JP2018103479A - Liquid injection device and control method for the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid injection device capable of securing a larger displacement amount of a compliance member to a pressure change in a common liquid chamber, and a control method for the liquid injection device.SOLUTION: A liquid injection device comprises: a plurality of nozzles (30) injecting liquid; a plurality of pressure chambers (33) communicating with the plurality of nozzles; and a plurality of driving elements (31) generating pressure fluctuation of the liquid in the plurality of pressure chambers. The liquid injection device can execute a liquid discharge mode for discharging the liquid from the pressure chambers and introducing air into the pressure chambers. The plurality of nozzles has a first nozzle (30a) discharging the liquid in the liquid discharge mode and a second nozzle (30b) for air intake introducing the air into the pressure chambers in the liquid discharge mode.SELECTED DRAWING: Figure 6

Description

  The present invention relates to a liquid ejecting apparatus capable of suppressing damage to structural members due to freezing of liquid in a liquid flow path, and a control method for the liquid ejecting apparatus.

  The liquid ejecting apparatus includes a liquid ejecting head and ejects (discharges) various liquids from the liquid ejecting head. As this liquid ejecting apparatus, for example, there is an image recording apparatus such as an ink jet printer or an ink jet plotter, but recently, various types of manufacturing have been made by taking advantage of the ability to accurately land a very small amount of liquid on a predetermined position. It is also applied to devices. For example, a display manufacturing apparatus that manufactures color filters such as liquid crystal displays, an electrode forming apparatus that forms electrodes such as organic EL (Electro Luminescence) displays and FEDs (surface emitting displays), and chips that manufacture biochips (biochemical elements) Applied to manufacturing equipment. The recording head for the image recording apparatus ejects liquid ink, and the color material ejecting head for the display manufacturing apparatus ejects solutions of R (Red), G (Green), and B (Blue) color materials. The electrode material ejecting head for the electrode forming apparatus ejects a liquid electrode material, and the bioorganic matter ejecting head for the chip manufacturing apparatus ejects a bioorganic solution.

  This type of liquid ejecting head includes a liquid flow path from an inlet to a common liquid chamber (also called a reservoir or a manifold) and a pressure chamber to a nozzle, and an actuator (driving element) such as a piezoelectric element or a heating element. The pressure fluctuation is generated in the liquid in the pressure chamber by the driving of, and droplets are ejected from the nozzle by using the pressure fluctuation. In a general liquid ejecting apparatus equipped with a liquid ejecting head, the liquid may freeze depending on the installed environment. When the liquid in the liquid flow path inside the liquid ejecting head freezes, the members constituting the liquid ejecting head may be damaged due to volume expansion accompanying freezing. For this reason, in a situation where there is a risk of liquid freezing, a configuration has been proposed in which volume expansion during freezing is reduced by discharging the liquid in the liquid flow path and introducing air (for example, Patent Document 1). reference). In the invention disclosed in Patent Document 1, a large amount of liquid in a pressure chamber (pressure generation chamber) is discharged at a time by driving driving elements corresponding to a large number of nozzles, thereby causing an insufficient supply of ink. Thus, air is drawn into the pressure chamber from the nozzle.

JP, 2006-041489, A

  However, recent liquid ejecting apparatuses are designed so that a large amount of liquid can be ejected from the liquid ejecting head in a short time. Therefore, depending on the structure of the liquid ejecting head and the environmental conditions, the method of Patent Document 1 described above is possible. However, in some cases, air could not be sufficiently drawn into the flow path.

  The present invention has been made in view of such circumstances, and an object thereof is to provide a liquid ejecting apparatus capable of more reliably drawing air into a liquid flow path, and a control method for the liquid ejecting apparatus. Is.

The liquid ejecting apparatus of the present invention has been proposed in order to achieve the above-described object, and includes a nozzle that ejects liquid, a pressure chamber that communicates with the nozzle, and a drive that causes pressure fluctuations in the liquid in the pressure chamber. Each with multiple elements,
A liquid discharge mode in which liquid is discharged from the pressure chamber and air is introduced into the pressure chamber can be executed;
The plurality of nozzles include a first nozzle that discharges liquid in the liquid discharge mode, and a second nozzle for intake that introduces air into the pressure chamber in the liquid discharge mode.

  According to the present invention, by providing the second nozzle for intake separately from the first nozzle for liquid discharge, air can be more actively drawn into the liquid flow path in the liquid discharge mode. This makes it possible to more reliably replace the liquid in the liquid flow path with air regardless of the structure of the liquid jet head, environmental conditions, and the like.

In the above-described configuration, a common liquid chamber communicating with each of the plurality of pressure chambers is provided,
In the liquid discharge mode, the vibration is excited by synchronizing the liquid discharge operation from the first nozzle with the period of the liquid vibration in the common liquid chamber, and air is supplied from the second nozzle to the pressure chamber side. It is desirable to adopt a configuration that is an operation to be introduced.

  According to this configuration, by synchronizing the liquid discharging operation from the first nozzle with the vibration period of the liquid in the common liquid chamber, the vibration is excited, so that the second liquid can be utilized by utilizing the liquid vibration in the common liquid chamber. It becomes possible to further promote the introduction of air from the nozzle. As a result, the liquid in the liquid flow path can be more reliably replaced with air.

  Moreover, in the said structure, it is desirable to employ | adopt the structure which partitions off a part of said common liquid chamber and is provided with the compliance member which has flexibility.

  According to this configuration, since a part of the common liquid chamber is partitioned by the compliance member having flexibility, it is possible to obtain a larger vibration by using the vibration of the compliance member. Thereby, introduction of air from the second nozzle can be further promoted.

In the above configuration, a drive waveform generation circuit that generates a first drive waveform for driving the first drive element corresponding to the first nozzle and a second drive waveform for driving the second drive element corresponding to the second nozzle. Prepared,
The first driving waveform is a driving waveform for ejecting the liquid in the pressure chamber from the first nozzle by driving the first driving element,
The second drive waveform is a force that expands the pressure chamber and depressurizes the liquid in the pressure chamber, rather than a force that contracts the pressure chamber and pressurizes the liquid in the pressure chamber by driving the second drive element. It is desirable to adopt a configuration in which the drive waveform is a large drive waveform, and the first drive waveform is a drive waveform applied to the second drive element at the timing of application to the first drive element.

  According to this configuration, the first drive element that depressurizes the pressure chamber and draws air from the second nozzle at the timing when the first drive waveform for discharging the liquid from the first nozzle is applied to the first drive element is the second drive. By being applied to the element, introduction of air from the second nozzle can be further promoted.

In the above configuration, the second drive waveform includes an expansion element that expands the pressure chamber, and a contraction element that contracts the pressure chamber expanded by the expansion element,
It is desirable to employ a configuration in which the potential change rate of the expansion element is larger than the potential change rate of the contraction element.

  According to this configuration, the force that expands the pressure chamber and depressurizes the liquid in the pressure chamber is larger than the force that contracts the pressure chamber and pressurizes the liquid in the pressure chamber. The introduction can be promoted.

  In the second drive waveform, a configuration in which the potential difference of the waveform element that expands the pressure chamber is larger than the potential difference of the waveform element that contracts the pressure chamber may be employed.

  According to this configuration, the force that expands the pressure chamber and depressurizes the liquid in the pressure chamber is larger than the force that contracts the pressure chamber and pressurizes the liquid in the pressure chamber. The introduction can be promoted.

Further, in the above configuration, a capping mechanism having a cap that seals the nozzle forming surface on which the nozzle is formed, and a pressure reducing mechanism that decompresses the sealing space in the cap in a state where the nozzle forming surface is sealed by the cap. With
In the liquid discharge mode, the capping mechanism arranges the second nozzle outside the cap, and seals the nozzle forming surface with the cap with the first nozzle facing the sealing space. In this state, it is possible to employ a configuration in which the liquid is discharged from the first nozzle by the pressure reducing mechanism.

  According to this configuration, by using the capping mechanism to discharge the liquid from the first nozzle and introducing air from the second nozzle, it is possible to generate a liquid flow at a high flow rate in the liquid flow path, It becomes possible to replace the liquid in the liquid channel with air reliably and more quickly.

The liquid ejecting apparatus control method according to the present invention includes a liquid ejecting apparatus including a nozzle that ejects liquid, a pressure chamber that communicates with the nozzle, and a plurality of drive elements that cause pressure fluctuations in the liquid in the pressure chamber. A control method,
A liquid discharge mode in which liquid is discharged from the pressure chamber and air is introduced into the pressure chamber can be executed;
In the liquid discharge mode, the liquid is discharged from the first nozzle among the plurality of nozzles, while air is introduced into the pressure chamber from the remaining second nozzles.

It is a front view explaining the structure of one form of a liquid ejecting apparatus. 3 is a block diagram illustrating an electrical configuration of the liquid ejecting apparatus. FIG. FIG. 3 is a cross-sectional view of a liquid ejecting head. FIG. 4 is an enlarged view of a region X in FIG. 3. It is an enlarged view around a compliance section. It is a schematic diagram of the ink flow path from a reservoir to a nozzle. 6 is a graph showing a relationship between ink flow velocity and pressure loss in an ink supply path in an ink discharge mode. It is a schematic diagram explaining an ink discharge mode. It is a wave form diagram explaining the structure of the drive pulse for intake. It is a wave form diagram explaining the modification of the drive pulse for intake. It is a figure explaining the structure of 2nd Embodiment. It is a figure explaining the structure of 3rd Embodiment.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be described with reference to the accompanying drawings. In the embodiments described below, various limitations are made as preferred specific examples of the present invention. However, the scope of the present invention is not limited to the following description unless otherwise specified. However, the present invention is not limited to these embodiments. In the following, an ink jet recording apparatus (hereinafter referred to as a printer) will be described as an example of the liquid ejecting apparatus of the invention.

  FIG. 1 is a front view illustrating a configuration of a printer 1 including a recording head 10 which is a kind of liquid ejecting head. FIG. 2 is a block diagram illustrating the electrical configuration of the printer 1. The printer 1 includes a frame 2 and a platen 3 disposed in the frame 2, and a recording sheet, fabric, resin sheet, or the like is placed on the platen 3 by a transport mechanism 4 (see FIG. 2). A recording medium (a kind of liquid landing target) is conveyed. A guide rod 5 is installed in the frame 2 in parallel with the platen 3, and a carriage 6 on which a recording head 10 is mounted is slidably supported on the guide rod 5. The carriage 6 is configured to reciprocate in the main scanning direction perpendicular to the conveyance direction of the recording medium along the guide rod 5 by driving a carriage moving mechanism 7 (see FIG. 2). The printer 1 uses ink (a kind of liquid in the present invention) from a nozzle 30 (see FIG. 3) of the recording head 10 while moving the carriage 6 relative to the recording medium placed on the platen 3 in the main scanning direction. Is ejected to land the ink on the recording medium, thereby forming (recording / printing) a landing pattern such as characters and images.

  An ink cartridge 8 (a type of liquid storage member) that stores ink is detachably mounted on the carriage 6. Examples of the ink include water-based dye ink or pigment ink, organic solvent-based (ecosolvent-based) ink having higher weather resistance than these water-based inks, and photo-curable ink that is cured by irradiation with ultraviolet rays. Well-known various compositions can be used. In the present embodiment, the configuration in which the ink cartridge 8 is mounted on the carriage 6 is illustrated. However, the present invention is not limited to this, and the ink cartridge 8 is disposed on the main body side of the printer 1 and is recorded via the ink supply tube. It is also possible to employ a configuration supplied to the head 10.

  At the home position, which is a non-recording area of the printer 1, a wiping mechanism 11 that wipes the nozzle forming surface (the surface facing the platen 3, see FIG. 3) of the nozzle plate 24 of the recording head 10 mounted on the carriage 6. Is arranged. The wiping mechanism 11 has a wiper 12, and the wiper 12 is configured by an elastic / flexible member such as rubber or elastomer. In the wiping mechanism 11, the wiper 12 is disposed at a position where the tip of the wiper 12 can come into contact with the nozzle forming surface of the recording head 10 during wiping. Then, the nozzle forming surface is wiped by the wiper 12 by relatively moving the wiper 12 in a state where the tip of the wiper 12 is in contact with the nozzle forming surface.

  A capping mechanism 13 is disposed adjacent to the wiping mechanism 11 at or near the home position. The capping mechanism 13 has a cap 14 (a kind of sealing member) made of a tray-like elastic member that can come into contact with the nozzle forming surface of the recording head 10. The capping mechanism 13 is configured such that the space in the cap 14 functions as a sealing space, and can be brought into close contact with the nozzle forming surface with the nozzle 30 of the recording head 10 facing the sealing space. Further, a pump unit 16 is connected to the cap 14 via a drain tube 15 (see FIG. 12), and the operation of the pump unit 16 can reduce the pressure in the sealed space of the cap 14. it can. In the cleaning process for eliminating the clogging of the nozzles 30 and the ink flow paths of the recording head 10, the pump unit 16 is operated in close contact with the nozzle forming surface, and the inside of the sealed space (sealed space) is negative pressure. Then, ink and bubbles in the recording head 10 are sucked from the nozzles 30 and discharged into the sealed space of the cap 14. As will be described later, the capping mechanism 13 performs suction in a state where the remaining nozzles 30 (discharge nozzles 30a) are sealed by the cap 14 except for some of the nozzles 30 (intake nozzles 30b) on the nozzle formation surface. Is also used for the process of introducing air from the intake nozzle 30b into the flow path of the recording head 10. Details of this point will be described later.

  As shown in FIG. 2, the printer 1 in this embodiment includes a CPU 17, a storage device 18, a drive signal generation circuit 19 (corresponding to a drive waveform generation circuit in the present invention), an input / output interface 20, a transport mechanism 4, and carriage movement. It has a mechanism 7, a wiping mechanism 11, a capping mechanism 13, a pump unit 16, a temperature sensor 21, and a recording head 10. The input / output interface 20 receives a request for a printing operation from the external device side, print setting information, print data (image data), etc., outputs the status information of the printer 1 to the external device, and transmits and receives various data. . The CPU 17 is an arithmetic processing unit for controlling the entire printer, and controls a printing operation (liquid ejection operation) by the recording head 10. The storage device 18 is an element that stores a program for the CPU 17 and data used for various controls, and includes a ROM, a RAM, and an NVRAM (nonvolatile storage element). The drive signal generation circuit 19 generates a drive signal including a drive pulse for driving the piezoelectric element 31 of the recording head 10 based on the waveform data regarding the waveform of the drive signal. The temperature sensor 21 detects the temperature inside the printer 1, particularly in the vicinity of the recording head 10, and outputs it to the CPU 17.

Next, the configuration of the recording head 10 in the present embodiment will be described.
3 is a cross-sectional view of the recording head 10, and FIG. 4 is an enlarged view of a region X in FIG. FIG. 5 is an enlarged view of the periphery of the reservoir 43 in FIG. The recording head 10 according to the present embodiment is a unit in which a plurality of head components such as a fixed plate 23, a nozzle plate 24, a communication plate 25, an actuator substrate 26, a compliance substrate 27, and a holder 28 are laminated and bonded by an adhesive or the like. It has become. In the following description, the stacking direction of the constituent members of the recording head 10 will be described as the vertical direction as appropriate.

  The actuator substrate 26 in the present embodiment includes a pressure chamber forming substrate 29 formed with a pressure chamber 33 communicating with the nozzles 30 formed on the nozzle plate 24, and a drive element that causes pressure fluctuations in the ink in each pressure chamber 33. And a protective substrate 32 that protects the pressure chamber forming substrate 29 and the piezoelectric element 31 in a laminated state. A wiring empty portion 40 through which the flexible substrate 39 on which the drive IC 38 is mounted is opened at a substantially central portion in plan view of the protective substrate 32. A lead electrode of the piezoelectric element 31 is disposed in the wiring space 40, and a wiring terminal of the flexible substrate 39 is electrically connected to the lead electrode. A drive signal sent from the drive signal generation circuit 19 is supplied to the piezoelectric element 31 through the flexible substrate 39. The flexible substrate 39 is not limited to the one provided with the drive IC 38, and a configuration in which the drive IC 38 is separately disposed on the protective substrate 32 via a so-called interposer may be employed.

  The pressure chamber forming substrate 29 of the actuator substrate 26 is made of a silicon single crystal substrate. In the pressure chamber forming substrate 29, a plurality of spaces corresponding to the nozzles 30 are provided as spaces for forming the pressure chambers 33. The pressure chamber 33 is a hollow portion that is long in a direction intersecting with the nozzle row (orthogonal in the present embodiment). A nozzle communication port 34 communicates with one end of the pressure chamber 33 in the longitudinal direction, and an individual communication port 35 communicates with the other end. Two rows of pressure chambers 33 are formed on the pressure chamber forming substrate 29 in the present embodiment.

A vibration plate 36 is laminated on the upper surface of the pressure chamber forming substrate 29 (the surface opposite to the communication plate 25 side), and the upper opening of the pressure chamber 33 is sealed by the vibration plate 36. That is, a part of the pressure chamber 33 is partitioned by the diaphragm 36. The vibration plate 36 includes, for example, an elastic film made of silicon dioxide (SiO ₂ ) formed on the upper surface of the pressure chamber forming substrate 29 and an insulator film made of zirconium oxide (ZrO ₂ ) formed on the elastic film. And consist of And the piezoelectric element 31 is laminated | stacked on the area | region corresponding to each pressure chamber 33 on this diaphragm 36, respectively.

  The piezoelectric element 31 of the present embodiment is a so-called bending mode piezoelectric element. For example, the piezoelectric element 31 is formed by sequentially laminating a lower electrode layer, a piezoelectric layer, and an upper electrode layer (all not shown) on the vibration plate 36. The piezoelectric element 31 configured in this manner bends and deforms in the vertical direction when an electric field corresponding to the potential difference between both electrodes is applied between the lower electrode layer and the upper electrode layer. In the present embodiment, two rows of piezoelectric elements 31 are formed corresponding to the rows of pressure chambers 33 formed in two rows. The lower electrode layer and the upper electrode layer extend as lead electrodes from the rows of the piezoelectric elements 31 on both sides to the inside of the wiring space 40 between the rows, and are electrically connected to the flexible substrate 39 as described above. ing.

  The protective substrate 32 is laminated on the vibration plate 36 so as to cover the rows of the piezoelectric elements 31 formed in two rows. Inside the protective substrate 32, a long accommodation space 41 that can accommodate the rows of piezoelectric elements 31 is formed. The accommodation space 41 is a recess formed partway in the height direction of the protective substrate 32 from the lower surface side (the diaphragm 36 side) of the protective substrate 32 toward the upper surface side (the holder 28 side). In the protection substrate 32 in the present embodiment, accommodation spaces 41 are respectively formed on both sides of the wiring vacant portion 40. A communication plate 25 having a larger area than the actuator substrate 26 is joined to the lower surface of the actuator substrate 26.

  Similar to the pressure chamber forming substrate 29, the communication plate 25 is made of a silicon single crystal substrate. In the communication plate 25 in the present embodiment, a nozzle communication port 34 for communicating the pressure chamber 33 and the nozzle 30, a reservoir 43 (a kind of common liquid chamber, also referred to as a manifold) provided in common to each pressure chamber, and The individual communication port 35 communicating the reservoir 43 and the pressure chamber 33 is formed by, for example, anisotropic etching. The reservoirs 43 are empty portions extending along the nozzle row direction, and two reservoirs 43 are formed corresponding to each nozzle row of the nozzle plate 24 in the communication plate 25 in the present embodiment. It is also possible to employ a configuration in which a plurality of reservoirs are provided for one nozzle row, and different types of ink are assigned to the respective reservoirs. The reservoir 43 is formed by anisotropic etching from the lower surface side of the communication plate 25. Ink is introduced into the reservoir 43 through an introduction port 52 of a liquid chamber empty portion 51 provided in the holder 28 as will be described later. A plurality of individual communication ports 35 are formed along the nozzle row direction corresponding to the respective pressure chambers 33. The individual communication port 35 communicates with the end portion on the other side in the longitudinal direction of the pressure chamber 33 (the side opposite to the side communicating with the nozzle communication port 34).

  As shown in FIGS. 4 and 5, the reservoir 43 includes a first reservoir 43 a that communicates with the liquid chamber cavity 51 of the holder 28, and a first reservoir 43 a that communicates with the first reservoir 43 a and the pressure chamber 33. 2 reservoir portions 43b. The first reservoir portion 43 a is an empty portion having an opening having a shape and a size that follows the opening shape on the bottom surface side of the liquid chamber empty portion 51 of the holder 28, and is a portion that penetrates the thickness direction of the communication plate 25. . In the present embodiment, the introduction port 52 of the holder 28 is disposed at a position corresponding to the longitudinal direction of the first reservoir 43a, that is, the center in the nozzle row direction (see FIG. 6). The second reservoir portion 43b is a portion that is recessed from the lower surface side to the middle of the plate thickness direction while leaving the thin portion 43c on the upper surface side of the communication plate 25, and in the nozzle row direction with respect to the first reservoir portion 43a. It is formed adjacent to the intersecting direction (the orthogonal direction in the present embodiment). The second reservoir portion 43b extends along the first reservoir portion 43a from one end of the first reservoir portion 43a to the other end in the nozzle row direction. One end of the second reservoir 43b in the direction intersecting the nozzle row direction communicates with the first reservoir 43a, while the other end of the second reservoir 43b is joined to the communication plate 25. It is formed so as to communicate with individual communication ports 35 communicating with 29 pressure chambers 33. The opening on the lower surface side of the reservoir 43 is sealed with the compliance sheet 44 of the compliance substrate 27.

  A nozzle plate 24 in which a plurality of nozzles 30 are formed is joined to a substantially central portion of the lower surface of the communication plate 25. The nozzle plate 24 in the present embodiment is a plate material having an outer shape smaller than the communication plate 25 and the actuator substrate 26, and is composed of a silicon single crystal substrate. The nozzle plate 24 is located at a position deviated from the opening of the reservoir 43 on the lower surface of the communication plate 25, and the nozzle communication port 34 and the plurality of nozzles 30 communicate with each other in a region where the nozzle communication port 34 is opened. In such a state, it is joined with an adhesive or the like. The nozzle plate 24 in the present embodiment is formed with a total of two nozzle rows in which a plurality of nozzles 30 are arranged. In the present embodiment, one nozzle row is composed of, for example, 400 nozzles 30.

  In addition, on the lower surface of the communication plate 25, a compliance substrate 27 having a through-opening 46 having a shape following the outer shape of the nozzle plate 24 formed at the center so as to surround the nozzle plate 24 is joined. The through opening 46 of the compliance substrate 27 communicates with the through hole 23a of the fixing plate 23, and the nozzle plate 24 is arranged inside thereof.

  The compliance substrate 27 is positioned and joined to the lower surface of the communication plate 25 and seals the opening of the reservoir 43 on the lower surface of the communication plate 25. As shown in FIGS. 4 and 5, the compliance substrate 27 in the present embodiment is configured by joining a compliance sheet 44 (a kind of compliance member) and a support plate 45 that supports the compliance sheet 44. The compliance sheet 44 of the compliance substrate 27 is bonded to the lower surface of the communication plate 25 so that the compliance sheet 44 is sandwiched between the communication plate 25 and the support plate 45. The compliance sheet 44 is made of a flexible thin film, for example, a synthetic resin material such as polyphenylene sulfide (PPS). The support plate 45 is formed of a metal material such as stainless steel having higher rigidity and thickness than the compliance sheet 44. In a region of the support plate 45 facing the reservoir 43, a compliance opening 48 is formed by removing a part of the support plate 45 in a shape following the opening of the lower surface of the reservoir 43. For this reason, the opening on the lower surface side of the reservoir 43 is sealed only with the compliance sheet 44 having flexibility. In other words, the compliance sheet 44 defines a part of the reservoir 43.

  A portion corresponding to the compliance opening 48 on the lower surface of the support plate 45 is sealed by the fixing plate 23. Thereby, a compliance space 47 is formed between the flexible region of the compliance sheet 44 and the fixing plate 23 facing the flexible region. The flexible region of the compliance sheet 44 in the compliance space 47 is displaced to the reservoir 43 side or the compliance space 47 side in accordance with the pressure fluctuation in the ink flow path, particularly in the reservoir 43. Therefore, the thickness of the support plate 45 is determined according to the height required for the compliance space 47.

  The actuator substrate 26 and the communication plate 25 are fixed to the holder 28. The holder 28 has substantially the same shape as the communication plate 25 in a plan view, and an accommodation space 49 for accommodating the actuator substrate 26 is formed on the lower surface side of the holder 28. Then, the lower surface of the holder 28 is sealed by the communication plate 25 in a state where the actuator substrate 26 is accommodated in the accommodation space 49. As shown in FIG. 3, an insertion space 50 that communicates with the accommodation space 49 is formed at a substantially central portion of the holder 28 in plan view. The insertion space 50 communicates with the wiring space 40 of the actuator substrate 26. The flexible board 39 is configured to be inserted into the wiring cavity 40 through the insertion cavity 50. Further, inside the holder 28, a liquid chamber space 51 that communicates with the reservoir 43 of the communication plate 25 is formed on both sides of the insertion space 50 and the accommodation space 49. In addition, on the upper surface of the holder 28, an introduction port 52 communicating with the liquid chamber empty space 51 is opened. Ink sent from the ink cartridge 8 is introduced into the liquid chamber space 51 through the introduction port 52. In other words, the ink sent from the ink cartridge 8 is introduced into the introduction port 52, the liquid chamber space 51, and the reservoir 43, and is supplied from the reservoir 43 to the pressure chambers 33 through the individual communication ports 35.

  The fixed plate 23 is a metal plate material such as stainless steel. In the present embodiment, the fixing plate 23 has a through-hole 23 a having a shape that follows the outer shape of the nozzle plate 24 in order to expose the nozzle 30 formed on the nozzle plate 24 at a position corresponding to the nozzle plate 24. It is formed so as to penetrate the direction. As described above, the through hole 23 a communicates with the through opening 46 of the compliance substrate 27. In this embodiment, the lower surface of the fixed plate 23 in the fixed plate 23 and the exposed portion of the nozzle plate 24 in the through hole 23a constitute a nozzle forming surface.

  In the recording head 10 having the above configuration, the flow path from the liquid chamber empty portion 51 to the nozzle 30 through the reservoir 43 and the pressure chamber 33 is filled with ink, and according to the drive signal from the drive IC 38. When the piezoelectric element 31 is driven, pressure vibration is generated in the ink in the pressure chamber 33, and ink is ejected from a predetermined nozzle 30 by this pressure vibration. Further, the compliance sheet 44 is displaced (bends) in accordance with the pressure fluctuation generated in the ink flow path (in the reservoir 43) with the recording operation (liquid ejecting operation) of the recording head 10, whereby the pressure fluctuation. Is absorbed. Thereby, for example, the pressure fluctuation generated in the pressure chamber 33 when ink is ejected from one nozzle 30 is transmitted from the individual communication port 35 to the reservoir 43 and further to the pressure chamber 33 on the other nozzle 30 side. Variations in the ejection characteristics (the amount of ink droplets ejected from the nozzles 30 and the flying speed) are suppressed.

  FIG. 6 shows the flow of ink and air in an ink discharge mode (a kind of liquid discharge mode in the present invention) performed to prevent problems due to freezing of ink in the ink flow path (corresponding to the liquid flow path in the present invention). FIG. 6 is a schematic diagram illustrating an ink flow path from the reservoir 43 to the nozzle 30. In the drawing, hatched arrows indicate the flow of ink, and white arrows indicate the flow of air (or the flow of ink that moves with air). In the printer 1 configured as described above, the ink discharge mode is performed, for example, when the temperature around the recording head 10 (temperature detected by the temperature sensor 21) approaches a temperature at which ink may freeze. In the printer 1 according to the present embodiment, a large amount of ink is ejected from a large number of nozzles 30 (discharge nozzles 30a) among the nozzles 30 constituting the same nozzle row, thereby increasing pressure loss in the ink supply path. By intentionally causing an insufficient supply of ink to the reservoir 43, an operation of drawing air into the ink flow path from the remaining part of the nozzles (the intake nozzle 30b) is performed. As described above, the ink discharge mode is executed and the ink in the ink flow path is replaced with air, so that it is possible to prevent the head constituent member from being damaged due to the expansion when the ink is frozen.

  FIG. 7 is a graph showing the relationship between the ink flow rate (g / s) in the ink supply path (for example, the inlet 52) and the pressure loss [Pa] in the ink discharge mode. In the figure, the straight lines indicated by the broken line, the alternate long and short dash line, and the alternate long and two short dashes line indicate threshold values for the pressure loss necessary for the ink to be discharged from the ink flow path and replaced with air. Th1 is a threshold value in the conventional ink discharge mode, and Th2 and Th3 are threshold values in the ink discharge mode according to the present invention. As shown in the figure, the pressure loss increases as the ink flow rate increases. The degree of the pressure loss varies depending on the type (structure) of the liquid jet head, the composition (viscosity) of the liquid, the environmental temperature / humidity, and the like. . For this reason, in the conventional ink discharge mode, for example, in the recording head A, when the pressure loss is increased to a certain flow velocity, the pressure loss exceeds the threshold Th1, and thus the ink can be discharged from the ink flow path. In the head, even if the flow rate is increased, the pressure loss does not easily exceed the threshold value Th1, and the ink in the ink flow path cannot be replaced with air without reaching the state of insufficient ink supply from the upstream to the reservoir. For this reason, the B or C recording head wastes ink from the ink cartridge 8.

  In view of this, the ink discharge mode according to the present invention is configured to lower the threshold value so that the ink discharge mode is more easily reached due to insufficient ink supply from the upstream to the reservoir. Hereinafter, this point will be described.

  In the ink discharge mode in the present embodiment, for each nozzle 30 constituting the nozzle row for each reservoir 43, a discharge nozzle 30a that discharges ink (corresponding to the first nozzle in the present invention) and an intake air that sucks air. Nozzle 30b (corresponding to the second nozzle in the present invention) is set. The intake nozzle 30 b is a nozzle 30 located farther from the introduction port 52 through which ink is supplied to the reservoir 43. For example, as shown in FIG. 6, when the predetermined nozzle row is composed of 400 nozzles 30, in the configuration where the introduction port 52 is located at the center in the longitudinal direction (nozzle row direction) of the reservoir 43, The first nozzle 30 and the 400th nozzle 30 located at both ends of the row are the intake nozzles 30b, respectively, and the remaining second to 399th nozzles 30 are the discharge nozzles 30a. Of all the nozzles 30 constituting the same nozzle row, the number of nozzles 30 set as the intake nozzle 30b is preferably 1 or more and 30% or less of the total number of nozzles. In this way, by setting the discharge nozzle 30a and the intake nozzle 30b, that is, by providing the intake nozzle 30b separately from the discharge nozzle 30a, air is introduced into the ink flow path in the ink discharge mode. Can be pulled in more aggressively. As a result, it is possible to lower the threshold value of the pressure loss at which ink is discharged from the ink flow path and replaced with air. For this reason, it becomes possible to more reliably replace the ink in the ink flow path with air by the ink discharge mode regardless of the type of the print head, environmental conditions, and the like. In the present embodiment, the intake nozzle 30b is arranged at the end of the nozzle row, so that when the large amount of ink is discharged from the discharge nozzle 30a, the discharged ink (mist) is used for intake. It is suppressed that the ink is again taken into the ink flow path from the nozzle 30b.

  FIG. 8 is a schematic diagram for explaining the ink discharge mode according to the present invention, and the period of ink pressure vibration (hereinafter referred to as reservoir vibration) inside the reservoir 43 (or the natural vibration period of the compliance sheet 44); A timing chart for driving timing of the piezoelectric element 31 corresponding to each nozzle 30 (ink ejection, non-ejection (stop) of the discharge nozzle 30a, or intake operation of the intake nozzle 30b) is shown in association with each other. . Note that the period of the reservoir vibration in the figure is different from the actual one, but is simplified for convenience of explanation. In the ink discharge mode in the present embodiment, an operation of discharging ink from the discharge nozzle 30a (hereinafter referred to as ink discharge operation) and an operation of stopping discharge of ink from the discharge nozzle 30a (hereinafter referred to as pause operation) are performed. By alternately repeating in synchronization with the vibration cycle of the pressure of the liquid in the reservoir 43, that is, by repeating the ink discharge operation intermittently in synchronization with the cycle of the reservoir vibration, the reservoir vibration is excited to have a larger amplitude. Get. Thus, in the ink discharge mode, air can be more actively drawn into the ink flow path from the intake nozzle 30b using the reservoir vibration. That is, during the ink discharging operation, the liquid in the reservoir 43 is further decompressed, and the supply of ink from the upstream side of the reservoir 43 cannot keep up with pressure loss. As a result, it is possible to further reduce the pressure loss threshold at which ink is discharged from the ink flow path and replaced with air. That is, in FIG. 7, the threshold value Th2 can be set lower than the conventional threshold value Th1. For this reason, it becomes possible to more reliably replace the ink in the ink flow path with air by the ink discharge mode regardless of the type of the print head, environmental conditions, and the like. Although the compliance sheet 44 is not necessarily provided, in the configuration including the compliance sheet 44, it is possible to obtain a greater vibration by using the vibration of the compliance sheet 44. As a result, the introduction of air into the intake nozzle 30b can be further promoted.

  More specifically, the ink discharge mode in the present embodiment will be described. As shown in FIG. 8, in the period in which the pressure of the reservoir vibration decreases, a little before the minimum value at which the pressure decreases most (just before the maximum value side). ) By continuously applying the ejection drive pulse Pd a plurality of times to the piezoelectric element 31 (corresponding to the first drive element in the present invention) corresponding to the discharge nozzle 30a from the timing until the minimum value is reached. Then, an ink discharging operation for discharging ink simultaneously from all the discharging nozzles 30a constituting the same nozzle row is performed. In other words, by simultaneously discharging ink from all the discharge nozzles 30a at the timing when the pressure in the reservoir 43 becomes the lowest, ink supply is insufficiently supplied to the reservoir 43, and the air from the intake nozzle 30b is discharged. Promote intrusion. Various well-known drive pulses can be used as the ejection drive pulse Pd at this time, but it is more desirable to eject more ink. In short, it is desirable to employ a driving pulse that pressurizes the inside of the pressure chamber 33 by time average by driving the piezoelectric element 31 and has a larger voltage and its rate of change. Further, regarding the duration t of the ink discharge operation, when the reservoir vibration cycle is Tr, for example, t = Tr / 3 to Tr / 4.

  In the present embodiment, the intake drive pulse Pv is applied to the piezoelectric element 31 (corresponding to the second drive element in the present invention) corresponding to the intake nozzle 30b in accordance with the ink discharge operation, thereby performing the intake operation. The pressure chamber 33 corresponding to the nozzle 30b is decompressed to introduce air (hereinafter referred to as an intake operation).

  FIG. 9 is a waveform diagram illustrating the configuration of the intake drive pulse Pv. The intake drive pulse Pv in the present embodiment has an expansion element p1, a hold element p2, and a contraction element p3. The expansion element p1 is a waveform element that lowers the potential with a predetermined gradient from a reference potential Eb corresponding to a reference volume of the pressure chamber 33 (a volume serving as a reference for expansion or contraction) to an expansion potential Ev lower than the reference potential Eb. is there. The hold element p2 is a waveform element that maintains the expansion potential Ev, which is the terminal potential of the expansion element p1, for a predetermined time. The contraction element p3 is a waveform element generated following the hold element p2, and is a waveform element in which the potential returns with a constant gradient from the expansion potential Ev to the reference potential Eb. In this embodiment, the potential difference of the expansion element p1 and the potential difference of the contraction element p3 are both equal to the difference between the reference potential Eb and the expansion potential Ev, but the potential change rate of the expansion element p1 (degree of potential change with respect to time change). Is set larger than the potential change rate of the contraction element p3. Therefore, the intake drive pulse Pv has a greater force for expanding the pressure chamber 33 and depressurizing the liquid in the pressure chamber 33 than for compressing the pressure chamber 33 to pressurize the liquid in the pressure chamber 33. The driving pulse is as follows. That is, the intake drive pulse Pv is a drive pulse that depressurizes the inside of the pressure chamber 33 on a time average basis by driving the piezoelectric element 31.

  When such an intake drive pulse Pv is applied to the piezoelectric element 31, first, the expansion element p1 causes the piezoelectric element 31 to move outside the pressure chamber 33 (on the side away from the nozzle plate 24) from the initial position corresponding to the reference potential Eb. The pressure chamber 33 rapidly expands from the reference volume corresponding to the reference potential Eb to the expansion volume corresponding to the expansion potential Ev. Due to the expansion of the pressure chamber 33, the pressure chamber 33 is depressurized, and air is drawn into the pressure chamber 33 from the intake nozzle 30b. At this timing, the discharge nozzle 30a simultaneously discharges (injects) ink, so that the pressure in the reservoir 43 becomes negative and synergistic with the drawing of ink from the pressure chamber 33 corresponding to the intake nozzle 30b to the reservoir 43. By the action, it is possible to further promote the introduction of air from the intake nozzle 30b. As a result, it is possible to further reduce the pressure loss threshold at which ink is discharged from the ink flow path and replaced with air. That is, in FIG. 7, the threshold value Th3 can be made lower than the conventional threshold value Th2. Then, after the expansion state of the pressure chamber 33 is maintained over the application period of the hold element p2, the piezoelectric element 31 is deflected to the inside of the pressure chamber 33 (side closer to the nozzle plate 24) by the contraction element p3, and the pressure is increased. The chamber 33 returns relatively slowly from the expansion volume corresponding to the expansion potential Ev to the reference volume. In the present embodiment, the intake operation is performed in accordance with the ink discharge operation and the intake operation is not performed in the pause operation. However, the intake operation is continuously performed in the pause operation. A configuration can also be adopted.

  FIG. 10 is a waveform diagram of an intake drive pulse Pv ′ that is a modification of the intake drive pulse Pv. The intake drive pulse Pv ′ includes a first contraction element p11, a contraction hold element p12, an expansion element p13, an expansion hold element p14, and a second contraction element p15. The first contraction element p11 is a waveform element that increases the potential from the reference potential Eb to the contraction potential E1 that is higher than the reference potential Eb. The contraction hold element p12 maintains the contraction potential E1, which is the terminal potential of the first contraction element p11, for a certain period of time. The expansion element p13 is a waveform element generated following the contraction hold element p12, and is a waveform element that lowers the potential from the contraction potential E1 to the expansion potential E2 lower than the reference potential Eb. The expansion hold element p14 maintains the expansion potential E2 that is the terminal potential of the expansion element p13 for a certain period of time. The second contraction element p15 is a waveform element generated following the expansion hold element p14, and is a waveform element in which the potential returns with a constant gradient from the expansion potential E2 to the reference potential Eb.

  In the intake drive pulse Pv ′, the potential difference (E1−E2) of the expansion element p13 that is a waveform element that expands the pressure chamber 33 is different from the potential difference (E1) of the first contraction element p11 that is a waveform element that contracts the pressure chamber 33. -Eb) and the potential difference (Eb-E2) of the second contraction element p15 is characteristic. The potential change rate of the expansion element p13 is set to be larger than the potential change rates of the contraction elements p11 and p15. Therefore, the intake drive pulse Pv ′ has a force that expands the pressure chamber 33 and depressurizes the liquid in the pressure chamber 33 rather than a force that contracts the pressure chamber 33 and pressurizes the liquid in the pressure chamber 33. The driving pulse is further increased. In other words, the intake drive pulse Pv ′ is a drive pulse that depressurizes the pressure chamber 33 on a time average basis by driving the piezoelectric element 31. In accordance with the ink discharging operation, the pressure chamber 33 is expanded by applying the intake drive pulse Pv ′ to the piezoelectric element 31 (corresponding to the second drive element in the present invention) corresponding to the intake nozzle 30b. Since the force for depressurizing the pressure chamber 33 is increased, the introduction of air from the intake nozzle 30b can be more effectively promoted.

Next, another embodiment of the present invention will be described.
FIG. 11 is a schematic diagram for explaining the ink discharge mode according to the second embodiment of the present invention, and similarly to FIG. 8, the period of the reservoir vibration and the timing of the drive timing of the piezoelectric element 31 corresponding to each nozzle 30. A chart is associated with the chart. In the ink discharge mode in the first embodiment, the ink discharge operation and the pause operation of the discharge nozzle 30a are alternately repeated in synchronization with the reservoir vibration, that is, the ink discharge operation is synchronized with the period of the reservoir vibration. In this configuration, the reservoir vibration is excited by repeating intermittently. However, the present invention is not limited to this. In the ink discharging operation in the present embodiment, the reservoir vibration is excited by providing the ink discharging operation with coarseness and density without performing the pause operation. In other words, the frequency of application of the ejection drive pulse Pd to the piezoelectric element 31 corresponding to the discharge nozzle 30a gradually becomes dense (higher) from the maximum of the reservoir vibration to the minimum, while from the minimum of the reservoir vibration to the maximum. It is set so as to become gradually rougher (lower). Regarding the application frequency of the ejection drive pulse Pd, it is desirable that the difference between the maximum frequency and the minimum frequency is 30% or more. Thereby, in the ink discharge mode, the reservoir vibration can be excited, and air can be more actively drawn into the ink flow path from the intake nozzle 30b using the reservoir vibration. Further, in this configuration, the drive voltage (potential difference between the maximum potential and the minimum potential) of the ejection drive pulse Pd gradually increases from the maximum of the reservoir vibration to the minimum, while gradually increases from the minimum of the reservoir vibration to the maximum. It is also possible to adopt a configuration that is set to be low. Thereby, the reservoir vibration can be excited more effectively. It should be noted that the application frequency of the reference drive pulse Pv to the piezoelectric element 31 corresponding to the intake nozzle 30b may be the same as the application frequency of the ejection drive pulse Pd or may be constant.

  FIG. 12 is a schematic diagram illustrating an ink discharge mode according to the third embodiment of the present invention, and is a schematic diagram illustrating a state where the nozzle forming surface of the recording head 10 is sealed by the capping mechanism 13. As described above, the capping mechanism 13 includes the tray-like cap 14 and is configured to displace the cap 14 to a position where the cap 14 abuts on or separates from the nozzle formation surface of the recording head 10. In the present embodiment, the capping mechanism 13 can perform capping while disposing the suction nozzle 30b outside the cap 14 while facing the discharge nozzle 30a in the sealed space in the ink discharge mode. It is configured as follows. That is, for example, in order to prevent evaporation of the ink solvent from the nozzles 30 or to perform a cleaning operation for discharging the thickened ink, bubbles, or the like inside the recording head 10 from each nozzle 30 to restore the ejection ability. In the normal capping performed, all the nozzles 30 (30a, 30b) are capped so as to face the sealed space 53 as indicated by broken lines in FIG. On the other hand, in the ink discharge mode, the capping position is shifted from the normal position to one side in the nozzle row direction (the direction of the arrow in the figure) so that only the intake nozzle 30b is disposed outside the cap 14. Capped. In this state, the pump unit 16 that functions as a decompression mechanism is operated, so that the inside of the sealed space 53 is decompressed, and the ink in the recording head 10 is sucked through the discharge nozzle 30a, whereby the ink in the ink flow path. And the pressure acting on the liquid in the reservoir 43 is negative, and at the same time, it is disposed outside the cap 14 and is not affected by the pressure reduction by the pump unit 16. Air is introduced into the ink flow path from the intake nozzle 30b. By using this capping mechanism 13 to discharge ink from the discharge nozzle 30a and to introduce air from the intake nozzle 30b, it is possible to generate a high flow rate of ink in the ink flow path, and more reliably and reliably. It becomes possible to replace the ink in the ink flow path with air more quickly. At this time, the above-described intake drive pulse Pv may be applied to the piezoelectric element 31 corresponding to the intake nozzle 30b. Thereby, introduction of air can be promoted more effectively. In the present embodiment, it is desirable that the nozzle 30 located at one end of the nozzles 30 constituting the nozzle row is set as the intake nozzle 30b.

In each of the above-described embodiments, the so-called flexural vibration type piezoelectric element 31 is exemplified as the drive element. However, the present invention is not limited to this, and for example, a so-called longitudinal vibration type piezoelectric element can be employed. In this case, the intake drive pulse Pv (Pv ′) illustrated in the above embodiment has a waveform in which the direction of potential change, that is, the vertical (polarity) is inverted. In addition, the actuator is not limited to the piezoelectric element, and other actuators such as an electrostatic actuator may be employed.
In addition, some of the plurality of nozzles 30 formed on the nozzle plate 24 may be nozzles 30 (dummy nozzles) that are neither the discharge nozzle 30a nor the intake nozzle 30b. It is preferable to act as the discharge nozzle 30a or the intake nozzle 30b.
Further, in the intake drive pulse Pv ′ shown in FIG. 10, the potential difference (E1-E2) of the expansion element p13 that is a waveform element that expands the pressure chamber 33 is the first contraction that is a waveform element that contracts the pressure chamber. The potential difference (E1-Eb) of the element p11 and the potential difference (Eb-E2) of the second contraction element p15 are larger, and the potential change rate of the expansion element p13 is larger than the potential change rate of the contraction elements p11, p15. It was set. However, the potential difference (E1-E2) of the expansion element p13 can introduce air from the intake nozzle 30b more than the potential difference (E1-Eb) of the first contraction element p11 and the potential difference (Eb-E2) of the second contraction element p15. If it is sufficiently large, the potential change rate of the expansion element p13 can be made equal to the potential change rates of the contraction elements p11 and p15.

  In the above description, the ink jet recording head 10 (recording head 10), which is a kind of liquid ejecting head, has been described as an example. However, the present invention may be applied to other liquids that may cause damage to components due to freezing of the liquid. The present invention can also be applied to an ejection head and a liquid ejection apparatus including the ejection head. For example, a color material ejecting head used for manufacturing a color filter such as a liquid crystal display, an electrode material ejecting head used for forming an electrode such as an organic EL (Electro Luminescence) display, FED (surface emitting display), a biochip (biochemical element) The present invention can also be applied to a liquid ejecting head including a plurality of bio-organic matter ejecting heads and the like and a liquid ejecting apparatus including the same.

  DESCRIPTION OF SYMBOLS 1 ... Printer, 2 ... Frame, 3 ... Platen, 4 ... Conveyance mechanism, 5 ... Guide rod, 6 ... Carriage, 7 ... Carriage moving mechanism, 8 ... Ink cartridge, 10 ... Recording head, 11 ... Wiping mechanism, 12 ... Wiper , 13 ... Capping mechanism 13 ... Cap, 15 ... Drain tube, 16 ... Pump unit, 17 ... CPU, 18 ... Storage device, 19 ... Drive signal generation circuit, 20 ... I / O interface, 21 ... Temperature sensor, 23 ... Fixed Plate, 24 ... Nozzle plate, 25 ... Communication plate, 26 ... Actuator substrate, 27 ... Compliance substrate, 28 ... Holder, 29 ... Pressure chamber forming substrate, 30 ... Nozzle, 31 ... Piezoelectric element, 32 ... Protection substrate, 33 ... Pressure Chamber 34 ... Nozzle communication port 35 ... Individual communication port 36 ... Diaphragm 38 ... Drive IC 39 ... Flexi 40 ... wiring empty space, 41 ... accommodating space, 43 ... reservoir, 44 ... compliance sheet, 45 ... support plate, 46 ... through opening, 47 ... compliance space, 48 ... compliance opening, 49 ... accommodating empty space, 50 ... insertion empty part, 51 ... liquid chamber empty part, 52 ... inlet, 53 ... sealed space

Claims (8)

A plurality of nozzles that eject liquid, a pressure chamber that communicates with the nozzle, and a plurality of drive elements that cause pressure fluctuations in the liquid in the pressure chamber,
A liquid discharge mode in which liquid is discharged from the pressure chamber and air is introduced into the pressure chamber can be executed;
The plurality of nozzles includes: a first nozzle that discharges liquid in the liquid discharge mode; and a second nozzle for intake that introduces air into the pressure chamber in the liquid discharge mode. apparatus. A common liquid chamber communicating with each of the plurality of pressure chambers;
In the liquid discharge mode, the vibration is excited by synchronizing the liquid discharge operation from the first nozzle with the period of the liquid vibration in the common liquid chamber, and air is supplied from the second nozzle to the pressure chamber side. The liquid ejecting apparatus according to claim 1, wherein the liquid ejecting apparatus is an introducing operation.   The liquid ejecting apparatus according to claim 2, wherein a part of the common liquid chamber is partitioned and a compliance member having flexibility is provided. A drive waveform generation circuit for generating a first drive waveform for driving the first drive element corresponding to the first nozzle and a second drive waveform for driving the second drive element corresponding to the second nozzle;
The first driving waveform is a driving waveform for ejecting the liquid in the pressure chamber from the first nozzle by driving the first driving element,
The second drive waveform is a force that expands the pressure chamber and depressurizes the liquid in the pressure chamber, rather than a force that contracts the pressure chamber and pressurizes the liquid in the pressure chamber by driving the second drive element. 4. The drive waveform applied to the second drive element at a timing at which the first drive waveform is applied to the first drive element, wherein the first drive waveform is applied to the first drive element. The liquid ejecting apparatus according to any one of the above. The second drive waveform has an expansion element that expands the pressure chamber, and a contraction element that contracts the pressure chamber expanded by the expansion element,
The liquid ejecting apparatus according to claim 4, wherein a potential change rate of the expansion element is larger than a potential change rate of the contraction element.   6. The liquid ejecting apparatus according to claim 4, wherein, in the second drive waveform, a potential difference of a waveform element that expands the pressure chamber is larger than a potential difference of a waveform element that contracts the pressure chamber. . A capping mechanism having a cap that seals the nozzle forming surface on which the nozzle is formed, and a pressure reducing mechanism that decompresses the sealing space in the cap in a state where the nozzle forming surface is sealed by the cap;
In the liquid discharge mode, the capping mechanism arranges the second nozzle outside the cap, and seals the nozzle forming surface with the cap with the first nozzle facing the sealing space. The liquid ejecting apparatus according to claim 1, wherein the liquid is discharged from the first nozzle by the pressure reducing mechanism in a state. A control method of a liquid ejecting apparatus comprising a nozzle that ejects liquid, a pressure chamber communicating with the nozzle, and a plurality of drive elements that cause pressure fluctuations in the liquid in the pressure chamber,
A liquid discharge mode in which liquid is discharged from the pressure chamber and air is introduced into the pressure chamber can be executed;
In the liquid discharge mode, the liquid is discharged from the first nozzle of the plurality of nozzles, while air is introduced into the pressure chamber from the remaining second nozzles.

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