in Figure 14(b), the ejection amount x with respect to the pulse width p is approximated by the straight line x = a4 * p + b3. The slope a4 uses the value calculated in step S109. The pulse width adjustment amount p' is calculated as p' = (Xs - Xg) / a4.

[0099] After adjusting the setting of the pulse width p, the CPU 201 returns to the process of step S113. If step S115 is YES, that is, if the droplet ejection speeds and ejection amounts for all of the active nozzles 20-1 to 20-N have converged within the target ranges, the CPU 201 ends the process.

[0100] In the above steps S101 to S116, the control unit 200 does not change the settings of the ejection timing of the droplets ejected from the nozzles 20-1 to 20-N in use.

[0101] As described above, according to this embodiment, the control unit 200 updates the settings of the pulse width p and voltage V of the drive signals S-1 to SN applied to the piezoelectric elements 100-1 to 100-N corresponding to the active nozzles 20-1 to 20-N based on the data on the ejection volume x and ejection velocity y of droplets ejected from the representative nozzle 20-R. By adjusting the pulse width p while maintaining a constant voltage V, it is possible to adjust the ejection volume x and ejection velocity y without causing changes in crosstalk due to voltage fluctuations. In other words, even when the ejection volume y and ejection volume x of droplets ejected from one active nozzle 20 among the active nozzles 20-1 to 20-N are adjusted, deviations in the ejection volume y and ejection volume x of droplets ejected from the other active nozzles 20 can be reduced. This reduces the time required to adjust the ejection volume y and ejection volume x of droplets ejected from the active nozzles 20-1 to 20-N.

[0102] [Variations] In the above-described embodiment, the area ZA is defined by two lines LA and LB (LA', LB') whose slope is the first rate of change a2, but the present invention is not limited to this. Fig. 15 is an explanatory diagram of an example of an area ZA' according to a modified example. Note that in this modified example, configurations and processes different from those of the above-described embodiment will be described.

[0103] In the modified example, in step S108 of the flowchart in FIG. 7, the control unit 200 defines a coordinate space CS1, and determines two lines LA″ and LB″ with a slope equal to the first change rate a1 so as to sandwich the target area TA in the coordinate space CS1, and defines the area sandwiched between the two lines LA″ and LB″ as area ZA′. Area ZA′ is an example of the second area. The two lines LA″ and LB″ are parallel to each other.

[0104] Line LA'' is a line with a slope of a first change rate a1 that passes through the upper limit of the target discharge speed Yg and the lower limit of the target discharge volume Xg. Line LB'' is a line with a slope of a first change rate a1 that passes through the lower limit of the target discharge speed Yg and the upper limit of the target discharge volume Xg.

[0105] Then, for the nozzle 20-i in use, if step S115 in the flowchart of FIG. 7 is NO, i.e., if the ejection speed Ys-i detected in step S114 is outside the range of the target ejection speed Yg, and / or if the ejection volume Xs-i detected in step S114 is outside the range of the target ejection volume Xg, then in step S116, the CPU 201 adjusts the setting of the voltage V of the drive signal Si while keeping the pulse width p of the drive signal Si constant.

[0106] As described above, according to this modification, the control unit 200 updates the settings of the pulse width p and voltage V of the drive signals S-1 to SN applied to the piezoelectric elements 100-1 to 100-N corresponding to the active nozzles 20-1 to 20-N based on the data on the ejection volume x and ejection velocity y of droplets ejected from the representative nozzle 20-R. By adjusting the voltage V while maintaining the pulse width p constant, it is possible to adjust the ejection volume x and ejection velocity y without causing changes in crosstalk due to pulse width fluctuations. In other words, even when the ejection volume y and ejection volume x of droplets ejected from one of the active nozzles 20-1 to 20-N are adjusted, deviations in the ejection volume y and ejection volume x of droplets ejected from the other active nozzles 20 can be reduced. This reduces the time required to adjust the ejection volume y and ejection volume x of droplets ejected from the active nozzles 20-1 to 20-N.

[0107] Thus, according to the above embodiment and the above modified example, in step S112, the settings of the voltage V and pulse width p of the drive signals S-1 to SN are updated, thereby providing a technique that is advantageous for shortening the adjustment time of the ejection velocity y and ejection volume x of the droplets ejected from each of the nozzles 20-1 to 20-N.

[0108] [Example] Below, Examples 1 to 10 and Comparative Example 1 will be described as experimental results. Figures 16, 17, and 18 are graphs showing the discharge speed versus discharge amount for Example 1. Figure 19(a) is a graph showing the measurement results of the discharge speed of each used nozzle for Example 1. Figure 19(b) is a graph showing the measurement results of the discharge amount of each used nozzle for Example 1. Figure 20 is a table showing the experimental conditions and evaluations for Examples 1 to 10 and Comparative Example 1.

[0109] Example 1 A liquid ejection head 3, as shown in Figure 2, was installed on a liquid ejection device 1. The liquid ejection head 3 ejected droplets from nozzles 20 connected to multiple pressure chambers 19. The total number of nozzles 20 in the liquid ejection head 3 was 256. Two nozzle rows 30 were arranged at intervals in the X direction of Figure 2, and each nozzle row 30 had 128 nozzles 20 arranged at intervals in the Y direction. The 128 nozzles 20 in the nozzle row 30 were arranged at intervals of 150 dpi. A substrate for detecting the impact position was placed on the stage 10. The distance between the substrate and the orifice surface of the liquid ejection head 3 was set to 300 μm. The liquid used for ejection had a viscosity of 10 mPa·s and a surface tension of 40 mN / m. The hydrodynamic resonance frequency of each pressure chamber 19 was 150 kHz, and the resonance period of each pressure chamber 19 was 6.7 μs.

[0110] 7, the CPU 201 acquires input information from the input device 211 and sets the input information (conditions) in the drive control unit 207, etc. The set conditions are a target discharge speed Yg of 5.0 [m / s] ±10%, and a target discharge amount Xg of 1.43 [pl] ±2%.

[0111] In the drive signal Si before adjustment, the time width of the rising portion was set to 1.2 [μs], the pulse width (time width of the hold portion) to 2.2 [μs], the time width of the falling portion to 1.2 [μs], and the voltage of the hold portion to 15.2 [V]. The nozzles in use 20-1 to 20-N were a total of 128 nozzles (i.e., N = 128) in only one nozzle row 30, and the ejection timing was simultaneous for all the nozzles in use 20-1 to 20-N. The drive waveform was a pull-push type.

[0112] In step S102, the drive control unit 207 simultaneously drives a total of 128 working piezoelectric elements 100-1 to 100-N to eject droplets from the working nozzles 20-1 to 20-N.

[0113] In step S103, the CPU 201 measured the discharge speed y (= Yp-1 to Yp-N) and discharge volume x (= Xp-1 to Xp-N) of the nozzles 20-1 to 20-N in use. The discharge speed y and discharge volume x were measured based on images captured by an imaging device. Figures 8(b) and 8(c) show the measurement results. The average value of the discharge speeds Yp-1 to Yp-N was 4.74 [m / s], with a 3σ variation of 45.4%. The average value of the discharge volumes Xp-1 to Xp-N was 1.51 [pl], with a 3σ variation of 18.1%.

[0114] In step S104, the drive control unit 207 designates one nozzle 20 located at the end of the nozzle row 30 as the representative nozzle 20-R, keeps the pulse width p constant at 2.2 [μs], and changes the voltage V from 14.4 [V] to 16.0 [V] in increments of 0.4 [V] to sequentially eject a plurality of droplets from the representative nozzle 20-R. In Example 1, the representative nozzle 20-R is the same as one of the operating nozzles 20-1 to 20-N.

[0115] In step S105, the CPU 201 measured the ejection velocity y and ejection volume x of each of the multiple droplets and calculated the first rate of change a1. Figures 9(a) to 9(c) show the measurement results. The slope of the approximate line shown in Figure 9(c) is the first rate of change a1 of the velocity y with respect to the ejection volume x when the voltage is changed, and the first rate of change a1 was 8.18 [m / s / pl].

[0116] In step S106, the drive control unit 207 uses the representative nozzle 20-R used in step S104 to sequentially eject multiple droplets from the representative nozzle 20-R by setting the voltage V to a constant 15.2 [V] and changing the pulse width p from 1.6 [μs] to 2.8 [μs] in increments of 0.2 [μs].

[0117] In step S107, the CPU 201 measured the ejection velocity y and ejection volume x of each of the plurality of droplets and calculated the second rate of change a2. Figures 10(a) to 10(c) show the measurement results. As shown in Figure 10(a), the ejection velocity y versus the pulse width p is a quadratic curve, and the ejection velocity y reaches its maximum value when the pulse width p is 2.2 μs (the value before adjustment).

[0118] The ejection volume x versus the pulse width p is linear as shown in FIG. 10(b). Therefore, the ejection velocity y versus the ejection volume x also follows a quadratic curve as shown in FIG. 10(c). Therefore, the second change rate a2 is divided into a positive case shown in FIG. 11(a) and a negative case shown in FIG. 11(b) at the pulse width p = 2.2 [μs]. In Example 1, the ejection volume before adjustment is greater than the target ejection volume. Therefore, the positive value shown in FIG. 11(a) was used as the second change rate a2. In other words, the slope of the approximate straight line shown in FIG. 10(c) was taken as the second change rate a2. The second change rate a2 was 4.04 [m / s / pl].

[0119] Next, in step S108, the CPU 201 calculated the area ZA as shown in FIG. 16. Line LA is a straight line with a slope of the second change rate a2 that passes through the points (black dots) where the upper limit of the target discharge speed Yg and the lower limit of the target discharge speed Xg are located in a coordinate space CS1, with the discharge speed x as the x-axis and the discharge speed y as the y-axis. As set in step S101, the upper limit of the target discharge speed Yg is 5.5 [m / s], and the lower limit of the target discharge speed Xg is 1.4014 [pl]. Line LB is a straight line with a slope of the second change rate a2 that passes through the points (white dots) where the lower limit of the target discharge speed Yg and the upper limit of the target discharge speed Xg are located in the coordinate space CS1. As set in step S101, the lower limit of the target discharge speed Yg is 4.5 [m / s], and the upper limit of the target discharge speed Xg is 1.4586 [pl].

[0120] 16 shows coordinate points P1-1 to P1-N that indicate the relationship between the discharge volume x and discharge speed y of the 128 active nozzles 20-1 to 20-N in the coordinate space CS1. As shown in Fig. 16, it can be seen that among the coordinate points P1-1 to P1-N, some points are outside the area ZA that was set based on the discharge state of droplets from the representative nozzle 20-R.

[0121] Subsequently, in steps S109 and S110, the CPU 201 calculated the voltage V and pulse width p such that the ejection speed y and ejection volume x of the droplets ejected from the nozzles 20-1 to 20-N in use fall within the target area TA.

[0122] Focusing on representative nozzle 20-R included in the 128 active nozzles 20-1 to 20-N, the discharge speed y (= Yp) is 5.0 [m / s], the discharge amount x (= Xp) is 1.5 [pl], and in step S109, the voltage V calculated when it is estimated that coordinate point P1 (Xp, Yp) will transition to region ZA is V = 15.5 [V]. The calculated voltage V (= 15.5 [V]) is the voltage before adjustment V0 (= 15.2 [V]) + the voltage adjustment amount (= 0.3 [V]).

[0123] Next, in step S110, the CPU 201 calculated the pulse width p at which the coordinate point P1 (intersection point P3) falls within the target area TA using the estimated ejection speed Y', estimated ejection volume X', and second change rate a2 corresponding to the voltage V (= 15.5 [V]). The calculation result was p = 2.0 [μs]. The calculated pulse width p (= 2.0 [μs]) is the pulse width p0 before adjustment (= 2.2 [μs]) + pulse width adjustment amount (= -0.2 [μs]).

[0124] The CPU 201 performs this calculation for all 128 active nozzles 20-1 to 20-N (step S111), and in step S112 updates the drive waveform settings of the drive signals S-1 to SN all at once.

[0125] Next, in step S113, the drive control unit 207 causes droplets to be ejected from the active nozzles 20-1 to 20-N using the updated drive signals S-1 to SN, and in step S114, the ejection speed y and ejection volume x of each nozzle 20-1 to 20-N are measured. The measurement results are shown in Figure 17. As shown in Figure 17, all of the points indicating the ejection speed y and ejection volume x of the active nozzles 20-1 to 20-N fall within the area ZA.

[0126] Next, in steps S115 and S116, the CPU 201 adjusted the pulse width p for 76 points outside the target area TA out of the 128 points corresponding to the 128 operating nozzles 20-1 to 20-N shown in Figure 17, while keeping the adjusted voltage V constant.

[0127] The following explanation focuses on one nozzle 20 out of the 76 used nozzles 20, which had a droplet ejection speed y of 4.78 [m / s] and a droplet ejection volume x of 1.3 [pl]. When the pulse width p is adjusted by the pulse width adjustment amount (= +0.4 [μs]), the calculated value of the ejection speed y becomes 5.39 [m / s] and the calculated value of the ejection volume x becomes 1.43 [pl].

[0128] In this way, for the 76 points (nozzles) that were outside the target area TA, the pulse width was readjusted all at once while the voltage was kept constant, and the ejection volume and ejection speed were measured again. The results are shown in Figure 18. As shown in Figure 18, all 128 points fell within the target area TA.

[0129] Fig. 19(a) is a graph showing the measurement results of the discharge speed according to Example 1. Fig. 19(b) is a graph showing the measurement results of the discharge amount according to Example 1. The average discharge speed y was 5.04 [m / s], and the variation in the discharge speed y was 10% at 3σ. The average discharge amount x was 1.43 [pl], and the variation in the discharge amount x was 1.8% at 3σ.

[0130] <Example 2> In Example 2, the nozzle 20 at the center position (64th from the end) of the nozzle row 30 was set as the representative nozzle 20-R, and an experiment was carried out in the same manner as in Example 1.

[0131] Example 3 In Example 1 above, an experiment was conducted using an example in which one of the N operating nozzles 20-1 to 20-N was the representative nozzle 20-R, but in Example 3, an experiment was conducted using an example in which at least two of the N operating nozzles 20-1 to 20-N were the representative nozzles 20-R. Specifically, in Example 3, the two nozzles 20 at both ends of the nozzle row 30 were designated as the representative nozzles 20-R.

[0132] In step S104, the drive control unit 207 keeps the pulse width p of the drive signal SR applied to each of the two representative piezoelectric elements 100-R constant and changes the voltage V of the drive signal SR, thereby sequentially ejecting multiple droplets from each of the two representative nozzles 20-R corresponding to the two representative piezoelectric elements 100-R (second ejection process).

[0133] In step S105, the CPU 201 causes the discharge amount detection unit 208 to detect the discharge amount of each of the plurality of droplets discharged from each of the two representative nozzles 20-R, causes the discharge rate detection unit 209 to detect the discharge rate of each of the plurality of droplets, and averages the slope of the discharge rate versus discharge rate of each of the plurality of droplets discharged from each of the two representative nozzles 20-R to obtain data on the first change rate a1 (second acquisition process).

[0134] Furthermore, in step S106, the drive control unit 207 keeps the voltage V of the drive signal SR applied to each of the two representative piezoelectric elements 100-R constant and changes the pulse width p of the drive signal SR, thereby sequentially ejecting multiple droplets from each of the two representative nozzles 20-R corresponding to the two representative piezoelectric elements 100-R (third ejection process).

[0135] In step S107, the CPU 201 causes the discharge amount detection unit 208 to detect the discharge amount of each of the plurality of droplets discharged from each of the two representative nozzles 20-R, and causes the discharge rate detection unit 209 to detect the discharge rate of each of the plurality of droplets, and then averages the slope of the discharge rate versus the discharge rate of the plurality of droplets discharged from each of the two representative nozzles 20-R to obtain data on the second change rate a2 (fourth acquisition process). In this case, the second change rate a2 was set to the average value of the slope that was a positive value so that the second change rate a2 was adjusted on the side below the pulse width at which the discharge rate reached its maximum value. In Example 3, experiments were conducted under the same conditions as in Example 1, except for these conditions.

[0136] Example 4 In Example 4, the ejection timing of droplets ejected from the nozzles 20-1 to 20-N in use was set for each nozzle, taking into consideration deviations in the ejection angles (deviations in landing positions) of the nozzles 20-1 to 20-N in use. In Example 4, the experiment was carried out under the same conditions as in Example 3, except for the ejection timing.

[0137] For example, suppose the discharge angle of a certain nozzle 20 is off by 0.1 degrees from the vertical direction due to manufacturing variations. Because the distance between the substrate used to detect the landing position and the orifice surface is set to 300 μm, the deviation in the discharge angle will cause the droplets to land at a position that is off by 0.5 μm compared to when the droplets land perpendicular to the substrate. If the substrate transport speed is set to 0.1 m / s, the deviation in the discharge angle can be corrected by adjusting the timing at which the discharge starts by 5 μs.

[0138] <Example 5> In Example 5, the drive signal S commonly applied to the piezoelectric elements 100-1 to 100-N corresponding to the nozzles 20-1 to 20-N was a PULL-PUSH-PULL drive waveform shown in FIG. 6(c).

[0139] In the drive signal S, the time width of the rising portion was set to 1.2 [μs], the pulse width to 2.2 [μs], the time width of the falling portion to 1.2 [μs], the second voltage hold time to 2.2 [μs], the time width of the second rising portion to 1.2 [μs], the voltage of the first hold portion to 15.2 [V], and the voltage of the second hold portion to -10.8 [V].

[0140] The average discharge speed Yp before adjustment was 5.04 m / s, and the variation of the discharge speed Yp before adjustment was 43.8% at 3σ. The average discharge volume Xp before adjustment was 1.21 pl, and the variation of the discharge volume Xp before adjustment was 17.8% at 3σ.

[0141] Because the discharge rate Xp before adjustment was smaller than the target discharge rate Xg, the second change rate a2 was calculated from the profile in the region equal to or greater than the discharge rate Xm shown in Figure 11(b). In Example 5, the experiment was conducted in the same manner as in Example 1, except for the above.

[0142] Example 6 In Example 6, as shown in FIG. 15 , when the x-axis represents the discharge volume x and the y-axis represents the discharge velocity y, a region ZA′ was defined as a region sandwiched between a line LA″, which passes through the upper limit of the target discharge velocity Yg and the lower limit of the target discharge volume Xg and has a slope equal to the first change rate a1, and a line LB″, which passes through the lower limit of the target discharge velocity Yg and the upper limit of the target discharge volume Xg and has a slope equal to the first change rate a1. Then, a pulse width p was calculated using the second change rate a2 so that it would fall within the region ZA′, and a voltage V that would achieve the target discharge velocity and target discharge volume was calculated using the discharge velocity y and discharge volume x estimated from the calculated pulse width p and the first change rate a1. In Example 6, an experiment was conducted in the same manner as in Example 5 except for this.

[0143] Example 7 In Example 7, all of the nozzles 20 included in one nozzle row 30 were designated as representative nozzles 20-R. Furthermore, in Example 7, the ejection timing was set for each nozzle 20, similar to Example 4. Furthermore, data on the change rates a1 and a2 were obtained for each nozzle 20, and the pulse width p and voltage V were calculated for each nozzle 20 from the slope of the change rate corresponding to the nozzle 20, and an experiment was performed in the same manner as in Example 1.

[0144] Example 8 In Example 8, the ejection timing was set for each nozzle 20 in the same manner as in Example 4. In addition, the pulse width p and voltage V were calculated so as to fall within the region ZA' in the same manner as in Example 6, and correction was performed in the same manner as in Example 1.

[0145] Example 9 In Example 9, the ejection timing was set for each nozzle 20, similar to Example 4. Furthermore, in Example 9, the drive signal S commonly applied to the piezoelectric elements 100-1 to 100-N corresponding to the nozzles 20-1 to 20-N was set to have a PULL-PUSH-PULL type drive waveform as shown in Fig. 6(c).

[0146] In the drive signal S, the time width of the rising portion was set to 1.2 [μs], the pulse width to 2.2 [μs], the time width of the falling portion to 1.2 [μs], the second voltage hold time to 2.2 [μs], the time width of the second rising portion to 1.2 [μs], the voltage of the first hold portion to 15.2 [V], and the voltage of the second hold portion to -3.6 [V].

[0147] The average discharge speed Yp before adjustment was 5.01 m / s, and the variation of the discharge speed Yp before adjustment was 50.7% at 3σ. The average discharge volume Xp before adjustment was 1.41 pl, and the variation of the discharge volume Xp before adjustment was 24.2% at 3σ.

[0148] Since there was a mixture of nozzles whose pre-adjustment discharge volume Xp was greater than the target discharge volume Xg and nozzles whose pre-adjustment discharge volume Xp was smaller than the target discharge volume Xg, the second change rate a2 was calculated from the profile of the region equal to or less than the discharge volume Xm shown in Figure 11(a) for nozzles whose pre-adjustment discharge volume Xp was greater than the target discharge volume Xg, and the second change rate a2 was calculated from the profile of the region equal to or greater than the discharge volume Xm shown in Figure 11(b) for nozzles whose pre-adjustment discharge volume Xp was smaller than the target discharge volume Xg.

[0149] In Example 9, the experiment was carried out in the same manner as in Example 1, except for the above.

[0150] Example 10 In Example 10, the ejection timing was set to be simultaneous, and the rate of change was obtained for each nozzle in the same manner as in Example 7. In Example 10, the experiment was carried out in the same manner as in Example 8, except for the above.

[0151] <Comparative Example 1> In Comparative Example 1, all nozzles included in one nozzle row were designated as representative nozzles. The ejection timing was simultaneous, as in Example 1. The common drive waveform was a pull-push type, as in Example 1. Droplets were ejected from one end nozzle of the 128 nozzles included in one nozzle row, and the ejection speed and ejection volume of the droplets were measured. The voltage and pulse width of the drive signal were adjusted so that the droplets would achieve the target ejection speed and target ejection volume. After adjusting the drive signal corresponding to that nozzle, the drive signal corresponding to the adjacent unadjusted nozzle was adjusted in the same manner. The above process was repeated until all drive signals corresponding to all nozzles were adjusted. After adjusting all drive signals for all nozzles, droplets were ejected from all nozzles, and the ejection speed and ejection volume of each droplet were measured.

[0152] The conditions and evaluation results for Examples 1 to 10 and Comparative Example 1 are shown in Fig. 13. In the "Evaluation" section of the table shown in Fig. 20, the case where the variation 3σ in the discharge speed was 10% or less and the variation in the discharge amount was 2% or less was rated "A", the case where the variation 3σ in the discharge speed was 14% or less and the variation in the discharge amount was 4% or less was rated "B", and the case where the variation 3σ in the discharge speed was 14% or more or the variation in the discharge amount was 4% or more was rated "C".

[0153] In Comparative Example 1, the pressure propagating to the surroundings changes with each correction, causing the influence of crosstalk to fluctuate, resulting in large variations in the ejection amount and ejection speed for each nozzle. In contrast, in Examples 1 to 10, it was possible to keep the variations small.

[0154] [Embodiment of manufacturing method of article] In this embodiment, an article is manufactured using the liquid ejection device described above. The article may be an intermediate product or a final product. The article manufacturing method according to this embodiment is suitable for manufacturing an article such as an organic light-emitting diode (OLED) panel using a liquid ejection device. The article manufacturing method according to this embodiment includes a step (coating step) of depositing or applying a solution film (a solution containing a solute and a solvent for forming an organic film) on a substrate by a printing method or the like using a liquid ejection device to obtain a coated substrate. The method also includes a step (drying step) of drying the solution film on the coated substrate to obtain a dry substrate on which a dry film has been formed. Furthermore, this manufacturing method includes other well-known steps (such as baking, cooling, dehumidification, dry cleaning, electrode formation, and sealing film formation). The article manufacturing method according to this embodiment is advantageous over conventional methods in at least one of the performance, quality, productivity, and production cost of the article.

[0155] [Other variations] The present disclosure is not limited to the above-described embodiments and modifications, and many modifications of the embodiments or modifications are possible within the technical concept of the present disclosure. Furthermore, the effects described in the present embodiment or modifications are merely a list of the most preferable effects resulting from the present disclosure, and are not limited to those described in the present embodiment.

[0156] The disclosure of the above embodiments includes the following sections.

[0157] (Section 1) a liquid ejection head having a plurality of nozzles and a plurality of piezoelectric elements including a first piezoelectric element and a second piezoelectric element respectively corresponding to the plurality of nozzles; a control unit that controls each of the plurality of piezoelectric elements so that droplets are ejected from each of the plurality of nozzles; The control unit a first ejection process of applying a first drive signal having a set voltage and pulse width to a first piezoelectric element among the plurality of piezoelectric elements to eject droplets from a first nozzle among the plurality of nozzles that corresponds to the first piezoelectric element; a first acquisition process for acquiring data on a first discharge speed and a first discharge amount of the droplets discharged in the first discharge process; a second ejection process in which a pulse width of a second drive signal applied to the first piezoelectric element or the second piezoelectric element among the plurality of piezoelectric elements is kept constant and a voltage of the second drive signal is changed to eject a plurality of droplets from a second nozzle among the plurality of nozzles that corresponds to the second piezoelectric element; a second acquisition process for acquiring data on a first rate of change of a discharge speed with respect to a discharge amount of the plurality of droplets discharged in the second discharge process; a third ejection process in which the voltage of the second drive signal is kept constant and the pulse width is changed to eject a plurality of droplets from the second nozzle; a third acquisition process for acquiring data on a second rate of change of the ejection speed with respect to the ejection amount of the plurality of droplets ejected in the third ejection process; an update process for updating the settings of the voltage and the pulse width of the first drive signal based on the first rate of change and the second rate of change. A liquid ejection device characterized by:

[0158] (Section 2) In the update process, the control unit In a coordinate space having the droplet discharge amount as a first coordinate axis and the droplet discharge speed as a second coordinate axis, two lines are obtained, each having a slope equal to one of the first rate of change and the second rate of change, so as to sandwich a first region defined by the upper and lower limits of the target discharge amount and the upper and lower limits of the target discharge speed; updating the settings of the voltage and the pulse width of the first drive signal so that a coordinate point defined by the set of the first discharge speed and the first discharge amount in the coordinate space transitions to a second region sandwiched between the two lines; Item 1. A liquid ejection device according to item 1.

[0159] (Section 3) the control unit updates the settings of the voltage and the pulse width of the first drive signal so that the coordinate point transitions to the first region. Item 3. The liquid ejection device according to item 2, characterized in that:

[0160] (Section 4) the one rate of change is the second rate of change. Item 4. The liquid ejection device according to item 2 or 3, characterized in that:

[0161] (Section 5) The control unit a fourth ejection process of applying the updated first drive signal to the first piezoelectric element after updating the setting of the first drive signal to eject droplets from the first nozzle; a fourth acquisition process for acquiring data on a second discharge speed and a second discharge amount of the droplets discharged in the fourth discharge process; and if the second ejection speed is out of the range of the target ejection speed and / or the second ejection amount is out of the range of the target ejection amount, further executing an adjustment process of adjusting the setting of the pulse width of the first drive signal while keeping the voltage of the first drive signal constant. 5. The liquid ejection device according to item 4, characterized in that:

[0162] (Section 6) the one rate of change is the first rate of change; Item 4. The liquid ejection device according to item 2 or 3, characterized in that:

[0163] (Section 7) The control unit a fourth ejection process of applying the updated first drive signal to the first piezoelectric element after updating the setting of the first drive signal to eject droplets from the first nozzle; a fourth acquisition process for acquiring data on a second discharge speed and a second discharge amount of the droplets discharged in the fourth discharge process; and if the second ejection speed is outside the range of the target ejection speed and / or the second ejection amount is outside the range of the target ejection amount, further executing an adjustment process of adjusting the setting of the voltage of the first drive signal while keeping the pulse width of the first drive signal constant. Item 6. A liquid ejection device according to item 5, characterized in that:

[0164] (Section 8) In the third acquisition process, the control unit a profile of the ejection speed relative to the ejection amount of the droplets ejected in the second ejection process is obtained; A third discharge velocity that is a maximum value is obtained from the profile; When the first discharge amount is larger than the target discharge amount, the second change rate is calculated based on a region of the profile that is equal to or smaller than a third discharge amount corresponding to the third discharge speed. 8. The liquid ejection device according to any one of items 1 to 7, characterized in that:

[0165] (Section 9) the second rate of change is a positive value; Item 9. A liquid ejection device according to item 8, characterized in that:

[0166] (Section 10) In the third acquisition process, the control unit a profile of the ejection speed relative to the ejection amount of the droplets ejected in the second ejection process is obtained; A third discharge velocity that is a maximum value is obtained from the profile; When the first discharge amount is smaller than the target discharge amount, the second change rate is calculated based on a region of the profile that is equal to or larger than a third discharge amount corresponding to the third discharge speed. 8. The liquid ejection device according to any one of items 1 to 7, characterized in that:

[0167] (Section 11) the second rate of change is a negative value; Item 11. A liquid ejection device according to item 10.

[0168] (Section 12) the control unit does not change the setting of the ejection timing of the droplets ejected from the first nozzles, 12. The liquid ejection device according to any one of items 1 to 11, characterized in that:

[0169] (Section 13) the plurality of piezoelectric elements are disposed in the plurality of pressure chambers, respectively; a time width from a rising edge start timing to a falling edge start timing of the first drive signal after adjustment by the adjustment process is equal to or greater than ¼ and equal to or less than ¾ of a resonance period of a pressure chamber in which the first piezoelectric element is arranged among the plurality of pressure chambers; Item 8. The liquid ejection device according to item 5 or 7, characterized in that:

[0170] (Section 14) two or more nozzles among the plurality of nozzles are included in one nozzle row, the first nozzle is each of the two or more nozzles, the first piezoelectric element is each of two or more piezoelectric elements among the plurality of piezoelectric elements corresponding to the two or more nozzles; 14. The liquid ejection device according to any one of items 1 to 13, characterized in that:

[0171] (Section 15) the second nozzles are at least two nozzles among the two or more nozzles; The control unit In the second ejection process, a plurality of droplets are ejected from each of the at least two nozzles; in the second acquisition process, the first change rate data is acquired by averaging the gradients of the ejection speeds with respect to the ejection amounts of the plurality of droplets ejected from each of the at least two nozzles in the second ejection process; In the third ejection process, a plurality of droplets are ejected from each of the at least two nozzles; In the third acquisition process, the second change rate data is acquired by averaging the gradients of the ejection speeds with respect to the ejection amounts of the plurality of droplets ejected from each of the at least two nozzles in the third ejection process. Item 15. A liquid ejection device according to item 14, characterized in that:

[0172] (Section 16) the control unit collectively updates the settings of the voltage and the pulse width of the drive signal to be applied to each of the two or more piezoelectric elements in the update process. 16. The liquid ejection device according to item 14 or 15,

[0173] (Section 17) a liquid ejection head having a plurality of nozzles and a plurality of piezoelectric elements including a first piezoelectric element and a second piezoelectric element respectively corresponding to the plurality of nozzles; a computer that controls each of the plurality of piezoelectric elements so that droplets are ejected from each of the plurality of nozzles, The computer a first ejection process of applying a first drive signal having a set voltage and pulse width to a first piezoelectric element among the plurality of piezoelectric elements to eject droplets from a first nozzle among the plurality of nozzles that corresponds to the first piezoelectric element; a first acquisition process for acquiring data on a first discharge speed and a first discharge amount of the droplets discharged in the first discharge process; a second ejection process in which a pulse width of a second drive signal applied to the first piezoelectric element or the second piezoelectric element among the plurality of piezoelectric elements is kept constant and a voltage of the second drive signal is changed to eject a plurality of droplets from a second nozzle among the plurality of nozzles that corresponds to the second piezoelectric element; a second acquisition process for acquiring data on a first rate of change of a discharge speed with respect to a discharge amount of the plurality of droplets discharged in the second discharge process; a third ejection process in which the voltage of the second drive signal is kept constant and the pulse width is changed to eject a plurality of droplets from the second nozzle; a third acquisition process for acquiring data on a second rate of change of the ejection speed with respect to the ejection amount of the plurality of droplets ejected in the third ejection process; an update process for updating the settings of the voltage and the pulse width of the first drive signal based on the first rate of change and the second rate of change. A method for controlling a liquid ejection device.

[0174] (Section 18) 1. A method for manufacturing an article, comprising: Item 17. A method for manufacturing an article, comprising a step of supplying droplets to a substrate using the liquid ejection device according to any one of items 1 to 16.

[0175] (Section 19) Item 18. A program for causing the computer to execute the control method according to Item 17.

[0176] (Section 20) 20. A computer-readable recording medium having the program according to item 19 recorded thereon. [Explanation of symbols]

[0177] a1...first change rate, a2...second change rate, Si...drive signal (first drive signal), SR...drive signal (second drive signal), Xg...target discharge amount, Xp...discharge amount (first discharge amount), Xs...discharge amount (second discharge amount), Yg...target discharge speed, Yp...discharge speed (first discharge speed), Ys...discharge speed (second discharge speed), 1...liquid discharge device, 3...liquid discharge head, 20...nozzle, 20-i...used nozzle (first nozzle), 20-R...representative nozzle (second nozzle), 100...piezoelectric element, 100-i...used piezoelectric element (first piezoelectric element), 100-R...representative piezoelectric element (second piezoelectric element), 200...control unit

Claims

1. a liquid ejection head having a plurality of nozzles and a plurality of piezoelectric elements including a first piezoelectric element and a second piezoelectric element respectively corresponding to the plurality of nozzles; a control unit that controls each of the plurality of piezoelectric elements so that droplets are ejected from each of the plurality of nozzles; The control unit a first ejection process of applying a first drive signal having a set voltage and pulse width to a first piezoelectric element among the plurality of piezoelectric elements to eject droplets from a first nozzle among the plurality of nozzles that corresponds to the first piezoelectric element; a first acquisition process for acquiring data on a first discharge speed and a first discharge amount of the droplets discharged in the first discharge process; a second ejection process in which a pulse width of a second drive signal applied to the first piezoelectric element or the second piezoelectric element among the plurality of piezoelectric elements is kept constant and a voltage of the second drive signal is changed to eject a plurality of droplets from a second nozzle among the plurality of nozzles that corresponds to the second piezoelectric element; a second acquisition process for acquiring data on a first rate of change of a discharge speed with respect to a discharge amount of the plurality of droplets discharged in the second discharge process; a third ejection process in which the voltage of the second drive signal is kept constant and the pulse width is changed to eject a plurality of droplets from the second nozzle; a third acquisition process for acquiring data on a second rate of change of the ejection speed with respect to the ejection amount of the plurality of droplets ejected in the third ejection process; and performing an update process of updating the settings of the voltage and the pulse width of the first drive signal based on the first rate of change and the second rate of change. A liquid ejection device characterized by:

2. In the update process, the control unit In a coordinate space having the droplet discharge amount as a first coordinate axis and the droplet discharge speed as a second coordinate axis, two lines are obtained, each having a slope equal to one of the first rate of change and the second rate of change, so as to sandwich a first region defined by the upper and lower limits of the target discharge amount and the upper and lower limits of the target discharge speed; updating the settings of the voltage and the pulse width of the first drive signal so that a coordinate point defined by the set of the first ejection speed and the first ejection amount transitions to a second region sandwiched between the two lines in the coordinate space; The liquid ejection device according to claim 1 .

3. the control unit updates the settings of the voltage and the pulse width of the first drive signal so that the coordinate point transitions to the first region.

3. The liquid ejection device according to claim 2.

4. the one rate of change is the second rate of change, 3. The liquid ejection device according to claim 2.

5. The control unit a fourth ejection process of applying the updated first drive signal to the first piezoelectric element after updating the setting of the first drive signal to eject droplets from the first nozzle; a fourth acquisition process for acquiring data on a second discharge speed and a second discharge amount of the droplets discharged in the fourth discharge process; and if the second ejection speed is outside the range of the target ejection speed and / or if the second ejection amount is outside the range of the target ejection amount, further executing an adjustment process of adjusting the setting of the pulse width of the first drive signal while keeping the voltage of the first drive signal constant.

5. The liquid ejection device according to claim 4.

6. the one rate of change is the first rate of change; 3. The liquid ejection device according to claim 2.

7. The control unit a fourth ejection process of applying the updated first drive signal to the first piezoelectric element after updating the setting of the first drive signal to eject droplets from the first nozzle; a fourth acquisition process for acquiring data on a second discharge speed and a second discharge amount of the droplets discharged in the fourth discharge process; and if the second ejection speed is outside the range of the target ejection speed and / or if the second ejection amount is outside the range of the target ejection amount, further executing an adjustment process of adjusting the setting of the voltage of the first drive signal while keeping the pulse width of the first drive signal constant.

6. The liquid ejection device according to claim 5.

8. In the third acquisition process, the control unit obtaining a profile of the ejection speed with respect to the ejection amount of the droplets ejected in the second ejection process; A third discharge velocity that is a maximum value is obtained from the profile; When the first discharge amount is larger than the target discharge amount, the second change rate is calculated based on a region of the profile that is equal to or smaller than a third discharge amount corresponding to the third discharge speed. The liquid ejection device according to claim 1 .

9. the second rate of change is a positive value; 9. The liquid ejection device according to claim 8.

10. In the third acquisition process, the control unit obtaining a profile of the ejection speed with respect to the ejection amount of the droplets ejected in the second ejection process; A third discharge velocity that is a maximum value is obtained from the profile; When the first discharge amount is smaller than the target discharge amount, the second change rate is calculated based on a region of the profile that is equal to or larger than a third discharge amount corresponding to the third discharge speed. The liquid ejection device according to claim 1 .

11. the second rate of change is a negative value; The liquid ejection device according to claim 10 .

12. the control unit does not change the setting of the ejection timing of the droplets ejected from the first nozzles, The liquid ejection device according to claim 1 .

13. the plurality of piezoelectric elements are disposed in the plurality of pressure chambers, respectively; a time width from a rising edge start timing to a falling edge start timing of the first drive signal after adjustment by the adjustment process is equal to or greater than ¼ and equal to or less than ¾ of a resonance period of a pressure chamber in which the first piezoelectric element is arranged among the plurality of pressure chambers; 6. The liquid ejection device according to claim 5.

14. two or more nozzles among the plurality of nozzles are included in one nozzle row, the first nozzle is each of the two or more nozzles, the first piezoelectric element is each of two or more piezoelectric elements among the plurality of piezoelectric elements corresponding to the two or more nozzles; The liquid ejection device according to claim 1 .

15. the second nozzles are at least two nozzles among the two or more nozzles, The control unit In the second ejection process, a plurality of droplets are ejected from each of the at least two nozzles; In the second acquisition process, the first change rate data is acquired by averaging the gradients of the ejection speeds of the plurality of droplets ejected from each of the at least two nozzles in the second ejection process; In the third ejection process, a plurality of droplets are ejected from each of the at least two nozzles; In the third acquisition process, the second change rate data is acquired by averaging the gradients of the ejection speeds with respect to the ejection amounts of the plurality of droplets ejected from each of the at least two nozzles in the third ejection process.

15. The liquid ejection device according to claim 14.

16. the control unit collectively updates the settings of the voltage and the pulse width of the drive signal to be applied to each of the two or more piezoelectric elements in the update process.

15. The liquid ejection device according to claim 14.

17. a liquid ejection head having a plurality of nozzles and a plurality of piezoelectric elements including a first piezoelectric element and a second piezoelectric element respectively corresponding to the plurality of nozzles; a computer that controls each of the plurality of piezoelectric elements so that droplets are ejected from each of the plurality of nozzles, The computer a first ejection process of applying a first drive signal having a set voltage and pulse width to a first piezoelectric element among the plurality of piezoelectric elements to eject droplets from a first nozzle among the plurality of nozzles that corresponds to the first piezoelectric element; a first acquisition process for acquiring data on a first discharge speed and a first discharge amount of the droplets discharged in the first discharge process; a second ejection process in which a pulse width of a second drive signal applied to the first piezoelectric element or the second piezoelectric element among the plurality of piezoelectric elements is kept constant and a voltage of the second drive signal is changed to eject a plurality of droplets from a second nozzle among the plurality of nozzles that corresponds to the second piezoelectric element; a second acquisition process for acquiring data on a first rate of change of a discharge speed with respect to a discharge amount of the plurality of droplets discharged in the second discharge process; a third ejection process in which the voltage of the second drive signal is kept constant and the pulse width is changed to eject a plurality of droplets from the second nozzle; a third acquisition process for acquiring data on a second rate of change of the ejection speed with respect to the ejection amount of the plurality of droplets ejected in the third ejection process; and performing an update process of updating the settings of the voltage and the pulse width of the first drive signal based on the first rate of change and the second rate of change. A method for controlling a liquid ejection device.

18. 1. A method for manufacturing an article, comprising: A method for manufacturing an article, comprising the step of supplying droplets to a substrate using the liquid ejection device according to claim 1 .

19. A program for causing the computer to execute the control method according to claim 17.

20. 20. A computer-readable recording medium on which the program according to claim 19 is recorded.

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