Droplet discharge apparatus and droplet discharge method

Abstract

To provide a droplet discharge apparatus capable of reducing the occurrence of periodic unevenness in a print result while keeping delay times of drive timings of drive elements uniform.SOLUTION: A flow path member 12 has a common flow path 12A and a plurality of individual flow paths 12B respectively communicating with a plurality of nozzles N. The plurality of individual flow paths 12B include first to fourth individual flow paths 12B, and the common flow path 12A has first to fourth connection ports C to which the first to fourth individual flow paths 12B are respectively connected. A distance D1 between the first connection port C and the second connection port C differs from a distance D2 between the third connection port C and the fourth connection port C. A controller 5 drives first and third piezoelectric elements 13X corresponding to first and third nozzles N at a first timing, and drives second and fourth piezoelectric elements 13X corresponding to second and fourth nozzles N at a second timing delayed by a predetermined time from the first timing.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to a droplet ejection device and a droplet ejection method using the droplet ejection device. [Background technology]

[0002] Conventionally, a liquid ejection device has been known that includes a plurality of nozzles that eject liquid, a plurality of actuators corresponding to the plurality of nozzles, a liquid supply unit that communicates with the plurality of nozzles, and a drive signal supply unit (see Patent Document 1). In this liquid ejection device, the plurality of nozzles are arranged in an array in the row and column directions. In the same drive cycle, the drive signal supply unit delays the timing of supplying a drive signal to the actuators corresponding to adjacent nozzles in the row direction by a predetermined time, and also delays the timing of supplying a drive signal to the actuators corresponding to adjacent nozzles in the column direction by a predetermined time. This allows pressure vibrations between adjacent nozzles in the row and column directions to cancel each other out, suppressing degradation of print quality due to crosstalk. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2020-032715 Summary of the Invention [Problem to be solved by the invention]

[0004] However, as printing speeds increase, it is necessary to shorten the actuator drive cycle, and there is a limit to the types of delay times that can be set within the same drive cycle. Also, if multiple types of delay times are set within the same drive cycle, drive control becomes complicated. For this reason, it is desirable to set a uniform (single) delay time for the actuator drive timing.

[0005] In the liquid ejection device described above, if the delay time for the actuator drive timing is uniform (one type), then the effects of crosstalk, such as fluctuations in droplet velocity and volume and changes in droplet separation state, will be uniform among nozzles with delayed ejection timing. If nozzles that are affected by uniform crosstalk are periodically arranged in the row and column directions, periodic unevenness may occur in the print results, depending on the print pattern.

[0006] The present invention has been made to solve the above-mentioned problems, and aims to provide a droplet ejection device and a droplet ejection method that can reduce periodic unevenness in the printing results while uniforming the delay time of the drive timing of the drive element. [Means for solving the problem]

[0007] According to a first aspect of the present invention, there is provided a droplet ejection device comprising: a flow path member having an ejection surface on which a plurality of nozzles open, a plurality of individual flow paths respectively communicating with the plurality of nozzles, and at least one common flow path communicating with the plurality of individual flow paths; a plurality of drive elements fixed to the flow path member to correspond to the plurality of nozzles, respectively; and a controller configured to drive the plurality of drive elements. The plurality of nozzles include a first nozzle and a second nozzle adjacent to each other along a first direction parallel to the ejection surface, and a third nozzle and a fourth nozzle adjacent to each other along a second direction parallel to the ejection surface and intersecting the first direction. The plurality of individual flow paths include a first individual flow path communicating with the first nozzle, a second individual flow path communicating with the second nozzle, a third individual flow path communicating with the third nozzle, and a fourth individual flow path communicating with the fourth nozzle. The at least one common flow path has a first connection port connected to the first individual flow path, a second connection port connected to the second individual flow path, a third connection port connected to the third individual flow path, and a fourth connection port connected to the fourth individual flow path. The multiple drive elements include a first drive element corresponding to the first nozzle, a second drive element corresponding to the second nozzle, a third drive element corresponding to the third nozzle, and a fourth drive element corresponding to the fourth nozzle. A distance between the first connection port and the second connection port is different from a distance between the third connection port and the fourth connection port. The controller is configured to drive the first drive element and the third drive element at a first timing without driving the second drive element and the fourth drive element, and to drive the second drive element and the fourth drive element at a second timing delayed by a predetermined time from the first timing.

[0008] According to a second aspect of the present invention, there is provided a droplet ejection method using a droplet ejection device. The droplet ejection device includes a flow path member having an ejection surface on which a plurality of nozzles open, a plurality of individual flow paths each communicating with the plurality of nozzles, and at least one common flow path communicating with the plurality of individual flow paths, and a plurality of drive elements fixed to the flow path member so as to correspond to the plurality of nozzles, respectively. The plurality of nozzles include a first nozzle and a second nozzle adjacent to each other along a first direction parallel to the ejection surface, and a third nozzle and a fourth nozzle adjacent to each other along a second direction parallel to the ejection surface and intersecting the first direction. The plurality of individual flow paths include a first individual flow path communicating with the first nozzle, a second individual flow path communicating with the second nozzle, a third individual flow path communicating with the third nozzle, and a fourth individual flow path communicating with the fourth nozzle. The at least one common flow path has a first connection port connected to the first individual flow path, a second connection port connected to the second individual flow path, a third connection port connected to the third individual flow path, and a fourth connection port connected to the fourth individual flow path. The multiple drive elements include a first drive element corresponding to the first nozzle, a second drive element corresponding to the second nozzle, a third drive element corresponding to the third nozzle, and a fourth drive element corresponding to the fourth nozzle. A distance between the first connection port and the second connection port is different from a distance between the third connection port and the fourth connection port. The method includes driving the first drive element and the third drive element at a first timing without driving the second drive element and the fourth drive element, and driving the second drive element and the fourth drive element at a second timing delayed by a predetermined time from the first timing. [Effects of the Invention]

[0009] According to the first and second aspects of the present invention, it is possible to reduce periodic unevenness in the print result while making the delay time of the drive timing of the drive element uniform. [Brief explanation of the drawings]

[0010] [Figure 1]1 is a plan view of a printer 100 according to a first embodiment of the present invention. [Figure 2] FIG. 2 is a block diagram showing the electrical configuration of the printer 100. [Figure 3] FIG. 2 is a plan view of a head 1 that constitutes a head unit 1x of a printer 100. [Figure 4] FIG. 4 is a cross-sectional view of the head 1 taken along line IV-IV in FIG. [Figure 5] 10 is a diagram showing an example of the correspondence between the nozzles N of the head 1 and the pixels arranged in the medium width direction on the medium M, and the drive timing of the drive elements corresponding to each nozzle N. FIG. [Figure 6] 10 is a diagram showing another example of the correspondence between the nozzles N of the head 1 and the pixels arranged in the medium width direction on the medium M, and the drive timing of the drive elements corresponding to each nozzle N. FIG. [Figure 7] 10 is a diagram showing an example of the correspondence between the nozzles N of the head 1 according to the second embodiment of the present invention and the pixels arranged in the medium width direction on the medium M, and the drive timing of the drive elements corresponding to each nozzle N. [Figure 8] 10 is a diagram showing an example of the correspondence between the nozzles N of the head 1 according to the third embodiment of the present invention and the pixels arranged in the medium width direction on the medium M, and the drive timing of the drive elements corresponding to each nozzle N. [Figure 9] FIG. 10 is a plan view of a printer 100 according to a fourth embodiment of the present invention. [Figure 10] This shows another example of the correspondence between the nozzles N of the head 1 and the pixels aligned in the transport direction on the medium M, and the drive timing of the drive elements corresponding to each nozzle N, when two ejection processes are performed with one transport process in between. DETAILED DESCRIPTION OF THE INVENTION

[0011] [First embodiment] <Overall configuration of the printer 100> 1, the printer 100 according to the first embodiment of the present invention includes a housing 100a, four head units 1x, a platen 3, a transport mechanism 4, and a controller 5. The four head units 1x, the platen 3, the transport mechanism 4, and the controller 5 are arranged inside the housing 100a. The printer 100 also includes an input unit made up of buttons arranged on the outer surface of the housing 100a.

[0012] The four head units 1x are aligned in the transport direction. The transport direction is the direction in which a medium M, such as paper, is transported by the transport mechanism 4, and is perpendicular to the vertical direction. Each head unit 1x is long in the medium width direction. The medium width direction is the direction along the width of the medium M, and is perpendicular to the vertical direction and the transport direction. Each head unit 1x is a line type that ejects ink onto the medium M while its position is fixed. Each head unit 1x includes, as an example, ten heads 1. The ten heads 1 are arranged in a staggered pattern in the medium width direction.

[0013] The platen 3 is a plate along a plane perpendicular to the vertical direction, and is disposed below the four head units 1x. The medium M is supported on the upper surface of the platen 3.

[0014] The transport mechanism 4 includes two roller pairs 41, 42 and a transport motor 43 shown in FIG. 2. In the transport direction, four head units 1x and a platen 3 are arranged between the two roller pairs 41, 42. When the transport motor 43 is driven under the control of the controller 5, the roller pairs 41, 42 rotate. As the roller pairs 41, 42 rotate, the medium M sandwiched between the roller pairs 41, 42 is transported in the transport direction.

[0015] As shown in FIG. 2, the controller 5 includes a CPU 51, a ROM 52, and a RAM 53.

[0016] 1 and data input from the input unit, the CPU 51 executes various controls in accordance with programs and data stored in the ROM 52 and RAM 53. The external device EX is, for example, a PC.

[0017] The ROM 52 stores programs and data for the CPU 51 to perform various controls. The RAM 53 temporarily stores data used when the CPU 51 executes the programs.

[0018] <Configuration of Head 1> As shown in FIG. 4, the head 1 includes a flow path member 12 and an actuator member 13.

[0019] 3, two supply ports 121 and two return ports 122 are opened on the upper surface 12b of the flow path member 12. The two supply ports 121 and the two return ports 122 are each connected to an ink tank (not shown) via a tube.

[0020] The flow path member 12 has two common flow paths 12A and a plurality of individual flow paths 12B.

[0021] Each common flow path 12A extends in the medium width direction. A supply port 121 is connected to one end of each common flow path 12A in the medium width direction, and a return port 122 is connected to the other end of each common flow path 12A in the medium width direction. The two common flow paths 12A communicate with an ink tank via the two supply ports 121 and the two return ports 122, and also communicate with multiple individual flow paths 12B.

[0022] Each individual flow path 12B is connected to one of the two common flow paths 12A. Each individual flow path 12B includes a nozzle N, a pressure chamber P communicating with the nozzle N, and a connection port C to the common flow path 12A.

[0023] A plurality of nozzles N open to a lower surface 12a of the flow path member 12, and a plurality of pressure chambers P open to an upper surface 12b of the flow path member 12. In a plane perpendicular to the vertical direction, the openings of the nozzles N are substantially circular, and the openings of the pressure chambers P are substantially rectangular. Furthermore, in a plane perpendicular to the vertical direction, the connection ports C also have a substantially circular shape.

[0024] 3, the multiple nozzles N form four nozzle rows NR1, NR2, NR3, and NR4 aligned in the transport direction. Each of the nozzle rows NR1 to NR4 is made up of multiple nozzles N aligned at equal intervals (pitch NP) in the medium width direction.

[0025] In this embodiment, the positions of the nozzles N in the medium width direction are offset between the nozzle rows NR1 and NR2. For example, the positions of the nozzles N in the nozzle row NR2 are offset by half a pitch NP to the left in the medium width direction relative to the nozzles N in the nozzle row NR1. Similarly, the positions of the nozzles N in the nozzle rows NR3 and NR4 are offset in the medium width direction. For example, the positions of the nozzles N in the nozzle row NR4 are offset by half a pitch NP to the left in the medium width direction relative to the nozzles N in the nozzle row NR3.

[0026] The positions of the nozzles N in the medium width direction are also shifted between the nozzle rows NR1 and NR3. For example, the positions of the nozzles N in the nozzle row NR3 are shifted to the left in the medium width direction by 1 / 4 of the pitch NP relative to the nozzles N in the nozzle row NR1. The positions of the nozzles N in the medium width direction are also shifted between the nozzle rows NR2 and NR4 in the same way. For example, the positions of the nozzles N in the nozzle row NR4 are shifted to the left in the medium width direction by 1 / 4 of the pitch NP relative to the nozzles N in the nozzle row NR2.

[0027] 3, the multiple connection ports C also form four connection port rows CR1, CR2, CR3, and CR4 aligned in the conveyance direction. Each of the connection port rows CR1 to CR4 is made up of multiple connection ports C aligned at equal intervals (distance D1) in the medium width direction. Note that distance D1 refers to the distance along a plane parallel to the lower surface 12a of the flow path member 12 between the centers of two connection ports C adjacent in the medium width direction. In this embodiment, distance D1 is, for example, 500 μm.

[0028] The positions of the connection ports C in the medium width direction are offset between connection port rows CR1 and CR2. For example, the positions of the connection ports C in connection port row CR2 are offset by half the distance D1 to the left in the medium width direction relative to the connection ports C in connection port row CR1. The positions of the connection ports C in the medium width direction are also offset between connection port rows CR3 and CR4. For example, the positions of the connection ports C in connection port row CR4 are offset by half the distance D1 to the left in the medium width direction relative to the connection ports C in connection port row CR3.

[0029] The positions of the connection ports C in the two connection port rows CR1 and CR3 are also offset in the medium width direction. For example, the positions of the connection ports C in connection port row CR3 are offset by 1 / 4 of the distance D1 to the left in the medium width direction relative to the connection ports C in connection port row CR1. The positions of the connection ports C in the two connection port rows CR2 and CR4 are also offset in the medium width direction. For example, the positions of the connection ports C in connection port row CR4 are offset by 1 / 4 of the distance D1 to the left in the medium width direction relative to the connection ports C in connection port row CR2.

[0030] In other words, connection port row CR1 is offset rearward and to the right relative to connection port row CR2, and connection port row CR2 is offset forward and to the left relative to connection port row CR1. Similarly, connection port row CR3 is offset rearward and to the right relative to connection port row CR4, and connection port row CR4 is offset forward and to the left relative to connection port row CR3. In the following description, the direction in which connection port rows CR1 and CR2 are offset from each other is referred to as the intersecting direction. The intersecting direction is parallel to the lower surface 12a of the flow path member 12 and intersects with the medium width direction and the conveying direction. Like connection port rows CR1 and CR2, connection port rows CR3 and CR4 are also offset from each other in the intersecting direction.

[0031] Each connection port C constituting connection port row CR1 and each connection port C constituting connection port row CR2 are spaced apart in the intersecting direction by a distance D2. Note that distance D2 refers to the distance along a plane parallel to the lower surface 12a of the flow path member 12 between the centers of two connection ports C adjacent in the intersecting direction. In this embodiment, distance D2 is, for example, 800 μm, which is different from distance D1.

[0032] The ink in the ink tank is supplied to two common flow paths 12A through two supply ports 121 by driving the pump 10 shown in Figure 2 under the control of the controller 5, and is distributed from the two common flow paths 12A to multiple individual flow paths 12B.

[0033] The ink in each individual flow path 12B is ejected as an ink droplet from the nozzle N by reducing the volume of the pressure chamber P by driving the piezoelectric element 13X, which will be described later.

[0034] The ink that moves from one end to the other end in the medium width direction in each common flow path 12A and reaches the return port 122 is returned to the ink tank via a tube.

[0035] 4, the actuator member 13 is fixed to the upper surface 12b of the flow path member 12. The actuator member 13 includes a metallic vibration plate 13A, a piezoelectric layer 13B, and a plurality of individual electrodes 13C.

[0036] The actuator member 13 is formed by sequentially depositing a thin film that will become the piezoelectric layer 13B and a thin film that will become the individual electrode 13C on the upper surface of the diaphragm 13A.

[0037] The vibration plate 13A is disposed on the upper surface 12b of the flow path member 12 so as to cover the multiple pressure chambers P. The piezoelectric layer 13B is disposed on the upper surface of the vibration plate 13A. The individual electrodes 13C are disposed on the upper surface of the piezoelectric layer 13B so as to overlap the pressure chambers P in the vertical direction.

[0038] The portions of the vibration plate 13A and the piezoelectric layer 13B sandwiched between the individual electrodes 13C and the pressure chambers P function as piezoelectric elements 13X. That is, one piezoelectric element 13X is provided for each pressure chamber P. Since each pressure chamber P communicates with one nozzle N, it can be said that one piezoelectric element 13X corresponds to each nozzle N. The piezoelectric elements 13X can be independently deformed in response to the electric potential applied to the individual electrodes 13C.

[0039] The diaphragm 13A and the individual electrodes 13C are electrically connected to a driver IC 14. The driver IC 14 maintains the potential of the diaphragm 13A at ground potential while varying the potential of the individual electrodes 13C. The diaphragm 13A functions as a common electrode shared by the multiple piezoelectric elements 13X. The driver IC 14 generates a drive signal based on a control signal from the controller 5 and supplies the drive signal to the individual electrodes 13C. The drive signal varies the potential of the individual electrodes 13C between a predetermined drive potential and ground potential.

[0040] Next, a method for driving the piezoelectric elements 13X by the controller 5 will be described with reference to Figures 3 and 5. In each ejection cycle (the cycle in which ink droplets are ejected from each nozzle N to form one dot on the medium M), the controller 5 shifts the drive timing of the corresponding piezoelectric element 13X by a predetermined time depending on the arrangement position of the nozzle N on the lower surface 12a of the flow path member 12.

[0041] Specifically, in each ejection cycle, the piezoelectric elements 13X corresponding to the nozzles N not shaded in black in FIG. 5 are driven at a first timing. The nozzles N not shaded in black are the odd-numbered nozzles N from the right in the medium width direction in nozzle row NR1, the odd-numbered nozzles N from the right in the medium width direction in nozzle row NR2, and all the nozzles N constituting nozzle row NR3. Meanwhile, the piezoelectric elements 13X corresponding to the nozzles N shaded in black in FIG. 5 are driven at a second timing that is delayed by a predetermined time from the first timing. The nozzles N shaded in black are the even-numbered nozzles N from the right in the medium width direction in nozzle row NR1, the even-numbered nozzles N from the right in the medium width direction in nozzle row NR2, and all the nozzles N constituting nozzle row NR4. In this embodiment, the delay time is uniform (one type), for example, 2.0 μs. Hereinafter, the piezoelectric element 13X driven at the first timing will also be referred to as a first-driven piezoelectric element 13X, and the piezoelectric element 13X driven at the second timing will also be referred to as a second-driven piezoelectric element 13X.

[0042] The controller 5 drives the leading-driving piezoelectric element 13X without driving the trailing-driving piezoelectric element 13X at a first timing, and drives the trailing-driving piezoelectric element 13X without driving the leading-driving piezoelectric element 13X at a second timing. Note that, in order to shift the drive timing of the leading-driving piezoelectric element 13X and the trailing-driving piezoelectric element 13X, for example, the drive waveform of the drive signal supplied to the leading-driving piezoelectric element 13X and the drive waveform of the drive signal supplied to the trailing-driving piezoelectric element 13X may be changed in one ejection cycle. Specifically, the timing at which the potential of the individual electrode 13C is changed may be changed between the drive waveform of the leading-driving piezoelectric element 13X and the drive waveform of the trailing-driving piezoelectric element 13X.

[0043] Next, the influence of crosstalk between two nozzles N adjacent in the medium width direction will be described using nozzles N11 and N12 shown in FIG. 5 as an example. First, the controller 5 drives the piezoelectric element 13X corresponding to nozzle N11 at a first timing. As described above, the distance D1 between the two connection ports C11 and C12 adjacent in the medium width direction is 500 μm. Therefore, assuming that the speed of the pressure wave in the ink is 500 m / s, the time required for the pressure wave generated by driving the piezoelectric element 13X corresponding to nozzle N11 to travel from the connection port C11 to the connection port C12 is 1.0 μs (= 500 μm / 500 m / s). Then, the controller 5 drives the piezoelectric element 13X corresponding to nozzle N12 at a second timing delayed by 2.0 μs from the first timing. In other words, the controller 5 drives the post-driving piezoelectric element 13X 1.0 [μs] (= 2.0 [μs] - 1.0 [μs]) after the pressure wave caused by driving the pre-driving piezoelectric element 13X reaches the connection port C12. Therefore, in the nozzle N12, the influence of crosstalk occurs corresponding to the effective delay time of 1.0 [μs], which is the actual delay time of 2.0 [μs] minus the arrival time of the pressure wave of 1.0 [μs].

[0044] Next, the influence of crosstalk between two adjacent nozzles N in the intersecting direction will be described using nozzles N31 and N41 shown in FIG. 5 as an example. First, the controller 5 drives the piezoelectric element 13X corresponding to nozzle N31 at a first timing. As described above, the distance D2 between the two adjacent connection ports C31 and C41 in the intersecting direction is 800 μm. Therefore, assuming that the speed of the pressure wave in the ink is 500 m / s, the time required for the pressure wave generated by driving the piezoelectric element 13X corresponding to nozzle N31 to travel from the connection port C31 to the connection port C41 is 1.6 μs (= 800 μm / 500 m / s). Then, the controller 5 drives the piezoelectric element 13X corresponding to nozzle N41 at a second timing delayed by 2.0 μs from the first timing. In other words, the controller 5 drives the post-driving piezoelectric element 13X 0.4 μs (= 2.0 μs - 1.6 μs) after the pressure wave caused by driving the pre-driving piezoelectric element 13X reaches the connection port C41. As a result, in the nozzle N41, the effect of crosstalk occurs corresponding to an effective delay time of 0.4 μs, which is obtained by subtracting the arrival time of the pressure wave, 1.6 μs, from the actual delay time of 2.0 μs.

[0045] In this manner, in this embodiment, the effective delay times can be made different between two nozzles N adjacent in the medium width direction and two nozzles N adjacent in the intersecting direction while maintaining the same actual delay time (one type). As a result, the effects of crosstalk, i.e., the ink droplet ejection speed, ink droplet volume, ink droplet separation state, etc., can be made different between two nozzles N adjacent in the medium width direction and two nozzles N adjacent in the intersecting direction. As shown in FIG. 5 , the multiple nozzles N are arranged at different positions in the medium width direction, and each nozzle N corresponds to one of multiple pixels aligned in the medium width direction on the medium M. This prevents multiple pixels aligned in the medium width direction from corresponding to nozzles with the same effective delay time (i.e., nozzles affected by crosstalk to the same degree). In other words, the pixels on which ink droplets ejected from nozzles affected by crosstalk to the same degree can be dispersed in the medium width direction. As a result, periodic unevenness in the print result can be reduced.

[0046] In the above embodiment, the lower surface 12a of the flow path member 12 is an example of an "ejection surface." The medium width direction is an example of a "first direction," the intersecting direction is an example of a "second direction," and the transport direction is an example of a "third direction." The nozzle N11 is an example of a "first nozzle," the nozzle N12 is an example of a "second nozzle," the nozzle N31 is an example of a "third nozzle," and the nozzle N41 is an example of a "fourth nozzle." The individual flow path 12B communicating with the nozzle N11 is an example of a "first individual flow path," the individual flow path 12B communicating with the nozzle N12 is an example of a "second individual flow path," the individual flow path 12B communicating with the nozzle N31 is an example of a "third individual flow path," and the individual flow path 12B communicating with the nozzle N41 is an example of a "fourth individual flow path." Connection port C11 is an example of a "first connection port," connection port C12 is an example of a "second connection port," connection port C31 is an example of a "third connection port," and connection port C41 is an example of a "fourth connection port." Furthermore, the piezoelectric element 13X corresponding to nozzle N11 is an example of a "first drive element," the piezoelectric element 13X corresponding to nozzle N12 is an example of a "second drive element," the piezoelectric element 13X corresponding to nozzle N31 is an example of a "third drive element," and the piezoelectric element 13X corresponding to nozzle N41 is an example of a "fourth drive element." The actual delay time is an example of a "predetermined time."

[0047] Additionally, nozzle row NR1 is an example of a “first nozzle row,” nozzle row NR2 is an example of a “second nozzle row,” nozzle row NR3 is an example of a “third nozzle row,” and nozzle row NR4 is an example of a “fourth nozzle row.” Nozzle rows NR1 and NR2 are examples of a “first nozzle row group,” and nozzle rows NR3 and NR4 are examples of a “second nozzle row group.”

[0048] In the above embodiment, in each ejection cycle, the piezoelectric element 13X corresponding to the nozzle N that is not painted black in Figure 5 is driven at a first timing, and the piezoelectric element 13X corresponding to the nozzle N that is painted black in Figure 5 is driven at a second timing, but the drive timing of the piezoelectric element 13X is not limited to this.

[0049] 6, the piezoelectric elements 13X corresponding to the non-blackened nozzles N may be driven at a first timing, and the piezoelectric elements 13X corresponding to the blackened nozzles N may be driven at a second timing. The non-blackened nozzles N are the even-numbered nozzles N from the right in the medium width direction of nozzle row NR1, the even-numbered nozzles N from the right in the medium width direction of nozzle row NR2, and all the nozzles N constituting nozzle row NR4. The blackened nozzles N are the odd-numbered nozzles N from the right in the medium width direction of nozzle row NR1, the odd-numbered nozzles N from the right in the medium width direction of nozzle row NR2, and all the nozzles N constituting nozzle row NR3.

[0050] Alternatively, the piezoelectric elements 13X corresponding to the odd-numbered nozzles N from the right in the medium width direction of nozzle row NR1, the odd-numbered nozzles N from the right in the medium width direction of nozzle row NR2, and all the nozzles N constituting nozzle row NR4 may be driven at a first timing, and the piezoelectric elements 13X corresponding to the even-numbered nozzles N from the right in the medium width direction of nozzle row NR1, the even-numbered nozzles N from the right in the medium width direction of nozzle row NR2, and all the nozzles N constituting nozzle row NR3 may be driven at a second timing.

[0051] Alternatively, the piezoelectric elements 13X corresponding to the even-numbered nozzles N from the right in the medium width direction of nozzle row NR1, the even-numbered nozzles N from the right in the medium width direction of nozzle row NR2, and all the nozzles N constituting nozzle row NR3 may be driven at a first timing, and the piezoelectric elements 13X corresponding to the odd-numbered nozzles N from the right in the medium width direction of nozzle row NR1, the odd-numbered nozzles N from the right in the medium width direction of nozzle row NR2, and all the nozzles N constituting nozzle row NR4 may be driven at a second timing.

[0052] In either case, it is possible to prevent consecutive pixels corresponding to nozzles with the same effective delay time (i.e., nozzles affected by the same degree of crosstalk) from being arranged in a row across the width of the medium. In other words, it is possible to disperse the pixels onto which ink droplets ejected from nozzles affected by the same degree of crosstalk land across the width of the medium. As a result, it is possible to reduce the occurrence of periodic unevenness in the print result.

[0053] 5 (hereinafter referred to as "first head 1") and the head 1 (hereinafter referred to as "second head 1") shown in FIG. 6 may be prepared, and the first head 1 and the second head 1 may be arranged in the transport direction. Specifically, the first head 1 and the second head 1 may be arranged in the transport direction so that the positions in the medium width direction of the plurality of nozzles N included in the first head 1 and the positions in the medium width direction of the plurality of nozzles N included in the second head 1 match. In other words, in the medium width direction, the positions of the nozzle rows NR1 of the first head 1 and the nozzle rows NR1 of the second head 1 match, the positions of the nozzle rows NR2 of the first head 1 and the nozzle rows NR2 of the second head 1 match, the positions of the nozzle rows NR3 of the first head 1 and the nozzle rows NR3 of the second head 1 match, and the positions of the nozzle rows NR4 of the first head 1 and the nozzle rows NR4 of the second head 1 match. In this case, one nozzle N included in the first head 1 and one nozzle N included in the second head 1 correspond to each pixel aligned in the medium width direction. A first color of ink may be supplied to the first head 1, and a second color of ink different from the first color may be supplied to the second head 1. In the first head 1, the drive timing of the piezoelectric element 13X corresponding to the nozzle N shaded in black in FIG. 5 may be delayed, and in the second head 1, the drive timing of the piezoelectric element 13X corresponding to the nozzle N shaded in black in FIG. 6 may be delayed. In this case, as can be seen by comparing FIGS. 5 and 6, the nozzle N of the first head 1 and the nozzle N of the second head 1 corresponding to each pixel are affected by crosstalk differently. For example, as shown in FIG. 5, the first pixel from the right in the medium width direction is associated with nozzle N11 of the first head 1, and there is no delay time for nozzle N11 of the first head 1, so it is not affected by crosstalk. 6, the nozzle N11 of the second head 1 also corresponds to the first pixel from the right in the medium width direction, and the effective delay time is 1.0 μs for the nozzle N11 of the second head 1. In other words, the nozzle N11 of the second head 1 is affected by crosstalk (for example, a reduction in the volume of the ink droplet) equivalent to an effective delay time of 1.0 μs.This prevents two color ink droplets ejected from two nozzles N that are affected by the same degree of crosstalk from landing on the same pixel, which would cause the effects of crosstalk to be superimposed on that pixel and make it stand out.

[0054] In the above embodiment, the nozzle rows NR3 and NR4 are each offset by ¼ of the pitch NP to the left in the medium width direction relative to the nozzle rows NR1 and NR2, but this is not limited to this. For example, in FIG. 5, the positions of the nozzles N constituting the nozzle row NR3 in the medium width direction may each match the positions of the nozzles N constituting the nozzle row NR1 in the medium width direction, and the positions of the nozzles N constituting the nozzle row NR4 in the medium width direction may each match the positions of the nozzles N constituting the nozzle row NR2 in the medium width direction. In this case, one of the nozzles N constituting the nozzle rows NR1 and NR2 and one of the nozzles N constituting the nozzle rows NR3 and NR4 correspond to each pixel aligned in the medium width direction. A first color ink may be supplied to the common flow path 12A to which the nozzles N constituting the nozzle rows NR1 and NR2 communicate, and a second color ink different from the first color may be supplied to the common flow path 12A to which the nozzles N constituting the nozzle rows NR3 and NR4 communicate. The drive timing of the piezoelectric elements 13X corresponding to the nozzles N shaded in black in FIG. 5 may be delayed. In this case, too, the effects of crosstalk differ between one nozzle N and the other nozzle N corresponding to each pixel. For example, in Figure 5, nozzle N22 and nozzle N42 correspond to the same pixel. Nozzle N22 is affected by crosstalk equivalent to a real delay time of 1.0 [μs], while nozzle N42 is affected by crosstalk equivalent to a real delay time of 0.4 [μs]. Therefore, if two ink droplets of two colors ejected from two nozzles N affected by crosstalk to the same degree land on the same pixel, the effects of crosstalk will be superimposed on that pixel, preventing that pixel from becoming noticeable.

[0055] [Second embodiment] Next, a second embodiment of the present invention will be described. The head 1 of the second embodiment differs in the number and arrangement of the common flow path 12A, the individual flow paths 12B, and the piezoelectric elements 13X. The following description will focus on the differences from the head 1 of the first embodiment.

[0056] As shown in FIG. 7, the flow path member 12 has four common flow paths 12A and a plurality of individual flow paths 12B.

[0057] Each individual flow path 12B is connected to one of the four common flow paths 12A. Each individual flow path 12B includes a nozzle N, a pressure chamber P communicating with the nozzle N, and a connection port C to the common flow path 12A.

[0058] The multiple nozzles N form eight nozzle rows NR1 to NR8 aligned in the transport direction. Each of the nozzle rows NR1 to NR8 is made up of multiple nozzles N aligned at equal intervals (pitch NP) in the medium width direction.

[0059] In this embodiment, the nozzles N in the nozzle rows NR1 to NR8 are positioned differently in the medium width direction. For example, the nozzles N in the nozzle row NR2 are offset by half a pitch NP to the left in the medium width direction relative to the nozzles N in the nozzle row NR1. The nozzles N in the nozzle row NR4 are offset by half a pitch NP to the left in the medium width direction relative to the nozzles N in the nozzle row NR3.

[0060] In addition, the nozzles N that make up nozzle row NR3 are offset by 1 / 4 of the pitch NP to the left in the medium width direction relative to the nozzles N that make up nozzle row NR1, and the nozzles N that make up nozzle row NR4 are offset by 1 / 4 of the pitch NP to the left in the medium width direction relative to the nozzles N that make up nozzle row NR2.

[0061] Furthermore, the nozzles N that make up the nozzle rows NR5 to NR8 are each offset by 1 / 8 of the pitch NP to the left in the medium width direction relative to the nozzles N that make up the nozzle rows NR1 to NR4.

[0062] In this embodiment, in each ejection cycle, the piezoelectric elements 13X corresponding to the nozzles N that are not shaded in black in FIG. 7 are driven at a first timing. The nozzles N that are not shaded in black are, in other words, the odd-numbered nozzles N from the right in the medium width direction in the nozzle rows NR1 and NR2, the even-numbered nozzles N from the right in the medium width direction in the nozzle rows NR5 and NR6, and all the nozzles N that make up the nozzle rows NR3 and NR8. On the other hand, the piezoelectric elements 13X corresponding to the nozzles N that are shaded in black in FIG. 7 are driven at a second timing that is delayed by a predetermined time from the first timing. The nozzles N that are shaded in black are, in other words, the even-numbered nozzles N from the right in the medium width direction in the nozzle rows NR1 and NR2, the odd-numbered nozzles N from the right in the medium width direction in the nozzle rows NR5 and NR6, and all the nozzles N that make up the nozzle rows NR4 and NR7.

[0063] By driving each piezoelectric element 13X at the above timing, as shown in FIG. 7, it is possible to prevent a series of pixels corresponding to nozzles N with the same effective delay time (i.e., nozzles N affected by the same degree of crosstalk) from appearing in a row among multiple pixels aligned in the width direction of the medium. In other words, it is possible to disperse pixels onto which ink droplets ejected from nozzles N affected by the same degree of crosstalk land in the width direction of the medium. As a result, it is possible to reduce the occurrence of periodic unevenness in the print result. In other words, it is possible to obtain the same effect as in the first embodiment.

[0064] In this embodiment, nozzle row NR5 is an example of a “fifth nozzle row,” nozzle row NR6 is an example of a “sixth nozzle row,” nozzle row NR7 is an example of a “seventh nozzle row,” and nozzle row NR8 is an example of an “eighth nozzle row.” Nozzle rows NR5 and NR6 are examples of a “third nozzle row group,” and nozzle rows NR7 and NR8 are examples of a “fourth nozzle row group.”

[0065] In this embodiment, the nozzle rows NR5 and NR6, and the nozzle rows NR7 and NR8 may not be provided in the flow path member 12 of the head 1. In other words, the flow path member 12 of the head 1 may be provided with the nozzle rows NR1 to NR4 and the nozzle rows NR7 and NR8, or may be provided with the nozzle rows NR1 to NR6.

[0066] Furthermore, the piezoelectric element 13X driven at the first timing in this embodiment may be driven at the second timing, and the piezoelectric element 13X driven at the second timing in this embodiment may be driven at the first timing. In other words, the driving order of the piezoelectric element 13X in this embodiment may be reversed.

[0067] [Third embodiment] Next, a third embodiment of the present invention will be described. The head 1 of the third embodiment also differs from the first embodiment in the number and arrangement of the common flow path 12A, the individual flow paths 12B, and the piezoelectric elements 13X. The following description will focus on the differences from the head 1 of the first embodiment.

[0068] 8, the flow path member 12 of the head 1 has one common flow path 12A and multiple individual flow paths 12B. Each individual flow path 12B is connected to the common flow path 12A. Each individual flow path 12B includes a nozzle N, a pressure chamber P communicating with the nozzle N, and a connection port C to the common flow path 12A.

[0069] The multiple nozzles N form two nozzle rows NR1 and NR2 aligned in the medium width direction. Each of the nozzle rows NR1 and NR2 is composed of multiple nozzles N aligned at equal intervals (pitch NP) in the transport direction. The nozzles N that form the nozzle row NR2 are shifted forward in the transport direction by half the pitch NP relative to the nozzles N that form the nozzle row NR1. Note that in FIG. 8, the distance D3 between the connection port C11 and the connection port C22 is longer than the distance D1 and the distance D2, and is, for example, 1100 μm.

[0070] In this embodiment, in each ejection cycle, the piezoelectric elements 13X corresponding to the nozzles N that are not shaded in black in FIG. 8 are driven at a first timing. The nozzles N that are not shaded in black are the first, third, and fifth to eighth nozzles N from the right in the medium width direction in nozzle row NR1, and the fifth and seventh nozzles N from the right in the medium width direction in nozzle row NR2. On the other hand, the piezoelectric elements 13X corresponding to the nozzles N that are shaded in black in FIG. 8 are driven at a second timing that is delayed by a predetermined time from the first timing. The nozzles N that are shaded in black are the second and fourth nozzles N from the right in the medium width direction in nozzle row NR1, and the first to fourth, sixth, and eighth nozzles N from the right in the medium width direction in nozzle row NR2.

[0071] Here, the influence of crosstalk in two nozzles N positioned as shown in FIG. 8 will be described using nozzles N11 and N22 as an example. First, the controller 5 drives the piezoelectric element 13X corresponding to nozzle N11 at a first timing. As described above, the distance D3 between the two connection ports C11 and C22 is 1100 μm. Therefore, assuming that the speed of the pressure wave in the ink is 500 m / s, the time required for the pressure wave generated by driving the piezoelectric element 13X corresponding to nozzle N11 to travel from the connection port C11 to the connection port C22 is 2.2 μs (= 1100 μm / 500 m / s). Then, the controller 5 drives the piezoelectric element 13X corresponding to nozzle N41 at a second timing delayed by 2.0 μs from the first timing. That is, the controller 5 drives the post-driving piezoelectric element 13X 0.2 μs (= 2.2 μs − 2.0 μs) before the pressure wave caused by driving the pre-driving piezoelectric element 13X reaches the connection port C41. As a result, in the nozzle N22, an effect of crosstalk occurs corresponding to an effective delay time −0.2 μs, which is obtained by subtracting the arrival time of the pressure wave, 2.2 μs, from the actual delay time, 2.0 μs.

[0072] By driving each piezoelectric element 13X at the above timing, as shown in FIG. 8, it is possible to prevent a series of pixels corresponding to nozzles N with the same effective delay time (i.e., nozzles N affected by the same degree of crosstalk) from appearing in a row among multiple pixels aligned in the width direction of the medium. In other words, it is possible to disperse pixels onto which ink droplets ejected from nozzles N affected by the same degree of crosstalk land in the width direction of the medium. As a result, it is possible to reduce the occurrence of periodic unevenness in the print result. In other words, it is possible to obtain the same effect as in the first embodiment.

[0073] In this embodiment, the nozzle N11 is an example of a "first nozzle" and a "third nozzle," the nozzle N12 is an example of a "second nozzle," and the nozzle N21 is an example of a "fourth nozzle."

[0074] [Fourth embodiment] Next, a fourth embodiment of the present invention will be described. As shown in FIG. 9, the printer 100 of the fourth embodiment is a serial printer equipped with a carriage CA carrying multiple heads 1. The printer 100 further includes two guide rails GR extending parallel to one another in the medium width direction, two pulleys PL mounted on one of the guide rails GR, and an endless belt BL looped around the two pulleys PL and connected to the carriage CA. A controller 5 drives a motor (not shown) to rotate the pulley PL. This causes the endless belt BL to travel along the medium width direction, and the carriage CA moves back and forth in the medium width direction in response to the movement of the endless belt BL. In this configuration, multiple heads 1 are aligned in the medium width direction. As shown in FIG. 10, each head 1 has multiple nozzles N aligned in the transport direction. Printing on the medium M is performed by alternately repeating a transport process in which the medium M is transported a predetermined distance in the transport direction and an ejection process in which ink droplets are ejected from the multiple nozzles N of each head 1 while the carriage CA is moved along the medium width direction.

[0075] 10, the flow path member 12 of the head 1 has one common flow path 12A and multiple individual flow paths 12B. Each individual flow path 12B is connected to the common flow path 12A. Each individual flow path 12B includes a nozzle N, a pressure chamber P communicating with the nozzle N, and a connection port C to the common flow path 12A.

[0076] The multiple nozzles N form two nozzle rows NR1 and NR2 aligned in the medium width direction. Each of the nozzle rows NR1 and NR2 is made up of multiple nozzles N aligned at equal intervals (pitch NP) in the transport direction. The nozzles N that form nozzle row NR2 are shifted forward in the transport direction by half the pitch NP relative to the nozzles N that form nozzle row NR1.

[0077] In this embodiment, in each ejection cycle, the piezoelectric elements 13X corresponding to the nozzles N that are not shaded in black in FIG. 10 are driven at a first timing. The nozzles N that are not shaded in black are the first, third, and fourth nozzles N from the rear in the transport direction of the nozzle row NR1, and the first nozzle N from the rear in the transport direction of the nozzle row NR2. On the other hand, the piezoelectric elements 13X corresponding to the nozzles N shaded in black in FIG. 10 are driven at a second timing that is delayed by a predetermined time from the first timing. The nozzles N shaded in black are the second nozzle N from the rear in the transport direction of the nozzle row NR1, and the second, third, and fourth nozzles N from the rear in the transport direction of the nozzle row NR2. Note that FIG. 10 shows the correspondence between the pixels and the nozzles N aligned in the transport direction on the medium M when two ejection processes are performed with one transport process in between.

[0078] By driving each piezoelectric element 13X at the above timing, it is possible to prevent a series of pixels aligned in the transport direction that correspond to nozzles N with the same effective delay time (i.e., nozzles N affected by the same degree of crosstalk). In other words, it is possible to disperse in the transport direction the pixels on which ink droplets ejected from nozzles N affected by the same degree of crosstalk land. As a result, it is possible to reduce the occurrence of periodic unevenness in the print result. In other words, it is possible to obtain the same effect as in the first embodiment.

[0079] In this embodiment, the first to third nozzles N from the rear in the transport direction of nozzle row NR1 are examples of the “first nozzle,” “second nozzle,” and “third nozzle,” respectively, and the third nozzle N from the rear in the transport direction of nozzle row NR2 is an example of the “fourth nozzle.” Furthermore, the transport direction is an example of the “first direction,” and the medium width direction is an example of the “third direction.”

[0080] The above describes the embodiments and modifications of the present invention, but the present invention is not limited to the above-described embodiments and modifications, and various design modifications are possible within the scope of the claims.

[0081] In the above embodiment and modified examples, the controller 5 may change the order of driving the piezoelectric elements 13X at the first timing and the piezoelectric elements 13X at the second timing, as well as the actual delay time, based on predetermined conditions. Examples of predetermined conditions include the printing speed, printing resolution, printing density, the temperature of the printer's operating environment, the back pressure of the ink supply system, and the type and lot of ink. The controller 5 may acquire these conditions as values input from an external device EX or an input unit of the printer 100, or may acquire them from various sensors provided in the printer 100.

[0082] In the above-described embodiment and modified examples, the electrodes constituting the piezoelectric element have a two-layer structure including an individual electrode and a common electrode, but may also have a three-layer structure. For example, a three-layer structure is a structure including a drive electrode to which a high potential or a low potential is selectively applied, a high-potential electrode that is maintained at a high potential, and a low-potential electrode that is maintained at a low potential.

[0083] The medium M is not limited to paper, but may be, for example, a cloth, a substrate, or a plastic.

[0084] The droplets ejected from the nozzles N are not limited to ink droplets. For example, the droplets may be droplets of a treatment liquid that aggregates or precipitates components in the ink.

[0085] The present invention is not limited to printers, but can also be applied to facsimiles, copiers, and multifunction peripherals. The present invention can also be applied to droplet ejection devices used for purposes other than image recording. For example, the present invention can be applied to a droplet ejection device that ejects a conductive liquid onto a substrate to form a conductive pattern. [Explanation of symbols]

[0086] 1 head 5 Controller 12 Flow path member 12A Common flow path 12B Individual flow path 13X Piezoelectric element 100 Printer (droplet ejection device) N nozzle P Pressure chamber C Connection port

Claims

1. A droplet ejection device, a flow path member having an ejection surface on which a plurality of nozzles are opened, a plurality of individual flow paths respectively communicating with the plurality of nozzles, and at least one common flow path communicating with the plurality of individual flow paths; a plurality of drive elements fixed to the flow path member so as to correspond to the plurality of nozzles, respectively; a controller configured to drive the plurality of drive elements; the plurality of nozzles include a first nozzle and a second nozzle adjacent to each other along a first direction parallel to the ejection surface, and a third nozzle and a fourth nozzle adjacent to each other along a second direction parallel to the ejection surface and intersecting the first direction, the plurality of individual flow paths include a first individual flow path communicating with the first nozzle, a second individual flow path communicating with the second nozzle, a third individual flow path communicating with the third nozzle, and a fourth individual flow path communicating with the fourth nozzle, the at least one common flow path has a first connection port to which the first individual flow path is connected, a second connection port to which the second individual flow path is connected, a third connection port to which the third individual flow path is connected, and a fourth connection port to which the fourth individual flow path is connected, the plurality of drive elements include a first drive element corresponding to the first nozzle, a second drive element corresponding to the second nozzle, a third drive element corresponding to the third nozzle, and a fourth drive element corresponding to the fourth nozzle, a distance between the first connection port and the second connection port and a distance between the third connection port and the fourth connection port are different, The controller is configured to drive the first drive element and the third drive element at a first timing without driving the second drive element and the fourth drive element, and to drive the second drive element and the fourth drive element at a second timing that is delayed by a predetermined time from the first timing, without driving the first drive element and the third drive element.

2. the plurality of nozzles form a first nozzle array group and a second nozzle array group that are aligned in a third direction parallel to the ejection surface and perpendicular to the first direction; the first nozzle array group includes a first nozzle array and a second nozzle array that are each formed along the first direction and adjacent to each other in the third direction; the second nozzle array group includes a third nozzle array and a fourth nozzle array that are each formed along the first direction and adjacent to each other in the third direction; the first nozzle row includes a plurality of the first nozzles and a plurality of the second nozzles, In the first nozzle row, the first nozzles and the second nozzles are alternately positioned at predetermined intervals along the first direction, the second nozzle row includes a plurality of the first nozzles and a plurality of the second nozzles, In the second nozzle row, the first nozzles and the second nozzles are alternately positioned at the predetermined intervals along the first direction, the third nozzle row includes a plurality of the third nozzles positioned at the predetermined intervals along the first direction, the fourth nozzle row includes a plurality of the fourth nozzles positioned at the predetermined intervals along the first direction, 2. The droplet ejection device according to claim 1, wherein the positions in the first direction of the plurality of first nozzles and the plurality of second nozzles included in the first nozzle row, the plurality of first nozzles and the plurality of second nozzles included in the second nozzle row, the plurality of third nozzles included in the third nozzle row, and the plurality of fourth nozzles included in the fourth nozzle row are different from each other.

3. the controller is configured to drive the plurality of drive elements to eject droplets from the plurality of nozzles onto a medium; The droplet ejection device according to claim 1 , wherein, on the medium, a pixel corresponding to the second nozzle and a pixel corresponding to the fourth nozzle are adjacent to each other in the first direction.

4. the plurality of nozzles further form at least one of a third nozzle row group and a fourth nozzle row group aligned with the first nozzle row group and the second nozzle row group in the third direction; the third nozzle array group includes a fifth nozzle array and a sixth nozzle array that are each formed along the first direction and are adjacent to each other in the third direction; the fifth nozzle row includes a plurality of the first nozzles and a plurality of the second nozzles, In the fifth nozzle row, the first nozzles and the second nozzles are alternately positioned at the predetermined intervals along the first direction, the sixth nozzle row includes a plurality of the first nozzles and a plurality of the second nozzles, In the sixth nozzle row, the first nozzles and the second nozzles are alternately positioned at the predetermined intervals along the first direction, one of the first nozzles and the second nozzles is located at an end of the first nozzle row and the second nozzle row on one side in the first direction, the other of the first nozzles and the second nozzles is located at an end of the fifth nozzle row and the sixth nozzle row on the one side in the first direction, the fourth nozzle array group includes a seventh nozzle array and an eighth nozzle array that are each formed along the first direction and adjacent to each other in the third direction, the seventh nozzle row includes a plurality of the fourth nozzles positioned at the predetermined intervals along the first direction, the eighth nozzle row includes a plurality of the third nozzles positioned at the predetermined intervals along the first direction, the third nozzle row is adjacent to the fourth nozzle row on one side in the third direction, the seventh nozzle row is adjacent to the eighth nozzle row on the one side in the third direction, 3. The droplet ejection device according to claim 2, wherein the positions in the first direction are different for the plurality of first nozzles and the plurality of second nozzles included in the first nozzle row, the plurality of first nozzles and the plurality of second nozzles included in the second nozzle row, the plurality of third nozzles included in the third nozzle row, the plurality of fourth nozzles included in the fourth nozzle row, the plurality of first nozzles and the plurality of second nozzles included in the fifth nozzle row, the plurality of first nozzles and the plurality of second nozzles included in the sixth nozzle row, the plurality of fourth nozzles included in the seventh nozzle row, and the plurality of third nozzles included in the eighth nozzle row.

5. The droplet ejection device according to claim 4 , wherein the plurality of nozzles form both the third nozzle row group and the fourth nozzle row group.

6. The droplet ejection device according to claim 1 , wherein the first nozzle, the second nozzle, and the third nozzle are positioned on the same straight line along the first direction.

7. The droplet ejection device according to claim 6 , further comprising a carriage that carries the flow path member and the plurality of drive elements and is configured to reciprocate in a third direction that is parallel to the ejection surface and perpendicular to the first direction.

8. the plurality of nozzles further form a third nozzle row group and a fourth nozzle row group aligned with the first nozzle row group and the second nozzle row group in the third direction; the flow path member has, as the at least one common flow path, a first common flow path through which a liquid of a first color flows and a second common flow path through which a liquid of a second color different from the first color flows; the first nozzle array group and the second nozzle array group communicate with the first common flow path; the third nozzle row group and the fourth nozzle row group communicate with the second common flow path; the third nozzle array group includes a fifth nozzle array and a sixth nozzle array that are each formed along the first direction and are adjacent to each other in the third direction, the fifth nozzle row includes a plurality of the first nozzles and a plurality of the second nozzles, In the fifth nozzle row, the first nozzles and the second nozzles are alternately positioned at the predetermined intervals along the first direction, the sixth nozzle row includes a plurality of the first nozzles and a plurality of the second nozzles, In the sixth nozzle row, the first nozzles and the second nozzles are alternately positioned at the predetermined intervals along the first direction, one of the first nozzles and the second nozzles is located at an end of the first nozzle row and the second nozzle row on one side in the first direction, the other of the first nozzles and the second nozzles is located at an end of the fifth nozzle row and the sixth nozzle row on the one side in the first direction, the fourth nozzle array group includes a seventh nozzle array and an eighth nozzle array that are each formed along the first direction and adjacent to each other in the third direction, the seventh nozzle row includes a plurality of the fourth nozzles positioned at the predetermined intervals along the first direction, the eighth nozzle row includes a plurality of the third nozzles positioned at the predetermined intervals along the first direction, the third nozzle row is adjacent to the fourth nozzle row on one side in the third direction, the seventh nozzle row is adjacent to the eighth nozzle row on the one side in the third direction, the first nozzles and the second nozzles included in the first nozzle row, the first nozzles and the second nozzles included in the second nozzle row, the third nozzles included in the third nozzle row, and the fourth nozzles included in the fourth nozzle row are positioned at different positions in the first direction, the plurality of first nozzles and the plurality of second nozzles included in the fifth nozzle row, the plurality of first nozzles and the plurality of second nozzles included in the sixth nozzle row, the plurality of fourth nozzles included in the seventh nozzle row, and the plurality of third nozzles included in the eighth nozzle row are positioned at different positions in the first direction, 3. The droplet ejection device according to claim 2, wherein the first nozzle row and the fifth nozzle row, the second nozzle row and the sixth nozzle row, the third nozzle row and the seventh nozzle row, and the fourth nozzle row and the eighth nozzle row are each positioned at the same position in the first direction.

9. The droplet ejection device according to claim 1, wherein the controller is configured to change at least one of the drive order of the first drive element and the second drive element, the drive order of the third drive element and the fourth drive element, and the predetermined time based on predetermined conditions.

10. the first nozzle and the third nozzle are the same nozzle, the first individual flow path and the third individual flow path are the same individual flow path, the first connection port and the third connection port are the same connection port, The droplet ejection device according to claim 1 , wherein the first drive element and the third drive element are the same drive element.

11. A droplet ejection method using a droplet ejection device, The droplet ejection device includes a flow path member having an ejection surface on which a plurality of nozzles are opened, a plurality of individual flow paths respectively communicating with the plurality of nozzles, and at least one common flow path communicating with the plurality of individual flow paths, and a plurality of drive elements fixed to the flow path member so as to correspond to the plurality of nozzles, respectively; the plurality of nozzles include a first nozzle and a second nozzle adjacent to each other along a first direction parallel to the ejection surface, and a third nozzle and a fourth nozzle adjacent to each other along a second direction parallel to the ejection surface and intersecting the first direction, the plurality of individual flow paths include a first individual flow path communicating with the first nozzle, a second individual flow path communicating with the second nozzle, a third individual flow path communicating with the third nozzle, and a fourth individual flow path communicating with the fourth nozzle, the at least one common flow path has a first connection port to which the first individual flow path is connected, a second connection port to which the second individual flow path is connected, a third connection port to which the third individual flow path is connected, and a fourth connection port to which the fourth individual flow path is connected, the plurality of drive elements include a first drive element corresponding to the first nozzle, a second drive element corresponding to the second nozzle, a third drive element corresponding to the third nozzle, and a fourth drive element corresponding to the fourth nozzle, a distance between the first connection port and the second connection port and a distance between the third connection port and the fourth connection port are different, The method comprises: driving the first drive element and the third drive element without driving the second drive element and the fourth drive element at a first timing; and driving the second drive element and the fourth drive element without driving the first drive element and the third drive element at a second timing delayed by a predetermined time from the first timing.

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