JP2023114731A - Liquid discharge device - Google Patents

Abstract

To provide a liquid discharge device improved in discharge characteristics.SOLUTION: The liquid discharge device comprises: a pressure chamber substrate, which is laminated on a first surface of a vibration plate, and has a bulkhead partitioning a pressure chamber communicating with a nozzle for discharging liquid; a piezoelectric element, which is laminated on a second surface of the vibration plate, and has a first active part overlapping with a center of the pressure chamber when viewed in a thickness direction of the vibration plate and a second active part overlapping with the pressure chamber, at a position closer to an outer edge of the pressure chamber than the first active part; a driving signal generating part that generates a first driving signal for driving the first active part and a second driving signal for driving the second active part. The first driving signal includes a first contractile element for contracting a volume of the pressure chamber for each periodic unit period, and the second driving signal includes a second contractile element for contracting the volume of the pressure chamber for unit period. The liquid discharge device executes a contraction process in which a first period during which the first contractile element is supplied to the first acting part and a second period during which the second contractile element is supplied to the second acting part overlap with each other.SELECTED DRAWING: Figure 9

Description

The present disclosure relates to a liquid ejection device.

2. Description of the Related Art A liquid ejecting apparatus typified by a piezo-type inkjet printer generally employs a configuration in which a piezoelectric element is arranged on a vibrating plate that constitutes a part of a wall surface of a pressure chamber that communicates with a nozzle. Here, liquid such as ink is contained in the pressure chamber. By deforming the diaphragm, the piezoelectric element expands or contracts the volume of the pressure chamber, thereby ejecting the liquid from the nozzle.

The piezoelectric element of such a liquid ejection device has, for example, an active portion that overlaps the central portion of the pressure chamber and an active portion that overlaps the end portion of the pressure chamber when viewed in the thickness direction of the diaphragm, as disclosed in Patent Document 1, for example. It may be divided into

JP-A-2000-25225

However, Patent Literature 1 does not disclose specific drive signals for driving the two active portions. Under such circumstances, it is desired to realize a liquid ejecting apparatus having excellent ejection characteristics.

In order to solve the above problems, one aspect of the liquid ejection device according to the present disclosure is a vibration plate having a first surface and a second surface facing in a direction opposite to the first surface; a pressure chamber substrate laminated thereon and having partition walls defining pressure chambers communicating with nozzles for ejecting liquid; and a second active portion overlapping the pressure chamber at a position closer to the outer edge of the pressure chamber than the first active portion; and a first drive driving the first active portion. and a second drive signal for driving the second active section, wherein the first drive signal cycles a first contraction element that contracts the volume of the pressure chamber. the second drive signal includes, for each unit period, a second contraction element for contracting the volume of the pressure chamber for each unit period, and the first contraction element causes the first active A contraction step is performed in which a first period during which the second contraction element is supplied to the second active section overlaps with a second period during which the second contraction element is supplied to the second active section.

Another aspect of the liquid ejecting apparatus according to the present disclosure includes a vibration plate having a first surface and a second surface facing in a direction opposite to the first surface, and a vibration plate laminated on the first surface to eject liquid. a pressure chamber substrate having partitions defining pressure chambers communicating with ejection nozzles; and a first active portion laminated on the second surface and overlapping the center of the pressure chambers when viewed in the thickness direction of the vibration plate. a piezoelectric element having a second active portion overlapping the pressure chamber at a position closer to the outer edge of the pressure chamber than the first active portion; a first drive signal for driving the first active portion; and a drive signal generation unit configured to generate a second drive signal for driving the unit, wherein the first drive signal generates a first period in which a first potential changes to a second potential for each periodic unit period. The second drive signal includes a second period during which the third potential changes to the fourth potential for each unit period, and the first period and the second period overlap each other.

1 is a configuration diagram schematically showing a liquid ejection device according to a first embodiment; FIG. 2 is a diagram showing the electrical configuration of the liquid ejection device according to the first embodiment; FIG. 4 is an exploded perspective view of a head chip; FIG. 4 is a cross-sectional view taken along line AA in FIG. 3; FIG. 4 is a plan view of a head chip; FIG. FIG. 6 is a cross-sectional view taken along line BB in FIG. 5; FIG. 4 is a diagram for explaining a switching circuit; 4 is a diagram for explaining a first drive signal and a second drive signal in the first embodiment; FIG. It is a figure for demonstrating the contraction process in 1st Embodiment. FIG. 4 is a schematic diagram for explaining deformation of a diaphragm due to a first drive signal; FIG. 5 is a schematic diagram for explaining deformation of the diaphragm due to the second drive signal; It is a figure for demonstrating the contraction process in 2nd Embodiment. It is a figure for demonstrating the 1st drive signal and the 2nd drive signal in 3rd Embodiment. It is a figure for demonstrating the contraction process and the expansion process in 3rd Embodiment. It is a figure for demonstrating the contraction process and the expansion process in 4th Embodiment. It is a figure for demonstrating the contraction process, the expansion process, and the damping process in 5th Embodiment. FIG. 12 is a diagram for explaining first drive signals and second drive signals in the sixth embodiment; FIG. It is a figure for demonstrating the contraction process and the expansion process in 6th Embodiment. It is a figure for demonstrating the contraction process and the expansion process in 7th Embodiment. FIG. 21 is a diagram for explaining first drive signals and second drive signals in the eighth embodiment; FIG. FIG. 20 is a diagram for explaining a contraction process, a first expansion process, and a second expansion process in the eighth embodiment; FIG. 21 is a diagram for explaining a contraction process, a first expansion process, and a second expansion process in the ninth embodiment; FIG. 20 is a diagram for explaining a contraction process and an expansion process in the tenth embodiment; 8A and 8B are diagrams for explaining a contraction process and an expansion process in Modification 1; FIG.

Preferred embodiments of the present disclosure will be described below with reference to the accompanying drawings. Note that the dimensions and scale of each part in the drawings are appropriately different from the actual ones, and some parts are shown schematically for easy understanding. Moreover, the scope of the present disclosure is not limited to these forms unless there is a description to the effect that the present disclosure is particularly limited in the following description.

For the sake of convenience, the following description will appropriately use the X-axis, Y-axis, and Z-axis that intersect with each other. Also, hereinafter, one direction along the X axis is the X1 direction, and the opposite direction to the X1 direction is the X2 direction. Similarly, opposite directions along the Y-axis are the Y1 direction and the Y2 direction. Also, directions opposite to each other along the Z axis are the Z1 direction and the Z2 direction. Also, viewing in a direction along the Z-axis may be referred to as "plan view".

Here, typically, the Z axis is the vertical axis, and the Z2 direction corresponds to the downward direction in the vertical direction. However, the Z-axis does not have to be a vertical axis. The X-axis, Y-axis, and Z-axis are typically orthogonal to each other, but are not limited to this, and may intersect at an angle within the range of 80° or more and 100° or less, for example.

1. First Embodiment 1-1. Overall Configuration of Liquid Ejecting Apparatus FIG. 1 is a configuration diagram schematically showing a liquid ejecting apparatus 100 according to the first embodiment. The liquid ejecting apparatus 100 is an inkjet printing apparatus that ejects ink, which is an example of liquid, onto the medium M as droplets. The medium M is typically printing paper. It should be noted that the medium M is not limited to printing paper, and may be a print target made of any material such as a resin film or fabric, for example.

As shown in FIG. 1, the liquid ejection device 100 has a liquid container 10, a control unit 20, a transport mechanism 30, a movement mechanism 40, and a liquid ejection head 50. As shown in FIG.

The liquid container 10 is a container that stores ink. Specific aspects of the liquid container 10 include, for example, a cartridge detachable from the liquid ejection device 100, a bag-like ink pack formed of a flexible film, and an ink tank capable of being replenished with ink. . Any type of ink can be stored in the liquid container 10 .

The control unit 20 includes, for example, a processing circuit such as a CPU (Central Processing Unit) or an FPGA (Field Programmable Gate Array) and a memory circuit such as a semiconductor memory, and controls the operation of each element of the liquid ejecting apparatus 100 .

The transport mechanism 30 transports the medium M in the Y2 direction under the control of the control unit 20 . The moving mechanism 40 reciprocates the liquid ejection head 50 in the X1 direction and the X2 direction under the control of the control unit 20 . In the example shown in FIG. 1, the moving mechanism 40 has a substantially box-shaped carriage 41 that houses the liquid ejection head 50, and an endless transport belt 42 to which the carriage 41 is fixed. The number of liquid ejection heads 50 mounted on the carriage 41 is not limited to one, and may be plural. Further, the liquid container 10 described above may be mounted on the carriage 41 in addition to the liquid ejection head 50 .

Under the control of the control unit 20, the liquid ejection head 50 ejects the ink supplied from the liquid container 10 toward the medium M from each of the plurality of nozzles in the Z2 direction. This ejection is performed in parallel with the transport of the medium M by the transport mechanism 30 and the reciprocating movement of the liquid ejection head 50 by the moving mechanism 40, thereby forming an ink image on the surface of the medium M. FIG.

1-2. Electrical Configuration of Liquid Ejecting Apparatus FIG. 2 is a diagram showing an electrical configuration of the liquid ejecting apparatus 100 according to the first embodiment. The control unit 20 will be described below with reference to FIG. 2, but prior to this, the liquid ejection head 50 will be briefly described.

As shown in FIG. 2, the liquid ejection head 50 has a head chip 51 and a switching circuit 52 .

The head chip 51 has a plurality of piezoelectric elements 51f, and ink is ejected from the nozzles by appropriately driving the plurality of piezoelectric elements 51f. Here, each piezoelectric element 51f includes an active portion P1 that is an example of a “first active portion”, an active portion P2 that is an example of a “second active portion”, and an active portion P2 that is an example of a “third active portion”. and a part P3. The active portion P1 is driven by receiving the supply signal Vin-A. On the other hand, each of the active portions P2 and P3 is driven by receiving the supply signal Vin-B. Details of the head chip 51 will be described later with reference to FIGS. 3 to 6. FIG.

Under the control of the control unit 20, the switching circuit 52 outputs a first drive signal Com-A and a second drive signal Com-B output from the control unit 20 for each of the plurality of piezoelectric elements 51f of the head chip 51. is supplied to each piezoelectric element 51f. The first drive signal Com-A is supplied to the active portion P1 as the supply signal Vin-A. The second drive signal Com-B is supplied to the active portions P2 and P3 as the supply signal Vin-B. Details of the switching circuit 52 will be described later with reference to FIG.

In the example shown in FIG. 2, the number of head chips 51 included in the liquid ejection head 50 is one, but the present invention is not limited to this, and the number of head chips 51 included in the liquid ejection head 50 may be two or more. .

As shown in FIG. 2, the control unit 20 has a control circuit 21, a memory circuit 22, a power supply circuit 23, and a drive signal generation circuit 24, which is an example of a "drive signal generation section."

The control circuit 21 has a function of controlling the operation of each part of the liquid ejecting apparatus 100 and a function of processing various data. The control circuit 21 includes, for example, processors such as one or more CPUs (Central Processing Units). Note that the control circuit 21 may include a programmable logic device such as an FPGA (field-programmable gate array) instead of or in addition to the CPU. Moreover, when the control circuit 21 is composed of a plurality of processors, the plurality of processors may be mounted on different substrates or the like.

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

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

The drive signal generation circuit 24 is a circuit that generates the first drive signal Com-A and the second drive signal Com-B. Specifically, the drive signal generation circuit 24 has, for example, a DA converter circuit and an amplifier circuit. In the drive signal generation circuit 24, the DA conversion circuit converts the waveform designation signal dCom from the control circuit 21 from a digital signal to an analog signal, and the amplifier circuit converts the analog signal using the power supply potential VHV from the power supply circuit 23. A first drive signal Com-A and a second drive signal Com-B are generated by amplification. Here, among the waveforms included in the first drive signal Com-A, the waveform signal actually supplied to the active portion P1 of the piezoelectric element 51f is the aforementioned supply signal Vin-A. Of the waveforms included in the second drive signal Com-B, the signal having the waveform actually supplied to the active portion P2 or the active portion P3 of the piezoelectric element 51f is the aforementioned supply signal Vin-B. The waveform designation signal dCom is a digital signal for defining the waveforms of the first drive signal Com-1 and the second drive signal Com-B.

The control circuit 21 controls the operation of each part of the liquid ejecting apparatus 100 by executing programs stored in the storage circuit 22 . Here, by executing the program, the control circuit 21 generates control signals Sk1 and Sk2, a print data signal SI, a waveform designation signal dCom, and a latch signal LAT as signals for controlling the operation of each part of the liquid ejection apparatus 100. It generates a change signal CNG and a clock signal CLK.

The control signal Sk1 is a signal for controlling driving of the transport mechanism 30 . The control signal Sk2 is a signal for controlling driving of the moving mechanism 40 . The print data signal SI is a digital signal for designating the operating state of the piezoelectric element 51f. The latch signal LAT and the change signal CNG are timing signals that are used together with the print data signal SI and define the ink ejection timing from each nozzle of the head chip 51 . These timing signals are generated, for example, based on the output of the encoder that detects the position of the carriage 41 described above.

1-3. Overall configuration of liquid ejection head

3 is an exploded perspective view of the head chip 51. FIG. 4 is a cross-sectional view taken along the line AA in FIG. 3. FIG. As shown in FIGS. 3 and 4, the head chip 51 includes a channel substrate 51a, a pressure chamber substrate 51b, a nozzle plate 51c, a vibration absorber 51d, a vibration plate 51e, a plurality of piezoelectric elements 51f, a cover 51g, a case 51h and wiring. and a substrate 51i.

Here, a pressure chamber substrate 51b, a vibration plate 51e, a plurality of piezoelectric elements 51f, a case 51h, and a cover 51g are installed in a region located in the Z1 direction from the flow path substrate 51a. On the other hand, a nozzle plate 51c and a vibration absorber 51d are installed in a region located in the Z2 direction from the flow path substrate 51a. Each element of the liquid ejection head 50 is generally a plate-shaped member elongated in the direction along the Y-axis, and is bonded to each other with an adhesive, for example.

As shown in FIG. 3, the nozzle plate 51c is a plate-like member provided with a plurality of nozzles N arranged in a direction along the Y-axis. Each nozzle N is a through hole through which ink passes. The nozzle plate 51c is manufactured, for example, by processing a silicon single crystal substrate by a semiconductor manufacturing technique using a processing technique such as dry etching or wet etching. However, other known methods and materials may be used as appropriate for manufacturing the nozzle plate 51c.

The channel substrate 51a is a plate-like member for forming an ink channel. As shown in FIGS. 2 and 3, the channel substrate 51a is provided with an opening R1, a plurality of supply channels Ra, and a plurality of communication channels Na. The opening R1 is an elongated through-hole extending in the direction along the Y-axis so as to extend continuously over the plurality of nozzles N when viewed from above in the direction along the Z-axis. On the other hand, each of the supply channel Ra and the communication channel Na is a through-hole provided for each nozzle N individually. Each of the plurality of supply channels Ra communicates with the opening R1. The channel substrate 51a is manufactured, for example, by processing a silicon single crystal substrate by semiconductor manufacturing technology, similarly to the nozzle plate 51c described above. However, other known methods and materials may be appropriately used for manufacturing the channel substrate 51a. A part of the supply channel Ra may be formed in the pressure chamber substrate 51b.

The pressure chamber substrate 51b is a plate-like member in which a plurality of pressure chambers C corresponding to a plurality of nozzles N are formed. The pressure chamber C is located between the flow path substrate 51a and the vibration plate 51e, and is a space called a cavity for applying pressure to the ink filled in the pressure chamber C. As shown in FIG. A plurality of pressure chambers C are arranged in a direction along the Y-axis. Each pressure chamber C is composed of holes that open on both sides of the pressure chamber substrate 51b, and has an elongated shape extending in the direction along the X-axis. The end of each pressure chamber C in the X2 direction communicates with the corresponding supply channel Ra. The cross-sectional area of the supply channel Ra is narrower than that of the pressure chamber C, and this portion functions as a channel resistance, so that backflow is suppressed when pressure is applied to the ink. On the other hand, the end of each pressure chamber C in the X1 direction communicates with the corresponding communication channel Na. The pressure chamber substrate 51b, like the nozzle plate 51c described above, is manufactured by processing a silicon single crystal substrate, for example, using a semiconductor manufacturing technique. However, other known methods and materials may be used as appropriate for manufacturing each of the pressure chamber substrates 51b.

A vibration plate 51e is arranged on the surface of the pressure chamber substrate 51b facing the Z1 direction. The diaphragm 51e is an elastically deformable plate-like member. In the example shown in FIG. 4, the diaphragm 51e has a first layer 51e1 that is an elastic film and a second layer 51e2 that is an insulating film, which are laminated in this order in the Z1 direction. The details of the diaphragm 51e will be described with reference to FIG. 6, which will be described later.

A plurality of piezoelectric elements 51f corresponding to different nozzles N or pressure chambers C are arranged on the surface of the vibration plate 51e facing the Z1 direction. Each piezoelectric element 51f is a passive element deformed by the supply of the first drive signal Com-A and the second drive signal Com-B, and has a long shape extending in the direction along the X-axis. The plurality of piezoelectric elements 51f are arranged in the direction along the Y-axis so as to correspond to the plurality of pressure chambers C. As shown in FIG. When the vibration plate 51e vibrates in association with the deformation of the piezoelectric element 51f, the pressure in the pressure chamber C fluctuates and ink is ejected from the nozzle N. Details of the piezoelectric element 51f will be described with reference to FIG. 6, which will be described later.

The case 51h is a case for storing the ink supplied to the plurality of pressure chambers C, and is bonded to the surface of the channel substrate 51a facing the Z1 direction with an adhesive or the like. The case 51h is made of, for example, a resin material and manufactured by injection molding. The case 51h is provided with an accommodating portion R2 and an inlet IH. The accommodation portion R2 is a concave portion having an outer shape corresponding to the opening portion R1 of the channel substrate 51a. The introduction port IH is a through hole that communicates with the housing portion R2. A space defined by the opening R1 and the storage portion R2 functions as a liquid storage chamber R, which is a reservoir for storing ink. Ink from the liquid container 10 is supplied to the liquid storage chamber R through the inlet IH.

The vibration absorber 51d is an element for absorbing pressure fluctuations in the liquid storage chamber R. As shown in FIG. The vibration absorber 51d is, for example, a compliance substrate that is an elastically deformable flexible sheet member. Here, the vibration absorber 51d blocks the opening R1 of the flow path substrate 51a and the plurality of supply flow paths Ra, and constitutes the bottom surface of the liquid storage chamber R. placed in

The cover 51g is a structure that protects the plurality of piezoelectric elements 51f and reinforces the mechanical strength of the pressure chamber substrate 51b and diaphragm 51e. The cover 51g is bonded to the surface of the diaphragm 51e with an adhesive, for example. The cover 51g is provided with recesses that accommodate the plurality of piezoelectric elements 51f.

A wiring substrate 51i is bonded to the surface of the pressure chamber substrate 51b or the diaphragm 51e facing the Z1 direction. The wiring board 51i is a mounting component on which a plurality of wirings for electrically connecting the control unit 20 and the liquid ejection head 50 are formed. The wiring board 51i is, for example, a flexible wiring board such as FPC (Flexible Printed Circuit) or FFC (Flexible Flat Cable). A switching circuit 52 is mounted on the wiring board 51i.

1-4. Details of Diaphragm and Piezoelectric Element FIG. 5 is a plan view of the head chip 51 . FIG. 6 is a cross-sectional view taken along line BB in FIG. In FIG. 5, the plan view shape of the pressure chamber C is indicated by a two-dot chain line. A wall-shaped partition 51b1 extending along the X direction is provided between two adjacent pressure chambers C of the pressure chamber substrate 51b. The partition wall 51b1 partitions the pressure chamber C. As shown in FIG.

In the example shown in FIG. 5, the planar shape of the pressure chamber C is a parallelogram. Such a pressure chamber C having a plan view shape is formed, for example, by anisotropically etching a silicon single crystal substrate having a plane orientation of (110). For example, an aqueous potassium hydroxide solution (KOH) or the like is used as an etchant for the anisotropic etching. Also, in the anisotropic etching, the first layer 51e1 of the vibration plate 51e is used as an etching stop layer. In addition, the planar view shape of the pressure chamber C is not limited to the example shown in FIG. 5, and is arbitrary.

As shown in FIG. 6, the diaphragm 51e has a first surface F1 and a second surface F2 facing in the direction opposite to the first surface F1. In the example shown in FIG. 6, the thickness direction of the diaphragm 51e is the direction along the Z-axis. Therefore, the first surface F1 is the surface of the diaphragm 51e facing the Z2 direction, and the second surface F2 is the surface of the diaphragm 51e facing the Z1 direction. A piezoelectric element 51f is arranged on the second surface F2. A pressure chamber substrate 51b is arranged on the first surface F1.

The diaphragm 51e has a first layer 51e1 and a second layer 51e1, which are laminated in this order in the Z1 direction. The first layer 51e1 is, for example, an elastic film made of silicon oxide (SiO ₂ ). The elastic film is formed, for example, by thermally oxidizing one surface of a silicon single crystal substrate. The second layer 51e1 is an insulating film made of, for example, zirconium oxide (ZrO ₂ ). The insulating film is formed, for example, by forming a zirconium layer by sputtering and thermally oxidizing the layer.

Note that the first layer 51e1 is not limited to silicon oxide, and may be made of other elastic material such as silicon alone. The constituent material of the second layer 51e1 is not limited to zirconium oxide, and may be other insulating materials such as silicon nitride. Another layer such as a metal oxide may be interposed between the first layer 51e1 and the second layer 51e1. In other words, the first layer 51e1 or the second layer 51e1 may be composed of multiple layers that are the same or different from each other. Further, part or all of the diaphragm 51e may be integrally made of the same material as the pressure chamber substrate 51b. Alternatively, the diaphragm 51e may be composed of a single layer of material.

As shown in FIG. 5, the piezoelectric element 51f overlaps the pressure chamber C in plan view. As shown in FIG. 6, the piezoelectric element 51f has a first electrode layer 51f1, a piezoelectric layer 51f2, and a second electrode layer 51f3, which are laminated in this order in the Z1 direction.

It should be noted that another layer such as a layer for enhancing adhesion may be appropriately interposed between the layers of the piezoelectric element 51f or between the piezoelectric element 51f and the vibration plate 51e. A seed layer may be provided between the first electrode layer 51f1 and the piezoelectric layer 51f2. The seed layer has a function of improving the orientation of the piezoelectric layer 51f2 when forming the piezoelectric layer 51f2. The seed layer is made of, for example, titanium (Ti) or a composite oxide having a perovskite structure such as Pb(Fe, Ti)O ₃ . When the seed layer is made of titanium, when the piezoelectric layer 51f2 is formed, the island-shaped Ti serves as crystal nuclei to improve the orientation of the piezoelectric layer 51f2. In this case, the seed layer is formed with a thickness of about 3 nm or more and 20 nm or less by a known film forming technique such as sputtering and a known processing technique using photolithography, etching, or the like. Further, when the seed layer is composed of the composite oxide, the orientation of the piezoelectric layer 51f2 is influenced by the crystal structure of the seed layer when the piezoelectric layer 51f2 is formed. improves. In this case, the seed layer is formed by, for example, forming a composite oxide precursor layer by a sol-gel method or a MOD (metal organic decomposition) method, and then firing and crystallizing the precursor layer.

The first electrode layer 51f1 has individual electrodes 51f1a, 51f1b, and 51f1c for each piezoelectric element 51f. Each of the individual electrodes 51f1a, 51f1b, and 51f1c extends in the direction along the X-axis. The individual electrodes 51f1a, 51f1b, and 51f1c are arranged in a direction along the Y-axis at intervals.

Here, the individual electrode 51f1a is arranged in the central portion of the pressure chamber C in the width direction and overlaps the center of the pressure chamber C in plan view. A first drive signal Com-A is supplied to the individual electrode 51f1a through wiring. On the other hand, the individual electrode 51f1b and the individual electrode 51f1c are each arranged at the end in the width direction of the pressure chamber C in a plan view, and the pressure chamber is positioned closer to the outer edge BD of the pressure chamber C than the individual electrode 51f1a. Overlaps C. A second drive signal Com-B is supplied to each of the individual electrodes 51f1b and 51f1c through wiring.

The first electrode layer 51f1 includes, for example, a first layer made of titanium (Ti), a second layer made of platinum (Pt), and a third layer made of iridium (Ir). , and these are stacked in this order in the Z1 direction. The first electrode layer 51f1 is formed by, for example, a known film forming technique such as sputtering, and a known processing technique using photolithography, etching, and the like.

Here, the aforementioned first layer of the first electrode layer 51f1 functions as an adhesion layer that improves adhesion of the first electrode layer 51f1 to the vibration plate 51e. Although the thickness of the first layer is not particularly limited, it is, for example, about 3 nm or more and 50 nm or less. The constituent material of the first layer is not limited to titanium. For example, chromium may be used instead of titanium.

In addition, platinum forming the second layer and iridium forming the third layer of the first electrode layer 51f1 are both electrode materials with excellent conductivity and have chemical properties close to each other. Therefore, the characteristics of the first electrode layer 51f1 as an electrode can be improved. Although the thickness of the second layer is not particularly limited, it is, for example, about 50 nm or more and 200 nm or less. Although the thickness of the third layer is not particularly limited, it is, for example, about 4 nm or more and 20 nm or less.

Note that the configuration of the first electrode layer 51f1 is not limited to the above example. For example, either the second layer or the third layer described above may be omitted, or a layer made of iridium may be further provided between the first layer and the second layer described above. Also, a layer composed of an electrode material other than iridium and platinum may be used in place of or in addition to the second and third layers. Examples of the electrode material include metal materials such as aluminum (Al), nickel (Ni), gold (Au), and copper (Cu). Two or more of them may be used in combination in the form of a laminate or an alloy.

The piezoelectric layer 51f2 is arranged between the first electrode layer 51f1 and the second electrode layer 51f3. The piezoelectric layer 51f2 has a strip shape extending in the direction along the Y-axis so as to be continuous over the plurality of piezoelectric elements 51f. The piezoelectric layer 51f2 may be provided individually for each piezoelectric element 51f or for each active portion P1, P2, P3.

The piezoelectric layer 51f2 is made of a piezoelectric material having a perovskite crystal structure represented by the general composition formula _ABO3 . Examples of the piezoelectric material include lead titanate (PbTiO ₃ ), lead zirconate titanate (Pb(Zr, Ti)O ₃ ), lead zirconate (PbZrO ₃ ), lead lanthanum titanate ((Pb, La) , TiO ₃ ), lead lanthanum zirconate titanate ((Pb, La) (Zr, Ti) O ₃ ), lead zirconium titanate niobate (Pb (Zr, Ti, Nb) O ₃ ), magnesium titanium zirconium niobate acid lead (Pb(Zr, Ti)(Mg, Nb)O ₃ ) and the like. Among them, lead zirconate titanate is preferably used as the constituent material of the piezoelectric layer 51f2. The piezoelectric layer 51f2 may contain a small amount of other elements such as impurities. Also, the piezoelectric material forming the piezoelectric layer 51f2 may be a non-lead material such as barium titanate.

The piezoelectric layer 51f2 is formed by, for example, forming a piezoelectric precursor layer by a liquid phase method such as a sol-gel method or a MOD (metal organic decomposition) method, and then firing and crystallizing the precursor layer. . Here, the piezoelectric layer 51f2 may be composed of a single layer, but when composed of a plurality of layers, even if the thickness of the piezoelectric layer 51f2 is increased, the characteristics of the piezoelectric layer 51f2 are likely to be improved. There are advantages.

The second electrode layer 51f3 is a strip-shaped common electrode that extends in the direction along the Y-axis so as to be continuous across the plurality of piezoelectric elements 51f. An offset potential VBS is supplied as a predetermined reference voltage to the second electrode layer 51f3.

The second electrode layer 51f3 has, for example, a layer made of iridium (Ir) and a layer made of titanium (Ti), which are stacked in this order in the Z1 direction. The second electrode layer 51f3 is formed by, for example, a known film forming technique such as sputtering, and a known processing technique using photolithography, etching, or the like.

The constituent material of the second electrode layer 51f3 is not limited to iridium and titanium. For example, metal materials such as platinum (Pt), aluminum (Al), nickel (Ni), gold (Au) or copper (Cu). It's okay. In addition, the second electrode layer 51f3 may be configured using one of these metal materials alone, or may be configured by combining two or more of these metal materials in the form of a laminate, an alloy, or the like. . Also, the second electrode layer 51f3 may be composed of a single layer.

The piezoelectric element 51f described above has active portions P1, P2, and P3. The active portion P1 is a portion of the piezoelectric element 51f where the individual electrode 51f1a, the piezoelectric layer 51f2, and the second electrode layer 51f3 all overlap when viewed in the thickness direction of the diaphragm 51e. The active portion P2 is a portion of the piezoelectric element 51f where the individual electrode 51f1b, the piezoelectric layer 51f2, and the second electrode layer 51f3 all overlap when viewed in the thickness direction of the diaphragm 51e. The active portion P3 is a portion of the piezoelectric element 51f where the individual electrode 51f1c, the piezoelectric layer 51f2, and the second electrode layer 51f3 all overlap when viewed in the thickness direction of the diaphragm 51e.

The active portion P1 is arranged between the active portion P2 and the active portion P3. In the example shown in FIG. 6, the active portion P2, the active portion P1, and the active portion P3 are arranged in this order in the Y1 direction. Also, each of the active portions P1, P2, and P3 extends in the direction along the X-axis.

Here, the active portion P1 overlaps the center of the pressure chamber C and does not overlap the outer edge BD of the pressure chamber C when viewed in the thickness direction of the diaphragm 51e. On the other hand, each of the active portion P2 and the active portion P3 overlaps the pressure chamber C at a position closer to the outer edge BD of the pressure chamber C than the active portion P1 when viewed in the thickness direction of the diaphragm 51e. In the example shown in FIG. 6, the active portion P2 and the active portion P3 are arranged across the pressure chamber C and the partition wall 51b1 when viewed in the thickness direction of the diaphragm 51e, and overlap the outer edge BD.

The width W1 of the active portion P1 along the Y axis is smaller than the width of the pressure chamber C along the Y axis, preferably smaller than the width of the pressure chamber C along the Y axis, and the width of the pressure chamber C along the Y axis. 1/2 or more of the width along. Also, the width W2 of the active portion P2 along the Y axis is smaller than the width of the pressure chamber C along the Y axis, preferably less than or equal to half the width of the pressure chamber C along the Y axis. Similarly, the width W3 of the active portion P3 along the Y-axis is smaller than the width of the pressure chamber C along the Y-axis, preferably less than half the width of the pressure chamber C along the Y-axis. Here, width W2 and width W3 may be equal to or different from each other.

1-5. Configuration of Switching Circuit FIG. 7 is a diagram for explaining the switching circuit 52 . The switching circuit 52 will be described below with reference to FIG.

As shown in FIG. 7, the switching circuit 52 is connected to the wiring LHa and the wiring LHb. The wiring LHa is a signal line that transmits the first drive signal Com-A. The wiring LHb is a signal line that transmits the second drive signal Com-B. A wiring LHd is connected to the second electrode layer 51f3 of the piezoelectric element 51f. The wiring LHd is a power supply line to which the offset potential VBS is supplied.

The switching circuit 52 has a plurality of switches SWa and a plurality of switches SWb corresponding to the plurality of piezoelectric elements 51f on a one-to-one basis, and a connection state specifying circuit 52a that specifies the connection state of these switches.

The switch SWa switches between conduction (on) and non-conduction (off) between the wiring LHa for transmitting the first drive signal Com-A and the individual electrode 51f1a of the piezoelectric element 51f. The switch SWb is a switch that switches between conduction (on) and non-conduction (off) between the wiring LHa for transmitting the second drive signal Com-B and the individual electrodes 51f1b and 51f1c of the piezoelectric element 51f. . Each of these switches is, for example, a transmission gate.

The connection state designating circuit 52a designates the ON/OFF state of the plurality of switches SWa and the plurality of switches SWb based on the clock signal CLK, the print data signal SI, the latch signal LAT and the change signal CNG supplied from the control circuit 21. A designation signal SLa is generated.

For example, although not shown, the connection state designation circuit 52a has a plurality of transfer circuits, a plurality of latch circuits, and a plurality of decoders corresponding to the plurality of piezoelectric elements 51f on a one-to-one basis. Among these circuits, the transfer circuit is supplied with the print data signal SI. Here, the print data signal SI includes an individual designation signal for each piezoelectric element 51f, and the individual designation signal is serially supplied. transferred in turn to Also, the latch circuit latches the individual designation signal supplied to the transfer circuit based on the latch signal LAT. The decoder also generates a connection state designation signal SLa based on the individual designation signal, latch signal LAT and change signal CNG.

On/off of the switch SWa and the switch SWb is switched according to the connection state designation signal SLa generated as described above. For example, the switch SWa and the switch SWb are turned on when the connection state designation signal SLa is at high level, and turned off when it is at low level. As described above, the switching circuit 52 supplies part or all of the waveform included in the first drive signal Com-A to the one or more piezoelectric elements 51f selected from the plurality of piezoelectric elements 51f. A, and part or all of the waveform included in the second drive signal Com-B is supplied as the supply signal Vin-B.

1-6. First Drive Signal and Second Drive Signal FIG. 8 is a diagram for explaining the first drive signal Com-A and the second drive signal Com-B in the first embodiment. The vertical axis “voltage” in the upper part of FIG. 8 is the potential difference between the first drive signal Com-A and the offset potential VBS, and the vertical axis “voltage” in the lower part of FIG. 8 is the second drive signal Com-B and the offset potential VBS. It is the potential difference from the potential VBS. The vertical axis “voltage” in the upper part of FIG. 8 may be the potential of the first drive signal Com-A, and the vertical axis “voltage” in the lower part of FIG. 8 may be the potential of the second drive signal Com-B. It may be an electric potential.

As shown in FIG. 8, each of the first drive signal Com-A and the second drive signal Com-B has a waveform that changes for each unit period Tu of a predetermined cycle. The unit period Tu is defined by the aforementioned latch signal LAT and the like, and corresponds to a print cycle in which dots are formed on the medium M by ink from the nozzles N. FIG.

In the example shown in FIG. 8, the first drive signal Com-A has a waveform that uses the intermediate potential Vca as a reference potential and returns from the intermediate potential Vca to the intermediate potential Vca via the potential VHa within the unit period Tu. Here, the intermediate potential Vca is an example of the "first potential" and the "fifth potential", and is a potential equal to or lower than the offset potential VBS, for example. The potential VHa is an example of a "second potential", which is higher than the offset potential VBS and higher than the intermediate potential Vca.

Here, the potential of the first drive signal Com-A is maintained at the intermediate potential Vca for the period P1a, rises from the intermediate potential Vca to the potential VHa for the period P2a, and is maintained at the potential VHa for the period P3a. The potential VHa drops to the intermediate potential Vca over the period P4a, and is maintained at the intermediate potential Vca over the period P5a. The period P2a is an example of the "first period". The period P3a is an example of the "first holding period". The period P4a is an example of the "third period". Note that the period P1a, the period P2a, the period P3a, the period P4a, and the period P5a are included in this order from the start point to the end point of the unit period Tu.

The waveform portion of the period P2a of the first drive signal Com-A described above is the contraction element ESa that causes the volume of the pressure chamber C to contract. The contraction element ESa is an example of the "first contraction element". A waveform portion of the period P3a of the first drive signal Com-A is the retention element ERa, which is an example of the "first retention element." A waveform portion of the period P4a of the first drive signal Com-A is an expansion element EEa that expands the volume of the pressure chamber C. As shown in FIG.

On the other hand, the second drive signal Com-B has a waveform that uses the intermediate potential Vcb as a reference potential and returns from the intermediate potential Vcb to the intermediate potential Vcb via the potential VHb within the unit period Tu. Here, the intermediate potential Vcb is an example of the "third potential" and the "sixth potential", and is, for example, a potential equal to or lower than the offset potential VBS. Potential VHb is an example of a “fourth potential” and is higher than offset potential VBS and higher than intermediate potential Vcb.

Here, the potential of the second drive signal Com-B is maintained at the intermediate potential Vcb for the period P1b, rises from the intermediate potential Vcb to the potential VHb for the period P2b, and is maintained at the potential VHb for the period P3b. Potential VHb drops to intermediate potential Vcb over period P4b, and is maintained at intermediate potential Vcb over period P5b. The period P4b is an example of the "second period". The period P3b is an example of the "second retention period". The period P2b is an example of the "fourth period". Note that the period P1b, the period P2b, the period P3b, the period P4b, and the period P5b are included in this order from the start point to the end point of the unit period Tu.

The waveform portion of the period P2b of the second drive signal Com-B described above is the expansion element EEb that expands the volume of the pressure chamber C. As shown in FIG. A waveform portion of the period P3b of the second drive signal Com-B is a retention element ERb, which is an example of a "second retention element." A waveform portion of the period P4b of the second drive signal Com-B is a contraction element ESb that causes the volume of the pressure chamber C to contract. The contraction element ESb is an example of the "second contraction element".

In this embodiment, the waveforms of the first drive signal Com-A and the second drive signal Com-B are substantially the same. However, the waveforms of the first drive signal Com-A and the second drive signal Com-B are out of phase with each other. Note that "the waveforms are substantially the same" means that the patterns match when waveforms based on electrical noise and errors are removed.

That is, the length of the period P1a of the first drive signal Com-A is longer than the length of the period P1b of the second drive signal Com-B. The length of the period P2a of the first drive signal Com-A and the length of the period P2b of the second drive signal Com-B are equal to each other. The length of the period P3a of the first drive signal Com-A and the length of the period P3b of the second drive signal Com-B are equal to each other. The length of the period P4a of the first drive signal Com-A and the length of the period P4b of the second drive signal Com-B are equal to each other. The length of the period P5a of the first drive signal Com-A is shorter than the length of the period P5b of the second drive signal Com-B.

Note that the waveforms of the first drive signal Com-A and the second drive signal Com-B may be different from each other. However, if the waveforms of the first drive signal Com-A and the second drive signal Com-B are substantially the same, the drive signal generation circuit 24 generates one waveform and supplies it with a phase shift. It may get better. Therefore, there is an advantage that the configuration of the drive signal generation circuit 24 can be simplified as compared with the case where the waveforms of the first drive signal Com-A and the second drive signal Com-B are different from each other.

The start timing of the period P3a of the first drive signal Com-A is later than the end timing of the period P3b of the second drive signal Com-B.

Here, at least part of the period P2a of the first drive signal Com-A and at least part of the period P4b of the second drive signal Com-B temporally overlap each other in the period PS.

In the example shown in FIG. 8, the start timing of the period P2a is after the start timing of the period P4b within the unit period Tu. Accordingly, within the unit period Tu, the end timing of the period P2a is later than the end timing of the period P4b.

1-7. Shrinking Step FIG. 9 is a diagram for explaining the shrinking step SS in the first embodiment. In FIG. 9, the first drive signal Com-A is indicated by a solid line, and the second drive signal Com-B is indicated by a broken line. In the example shown in FIG. 9, potential VHa and potential VHb are equal to each other, and intermediate potential Vca and intermediate potential Vcb are equal to each other.

Note that potential VHa and potential VHb may be different from each other, and intermediate potential Vca and intermediate potential Vcb may be different from each other. However, when the potential VHa and the potential VHb are equal to each other and the intermediate potential Vca and the intermediate potential Vcb are also equal to each other, there is an advantage that the configuration of the drive signal generation circuit 24 can be simplified as compared with the case where they are not equal. .

As described above, after the holding element ERb of the second drive signal Com-B is supplied to the active parts P2 and P3, the holding element ERb of the first drive signal Com-A is supplied to the active part P1 after the period PS. The supply of ERa is started. Here, the contraction process SS is performed in the period PS.

FIG. 10 is a schematic diagram for explaining deformation of the diaphragm 51e by the first drive signal Com-A. FIG. 11 is a schematic diagram for explaining deformation of the diaphragm due to the second drive signal Com-B. In these figures, for convenience of explanation, the illustration of the piezoelectric element 51F is omitted and the diaphragm 51e is schematically shown. 10 and 11, the diaphragm 51e in the natural state, which is the reference state, is indicated by a two-dot chain line. The "natural state of the diaphragm 51e" refers to the state of the diaphragm 51e when no voltage is applied to the piezoelectric element 51f.

When the active portions P1, P2, and P3 are all subjected to voltage application in the direction along the Z-axis, they expand in the direction along the Z-axis and try to contract in the direction orthogonal to the Z-axis. At this time, since the surfaces of the active portions P1, P2, and P3 facing the Z2 direction are fixed to the diaphragm 51e, the amounts of contraction of the surfaces of the active portions P1, P2, and P3 facing the Z2 direction are the same as those of the active portions P1 and P2. , P3 is smaller than the amount of shrinkage of the surface facing the Z1 direction. Therefore, the active portions P1, P2, and P3 are deformed so as to warp in the direction along the Z-axis, and accordingly the diaphragm 51e is also deformed.

Of the two ends of the active portions P2 and P3 in the direction along the Y-axis, the end of the pressure chamber C closer to the partition 511 is restricted in displacement by the partition 511, whereas the pressure chamber C The end of the side remote from the partition wall 511 is less subject to such displacement restriction. Therefore, when the active portions P2 and P3 try to contract in the direction along the Y axis, the ends on the far side are displaced in the Z1 direction. As a result, the diaphragm 51e is deformed so that the first surface F1 becomes concave. Therefore, when the holding element ERb of the second drive signal Com-B is supplied to the active portions P2 and P3, the diaphragm 51e deforms so that the first surface F1 becomes concave as shown in FIG. As a result, the volume of the pressure chamber C expands.

On the other hand, both ends of the active portion P1 in the direction along the Y-axis are located relatively far from the partition 511 of the pressure chamber C, and the displacement is not easily restricted by the partition 511 . Therefore, when the active portion P1 tries to contract in the direction along the Y axis, the diaphragm 51e deforms so that the first surface F1 becomes convex. Therefore, when the holding element ERa of the first drive signal Com-A is supplied to the active portion P1, the diaphragm 51e deforms so that the first surface F1 becomes convex as shown in FIG. As a result, the volume of the pressure chamber C shrinks.

Here, the active portions P2 and P3 return the diaphragm 51e from the state indicated by the solid line in FIG. try to Further, the active part P1 attempts to deform the diaphragm 51e from the state indicated by the two-dot chain line in FIG. do.

In the contraction step SS, when deforming the diaphragm 51e from the state indicated by the two-dot chain line in FIG. You can use the power to return. That is, in the contraction step SS, when the active part P1 deforms the diaphragm 51e from the reference state to the state in which the volume of the pressure chamber C is contracted, the active parts P2 and P3 vibrate from the state in which the volume of the pressure chamber C is expanded. A force can be used to try to return the plate 51e to its normal state. Therefore, the amount of deformation of the diaphragm 51e can be increased compared to a configuration in which only the active portion P1 is driven by the first drive signal Com-A. As a result, ink can be ejected from the nozzles N efficiently.

On the other hand, when the start timing of supply of the contraction element ESa of the first drive signal Com-A to the active portion P1 coincides with or after the end timing of supply to the active portions P2 and P3, the diaphragm 51e is When deforming the diaphragm 51e from the state shown by the two-dot chain line in FIG. 11 to the state shown by the solid line, the force that tries to return the diaphragm 51e from the state shown by the two-dot chain line in FIG. 10 to the state shown by the two-dot chain line is utilized. cannot be obtained, and the above effect cannot be obtained.

As described above, the liquid ejection apparatus 100 includes the vibration plate 51e, the pressure chamber substrate 51b, the piezoelectric element 51f, and the drive signal generation circuit 24, which is an example of the "drive signal generation section." Here, as described above, the diaphragm 51e has the first surface F1 and the second surface F2 facing in the direction opposite to the first surface F1. The pressure chamber substrate 51b is laminated on the first surface F1 and has partition walls 51b1 that define pressure chambers C communicating with nozzles N that eject ink, which is an example of "liquid." The piezoelectric element 51f is laminated on the second surface F2 and has an active portion P1 as an example of a "first active portion" and an active portion P2 as an example of a "second active portion". The active portion P1 overlaps the center of the pressure chamber C when viewed in the thickness direction of the diaphragm 51e. The active portion P2 overlaps the pressure chamber C at a position closer to the outer edge of the pressure chamber C than the active portion P1 when viewed in the thickness direction of the diaphragm 51e. The drive signal generation circuit 24 generates a first drive signal Com-A for driving the active portion P1 and a second drive signal Com-B for driving the active portion P2.

The first drive signal Com-A includes a contraction element ESa, which is an example of a "first contraction element", for each periodic unit period Tu. On the other hand, the second drive signal Com-B includes a contraction element ESb, which is an example of a "second contraction element", for each unit period Tu. Each of the contraction element ESa and the contraction element ESb causes the volume of the pressure chamber C to contract. Then, the liquid ejection device 100 executes the shrinking step SS. The contraction step SS is a period in which a period P2a, which is an example of a "first period", and a period P4b, which is an example of a "second period", overlap each other. During the period P2a, the contraction element ESa is supplied to the active portion P1. During the period P4b, the contraction element ESb is supplied to the active portion P2.

Here, the period P2a is a period during which the intermediate potential Vca, which is an example of the "first potential", changes to the potential VHa, which is an example of the "second potential", in each unit period Tu. A period P4b is a period during which the intermediate potential Vcb, which is an example of the "third potential", changes to the potential VHb, which is an example of the "fourth potential", in each unit period Tu.

In the liquid ejecting apparatus 100 described above, the period P2a and the period P4b overlap each other in the shrinking step SS. You can speed it up. Therefore, it is possible to increase the ejection speed of the ink from the nozzle N and increase the amount of ink ejected from the nozzle N per one ejection. Also, by increasing the displacement speed of the vibration plate 51e, the ink ejection period from the nozzles N can be shortened. As described above, the ejection characteristics of the liquid ejection apparatus 100 can be improved.

Here, as described above, during execution of the contraction step SS, the magnitude relationship between the potentials of the first drive signal Com-A and the second drive signal Com-B is reversed. That is, during the period in which the period P2a and the period P4b overlap each other, the magnitude relationship between the voltages of the first drive signal Com-A and the second drive signal Com-B is reversed.

Furthermore, as described above, in the unit period Tu, the start timing of the contraction element ESa is later than the start timing of the contraction element ESb. That is, in the unit period Tu, the start timing of the period P2a is after the start timing of the period P4b. Therefore, excessive stress is prevented from being generated between the portion of the diaphragm 51e deformed by the active portion P1 and the portion of the diaphragm 51e deformed by the active portion P2. As a result, damage such as cracks in the diaphragm 51e can be reduced.

Also, as described above, in the unit period Tu, the end timing of the contraction element ESa is later than the end timing of the contraction element ESb. Therefore, in the unit period Tu, the start timing of the contraction element ESa can be later than the start timing of the contraction element ESb.

Furthermore, as described above, the piezoelectric element 51f further has an active portion P3, which is an example of a "third active portion". The active portion P3 overlaps the pressure chamber C at a position closer to the outer edge of the pressure chamber C than the active portion P1 when viewed in the thickness direction of the diaphragm 51e. The active portion P1 is located between the active portion P2 and the active portion P3 when viewed in the thickness direction of the diaphragm 51e. Therefore, the active portion P3 can function in the same manner as the active portion P2.

Further, as described above, the piezoelectric element 51f has the first electrode layer 51f1, the piezoelectric layer 51f2, and the second electrode layer 51f3 in this order in the direction away from the vibration plate 51e. The piezoelectric layer 51f2 and the second electrode layer 51f3 are commonly provided over the active portion P1, the active portion P2 and the active portion P3. On the other hand, the first electrode layer 51f1 includes a plurality of individual electrodes 51f1a, 51f1b, 51f1c individually provided in the active portion P1, the active portion P2, and the active portion P3. Therefore, wiring routing can be simplified compared to a configuration in which an individual electrode is provided for each active portion in the second electrode layer 51f3. In addition, compared to the configuration in which the piezoelectric layer 51f2 is divided into active portions, the manufacturing of the piezoelectric layer 51f2 can be simplified.

2. Second Embodiment A second embodiment of the present disclosure will be described below. Below, it demonstrates centering around difference with 1st Embodiment.

FIG. 12 is a diagram for explaining the shrinking step SS in the second embodiment. As shown in FIG. 12, this embodiment is the same as the first embodiment except that the intermediate potential Vcb of the second drive signal Com-B is higher than the intermediate potential Vca of the first drive signal Com-A. is.

The ejection characteristics of the liquid ejecting apparatus 100 can be improved also by the second embodiment described above. In this embodiment, as described above, the intermediate potential Vcb is higher than the intermediate potential Vca. Therefore, by appropriately setting the difference between these potentials, it is possible to adjust the hardness and the like of the diaphragm 51e. As a result, the ejection characteristics of the plurality of head chips 51 can be made uniform even if there are manufacturing variations.

3. Third Embodiment A third embodiment of the present disclosure will be described below. Below, it demonstrates centering around difference with 1st Embodiment.

FIG. 13 is a diagram for explaining the first drive signal Com-A and the second drive signal Com-B in the third embodiment. In the example shown in FIG. 13, the first drive signal Com-A uses the intermediate potential Vca as a reference potential, and returns from the intermediate potential Vca to the intermediate potential Vca via the potential VLa and the potential VHa in this order within the unit period Tu. It has a waveform. The potential VLa is a potential lower than the intermediate potential Vca.

Here, the potential of the first drive signal Com-A is maintained at the intermediate potential Vca for the period P1c, then drops from the intermediate potential Vca to the potential VLa for the period P2c, and is maintained at the potential VLa for the period P3c. After increasing from potential VLa to potential VHa over period P4c and maintained at potential VHa over period P5c, potential falling from potential VHa to intermediate potential Vca over period P6c and maintained at intermediate potential Vca over period P7c. The period P2c is an example of the "third period". The period P4c is an example of the "first period". Note that the period P1c, the period P2c, the period P3c, the period P4c, the period P5c, the period P6c, and the period P7c are included in this order from the start point to the end point of the unit period Tu.

The waveform portion of the period P2c of the first drive signal Com-A described above is the expansion element EEa1 that expands the volume of the pressure chamber C. As shown in FIG. The expansion element EEa1 is an example of a "first expansion element." The waveform portion of the period P3c of the first drive signal Com-A is the holding element ERa1. A waveform portion of the period P4c of the first drive signal Com-A is a contraction element ESa that causes the volume of the pressure chamber C to contract. The contraction element ESa is an example of the "first contraction element". The waveform portion of the period P5c of the first drive signal Com-A is the holding element ERa2. The waveform portion of the period P6c of the first drive signal Com-A is the expansion element EEa2 that expands the volume of the pressure chamber C. As shown in FIG.

On the other hand, the second drive signal Com-B shown in FIG. 13 has a waveform in which the intermediate potential Vcb is used as a reference potential, and the intermediate potential Vcb returns to the intermediate potential Vcb via the potential VLb and the potential VHb in this order within the unit period Tu. have Potential VLb is a potential lower than intermediate potential Vcb.

Here, the potential of the second drive signal Com-B is maintained at the intermediate potential Vcb for the period P1d, drops from the intermediate potential Vcb to the potential VLb for the period P2d, and is maintained at the potential VLb for the period P3d. The potential increases from potential VLb to potential VHb for period P4d, is maintained at potential VHb for period P5d, decreases from potential VHb to intermediate potential Vcb for period P6d, and is maintained at intermediate potential Vcb for period P7d. The period P4d is an example of the "fourth period". The period P6d is an example of the "second period". Note that the period P1d, the period P2d, the period P3d, the period P4d, the period P5d, the period P6d, and the period P7d are included in this order from the start point to the end point of the unit period Tu.

The waveform portion of the period P2d of the second drive signal Com-B described above is the contraction element ESb1 that causes the volume of the pressure chamber C to contract. A waveform portion of the period P3d of the second drive signal Com-B is the holding element ERb1. A waveform portion of the period P4d of the second drive signal Com-B is an expansion element EEb that expands the volume of the pressure chamber C. As shown in FIG. The expansion element EEb is an example of a "second expansion element." A waveform portion of the period P5d of the second drive signal Com-B is the holding element ERb2. A waveform portion of the period P6d of the second drive signal Com-B is a contraction element ESb2 that causes the volume of the pressure chamber C to contract. The contraction element ESb2 is an example of the "second contraction element".

In this embodiment, the waveforms of the first drive signal Com-A and the second drive signal Com-B are substantially the same. However, the waveforms of the first drive signal Com-A and the second drive signal Com-B are out of phase with each other.

Here, the length of the period P1c of the first drive signal Com-A is longer than the length of the period P1d of the second drive signal Com-B. The length of the period P2c of the first drive signal Com-A and the length of the period P2d of the second drive signal Com-B are equal to each other. The length of the period P3c of the first drive signal Com-A and the length of the period P3d of the second drive signal Com-B are equal to each other. The length of the period P4c of the first drive signal Com-A and the length of the period P4d of the second drive signal Com-B are equal to each other. The length of the period P5c of the first drive signal Com-A and the length of the period P5d of the second drive signal Com-B are equal to each other. The length of the period P6c of the first drive signal Com-A and the length of the period P6d of the second drive signal Com-B are equal to each other. The length of the period P7c of the first drive signal Com-A is shorter than the length of the period P7d of the second drive signal Com-B.

Note that the waveforms of the first drive signal Com-A and the second drive signal Com-B may be different from each other. However, if the waveforms of the first drive signal Com-A and the second drive signal Com-B are the same, the drive signal generation circuit 24 may generate one waveform and supply it with a phase shift. There is Therefore, there is an advantage that the configuration of the drive signal generation circuit 24 can be simplified as compared with the case where the waveforms of the first drive signal Com-A and the second drive signal Com-B are different from each other.

The start timing of the period P3c of the first drive signal Com-A is later than the end timing of the period P3d of the second drive signal Com-B. Similarly, the start timing of the period P5c of the first drive signal Com-A is later than the end timing of the period P5d of the second drive signal Com-B.

Here, at least part of the period P2c of the first drive signal Com-A and at least part of the period P4d of the second drive signal Com-B temporally overlap each other in the period PE.

In the example shown in FIG. 13, the start timing of the period P2c is before the start timing of the period P4d within the unit period Tu. Also, within the unit period Tu, the end timing of the period P2c is earlier than the end timing of the period P4d. In the unit period Tu, the start timing of the period P2c may be after the start timing of the period P4d, and the end timing of the period P2c may be after the end timing of the period P4d.

At least part of the period P4c of the first drive signal Com-A and at least part of the period P6d of the second drive signal Com-B temporally overlap each other in the period PS.

In the example shown in FIG. 13, the start timing of the period P4c is before the start timing of the period P6d within the unit period Tu. Also, within the unit period Tu, the end timing of the period P2c is earlier than the end timing of the period P4d. In the unit period Tu, the period P4c may start after the period P6d starts, and the period P2c may end after the period P4d ends.

FIG. 14 is a diagram for explaining the contraction process SS and the expansion process SE in the third embodiment. In FIG. 14, the first drive signal Com-A is indicated by a solid line, and the second drive signal Com-B is indicated by a broken line. In the example shown in FIG. 14, potential VLa and potential VLb are equal, potential VHa and potential VHb are equal, and intermediate potential Vca and intermediate potential Vcb are equal.

Note that potential VLa and potential VLb may be different from each other, potential VHa and potential VHb may be different from each other, and intermediate potential Vca and intermediate potential Vcb may be different from each other. However, when potential VLa and potential VLb are equal, potential VHa and potential VHb are equal, and intermediate potential Vca and intermediate potential Vcb are equal, the configuration of drive signal generation circuit 24 is simpler than otherwise. It has the advantage of being able to

As described above, after completing the supply of the holding element ERb1 of the second drive signal Com-B to the active parts P2 and P3, the holding element ERb1 of the first drive signal Com-A to the active part P1 passes through the period PE. The supply of ERa1 is started. Here, the expansion process SE is performed in the period PE. The shrinking step SS is the same as that of the first embodiment described above.

During the period in which the holding element ERb1 of the second drive signal Com-B is supplied to the active portions P2 and P3, the diaphragm 51e is deformed so that the first surface F1 is convex. As a result, the volume of the pressure chamber C is contracted. On the other hand, during the period in which the holding element ERa1 of the first drive signal Com-A is supplied to the active portion P1, the diaphragm 51e is deformed so that the first surface F1 is concave. As a result, the volume of the pressure chamber C expands.

As described above, in the expansion step SE in which the volume of the pressure chamber C changes from the contracted state to the expanded state, the active part P1 deforms the diaphragm 51e from the reference state to a state in which the volume of the pressure chamber C expands. At this time, it is possible to utilize the force of returning the diaphragm 51e to the reference state from the state in which the active portions P2 and P3 have contracted the volume of the pressure chamber C. FIG. Therefore, the amount of deformation of the diaphragm 51e can be increased compared to a configuration in which only the active portion P1 is driven by the first drive signal Com-A. As a result, ink can be ejected from the nozzles N efficiently.

The ejection characteristics of the liquid ejecting apparatus 100 can be improved also by the third embodiment described above. In this embodiment, as described above, the first drive signal Com-A includes the expansion element EEa1, which is an example of the "first expansion element". Also, the second drive signal Com-B includes an expansion element EEb, which is an example of a "second expansion element". Each of the expansion element EEa1 and the expansion element EEb expands the volume of the pressure chamber C for each unit period Tu. Then, the liquid ejection device 100 executes the expansion step SE. The expansion step SE is a period in which a period P2c, which is an example of the "third period", and a period P4d, which is an example of the "fourth period", overlap each other. During period P2c, expansion element EEa1 is supplied to active portion P1. During the period P4d, the expansion element EEb is supplied to the active portions P2, P3.

In the expansion step SE, the period P2c and the period P4d overlap with each other, so that the momentum of the ink introduced into the pressure chamber C can be increased compared to a configuration in which these periods do not overlap. In addition, compared to a configuration in which these periods do not overlap, the ink ejection cycle from the nozzles N can be shortened.

Here, as described above, the expansion process SE is performed before the contraction process SS in the unit period Tu. Therefore, the amount of ink ejected from the nozzle N per one ejection can be increased.

Further, as described above, periods P4c and P4d do not overlap each other, and periods P2c and P6d do not overlap each other. Therefore, excessive stress is prevented from being generated between the portion of the diaphragm 51e deformed by the active portion P1 and the portion of the diaphragm 51e deformed by the active portion P2. As a result, damage such as cracks in the diaphragm 51e can be reduced.

4. Fourth Embodiment A fourth embodiment of the present disclosure will be described below. Below, it demonstrates centering around difference with 1st Embodiment.

FIG. 15 is a diagram for explaining the contraction process SS and the expansion process SE in the fourth embodiment. This embodiment is the same as the above-described third embodiment except that the contraction element ESb1 and the retention element ERb1 of the second drive signal Com-B are omitted. Therefore, the second drive signal Com-B of this embodiment is the same as the second drive signal Com-B of the first embodiment.

The ejection characteristics of the liquid ejecting apparatus 100 can be improved also by the fourth embodiment described above.

5. Fifth Embodiment A fifth embodiment of the present disclosure will be described below. Below, it demonstrates centering around difference with 1st Embodiment.

FIG. 16 is a diagram for explaining the contraction process SS, the expansion process SE, and the damping process SC in the fifth embodiment. This embodiment is the same as the above-described third embodiment except that the phases of the first drive signal Com-A and the second drive signal Com-B are different.

In this embodiment, the contraction step SS is performed by overlapping the period of the contraction element ESa of the first drive signal Com-A and the period of the contraction element ESb1 of the second drive signal Com-B in the period PS. Further, the expansion step SE is performed by overlapping the period PE of the expansion element EEa2 of the first drive signal Com-A and the period of the expansion element EEb of the second drive signal Com-B. Further, after the expansion step SE, the vibration damping step SC is performed in which the holding element ERb2 of the second drive signal Com-B applies a damping force to the diaphragm 51e. It is preferable that the timing of the vibration damping process SC and the potential VHb of the vibration damping process SC are appropriately requested according to the vibration period and amplitude of the vibration plate 51e caused by the processes before the expansion process SE.

The ejection characteristics of the liquid ejecting apparatus 100 can be improved also by the fifth embodiment described above. In the present embodiment, as described above, the expansion step SE is performed after the contraction step SS in the unit period Tu. Therefore, by performing the expansion step SE, ink can be supplied to the pressure chambers C in which the ink has decreased by performing the contraction step SS. Further, after the active portion P1 is driven by the first drive signal Com-A, the vibration of the diaphragm 51e can be damped by executing the damping step SC. As a result, the ejection cycle can be shortened while improving print quality.

6. Sixth Embodiment A sixth embodiment of the present disclosure will be described below. Below, it demonstrates centering around difference with 1st Embodiment.

FIG. 17 is a diagram for explaining the first drive signal Com-A and the second drive signal Com-B in the sixth embodiment. In the example shown in FIG. 17, the first drive signal Com-A is the same as the first drive signal COM-A of the first embodiment.

On the other hand, the second drive signal Com-B shown in FIG. 17 is a signal having an opposite phase to the first drive signal Com-A. That is, the second drive signal Com-B shown in FIG. 17 has a waveform that uses the intermediate potential Vcb as a reference potential and returns from the intermediate potential Vcb to the intermediate potential Vcb via the potential VLb within the unit period Tu. The intermediate potential Vcb is an example of the "third potential" and the "sixth potential". The potential VLb is an example of a "fourth potential".

Here, the potential of the second drive signal Com-B is maintained at the intermediate potential Vcb for the period P1b, then drops from the intermediate potential Vcb to the potential VLb for the period P2b, and is maintained at the potential VLb for the period P3b. Potential VLb rises to intermediate potential Vcb over period P4b, and is maintained at intermediate potential Vcb over period P5b. The period P2b is an example of the "second period". The period P4b is an example of the "fourth period".

The waveform portion of the period P2b of the second drive signal Com-B described above is an example of the “second contraction element”, and is the contraction element ESb that causes the volume of the pressure chamber C to contract. A waveform portion of the period P3b of the second drive signal Com-B is a retention element ERb, which is an example of a "second retention element." The waveform portion of the period P4b of the second drive signal Com-B is an example of a “second expansion element” and is an expansion element EEb that expands the volume of the pressure chamber C. FIG.

Here, at least part of the period P2a of the first drive signal Com-A and at least part of the period P2b of the second drive signal Com-B temporally overlap each other in the period PS. At least part of the period P4a of the first drive signal Com-A and at least part of the period P4b of the second drive signal Com-B temporally overlap each other in the period PE. By providing such periods PS and PE, it is possible to improve ejection characteristics as in the other embodiments.

In the example shown in FIG. 17, the length of the period P1a and the length of the period P1b are equal to each other. The length of the period P2a and the length of the period P2b are equal to each other. The length of the period P3a and the length of the period P3b are equal to each other. The length of the period P4a and the length of the period P4b are equal to each other. The length of the period P5a and the length of the period P5b are equal to each other. When the waveforms of the first drive signal Com-A and the second drive signal Com-B are in opposite phases to each other, there is an advantage that the configuration of the drive signal generation circuit 24 can be simplified as compared to the case where they are not. .

In the example of FIG. 17, the length of the period P3a and the length of the period P3b are the same, but these lengths may be different from each other. That is, the length of the period P3a may be longer or shorter than the length of the period P3b. In this case, even if there is an error in the phases of the first drive signal Com-A and the second drive signal Com-B for some reason, there is an advantage that fluctuations in ejection characteristics can be easily reduced.

FIG. 18 is a diagram for explaining the contraction process SS and the expansion process SE in the sixth embodiment. In FIG. 18, the first drive signal Com-A is indicated by a solid line, and the second drive signal Com-B is indicated by a broken line. In the example shown in FIG. 18, potential VHa and intermediate potential Vcb are equal to each other, and intermediate potential Vca and potential VLb are equal to each other.

Note that potential VHa and intermediate potential Vcb may be different from each other, and intermediate potential Vca and potential VLb may be different from each other. However, when the potential VHa and the intermediate potential Vcb are equal to each other, and the intermediate potential Vca and the potential VLb are also equal to each other, there is an advantage that the configuration of the drive signal generation circuit 24 can be simplified as compared with the case where they are not equal. .

During the period PS, the contraction process SS is performed. After that, in the period PE, the expansion process SE is performed.

According to the sixth embodiment described above, it is possible to improve the ejection characteristics of the liquid ejection apparatus 100 as in the first embodiment. In the present embodiment, as described above, the first drive signal Com-A includes the period P3a in which the voltage is held after the contraction element ESa as an example of the "first holding period." On the other hand, the second drive signal Com-B includes a period P3b for holding the voltage after the contraction element ESb as an example of the "second holding period." Here, when the lengths of the period P3a and the period P3b are different from each other, the periods P3a and P3b overlap even if there is some error in the phases of the first drive signal Com-A and the second drive signal Com-B. The length of the period is difficult to change. Therefore, it is possible to reduce variations in the amount of ink ejected from the nozzles N due to the error. On the other hand, when the lengths of the periods P3a and P3b are equal to each other, the length of the period in which the periods P3a and P3b overlap easily fluctuates due to the error. Therefore, the amount of ink ejected from the nozzles N tends to vary. However, in this case, there is an advantage that the drive signal generation circuit 24 can be simplified.

Further, as described above, the first drive signal Com-A and the second drive signal Com-B are signals having phases opposite to each other. Therefore, it is possible to reduce the influence of electrical noise (electrical crosstalk) between two ejection elements adjacent to each other. Further, in this case, each element included in the first drive signal Com-A and the second drive signal Com-B is executed at the same time. can shorten the time required for

Furthermore, as described above, intermediate potential Vcb is higher than intermediate potential Vca. Therefore, in the standby state in which ink is not ejected from the nozzles N, the second drive signal Com-B maintains the state in which the volume of the pressure chamber C is expanded. Therefore, since tension is applied to the diaphragm 51e, the spring constant of the diaphragm 51e can be increased. As a result, by shortening the natural vibration period of the vibration plate 51e, the ink ejection period from the nozzles N can be shortened.

Further, as described above, the first drive signal Com-A has a period P3a that is an example of the "first holding period" and a period P4a that is an example of the "third period" for each unit period Tu. include. The period P3a follows the period P2a, which is an example of the "first period," and holds the potential VHa, which is an example of the "second potential." The period P4a follows the period P3a and changes from the potential VHa to the intermediate potential Vca, which is an example of the "fifth potential." On the other hand, the second drive signal Com-B includes a period P3b that is an example of a "second holding period" and a period P4b that is an example of a "fourth period" for each unit period Tu. The period P3b follows the period P2b, which is an example of the "second period," and holds the potential VLb, which is an example of the "fourth potential." In the period P4b, following the period P3b, the potential VLb changes to the intermediate potential Vcb, which is an example of the “sixth potential”. The period P4a and the period P4b overlap each other. That is, the expansion step SE is performed. Therefore, the momentum of the ink introduced into the pressure chamber C can be increased. Also, the ink ejection cycle from the nozzles N can be shortened.

Here, as described above, in the period PE in which the period P4a and the period P4b overlap each other, the magnitude relationship between the potentials of the first drive signal Com-A and the second drive signal Com-B is reversed.

7. Seventh Embodiment A seventh embodiment of the present disclosure will be described below. Below, it demonstrates centering around difference with 1st Embodiment.

FIG. 19 is a diagram for explaining the contraction process and the expansion process in the seventh embodiment. This embodiment is the same as the sixth embodiment described above, except that the intermediate potential Vcb of the second drive signal Com-B is different from the potential VHa of the first drive signal Com-A, as shown in FIG. be.

The ejection characteristics of the liquid ejecting apparatus 100 can be improved also by the seventh embodiment described above. In this embodiment, as described above, the intermediate potential Vcb is different from the potential VHa. Therefore, by appropriately setting the intermediate potential Vcb, the hardness and the like of the diaphragm 51e can be adjusted. As a result, the ejection characteristics can be made uniform among the plurality of head chips 51 and among the plurality of pressure chambers C even if there are manufacturing variations.

8. Eighth Embodiment An eighth embodiment of the present disclosure will be described below. Below, it demonstrates centering around difference with 1st Embodiment.

FIG. 20 is a diagram for explaining the first drive signal and the second drive signal in the eighth embodiment. In the example shown in FIG. 20, the first drive signal Com-A is the same as the first drive signal COM-A of the sixth embodiment.

On the other hand, the second drive signal Com-B shown in FIG. 20 is a signal having an opposite phase to the first drive signal Com-A. That is, the second drive signal Com-B shown in FIG. 20 uses the intermediate potential Vcb as a reference potential, and returns from the intermediate potential Vcb to the intermediate potential Vcb via the potential VHb and the potential VLb in this order within the unit period Tu. It has a waveform.

Here, the potential of the second drive signal Com-B is maintained at the intermediate potential Vcb for the period P1d, rises from the intermediate potential Vcb to the potential VHb for the period P2d, and is maintained at the potential VHb for the period P3d. After falling from potential VHb to potential VLb over period P4d and maintained at potential VLb over period P5d, potential rises from potential VLb to intermediate potential Vcb over period P6d and is maintained at intermediate potential Vcb over period P7d. The period P4d is an example of the "second period". The period P6d is an example of the "fourth period".

The waveform portion of the period P2d of the second drive signal Com-B described above is an example of the “second expansion element”, and is the expansion element EEb1 that expands the volume of the pressure chamber C. FIG. A waveform portion of the period P3d of the second drive signal Com-B is a retention element ERb1, which is an example of a "second retention element." A waveform portion of the period P4d of the second drive signal Com-B is an example of a “second contraction element” and is a contraction element ESb that causes the volume of the pressure chamber C to contract. A waveform portion of the period P5d of the second drive signal Com-B is a retention element ERb2, which is an example of a "second retention element." The waveform portion of the period P6d of the second drive signal Com-B is an example of the “second expansion element” and is the expansion element EEb2 that expands the volume of the pressure chamber C. FIG.

Note that in the present embodiment, the waveform portion of the period P2c of the first drive signal Com-A is an example of the “first expansion element” and is the expansion element EEa1 that expands the volume of the pressure chamber C. FIG. The waveform portion of the period P3c of the first drive signal Com-A is the retention element ERa1, which is an example of the "first retention element." A waveform portion of the period P4c of the first drive signal Com-A is an example of a “first contraction element”, and is a contraction element ESa that causes the volume of the pressure chamber C to contract. The waveform portion of the period P5c of the first drive signal Com-A is the retention element ERa2, which is an example of the "first retention element." A waveform portion of the period P6c of the first drive signal Com-A is an example of a “first expansion element”, and is an expansion element EEa2 that expands the volume of the pressure chamber C. FIG.

Here, at least part of the period P2c of the first drive signal Com-A and at least part of the period P2d of the second drive signal Com-B temporally overlap each other in the period PE1. At least part of the period P4c of the first drive signal Com-A and at least part of the period P4d of the second drive signal Com-B temporally overlap each other in the period PS. Furthermore, at least part of the period P6c of the first drive signal Com-A and at least part of the period P6d of the second drive signal Com-B temporally overlap each other in the period PE2.

FIG. 21 is a diagram for explaining the contraction process SS, the first expansion process SE1, and the second expansion process SE2 in the eighth embodiment. In FIG. 21, the first drive signal Com-A is indicated by a solid line, and the second drive signal Com-B is indicated by a broken line. In the example shown in FIG. 21, potential VHa and potential VHb are equal to each other, and potential VLa and potential VLb are equal to each other. Further, intermediate potential Vcb is higher than intermediate potential Vca.

Note that potential VHa and potential VHb may be different from each other, and potential VLa and potential VLb may be different from each other.

In the period PE1, the first expansion step SE1 is performed. After that, the contraction process SS is performed in the period PS. Next, in period PE2, the second expansion step SE2 is performed. Each of the first expansion step SE1 and the second expansion step SE2 has the same effect as the expansion step SE described above. That is, it can be said that the first expansion step SE1 and the second expansion step SE2 are included in the expansion step SE.

According to the eighth embodiment as well, the ejection characteristics of the liquid ejection apparatus 100 can be improved. In this embodiment, as described above, the expansion step SE includes the first expansion step SE1 and the second expansion step SE2. Then, in the unit period Tu, the contraction process SS is performed between the first expansion process SE1 and the second expansion process SE2. Therefore, the amount of ink per ejection from the nozzle N can be increased as in the other embodiments. In addition, since each element included in the first drive signal Com-A and the second drive signal Com-B is executed at the same time, the time required for the unit period Tu is reduced compared to the first to fifth embodiments. can be shortened as a whole. That is, it is possible to achieve both an increase in the ejection amount and a shortening of the ejection cycle of the liquid from the nozzles N. FIG.

9. Ninth Embodiment A ninth embodiment of the present disclosure will be described below. Below, it demonstrates centering around difference with 1st Embodiment.

FIG. 22 is a diagram for explaining the contraction process SS, the first expansion process SE1, and the second expansion process SE2 in the ninth embodiment. This embodiment is the same as the eighth embodiment described above, except that the potential difference between the intermediate potential Vca and the intermediate potential Vcb is different.

In this embodiment, the potential difference between the intermediate potential Vca and the intermediate potential Vcb is smaller than in the eighth embodiment. In the example shown in FIG. 22, although intermediate potential Vcb is slightly higher than intermediate potential Vca, the potential difference between intermediate potential Vca and intermediate potential Vcb is extremely small. Note that intermediate potential Vca and intermediate potential Vcb may be equal to each other, or intermediate potential Vcb may be lower than intermediate potential Vca.

According to the ninth embodiment described above, it is possible to improve the ejection characteristics of the liquid ejection apparatus 100 as in the eighth embodiment.

10. Tenth Embodiment A tenth embodiment of the present disclosure will be described below. Below, it demonstrates centering around difference with 1st Embodiment.

FIG. 23 is a diagram for explaining the contraction process SS and the expansion process SE in the tenth embodiment. This embodiment is the same as the sixth embodiment described above, except that a waveform for the damping process SC is added to the second drive signal Com-B.

In this embodiment, the damping process SC is performed by dropping the potential of the second drive signal Com-B from the intermediate potential Vcb to the potential VLb1 after the expansion process SE. Potential VLb1 is a potential between intermediate potential Vcb and potential VLb.

According to the tenth embodiment as well, the ejection characteristics of the liquid ejecting apparatus 100 can be improved. In this embodiment, in addition to the same effects as those of the sixth embodiment, effects due to the damping process SC can be obtained.

11. Modifications Each form in the above examples can be modified in various ways. Specific modifications that can be applied to each of the above-described modes are exemplified below. In addition, two or more aspects arbitrarily selected from the following examples can be combined as appropriate within a range not contradicting each other.

11-1. Modification 1
24A and 24B are diagrams for explaining the contraction process SS and the expansion process SE in Modification 1. FIG.
Modification 1 is the same as the above-described sixth embodiment except that step SX is added before shrinking step SS.

In the example shown in FIG. 24, the step SX is executed by repeatedly dropping the potential of the second drive signal Com-B from the intermediate potential Vcb to the potential VLb a plurality of times before the shrinking step SS. The ejection characteristics of the liquid ejecting apparatus 100 can also be improved by the first modification described above. Note that the waveform used in step SX is not limited to the example shown in FIG. 24, and is arbitrary. According to the process SX, for example, it is possible to generate vibration to such an extent that ink is not ejected, put the pressure chamber C in an expanded state immediately before the period PS, and adjust so as to excite the vibration during ejection. Further, according to step SX, the intermediate potential Vcb, which is a high potential, is not always maintained in the standby state in which liquid is not discharged, so power consumption of the drive signal generation circuit 24 can be suppressed.

11-2. Modification 2
Although the configuration in which the piezoelectric layer is interposed between the individual electrodes and the common electrode is exemplified in the above embodiment, the present invention is not limited to this, and a configuration in which the piezoelectric layer is interposed between the individual electrodes is also possible. good.

11-3. Modification 3
In each of the above-described embodiments, the serial-type liquid ejection apparatus 100 in which the carriage 41 on which the liquid ejection head 50 is mounted is reciprocated is exemplified. It is possible to apply the present disclosure.

11-4. Modification 4
The liquid ejecting apparatus 100 exemplified in each of the above embodiments can be employed in various types of equipment such as facsimile machines and copiers, in addition to equipment dedicated to printing. However, the application of the liquid ejecting apparatus of the present disclosure is not limited to printing. For example, a liquid ejecting apparatus that ejects a colorant solution is used as a manufacturing apparatus for forming a color filter of a liquid crystal display device. Also, a liquid ejecting apparatus that ejects a solution of a conductive material is used as a manufacturing apparatus for forming wiring and electrodes of a wiring board.

DESCRIPTION OF SYMBOLS 10... Liquid container, 20... Control unit, 21... Control circuit, 22... Storage circuit, 23... Power supply circuit, 24... Drive signal generation circuit, 30... Conveyor mechanism, 40... Moving mechanism, 41... Carriage, 42... Conveyor belt , 50... Liquid ejection head 51... Head chip 51F... Piezoelectric element 51a... Flow path substrate 51b... Pressure chamber substrate 51b1... Partition wall 51c... Nozzle plate 51d... Vibration absorber 51e... Vibration plate 51f... Piezoelectric element 51f1 First electrode layer 51f1a Individual electrode 51f1b Individual electrode 51f1c Individual electrode 51f2 Piezoelectric layer 51f3 Second electrode layer 51g Cover 51h Case 51i Wiring board , 52... Switching circuit 52a... Connection state designating circuit 100... Liquid ejection device 200... External device 51e1... First layer 51e1... Second layer ABO3... General composition formula BD... Outer edge C... Pressure chamber , CLK... clock signal, CNG... change signal, COM-A... first drive signal, Com-1... first drive signal, Com-A... first drive signal, Com-B... second drive signal, EEa... expansion Elements EEa1...Expansion element EEa2...Expansion element EEb...Expansion element EEb1...Expansion element EEb2...Expansion element ERa...Retention element ERa1...Retention element ERa2...Retention element ERb...Retention element ERb1...Retention Elements ERb2... Holding element ESa... Shrinking element ESb... Shrinking element ESb1... Shrinking element ESb2... Shrinking element F1... First surface F2... Second surface IH... Introduction port Img... Print data LAT Latch signal, LHa wiring, LHb wiring, LHd wiring, M medium, N nozzle, Na communication channel, P1 active part, P1a period, P1b period, P1c period, P1d period , P2...active part, P2a...period, P2b...period, P2c...period, P2d...period, P3...active part, P3a...period, P3b...period, P3c...period, P3d...period, P4a...period, P4b...period , P4c...period, P4d...period, P5a...period, P5b...period, P5c...period, P5d...period, P6c...period, P6d...period, P7c...period, P7d...period, PE...period, PE1...period, PE2 Period, PS... Period, R... Liquid storage chamber, R1... Opening, R2... Storage part, Ra... Supply channel, SC... Damping process, SE... Expansion process, SE1... First expansion process, SE2... Second 2 expansion process, SI... print data signal, SLa... connection state designation signal, SS... contraction process, SWa... switch, SWb... switch, SX... process, Sk1... control signal, Sk2... control signal, Tu... unit period, VBS ...offset potential, VHV...power supply potential, VHa...potential, VHb...potential, VLa...potential, VLb...potential, VLb1...potential, Vca...intermediate potential, Vcb...intermediate potential, Vin-A... supply signal, Vin-B... Supply signals, W1... width, W2... width, W3... width, dCom... waveform designation signal.

Claims (20)

a diaphragm having a first surface and a second surface facing in a direction opposite to the first surface;
a pressure chamber substrate laminated on the first surface and having partition walls defining pressure chambers communicating with nozzles for ejecting liquid;
a first active portion laminated on the second surface and overlapping the center of the pressure chamber when viewed in the thickness direction of the diaphragm; and the pressure chamber at a position closer to the outer edge of the pressure chamber than the first active portion. a piezoelectric element having a second active portion that overlaps with the
a drive signal generator that generates a first drive signal for driving the first active section and a second drive signal for driving the second active section;
the first drive signal includes a first contraction element for contracting the volume of the pressure chamber for each periodic unit period;
the second drive signal includes, for each unit period, a second contraction element that contracts the volume of the pressure chamber for each unit period;
performing a contraction step in which a first period during which the first contraction element is supplied to the first active section and a second period during which the second contraction element is supplied to the second active section overlap with each other;
A liquid ejection device characterized by: During execution of the contraction step, the potential magnitude relationship between the first drive signal and the second drive signal is reversed.
2. The liquid ejecting apparatus according to claim 1, wherein: In the unit period, the start timing of the first contraction element is later than the start timing of the second contraction element.
3. The liquid ejecting apparatus according to claim 1, wherein: In the unit period, the end timing of the first contraction element is later than the end timing of the second contraction element.
4. The liquid ejecting apparatus according to claim 3, characterized in that: the first drive signal includes a first expansion element that expands the volume of the pressure chamber for each unit period;
the second drive signal includes a second expansion element that expands the volume of the pressure chamber for each unit period;
performing an expansion step in which a third period during which the first expansion element is supplied to the first active section and a fourth period during which the second expansion element is supplied to the second active section overlap;
4. The liquid ejecting apparatus according to any one of claims 1 to 3, characterized in that: In the unit period, the expansion step is performed before the contraction step,
6. The liquid ejecting apparatus according to claim 5, characterized in that: In the unit period, the expansion step is performed after the contraction step,
6. The liquid ejecting apparatus according to claim 5, characterized in that: The expansion step includes a first expansion step and a second expansion step,
In the unit period, the shrinking step is performed between the first expanding step and the second expanding step,
6. The liquid ejecting apparatus according to claim 5, characterized in that: the first drive signal includes a first hold period holding a voltage after the first constriction element;
the second drive signal includes a second hold period holding a voltage after the second constriction element;
the first holding period and the second holding period are different in length;
9. The liquid ejecting apparatus according to claim 7, wherein: wherein the first drive signal and the second drive signal are signals having phases opposite to each other;
9. The liquid ejecting apparatus according to claim 7, wherein: In a standby state in which liquid is not ejected from the nozzle, the second drive signal keeps the volume of the pressure chamber expanded.
10. The liquid ejecting apparatus according to any one of claims 7 to 9, characterized in that: the first period and the fourth period do not overlap each other;
the second period and the third period do not overlap each other;
12. The liquid ejecting apparatus according to any one of claims 5 to 11, characterized in that: a diaphragm having a first surface and a second surface facing in a direction opposite to the first surface;
a pressure chamber substrate laminated on the first surface and having partition walls defining pressure chambers communicating with nozzles for ejecting liquid;
a first active portion laminated on the second surface and overlapping the center of the pressure chamber when viewed in the thickness direction of the diaphragm; and the pressure chamber at a position closer to the outer edge of the pressure chamber than the first active portion. a piezoelectric element having a second active portion that overlaps with the
a drive signal generator that generates a first drive signal for driving the first active section and a second drive signal for driving the second active section;
The first drive signal includes a first period in which the first potential changes to the second potential in each periodic unit period,
the second drive signal includes a second period in which the third potential changes to the fourth potential for each unit period;
the first period and the second period overlap each other;
A liquid ejection device characterized by: In a period in which the first period and the second period overlap each other, the magnitude relationship between the voltages of the first drive signal and the second drive signal is reversed.
14. The liquid ejecting apparatus according to claim 13, characterized by: In the unit period, the start timing of the first period is later than the start timing of the second period.
15. The liquid ejecting apparatus according to claim 13 or 14, characterized in that: The first drive signal, for each unit period,
a first holding period, following the first period, for holding the second potential;
a third period in which the second potential changes to a fifth potential subsequent to the first holding period,
The second drive signal, for each unit period,
a second holding period that follows the second period and holds the fourth potential;
a fourth period in which the fourth potential changes to a sixth potential subsequent to the second holding period;
the third period and the fourth period overlap each other;
16. The liquid ejecting apparatus according to any one of claims 13 to 15, characterized by: In a period in which the third period and the fourth period overlap each other, the magnitude relationship between the potentials of the first drive signal and the second drive signal is reversed.
17. The liquid ejecting apparatus according to claim 16, characterized by: the first holding period and the second holding period are different in length;
18. The liquid ejecting apparatus according to claim 16 or 17, characterized in that: The piezoelectric element has a third active portion overlapping the pressure chamber at a position closer to the outer edge of the pressure chamber than the first active portion when viewed in the thickness direction of the diaphragm,
The first active portion is positioned between the second active portion and the third active portion when viewed in the thickness direction of the diaphragm,
19. The liquid ejecting apparatus according to any one of claims 1 to 18, characterized by: The piezoelectric element has a first electrode layer, a piezoelectric layer and a second electrode layer in this order in a direction away from the diaphragm,
The piezoelectric layer and the second electrode layer are provided in common over the first active section, the second active section and the third active section,
The first electrode layer includes a plurality of individual electrodes individually provided in the first active section, the second active section and the third active section,
20. The liquid ejecting apparatus according to claim 19, characterized by:

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