JP5900252B2 - Liquid ejection device - Google Patents

Description

  The present invention relates to a liquid ejecting apparatus that ejects liquid from a nozzle.

  The ink jet head mounted on the printer described in Patent Document 1 includes a flow path unit and a piezoelectric actuator. The flow path unit has an ink flow path including a plurality of nozzles and a plurality of pressure chambers connected to the plurality of nozzles. The piezoelectric actuator includes two piezoelectric layers continuously extending across a plurality of pressure chambers on the upper surface of the flow path unit, a common electrode disposed between the two piezoelectric layers, and a plurality of upper surfaces of the upper piezoelectric layer. And a plurality of individual electrodes formed in a portion facing the pressure chamber. The plurality of nozzles includes nozzles that discharge black ink and nozzles that discharge yellow, cyan, and magenta color inks. The nozzles that eject ink of each color are arranged in one direction. In the printer described in Patent Document 1, text printing or the like is performed using only nozzles that eject black ink, and color images are printed using both nozzles that eject black ink and nozzles that eject color ink. To do.

JP 2011-212901 A

  Here, in a printer as described in Patent Document 1, nozzles that discharge black ink are arranged at a higher density than nozzles that discharge color ink in one direction for the purpose of speeding up text printing. There are things to do. For example, when text printing is performed, printing is performed using all nozzles that eject black ink. On the other hand, when printing a color image, among nozzles that discharge color ink, and among nozzles that discharge black ink, some nozzles arranged at the same density as nozzles that discharge color ink; Print using. That is, when performing color printing, nozzles other than the above-mentioned part of the nozzles that eject black ink are not used. For this reason, in the nozzles that discharge black ink, there is a difference in the usage frequency between the some nozzles and the other nozzles. Thereby, in the piezoelectric layer, a difference occurs in the degree of deterioration of the piezoelectric layer between a portion corresponding to the part of the nozzles and a portion corresponding to the remaining nozzles. As a result, when text printing or the like is performed, there is a possibility that a difference occurs in the ink ejection characteristics between the some nozzles and the remaining nozzles, thereby affecting the image quality of the printed image.

  An object of the present invention is to provide a liquid ejection apparatus capable of reducing a difference in liquid ejection characteristics between nozzles that eject the same type of liquid due to deterioration of a piezoelectric layer.

  The liquid ejection device according to the present invention applies pressure to a plurality of nozzles, a flow path unit including a liquid flow path including a plurality of pressure chambers communicating with the plurality of nozzles, and liquid in the plurality of pressure chambers. A piezoelectric actuator; and a control device that controls the operation of the piezoelectric actuator, wherein the plurality of nozzles are arranged in a predetermined direction and a plurality of first nozzles arranged in a predetermined direction. And a plurality of second nozzles that are displaced from the plurality of first nozzles in the predetermined one direction and that discharge the same type of liquid as the plurality of first nozzles, and The plurality of pressure chambers are connected to the plurality of first nozzles, the plurality of first pressure chambers arranged in the predetermined one direction corresponding to the plurality of first nozzles, and the plurality of second chambers. Connected to the nozzle A plurality of second pressure chambers arranged in the predetermined direction corresponding to the plurality of second nozzles, and the piezoelectric actuator is disposed so as to cover the plurality of pressure chambers A piezoelectric layer; and a plurality of drive electrodes formed on a portion of the piezoelectric layer facing the plurality of pressure chambers, wherein the piezoelectric layer includes at least the first pressure chamber and the first pressure chamber. The controller extends continuously across the second pressure chamber disposed at the closest position, and the control device at least discharges liquid from the first nozzle and the second nozzle; The liquid is discharged from the plurality of nozzles selectively in any one of the second discharge modes in which the liquid is discharged from the first nozzle and the liquid is not discharged from the second nozzle, and the second nozzle In dispensing mode A drive signal is input to the plurality of drive electrodes to deform a first portion of the piezoelectric layer that faces the first pressure chamber, and a second portion of the piezoelectric layer that faces the second pressure chamber. The liquid is ejected from the plurality of first nozzles by deforming the first portion so as to assist the deformation of the first portion within a range where the liquid is not ejected from the second nozzle.

  According to the present invention, the difference in the degree of deterioration between the first portion and the second portion when the liquid is discharged from the nozzle in the second discharge mode can be reduced. Accordingly, it is possible to reduce a difference in liquid discharge characteristics between the first nozzle and the second nozzle when liquid is discharged from the nozzle in the first discharge mode.

1 is a schematic configuration diagram of a printer according to a first embodiment. It is a top view of the inkjet head of FIG. It is the III-III sectional view taken on the line of FIG. FIG. 2 is a block diagram illustrating a hardware configuration of a printer. 6 is a flowchart illustrating processing when recording an image in a printer. It is a figure which shows the drive signal provided to each individual electrode. FIG. 6 is a diagram illustrating an operation when black ink is ejected in a color recording mode in the first embodiment. It is a figure equivalent to FIG. 6 in 2nd Embodiment. FIG. 10 is a diagram illustrating an operation when black ink is ejected in a color recording mode in the second embodiment. FIG. 10 is a diagram illustrating an operation after FIG. 9 when black ink is ejected in the color recording mode in the second embodiment. It is a figure equivalent to FIG. 5 in 3rd Embodiment. FIG. 10 is a diagram corresponding to FIG. 9 in the third embodiment. It is a figure equivalent to FIG. 10 in 3rd Embodiment. 6 is a plan view of an inkjet head according to Modification 1. FIG. FIG. 10 is a diagram corresponding to FIG.

[First Embodiment]
Hereinafter, a preferred first embodiment of the present invention will be described.

  As shown in FIG. 1, the printer 1 according to the first embodiment includes a carriage 2, an inkjet head 3, and a paper transport roller 4. The carriage 2 reciprocates in the scanning direction along the two guide rails 6. In the following description, the right and left sides in the scanning direction shown in FIG.

  The inkjet head 3 is mounted on the carriage 2 and ejects ink from a plurality of nozzles 15a to 15c formed on the lower surface thereof. The paper transport rollers 4 are arranged on both sides of the inkjet head 3 in the paper feed direction orthogonal to the scanning direction, and transport the recording paper P in the paper feed direction. In the printer 1, printing is performed on the recording paper P by ejecting ink from the inkjet head 3 that reciprocates in the scanning direction together with the carriage 2 while transporting the recording paper P in the paper feeding direction by the paper transport roller 4. .

  Next, the inkjet head 3 will be described. As shown in FIGS. 2 and 3, the inkjet head 3 includes a flow path unit 21 and a piezoelectric actuator 22.

  The flow path unit 21 is formed by laminating four plates of a cavity plate 31, a base plate 32, a manifold plate 33, and a nozzle plate. The plates 31 to 33 are made of a metal material such as stainless steel. The nozzle plate 34 is made of a synthetic resin material such as polyimide.

  The cavity plate 31 is formed with a plurality of pressure chambers 10a, 10b, and 10c having a substantially elliptical planar shape with the scanning direction as the longitudinal direction. The plurality of pressure chambers 10a are arranged at a predetermined interval in the paper feeding direction to form a pressure chamber row 9a. The plurality of pressure chambers 10b are arranged at the predetermined intervals in the paper feeding direction on the left side of the pressure chamber row 9a, thereby forming the pressure chamber row 9b. Further, the pressure chamber 10b is shifted from the pressure chamber 10a in the paper feeding direction by a length that is half the predetermined interval. Furthermore, the number of the pressure chambers 10b is one more than the number of the pressure chambers 10a. All the pressure chambers 10a are located between two pressure chambers 10b adjacent to each other in the paper feeding direction. The plurality of pressure chambers 10c are arranged at the predetermined intervals in the paper feeding direction on the right side of the pressure chamber row 9a, thereby forming the pressure chambers 9c. In the cavity plate 31, three such pressure chamber rows 9c are arranged in the scanning direction. In the paper feed direction, the plurality of pressure chambers 10c constituting the three pressure chamber rows 9c are all arranged at the same position as the plurality of pressure chambers 10a.

  The base plate 32 has a plurality of substantially circular through holes 12a to 12c and 13a to 13c corresponding to the pressure chambers 10a to 10c. The plurality of through holes 12a and 13a are opposed to the right end and the left end of the plurality of pressure chambers 10a, respectively. The plurality of through holes 12b and 13b respectively face the left end and the right end of the plurality of pressure chambers 10b. The plurality of through holes 12c and 13c are opposed to the right end and the left end of the plurality of pressure chambers 10c, respectively.

  The manifold plate 33 is provided with a manifold channel 11a provided corresponding to the pressure chamber row 9a, a manifold channel 11b provided corresponding to the pressure chamber row 9b, and three pressure chambers 9c. The three manifold channels 11c thus formed are formed. The manifold channels 11a to 11c extend in the paper feeding direction. It faces the substantially right half of the plurality of pressure chambers 10a. The manifold channel 11b faces the substantially left half of the plurality of pressure chambers 10b. Further, the manifold channel 11a and the manifold channel 11b are connected to each other at the downstream end in the paper feeding direction. Black ink is supplied to the manifold channels 11a and 11b from the ink supply port 7B provided in the connection portion. The three manifold channels 11c are opposed to the substantially right half of the plurality of pressure chambers 10c constituting the corresponding pressure chamber row 9c. Color ink is supplied to the manifold channel 11c from the ink supply port 7C connected to the downstream end in the paper feeding direction. Specifically, yellow, cyan, and magenta inks are sequentially supplied from the left ink supply port 7C.

  The manifold plate 33 is formed with a plurality of substantially circular through holes 14a to 14c at portions facing the plurality of through holes 13a to 13c. In the nozzle plate 34, a plurality of nozzles 15a to 15c are formed in portions facing the plurality of through holes 14a to 14c, respectively. Accordingly, the plurality of nozzles 15a to 15c are arranged in the paper feed direction, similarly to the pressure chambers 10a to 10c, thereby forming nozzle rows 8a to 8c.

  The piezoelectric actuator 22 includes an ink separation layer 41, piezoelectric layers 42 and 43, a common electrode 44, a plurality of individual electrodes 45a to 45c, and the like. The ink separation layer 41 is made of a metal material such as stainless steel, and is joined to the upper surface of the cavity plate 31 so as to cover the plurality of pressure chambers 10a to 10c. The ink separation layer 41 is for preventing ink in the pressure chambers 10 a to 10 c from coming into contact with the piezoelectric layer 42.

  The piezoelectric layer 42 is made of a piezoelectric material mainly composed of lead zirconate titanate, which is a mixed crystal of lead titanate and lead zirconate, and straddles the plurality of pressure chambers 10a to 10c on the upper surface of the ink separation layer 41. It extends continuously. The piezoelectric layer 43 is made of the same piezoelectric material as the piezoelectric layer 42, and extends over the entire upper surface of the piezoelectric layer 42. The common electrode 44 extends substantially between the piezoelectric layer 42 and the piezoelectric layer 43. The common electrode 44 is always held at the ground potential by a driver IC 51 (see FIG. 4) described later.

  The plurality of individual electrodes 45a to 45c have a substantially elliptical planar shape that is slightly smaller than the pressure chambers 10a to 10c. The plurality of individual electrodes 45a are arranged on the upper surface of the piezoelectric layer 43 at a portion facing the substantially central portion of the pressure chamber 10a. Further, the right end portion of the individual electrode 45a extends to a portion that does not face the pressure chamber 10a, and the tip end portion serves as a connection terminal 46a. The plurality of individual electrodes 45 b are arranged in a portion facing the substantially central portion of the pressure chamber 10 b on the upper surface of the piezoelectric layer 43. Further, the left end portion of the individual electrode 45b extends to a portion that does not face the pressure chamber 10b, and the tip end portion serves as a connection terminal 46b. The plurality of individual electrodes 45 c are arranged on the upper surface of the piezoelectric layer 43 at a portion facing the substantially central portion of the pressure chamber 10 c. Further, the right end portion of the individual electrode 45c is drawn out to a portion that does not face the pressure chamber 10c, and the tip end portion serves as a connection terminal 46c. A drive signal is input to the plurality of individual electrodes 45a to 45c by a driver IC 51 (see FIG. 4). The drive signals input to the plurality of individual electrodes 45a to 45c will be described in detail later.

  Further, as described above, the piezoelectric layer 43 includes the first portion 43a sandwiched between the individual electrode 45a and the common electrode 44, corresponding to the arrangement of the common electrode 44 and the plurality of individual electrodes 45a to 45c. The second portion 43b sandwiched between the individual electrode 45b and the common electrode 44 and the third portion 43c sandwiched between the individual electrode 45c and the common electrode 44 are each polarized in the thickness direction.

  Next, the hardware configuration of the printer 1 will be described in detail. As shown in FIG. 4, the printer 1 includes a driver IC 51, a carriage motor 52, and a conveyance motor 53 in addition to the above-described carriage 2, inkjet head 3, and paper conveyance roller 4. The driver IC 51 is for driving the inkjet head 3. The carriage motor 52 is for driving the carriage 2. The transport motor 53 is for driving the paper transport roller 4. The printer 1 further includes an operation panel 54. The operation panel 54 includes a display and various operation buttons. The user can input various instructions to the printer 1 by operating the operation buttons on the operation panel 54.

  In addition, the printer 1 includes a receiving device 55, a reading device 56, and a control device 57. The receiving device 55 is an interface for receiving various data transmitted from the external device 61 such as a PC to the printer 1. Specifically, a known network card, USB device controller, or the like. The reading device 56 is a controller for reading data stored in an external memory 62 such as a memory card. Specifically, a known memory controller, a USB host controller, or the like.

  The control device 57 includes various control circuits including a central processing unit (CPU), a read only memory (ROM), a random access memory (RAM), and an application specific integrated circuit (ASIC). The control device 57 performs various processes such as a recording control process, an image data acquisition process, a mode information acquisition process, and a mode determination process in accordance with various programs stored in a memory such as a ROM or a RAM.

  The recording control process is a process for controlling operations of the driver IC 51, the carriage motor 52, the conveyance motor 53, and the like when the printer 1 records an image. The control device 57 controls the driver IC 51, the carriage motor 52, the conveyance motor 53, and the like to selectively record an image in any one of a monochrome recording mode and a color recording mode described later.

  The image data acquisition process is a process in which the control device 57 acquires the image data transmitted from the external device 61 to the printer 1 via the reception device 55. Here, the external device 61 creates image data that can be printed by the printer 1 and transmits the image data to the printer 1, for example, when the user gives an instruction to print a desired electronic file. The mode information acquisition process is a process for acquiring mode information indicating in which recording mode the image is to be recorded on the recording paper P. The control device 57 acquires mode information via the above-described receiving device 55. Here, the mode information is, for example, data created by the printer driver of the external device 61 automatically or in response to user selection. The mode determination process is a process for determining in which recording mode an image is to be recorded on the recording paper P based on the acquired mode information.

  In the printer 1, when the receiving device 55 receives an image recording instruction, the control device 57 starts the printing process shown in FIG. When the printing process is started, the control device 57 performs an image data acquisition process and a mode information acquisition process (S101). Then, after acquiring image data and mode information, the control device 57 performs mode determination processing (S102). Then, after determining in which recording mode the image data is to be recorded, a recording control process corresponding to the determined recording mode is performed (S103).

  Next, the operation of the piezoelectric actuator 22 when recording an image in the monochrome recording mode will be described. The monochrome recording mode is a mode for recording a monochrome image on the recording paper P by discharging black ink from the nozzles 15a and 15b.

  In the monochrome recording mode, as shown in FIG. 6A, the potentials of the individual electrodes 45a and 45b are held at a predetermined positive potential Vr in advance. As a result, an electric field in the thickness direction parallel to the polarization direction is generated in the first portion 43a and the second portion 43b of the piezoelectric layer 43 due to the potential difference between the individual electrodes 45a and 45c and the common electrode 44, respectively. Accordingly, the first portion 43a and the second portion 43b are contracted in the horizontal direction, and the drive portions 47a and 47b which are portions facing the pressure chambers 10a and 10b of the piezoelectric layers 42 and 43 and the ink separation layer 41 as a whole, The pressure chambers 10a and 10b are deformed to be convex.

  When ink is ejected from a certain nozzle 15a, as shown in FIG. 6A, the potential of the corresponding individual electrode 45a is switched to the ground potential at a predetermined timing T11, and then a timing T12 when a predetermined time elapses. Then, a drive signal instructing to return the potential of the individual electrode 45a to the potential Vr is input to the individual electrode 45a. When the potential of the individual electrode 45a is switched to the potential Vr, the potentials of the individual electrode 45a and the common electrode 44 become the same, and the first portion 43a extends to the state before contraction. As a result, the degree of deformation of the drive unit 47a is reduced, and the volume of the pressure chamber 10a is increased. As a result, the pressure in the pressure chamber 10a decreases, and ink is supplied from the manifold channel 11a to the pressure chamber 10a.

  After that, when the potential of the individual electrode 45a is returned to the potential Vr at timing T12, the drive unit 47a is deformed again, and the volume of the pressure chamber 10a is reduced. As a result, the pressure in the pressure chamber 10a increases, and ink is ejected from the nozzle 15a communicating with the pressure chamber 10a. On the other hand, when ink is ejected from the nozzle 15b, the same drive signal as described above is input to the individual electrode 45b.

  Next, the operation of the piezoelectric actuator 22 when recording an image in the color recording mode will be described. The color recording mode is a recording mode for recording a color image on the recording paper P by ejecting black ink from only the nozzle 15a of the nozzles 15a and 15b and ejecting color ink from the nozzle 15c.

  In the color recording mode, the potentials of all the individual electrodes 45c are previously held at the above-described potential Vr, and the potentials of all the individual electrodes 45a and 45b are previously set to the potential Vs between the ground potential and the potential Vr. Is held in. When color ink is ejected from a certain nozzle 15c, a drive signal as shown in FIG. 6B is input to the corresponding individual electrode 45c, as in the monochrome recording mode. At this time, since the drive signal input to the individual electrode 45c is the same drive signal input to the individual electrodes 45a and 45b in the monochrome recording mode, the configuration of the power supply connected to the control device 57 is simplified. be able to.

  On the other hand, when black ink is ejected from a certain nozzle 15a, as shown in FIG. 6C, the potential of the corresponding individual electrode 45a is switched to the ground potential at the timing T11, and then to the voltage Vs at the timing T12. A drive signal instructing to return is input to the individual electrode 45a. In parallel with this, the potentials of the two individual electrodes 45b corresponding to the individual electrode 45a are switched to the potential Vt between the ground potential and the potential Vs at the timing T13 before the timing T11. A drive signal instructing to return to the potential Vs at timing T14 after timing T12 is input to the two individual electrodes 45b.

  Here, the two individual electrodes 45b corresponding to the individual electrode 45a are arranged on the upstream side of the individual electrode 45a in the paper feeding direction, and the individual electrode 45b closest to the individual electrode 45a and the individual electrode 45a. This is the individual electrode 45b that is disposed on the downstream side in the paper feeding direction and is closest to the individual electrode 45a.

  In the state where the individual electrodes 45a and 45b are held at the potential Vs, as shown in FIG. 7A, the drive units 47a and 47b are deformed so as to protrude toward the pressure chambers 10a and 10b. At this time, since the first portion 43a and the second portion 43b of the piezoelectric layer 43 are contracted in the horizontal direction, the first portion 43a is pulled by the second portion 43b. In addition, the length of the arrow of FIG. 7 has shown the magnitude | size of the force in which the 2nd part 43b pulls the 1st part 43a.

  At the timing T13, when the potential of the individual electrode 45b is switched to Vt, the second portion 43b expands, and the force with which the second portion 43b pulls the first portion 43a is reduced, so the first portion 43a is likely to contract. . That is, the contraction of the first portion 43a is assisted by the extension of the second portion 43b. As a result, as shown in FIG. 7B, the first portion 43a contracts greatly, and the drive unit 47a is in a state of being greatly deformed before switching the potential of the individual electrode 45b. In this state, when the potential of the individual electrode 45a is switched to the ground potential at the timing T11, as shown in FIG. 7C, the degree of deformation of the drive unit 47a is reduced. After that, when the potential of the individual electrode 45a is returned to the potential Vs at the timing T12, the drive unit 47a is deformed again to the state shown in FIG. 7B, and black ink is ejected from the nozzle 15a. Then, after the black ink is ejected from the nozzle 15a, the potential of the individual electrode 45b is returned to the potential Vs, and the state shown in FIG.

  From the above, in the first embodiment, the drive unit 47a has a higher potential than the case where the potential of the individual electrode 45a is switched between the potential Vs and the ground potential while the potential of the individual electrode 45b is held at the potential Vs. The width of deformation increases. Therefore, the volume of ink ejected from the nozzle 15a can be increased.

  At this time, the potential of the individual electrode 45c is switched between the ground potential and the potential Vr, whereas the potential of the individual electrode 45a is switched between the ground potential and the potential Vs lower than the potential Vr. Even so, the volume of the black ink ejected from the nozzle 15a and the volume of the color ink ejected from the nozzle 15c can be made comparable. As a result, the deterioration of the first portion 43a can be suppressed as compared with the case where the potential of the individual electrode 45a is switched between the ground potential and the potential Vr.

  On the other hand, in the monochrome recording mode, since the potential of the individual electrode 45b provided corresponding to the nozzle 15b that does not eject ink is switched between the potential Vs and the potential Vt, the potential of the individual electrode 45b is kept at the potential Vs. The second portion 43b is deteriorated as compared with the case of making it.

  From the above, when the image is recorded in the second recording mode, the difference in the degree of deterioration between the first portion 43a and the second portion 43b becomes small. Thereby, when an image is recorded in the monochrome recording mode, it is possible to prevent a large difference in the ink ejection characteristics between the nozzle 15a and the nozzle 15b, thereby affecting the image quality.

  In the first embodiment, since one pressure chamber 10a is arranged between two adjacent pressure chambers 10b in the paper feeding direction, black ink is ejected from which nozzle 10a in the color recording mode. Sometimes, the contraction of the first portion 43a can be equally assisted by changing the potential of the corresponding two individual electrodes 45b as described above to deform the second portion 43b.

  In the first embodiment, the connection terminal 46a is arranged on the side opposite to the pressure chamber row 9b of the individual electrode 45a, and the connection terminal 46b is arranged on the side opposite to the pressure chamber row 9a of the individual electrode 45b. . For this reason, the connection terminals 46a and 46b do not exist between the pressure chamber row 9a and the pressure chamber row 9b. Therefore, the pressure chamber 10a and the pressure chamber 10b, that is, the first portion 43a and the second portion 43b can be arranged close to each other in the scanning direction. Thereby, the contraction of the first portion 43a can be efficiently assisted by the deformation of the second portion 43b.

  At this time, when the potential of the individual electrode 45b is switched, the drive unit 47b is deformed, and the pressure of the ink in the pressure chamber 10b is changed. However, since the potential Vt is a potential between the potential Vs and the ground potential, the change width of the potential of the individual electrode 45b is smaller than the change width of the potential of the individual electrode 45a. Therefore, the width of deformation of the drive unit 47b is small, and the second portion 43b can be deformed within a range where ink is not ejected from the nozzle 15b.

  In the first embodiment, the nozzles 15a, 15b, and 15c correspond to the first, second, and third nozzles according to the present invention, respectively. Further, the pressure chambers 10a, 10b, and 10c correspond to the first, second, and third pressure chambers according to the present invention, respectively. The potentials Vs, Vt, and Vr correspond to the first potential, the second potential, and the third potential according to the present invention, respectively. The ground potential corresponds to the reference potential according to the present invention. The monochrome recording mode and the color recording mode correspond to the first discharge mode and the second discharge mode according to the present invention, respectively. The same applies to the second and third embodiments described below.

[Second Embodiment]
Next, a preferred second embodiment of the present invention will be described. Since the second embodiment differs from the first embodiment only in the operation of the piezoelectric actuator 22 when discharging black ink from the nozzles 15a in the color recording mode, the operation of the piezoelectric actuator 22 at this time will be described below. explain.

  In the second embodiment, in the color recording mode, the potentials of all the individual electrodes 45c are previously held at the potential Vr, and the potentials of all the individual electrodes 45a and 45b are previously held at the potential Vs. . When black ink is ejected from a certain nozzle 15a, as shown in FIG. 8A, the potential of the corresponding individual electrode 45a is switched to the ground potential at a predetermined timing T21, and then to the potential Vs at timing T22. A drive signal instructing to return is input to the individual electrode 45a.

  In parallel with this, as shown in FIG. 8B, the potentials of the two individual electrodes 45b corresponding to the individual electrode 45a are switched to the ground potential at the timing T23 before the timing T21, and A drive signal instructing to return to the potential Vs at the timing T21 is input to the two individual electrodes 45b. Here, the timing T23 is such that the time between the timings T23 and T21 is shorter than the minimum falling time, which is the minimum time required to switch the potential of the individual electrode 45b from the potential Vs to the ground potential. Is set. Therefore, the potential of the individual electrode 45b is actually returned to the potential Vs before reaching the ground potential, as indicated by a broken line in FIG. 8B.

  Further, as shown in FIG. 8B, the potential of the two individual electrodes 45b is switched to the ground potential at a timing T24 before the timing T22, and the potential Vs at a timing T25 after the timing T22. A drive signal instructing to return to is input to the two individual electrodes 45b. Here, the timings T24 and T25 are set such that the time between the timings T24 and T25 is shorter than the minimum fall time. Therefore, the potential of the individual electrode 45b is actually returned to the potential Vs before reaching the ground potential, as indicated by a broken line in FIG. 8B.

  In a state where the potentials of the individual electrodes 45a and 45b are held at the potential Vs, as shown in FIG. 9A, the drive units 47a and 47b are deformed so as to protrude toward the pressure chambers 10a and 10b. . When a signal instructing to switch the potential of the individual electrode 45b to the ground potential is input at the timing T23, the potential of the individual electrode 45b decreases, and the second portion 43b expands as shown in FIG. 9B. To do.

  When the potential of the individual electrode 45a is switched from the potential Vs to the ground potential at timing T21, the first portion 43a extends to the state before contraction, and as shown in FIG. The degree becomes smaller. At the same time, when the potential of the individual electrode 45b is returned to the potential Vs at the timing T21, the second portion 43b returns to the contracted state. Thereby, the force with which the second portion 43b pulls the first portion 43a is increased, and the first portion 43a is easily extended. That is, the expansion of the first portion 43a is assisted by the contraction of the second portion 43b. Therefore, the degree of deformation of the drive unit 47a is smaller than when the potential of the individual electrode 45a is switched to the ground potential while the individual electrode 45b is held at the potential Vs.

  Further, when a signal instructing switching of the potential from the potential Vs to the ground potential is input to the individual electrode 45b at timing T24, the potential of the individual electrode 45b is lowered. Thereby, as shown to Fig.10 (a), the 2nd part 43b expand | extends and the force in which the 2nd part 43b pulls the 1st part 43a becomes small. In this state, when the potential of the individual electrode 45a is returned to the potential Vs at the timing T22, as shown in FIG. 10B, the drive unit 47a is deformed so as to protrude toward the pressure chamber 10a. At this time, as described above, since the second portion 43b has a small pulling force on the first portion 43a, the first portion 43a is easily contracted. That is, the contraction of the first portion 43a is assisted by the extension of the second portion 43b. Therefore, the amount of deformation of the drive unit 47a is larger than when the potential of the individual electrode 45a is returned to the potential Vs while the individual electrode 45b is held at the potential Vs.

  From the above, in the second embodiment, when the black ink is ejected from the nozzle 15a in the color recording mode, the driving is performed more than when the potential of the individual electrode 45a is switched while the individual electrode 45b is held at the potential Vs. The width of deformation of the portion 47a is increased. As a result, the volume of the black ink ejected from the nozzle 15a increases.

  At this time, as described above, the potential of the individual electrode 45b is returned to the potential Vs before reaching the ground potential. That is, the potential of the individual electrode 45b is switched between a certain potential between the ground potential and the potential Vs and the potential Vs. Thereby, the drive part 47b can be deform | transformed in the range in which black ink is not discharged from the nozzle 15b.

[Third Embodiment]
Next, a preferred third embodiment of the present invention will be described. However, the third embodiment is different from the first and second embodiments only in the operation of the piezoelectric actuator 22 when ink is ejected from the nozzles 15a to 15c. Therefore, the operation of the piezoelectric actuator 22 at this time will be described below. Will be described.

  In the third embodiment, the potentials of all the individual electrodes 45a to 45c are previously held at the ground potential. Then, when black ink is ejected from a certain nozzle 15a in the monochrome recording mode, the potential of the corresponding individual electrode 45a is switched to the potential Vr at a predetermined timing T31 as shown in FIG. At timing T32 after the black ink is ejected from 15a, a drive signal instructing to return the potential of the individual electrode 45a to the ground potential is input to the individual electrode 45a. When the potential of the individual electrode 45a is switched to the potential Vr, the driving unit 47a is deformed so as to protrude toward the pressure chamber 10a. As a result, the volume of the pressure chamber 10a decreases, the pressure of the pressure chamber 10a ink increases, and black ink is ejected from the nozzle 15a connected to the pressure chamber 10a.

  Also, when black ink is ejected from a certain nozzle 15b in the monochrome recording mode and when color ink is ejected from a certain nozzle 15c in the color recording mode, a drive signal as shown in FIG. , And input to the individual electrodes 45b and 45c, respectively.

  On the other hand, when black ink is ejected from a certain nozzle 15a in the color recording mode, the potential of the corresponding individual electrode 45a is switched to the potential Vs at the timing T31 as shown in FIG. A drive signal instructing to return to the ground potential at timing T32 is input to the individual electrode 45a.

  In parallel with this, as shown in FIG. 11C, the potentials of the two individual electrodes 45b corresponding to the individual electrode 45a are switched to the potential Vs at the timing T33 before the timing T31. A drive signal instructing to return to the ground potential at the timing T31 is input to the two individual electrodes 45b. Here, the timing T33 is set so that the time between the timings T33 and T31 is shorter than the minimum rise time, which is the minimum time required to switch the potential of the individual electrode 45b from the ground potential to the potential Vs. Has been. Therefore, the potential of the individual electrode 45b is actually returned to the ground potential before reaching the potential Vs, as indicated by a broken line in FIG.

  Further, as shown in FIG. 11C, the potential of the two individual electrodes 45b is switched to the potential Vs at the timing T34 before the timing T32, and is changed to the ground potential at the timing T35 after the timing T32. A drive signal instructing to return is input to the two individual electrodes 45b. Here, the timings T34 and T35 are set such that the time between the timings T34 and T35 is shorter than the above-described minimum rise time. Therefore, the potential of the individual electrode 45b is actually returned to the potential Vs before reaching the ground potential, as indicated by a broken line in FIG.

  In the state where the potentials of the individual electrodes 45a and 45b are held at the ground potential, as shown in FIG. 12A, the drive units 47a and 47b are almost undeformed. When a signal instructing to switch the potential of the individual electrode 45b to the potential Vs is input at timing T33, the potential of the individual electrode 45b rises and the second portion 43b contracts as shown in FIG. To do.

  At timing T31, when the potential of the individual electrode 45a is switched from the ground potential to the potential Vn, the first portion 43a contracts, and as shown in FIG. 12C, the drive unit 47a protrudes toward the pressure chamber 10a. It transforms to become. At the same time, when the potential of the individual electrode 45b is returned to the ground potential at the timing T31, the second portion 43b expands and the force with which the second portion 43b pulls the first portion 43a decreases. Tends to shrink. That is, the contraction of the first portion 43a is assisted by the extension of the second portion 43b. As a result, the first portion 43a is greatly contracted, and the drive unit 47a is deformed more than when the potential of the individual electrode 45a is switched to the potential Vs while the potential of the individual electrode 45b is held at the ground potential.

  From the above, in the third embodiment, when discharging black ink from the nozzle 15a in the color recording mode, the driving is performed more than when the potential of the individual electrode 45a is switched while the individual electrode 45b is held at the ground potential. The width of deformation of the portion 47a is increased. As a result, the volume of the black ink ejected from the nozzle 15a increases.

  Further, when a signal instructing switching of the potential from the ground potential to the potential Vs is input to the individual electrode 45b at timing T34, the potential of the individual electrode 45b increases as shown in FIG. The second portion 43b contracts, and the force with which the second portion 43b pulls the first portion 43a increases. In this state, when the potential of the individual electrode 45a is returned to the ground potential at the timing T32, as shown in FIG. 13B, the degree of deformation of the drive unit 47a is reduced. At this time, as described above, since the force with which the second portion 43b pulls the first portion 43a is large, the first portion 43a is easily extended. That is, the expansion of the first portion 43a is assisted by the contraction of the second portion 43b. Accordingly, the degree of deformation of the drive unit 47a is smaller than when the potential of the individual electrode 45a is returned to the ground potential while the potential of the individual electrode 45b is held at the ground potential.

  Accordingly, when the black ink is continuously ejected from the same nozzle 15a, the width of deformation of the drive unit 47a is increased. As a result, the volume of the black ink ejected from the nozzle 15a increases.

  At this time, as described above, the potential of the individual electrode 45b is returned to the ground potential before reaching the potential Vs. That is, the potential of the individual electrode 45b is switched between a certain potential between the ground potential and the potential Vs and the potential Vs. Thereby, the drive part 47b can be deform | transformed in the range in which black ink is not discharged from the nozzle 15b.

  Next, modified examples in which various changes are made to the first to third embodiments will be described. However, description of components having the same configurations as those of the first to third embodiments will be omitted as appropriate.

  In the first to third embodiments, the connection terminal 46a is drawn out to the side opposite to the pressure chamber row 9b, and the terminal 46b is drawn out to the side opposite to the pressure chamber row 9a. However, the present invention is not limited to this. . The connection terminal 46a may be drawn out to the pressure chamber 9b side. Further, the connection terminal 46b may be drawn out to the pressure chamber row 9a side.

  In the first to third embodiments, the piezoelectric layers 42 and 43 extend continuously across all the pressure chambers 10a to 10c, but the present invention is not limited to this. The piezoelectric layers 42 and 43 only need to extend continuously across at least the pressure chamber 10a and the pressure chamber 10b disposed closest to the pressure chamber 10a.

  For example, in one modification, as shown in FIG. 14, the pressure chamber rows 9a and the pressure chamber rows 9c of the respective colors are arranged in two rows in the scanning direction, and the right pressure chamber rows 9a, 9c are arranged. The pressure chambers 10a and 10c constituting the left pressure chamber rows 9a and 9c are respectively in the pressure chamber rows 9a and 9c on the downstream side in the paper feeding direction. They are displaced by a length that is half of the interval of 10c. Further, the pressure chamber 10a and the pressure chamber 10c have the same position in the paper feeding direction.

  On the other hand, the pressure chamber row 9b is disposed on the left side of the left pressure chamber row 9a and on the right side of the right pressure chamber row 9a. The pressure chambers 10b constituting the left pressure chamber row 9b are located downstream of the pressure chambers 10a constituting the left pressure chamber row 9a in the paper feeding direction, and the pressure chambers 10a, 10b in each pressure chamber row 9a, 9b. They are arranged by being shifted by a length of a quarter of the interval. The pressure chambers 10b constituting the right pressure chamber row 9b are located downstream of the pressure chambers 10a constituting the right pressure chamber row 9a in the paper feed direction, and the pressure chambers 10a, 10b in each pressure chamber row 9a, 9b. They are arranged by being shifted by a length of a quarter of the interval.

  In the first modification, the piezoelectric layers 42 and 43 are individually arranged for each portion of the upper surface of the ink separation layer 41 facing each pressure chamber 10c. In addition, the piezoelectric layers 42 and 43 are disposed on the upper surface of the ink separation layer 41 in the pressure chamber row 9a and the pressure chamber row 9b adjacent to each other, and the pressure chambers disposed at positions closest to the pressure chambers 10a. It is provided separately for each part extending over 10b.

  Even in this case, the deformation of the first portion 43a is changed by deforming the second portion 43b of the piezoelectric layer 43 in accordance with the deformation of the first portion 43a of the piezoelectric layer 43 corresponding to a certain nozzle 15a. This can be assisted by deformation of the portion 43b.

  In the second and third embodiments, when the black ink is ejected from the nozzle 15a in the color recording mode, the potential of the individual electrode 45a is switched from the potential Vs to the ground potential, and is switched from the ground potential to the potential Vs. In both cases, the potential of the individual electrode 45b is switched in accordance with the switching of the potential of the individual electrode 45a. However, the present invention is not limited to this. The potential of the individual electrode 45b may be switched only when either the potential of the individual electrode 45a is switched from the potential Vs to the ground potential or the ground potential is switched to the potential Vs.

  Further, the drive signal input to the individual electrode 45b when the black ink is ejected from the nozzle 15a in the color recording mode is not limited to that described in the first to third embodiments. Another signal that can deform the second portion 43b so as to assist the deformation of the first portion 43a may be input to the individual electrode 45b.

  In the first to third embodiments, the nozzles 10a and 10b that discharge black ink form the two nozzle rows 8a and 8b. However, the present invention is not limited to this. For example, in another modification (Modification 2), as shown in FIG. 15, the nozzle 15a is the only nozzle that ejects black ink, and the number of nozzles 15c that eject color ink is twice that of the nozzle 15a. They are arranged in the paper feed direction at intervals. In this case, when the portion of the piezoelectric layer facing the pressure chamber 10a is deformed, the portion of the piezoelectric layer facing the pressure chamber 10a adjacent to the pressure chamber 10a in the paper feeding direction may be deformed. .

  In the first to third embodiments, when recording is performed in the monochrome recording mode, the same drive signal that is input to the individual electrode 45c in the color recording mode is input to the individual electrodes 45a and 45b. Is not limited. In the monochrome recording mode, another drive signal may be input to the individual electrodes 45a and 45b.

  In the first to third embodiments, the image can be selectively recorded in any one of the monochrome recording mode and the color recording mode. However, the present invention is not limited to this. For example, the inkjet head includes only nozzles 15a and 15b that discharge black ink, and the high-resolution recording mode records black and white images by discharging black ink from both nozzles 15a and 15b. Alternatively, the black ink may be ejected only from the nozzle 15a, and the image may be selectively recorded in any one of the low-resolution recording modes in which a low-resolution monochrome image is recorded.

  Even in this case, when the image is recorded in the low resolution recording mode, the first portion 43a is assisted by the deformation of the second portion 43b in the same manner as in the first to third embodiments. The difference in the degree of deterioration between the portion 43a and the second portion 43b can be reduced. Therefore, when an image is recorded in the high resolution recording mode, it is possible to prevent a large difference from occurring in the ink ejection characteristics of the nozzle 15a and the nozzle 15b. In this case, the high-resolution recording mode corresponds to the first ejection mode according to the present invention. The low-resolution recording mode corresponds to the second ejection mode according to the present invention.

  In the above example, the example in which the present invention is applied to a printer that records an image on a recording sheet by ejecting ink from nozzles has been described. However, the present invention is not limited to this. The present invention can also be applied to a liquid ejecting apparatus other than a printer that ejects a liquid other than ink.

10a to 10c Pressure chamber 15a to 15c Nozzle 21 Flow path unit 22 Piezoelectric actuator 42, 43 Piezoelectric layer 44 Common electrode 45a to 45c Individual electrode 46a to 46c Connection terminal 57 Controller

Claims (11)

A flow path unit having a liquid flow path including a plurality of nozzles and a plurality of pressure chambers communicating with the plurality of nozzles;
A piezoelectric actuator that applies pressure to the liquid in the plurality of pressure chambers;
A control device for controlling the operation of the piezoelectric actuator,
The plurality of nozzles are:
A plurality of first nozzles arranged at predetermined intervals in a predetermined direction;
A plurality of second nozzles that are arranged in a predetermined direction and that are displaced from the plurality of first nozzles in the predetermined direction and that discharge the same type of liquid as the plurality of first nozzles; Have
The plurality of pressure chambers are:
A plurality of first pressure chambers connected to the plurality of first nozzles and arranged in the predetermined direction corresponding to the plurality of first nozzles;
A plurality of second pressure chambers connected to the plurality of second nozzles and arranged in the predetermined direction corresponding to the plurality of second nozzles;
The piezoelectric actuator is
A piezoelectric layer arranged to cover the plurality of pressure chambers;
A plurality of drive electrodes formed on a portion of the piezoelectric layer facing the plurality of pressure chambers,
The piezoelectric layer continuously extends over at least the first pressure chamber and the second pressure chamber disposed at a position closest to the first pressure chamber,
The controller is
At least one of a first discharge mode in which liquid is discharged from the first nozzle and the second nozzle, and a second discharge mode in which liquid is discharged from the first nozzle and liquid is not discharged from the second nozzle. Selectively ejecting the liquid from the plurality of nozzles,
In the second ejection mode, a drive signal is input to the plurality of drive electrodes,
The first portion of the piezoelectric layer that faces the first pressure chamber is deformed, and the second portion of the piezoelectric layer that faces the second pressure chamber is within a range in which liquid is not discharged from the second nozzle. A liquid ejecting apparatus, wherein the liquid is ejected from the plurality of first nozzles by deforming so as to assist the deformation of the first portion. The number of the plurality of second pressure chambers is greater than the number of the plurality of first pressure chambers,
The plurality of first pressure chambers are all disposed between the two second pressure chambers adjacent to each other in the predetermined direction.
The piezoelectric layer includes at least two second pressure chambers adjacent to each other in the predetermined direction, and the first pressure chamber located between the two second pressure chambers in the predetermined direction. Extending continuously across the three pressure chambers,
The controller is
In the second ejection mode, a drive signal is input to the plurality of drive electrodes,
The second portion corresponding to the two second pressure chambers adjacent to each other is positioned between the two second pressure chambers in the predetermined direction in a range in which liquid is not discharged from the second nozzle. The liquid ejecting apparatus according to claim 1, wherein the liquid ejecting apparatus is deformed so as to assist deformation of the first portion corresponding to the first pressure chamber. The plurality of second pressure chambers are disposed adjacent to one side of the plurality of first pressure chambers in a direction orthogonal to the predetermined one direction,
A plurality of connection terminals connected to the plurality of drive electrodes are formed on the surface of the piezoelectric layer opposite to the flow path unit,
The connection terminal corresponding to the first pressure chamber is arranged to be shifted from the first pressure chamber to the opposite side to the second pressure chamber in a direction orthogonal to the predetermined one direction;
The connection terminal corresponding to the second pressure chamber is arranged to be shifted from the second pressure chamber to the opposite side to the first pressure chamber in a direction orthogonal to the predetermined one direction. The liquid ejection device according to claim 1 or 2. The drive electrode is
A reference electrode held at a predetermined reference potential;
A plurality of individual electrodes individually provided for the pressure chamber,
The reference electrode and the individual electrode sandwich a portion of the piezoelectric layer facing the pressure chamber from the thickness direction,
The control device, in the second discharge mode,
In advance, the potential of the first individual electrode that is the individual electrode corresponding to the first pressure chamber and the potential of the second individual electrode that is the individual electrode corresponding to the second pressure chamber are set to be higher than the reference potential. Hold at a high predetermined first potential,
When discharging liquid from the first nozzle,
A first drive signal instructing to return the first individual electrode to the first potential after switching to the reference potential is input to the first individual electrode,
Prior to switching the potential of the first individual electrode to the reference potential, the potential of the second individual electrode is switched to a predetermined second potential between the first potential and the reference potential. Inputting a second drive signal to the second individual electrode instructing that the potential of the second individual electrode is returned to the first potential after the potential of the first individual electrode is returned to the first potential. The liquid ejection apparatus according to claim 1, wherein the liquid ejection apparatus is a liquid ejection apparatus. The drive electrode is
A reference electrode held at a predetermined reference potential;
A plurality of individual electrodes individually provided for the pressure chamber,
The reference electrode and the individual electrode sandwich a portion of the piezoelectric layer facing the pressure chamber from the thickness direction,
The control device, in the second discharge mode,
In advance, the potential of the first individual electrode that is the individual electrode corresponding to the first pressure chamber and the potential of the second individual electrode that is the individual electrode corresponding to the second pressure chamber are set to be higher than the reference potential. Hold at a high predetermined first potential,
When discharging liquid from the first nozzle,
A first drive signal is input to the first individual electrode to instruct that the potential of the first individual electrode is switched to the reference potential and then returned to the first potential.
Same as switching the potential of the second individual electrode to the reference potential before switching the potential of the first individual electrode to the reference potential, and then switching the potential of the first individual electrode to the reference potential. A second drive signal instructing to return the potential of the second individual electrode to the first potential at a timing is input to the plurality of second individual electrodes,
In the second drive signal, the time from instructing to switch the potential of the second individual electrode to the reference potential until instructing to return to the first potential is the same as the potential of the second individual electrode. 4. The liquid ejection apparatus according to claim 1, wherein the liquid ejection device is shorter than a minimum fall time necessary for switching from the first potential to the reference potential. 5. The drive electrode is
A reference electrode held at a predetermined reference potential;
A plurality of individual electrodes individually provided for the pressure chamber,
The reference electrode and the individual electrode sandwich a portion of the piezoelectric layer facing the pressure chamber from the thickness direction,
The control device, in the second discharge mode,
In advance, the potential of the first individual electrode that is the individual electrode corresponding to the first pressure chamber and the potential of the second individual electrode that is the individual electrode corresponding to the second pressure chamber are set to be higher than the reference potential. Hold at a high predetermined first potential,
When discharging liquid from the first nozzle,
A first drive signal instructing to return the first individual electrode to the first potential after switching to the reference potential is input to the first individual electrode,
Before the potential of the first individual electrode is returned to the first potential, the potential of the second individual electrode is switched to the reference potential, and then the potential of the first individual electrode is returned to the first potential, A second drive signal for instructing to return the potential of the second individual electrode to the first potential is input to the plurality of second individual electrodes;
In the second drive signal, the time from instructing to switch the potential of the second individual electrode to the reference potential until instructing to return to the first potential is the same as the potential of the second individual electrode. 6. The liquid ejection apparatus according to claim 1, wherein the liquid ejection device is shorter than a minimum fall time necessary for switching from the first potential to the reference potential. The drive electrode is
A reference electrode held at a predetermined reference potential;
A plurality of individual electrodes individually provided for the pressure chamber,
The reference electrode and the individual electrode sandwich a portion of the piezoelectric layer facing the pressure chamber from the thickness direction,
The control device, in the second discharge mode,
The potential of the first individual electrode that is the individual electrode corresponding to the first pressure chamber and the potential of the second individual electrode that is the individual electrode corresponding to the second pressure chamber are previously held at the reference potential. Aside,
When discharging liquid from the first nozzle,
A first drive signal is input to the first individual electrode for instructing to return the potential of the first individual electrode to the reference potential after switching to a predetermined first potential higher than the reference potential,
Prior to switching the potential of the first individual electrode to the first potential, the potential of the second individual electrode is switched to the first potential, and then the potential of the first individual electrode is switched to the first potential. A second drive signal instructing to return the potential of the second individual electrode to the reference potential at the same timing as the second individual electrode;
In the second drive signal, the time from instructing to switch the potential of the second individual electrode to the first potential until instructing to return to the reference potential is the same as the potential of the second individual electrode. 4. The liquid ejection apparatus according to claim 1, wherein the liquid ejection device is shorter than a minimum rise time required to switch from the reference potential to the first potential. The drive electrode is
A reference electrode held at a predetermined reference potential;
A plurality of individual electrodes individually provided for the pressure chamber,
The reference electrode and the individual electrode sandwich a portion of the piezoelectric layer facing the pressure chamber from the thickness direction,
The control device, in the second discharge mode,
The potential of the first individual electrode that is the individual electrode corresponding to the first pressure chamber and the potential of the second individual electrode that is the individual electrode corresponding to the second pressure chamber are set to a predetermined reference potential in advance. Keep it,
When discharging liquid from the first nozzle,
A first drive signal is input to the first individual electrode for instructing to return the potential of the first individual electrode to the reference potential after switching to a predetermined first potential higher than the reference potential,
Before the potential of the first individual electrode is returned to the reference potential, the potential of the second electrode is switched to the first potential, and after the potential of the first individual electrode is returned to the reference potential, A second drive signal instructing to return the potential of the two electrodes to the reference potential is input to the plurality of second individual electrodes;
In the second drive signal, the time from instructing to switch the potential of the second individual electrode to the first potential until instructing to return to the reference potential is the same as the potential of the second individual electrode. 8. The liquid ejection apparatus according to claim 1, wherein the liquid ejection device is shorter than a minimum rise time necessary for switching from the reference potential to the first potential. The plurality of nozzles are arranged at the predetermined interval in the predetermined one direction, and a plurality of third nozzles that discharge different types of liquid from the plurality of first nozzles and the plurality of second nozzles. In addition,
The plurality of pressure chambers are connected to the plurality of third nozzles, and further include a plurality of third pressure chambers arranged in the predetermined direction corresponding to the plurality of third nozzles,
In the second discharge mode, liquid is discharged from the plurality of first nozzles and the plurality of third nozzles,
The controller is
In the second discharge mode,
A third drive signal for instructing to switch a potential of the third individual electrode corresponding to the third pressure chamber between a third potential higher than the first potential and the reference potential; The liquid ejecting apparatus according to claim 4, wherein liquid is ejected from the plurality of third nozzles by inputting to the third individual electrode. The plurality of first nozzles and the plurality of second nozzles eject black ink as a liquid,
The liquid ejecting apparatus according to claim 9, wherein the plurality of third nozzles ejects color ink as liquid. The controller is
In the first discharge mode, the same signal as the third drive signal input to the third individual electrode in the second discharge mode is used as the first drive signal and the second drive signal. 11. The liquid ejection apparatus according to claim 9, wherein liquid is ejected from the plurality of first nozzles and the plurality of second nozzles by inputting to the second individual electrode.