JP6589527B2 - Liquid ejection device - Google Patents

Description

  The present invention relates to a liquid ejection apparatus that ejects liquid (for example, ink) to a recording medium (for example, paper).

  Conventionally, a liquid ejecting head including a pressure chamber for storing a liquid, a piezoelectric film and a vibration film provided on one surface side of the pressure chamber, and a nozzle opening formed on the other surface of the pressure chamber facing the one surface has been proposed. Has been. The pressure chamber is partitioned by a partition wall.

  At locations corresponding to the partition walls, grooves are formed in the piezoelectric film, and the piezoelectric film is divided. Each divided piezoelectric film corresponds to each pressure chamber. The piezoelectric film deforms one surface of the pressure chamber, and droplets are discharged from the nozzle openings (see, for example, Patent Document 1).

JP 2014-184603 A

  In recent years, in order to realize high-definition recording, it is required to increase the density of the liquid jet head. When increasing the density of the head, it is necessary to reduce the width dimensions of the pressure chamber and the nozzle opening. Here, when the thickness of the diaphragm is not changed, the thickness dimension of the diaphragm relative to the width dimension of the pressure chamber is large, and the diaphragm is difficult to bend. Therefore, it is desirable to make the piezoelectric film and the vibration film thin.

  However, when the piezoelectric film is thinned, the reliability of the liquid jet head may be reduced. For example, if a defect occurs during the production of the piezoelectric film, it is difficult to repair the piezoelectric film due to its thinness. In addition, the allowable voltage of the piezoelectric film is also reduced by thinning, and the applied voltage to the liquid ejecting head is determined according to the specification of the main body (for example, a printer) to which the liquid ejecting head is attached. If it cannot be set below, the piezoelectric film may be damaged by a high voltage.

  The present invention has been made in view of such circumstances, and even when the nozzles are arranged at a high density, a liquid ejection device capable of sufficiently vibrating the pressure chamber and suppressing a decrease in reliability. The purpose is to provide.

  The liquid ejection device according to the present invention intersects the vibration film that forms one surface portion of the pressure chamber in which the liquid is stored, a piezoelectric film that is provided on the opposite side of the pressure chamber in the vibration film, and the vibration film. The first electrode covered with the piezoelectric film between the piezoelectric film and the vibration film, and the piezoelectric film and the vibration film between the pressure film and the pressure film. And a second electrode covering from the opposite side of the chamber, wherein a thickness of a connecting portion of the vibrating membrane to the partition is thinner than a thickness of the other portion of the vibrating membrane.

  In this invention, when forming a groove | channel, the connection part with the partition in a vibration film is comprised thinly. Accordingly, the vibration film is easily bent without making the entire piezoelectric film and vibration film thinner. Further, by covering the first electrode with the piezoelectric film, the piezoelectric film is positioned between the first electrode and the second electrode to prevent a short circuit.

  In the liquid discharge apparatus according to the present invention, the vibration film includes a first layer and a second layer provided on the opposite side of the pressure chamber in the first layer, and at least a part of the second layer. Is thinner than the other part of the second layer or deleted.

  In the present invention, at least a part of the second layer is thinned or deleted so that the vibration film is easily bent. For example, when the first layer is made of silicon dioxide and the second layer is made of zirconium oxide, the first layer can be used as an etching stop layer, and the second layer can be thinned or deleted. .

  The liquid ejection apparatus according to the present invention is characterized in that a part of the first layer corresponding to the part of the second layer is thinner than the other part of the first layer.

  In the present invention, the first layer is also thinned to make the vibrating membrane more flexible.

  The liquid ejection apparatus according to the present invention is characterized in that at least a part of the connecting portion is located inside the pressure chamber with respect to the partition wall.

  In the present invention, the vibration film is easily vibrated by positioning the thin part or the deleted part of the vibration film inside the pressure chamber with respect to the partition wall.

  In the liquid ejection device according to the present invention, the connecting portion extends in a predetermined direction, and the width of the end portion in the longitudinal direction of the connecting portion is narrower than the width of the central portion.

  In the present invention, the groove is formed so that the side surface of the connecting portion thinner than the other portions is inclined to form, for example, a rhombus in plan view. The diaphragm is bent at the wide central portion, and the rigidity of the diaphragm is secured at the narrow end.

  The liquid ejection apparatus according to the present invention is characterized in that the depth of the end portion in the longitudinal direction of the connecting portion is shallower than the depth of the central portion.

  In the present invention, the bottom surface of the connecting portion is inclined so that the depth of the end portion of the connecting portion thinner than the other portion is shallower than the depth of the central portion. The diaphragm is bent at the center portion where the depth is large, and the rigidity of the diaphragm is secured at the end portion where the depth is shallow.

  In the liquid ejection apparatus according to the present invention, the bottom surface and the side surface of the connection portion are such that the depth of the center portion is greater than the depth of the end portion in the width direction of the connection portion that intersects the longitudinal direction of the connection portion. Thus, it is inclined or curved.

  In the present invention, for example, the connecting portion is formed in a groove shape with a V-shaped or U-shaped cross section, and the vibration film is bent while ensuring the rigidity of the vibration film.

  The liquid ejection device according to the present invention is characterized in that the inclination of the end portion in the width direction of the connecting portion is larger than the inclination of the bottom surface or the side surface of the connecting portion in the center portion in the width direction.

  In the present invention, stress concentration at the end portion in the width direction of the connecting portion can be suppressed as compared with the case where the bottom surface of the connecting portion is flat.

  In the liquid ejection apparatus according to the present invention, the connecting portion is a groove, and the inclination of the groove in the piezoelectric film is larger than the inclination of the groove in the vibration film.

  In the present invention, the inclination of the groove on the piezoelectric film side is made larger than the inclination of the groove on the vibration film side to suppress stress concentration on the end portion in the width direction of the groove.

  In the liquid ejection device according to the present invention, the connecting portion of the vibrating membrane with the partition wall is made thinner inside the pressure chamber than the partition wall. As a result, the vibration film is easily bent without reducing the thickness of the piezoelectric film and the entire vibration film, and a decrease in reliability is suppressed. Moreover, a short circuit can be prevented by positioning a piezoelectric film between the first electrode and the second electrode.

FIG. 2 is a plan view schematically showing the printer according to the first embodiment. It is the schematic sectional drawing which made the II-II line shown in FIG. 1 the cutting line. It is a bottom view of an inkjet head. It is a top view of a head unit. 4 is a partially enlarged view schematically showing a portion surrounded by the V line in FIG. FIG. 6 is a schematic cross-sectional view taken along line VI-VI shown in FIG. 5. FIG. 6 is a schematic cross-sectional view taken along line VII-VII shown in FIG. 5. FIG. 6 is a longitudinal sectional view schematically showing a piezoelectric element of a printer according to a second embodiment. FIG. 10 is a longitudinal sectional view schematically showing a piezoelectric element of a printer according to a third embodiment. FIG. 10 is a partially enlarged view schematically showing a portion surrounded by X-rays in FIG. 9. FIG. 10 is a longitudinal sectional view schematically showing a piezoelectric element of a printer according to a fourth embodiment. FIG. 12 is a schematic cross-sectional view taken along line XII-XII shown in FIG. 11.

(Embodiment 1)
Hereinafter, the present invention will be described with reference to the drawings illustrating a printer according to a first embodiment. FIG. 1 is a plan view schematically showing a printer.

  In FIG. 1, the downstream side in the conveyance direction of the recording paper 100 is defined as the front side of the printer 1, and the upstream side in the conveyance direction is defined as the rear side of the printer 1. Further, a paper width direction that is parallel to a surface (a surface parallel to the paper surface of FIG. 1) on which the recording paper 100 is conveyed and orthogonal to the conveyance direction is defined as a left-right direction of the printer 1. The left side of the figure is the left side of the printer 1, and the right side of the figure is the right side of the printer 1. Further, a direction orthogonal to the conveyance surface of the recording paper 100 (a direction orthogonal to the paper surface of FIG. 1) is defined as the vertical direction of the printer 1. In FIG. 1, the front side is the upper side and the back side is the lower side. Below, it demonstrates using front, back, left, right, up and down suitably.

  As shown in FIG. 1, the printer 1 includes a housing 2, a platen 3, four inkjet heads 4 (liquid ejection devices), two transport rollers 5 and 6, and a control device 7.

  The platen 3 is placed flat in the housing 2. A recording sheet 100 is placed on the upper surface of the platen 3. The four inkjet heads 4 are juxtaposed in the front-rear direction (conveying direction) above the platen 3. The two transport rollers 5 and 6 are respectively arranged on the rear side (upstream side in the transport direction) and the front side (downstream side) with respect to the platen 3. The two transport rollers 5 and 6 are respectively driven by a motor (not shown) to transport the recording paper 100 on the platen 3 forward.

  The control device 7 is an ASIC including a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), an EEPROM (Electrically Erasable Programmable Read-Only Memory), and various control circuits. (Application Specific Integrated Circuit). The control device 7 is connected to an external device 9 such as a PC so as to be able to perform data communication, and controls each unit of the printer 1 based on print data transmitted from the external device 9.

  For example, the control device 7 controls a motor that drives the conveyance rollers 5 and 6 to convey the recording paper 100 in the conveyance direction by the conveyance rollers 5 and 6, and controls the inkjet head 4 toward the recording paper 100. Ink is ejected. As a result, an image is printed on the recording paper 100.

  A plurality of head holding portions 8 are attached to the housing 2. The plurality of head holding portions 8 are arranged in parallel in the front-rear direction above the platen 3 and at a position between the two transport rollers 5 and 6. The head holding unit 8 holds the inkjet head 4.

  The four inkjet heads 4 eject inks of four colors, cyan (C), magenta (M), yellow (Y), and black (K), respectively. Each inkjet head 4 is supplied with ink of a corresponding color from an ink tank (not shown).

  2 is a schematic cross-sectional view taken along the line II-II shown in FIG. 1, and FIG. 3 is a bottom view of the inkjet head 4. As shown in FIGS. 2 and 3, each inkjet head 4 includes a rectangular plate-like holder 10 that is long in the paper width direction and a plurality (nine in this embodiment) of head units 11 attached to the holder 10. And.

  The lower surface of each head unit 11 is an ink ejection surface 14 on which a plurality of nozzles 24 are formed. The plurality of nozzles 24 of each head unit 11 are juxtaposed along the paper width direction (arrangement direction), which is the longitudinal direction of the inkjet head 4, and constitutes two nozzle rows.

  The nine head units 11 are arranged side by side along the arrangement direction. The nine head units 11 are alternately arranged on the front side and the rear side in the transport direction. The left and right (arrangement direction) positions are deviated between the four head units 11 arranged on the front side and the five head units 11 arranged on the rear side. In other words, the nine head units 11 are arranged in a staggered manner along the arrangement direction, so that a front unit row consisting of four head units and a rear unit row consisting of five head units are configured. Has been. In the present embodiment, the plurality of head units 11 are arranged in parallel along a direction (paper width direction) orthogonal to the transport direction, but along a direction intersecting the transport direction at an angle other than 90 degrees. In other words, a plurality of head units 11 may be arranged obliquely.

  As shown in FIGS. 1 and 2, the reservoir 12 is provided above the plurality of head units 11. In FIG. 3, the reservoir 12 is not shown.

  The reservoir 12 is connected to an ink tank (not shown) via a tube 16 and temporarily stores ink supplied from the ink tank. The lower part of the reservoir 12 is connected to a plurality of head units 11, and ink is supplied from the reservoir 12 to each head unit 11.

  4 is a plan view of the head unit 11, FIG. 5 is a partially enlarged view schematically showing a portion surrounded by the V line in FIG. 4, and FIG. 6 is an abbreviated view taken along the line VI-VI shown in FIG. FIG.

  The head unit 11 includes a flow path substrate 20, a nozzle plate 21, a piezoelectric actuator 22, a cover member 23, and a COF 50 (Chip On Film). In FIG. 5, in order to facilitate understanding of the configuration of the piezoelectric actuator 22, the illustration of the cover member 23 positioned above the piezoelectric actuator 22 is omitted.

  The flow path substrate 20 is composed of a silicon single crystal substrate. The flow path substrate 20 has a plurality of rectangular pressure chambers 26 that are long in the transport direction. As shown in FIG. 4, the plurality of pressure chambers 26 are arranged in parallel in the paper width direction (arrangement direction), and constitute pressure chamber rows arranged in two rows in the transport direction. A vibration film 30 that covers the plurality of pressure chambers 26 is formed on the flow path substrate 20.

The vibration film 30 is a film containing silicon dioxide (SiO ₂ ) or silicon nitride (SiN _x ) formed by oxidizing or nitriding a part of the surface of the silicon flow path substrate 20. A communication hole 30 a is formed in a portion of the vibrating membrane 30 that overlaps the inner end of each pressure chamber 26.

  The nozzle plate 21 is bonded to the lower surface of the flow path substrate 20. The nozzle plate 21 is formed with a plurality of nozzles 24 penetrating vertically. The plurality of nozzles 24 are respectively connected to the plurality of pressure chambers 26.

  As shown in FIG. 4, each nozzle 24 is disposed so as to overlap the corresponding pressure chamber 26 in the vertical direction. The plurality of nozzles 24 are arranged in the paper width direction (arrangement direction) corresponding to the plurality of pressure chambers 26, and constitute two nozzle rows arranged in the transport direction. Between the two nozzle rows, the position of the nozzle 24 in the arrangement direction is shifted by a half (P / 2) of the arrangement pitch P in each nozzle row. Although the material of the nozzle plate 21 is not particularly limited, it can be a silicon single crystal substrate in the same manner as the flow path substrate 20. Or you may employ | adopt the thing made from a synthetic resin.

  The piezoelectric actuator 22 imparts ejection energy for ejecting from the nozzle 24 to the ink in the plurality of pressure chambers 26. As shown in FIGS. 4 to 6, the piezoelectric actuator 22 includes a plurality of piezoelectric elements 39 disposed on the upper surface of the vibration film 30 so as to correspond to the plurality of pressure chambers 26, respectively.

  Hereinafter, the configuration of the piezoelectric element 39 will be described. In the present embodiment, a plurality of thin films including a film to be the lower electrode 31 (first electrode), a film to be the piezoelectric film 32, and a film to be the upper electrode 33 (second electrode) are sequentially formed on the upper surface of the vibration film 30. By forming films, a plurality of piezoelectric elements 39 are formed.

  A plurality of lower electrodes 31 are formed on the upper surface of the vibration film 30. The plurality of lower electrodes 31 are arranged side by side in the arrangement direction, and are respectively provided for the plurality of pressure chambers 26. The plurality of lower electrodes 31 are individual electrodes for the plurality of piezoelectric elements 39. The material of the lower electrode 31 is not particularly limited. For example, the lower electrode 31 is made of platinum (Pt).

  Two piezoelectric films 32 are disposed on the lower electrode 31 so as to correspond to the two pressure chamber rows, respectively. The piezoelectric film 32 has a rectangular shape that is long in the arrangement direction, and is disposed across a plurality of pressure chambers 26 constituting a corresponding pressure chamber row. The piezoelectric film 32 is made of, for example, a piezoelectric material mainly composed of lead zirconate titanate (PZT), which is a mixed crystal of lead titanate and lead zirconate.

  On the upper surface of the piezoelectric film 32, an upper electrode 33 extending in the arrangement direction so as to straddle the plurality of pressure chambers 26 is formed. The upper electrode 33 is a common electrode for the plurality of piezoelectric elements 39. The upper electrode 33 is made of, for example, platinum (Pt) or iridium (Ir).

  In the above configuration, the portion of the upper electrode 33 that is the common electrode that faces the one pressure chamber 26, the lower electrode 31 that is the individual electrode, and the portion of the piezoelectric film 32 that faces the one pressure chamber 26 Two piezoelectric elements 39 are formed. In each piezoelectric element 39, a portion sandwiched between the upper electrode 33 and the lower electrode 31 of the piezoelectric film 32 is hereinafter referred to as an active portion 38.

  A wiring 35 is connected to the lower electrode 31 of each piezoelectric element 39. The wiring 35 is formed of aluminum (Al), gold (Au), or the like. The wiring 35 extends from the lower electrode 31 of the corresponding piezoelectric element 39 to the upstream side (backward) in the transport direction.

  As shown in FIG. 4, a plurality of driving contact portions 46 connected to a plurality of wirings 35 and an upper electrode 33 are connected to the upper surface of the rear end portion of the flow path substrate 20 exposed from the cover member 23 described later. Two ground contact portions 47 are provided.

  A COF 50 that is a wiring member is bonded to the upper surface of the rear end portion of the flow path substrate 20. The plurality of driving contact portions 46 on the flow path substrate 20 side are electrically connected to a plurality of wirings 55 (see FIG. 6) formed in the COF 50, respectively. The COF 50 is also formed with ground wiring (not shown). The ground contact portion 47 is electrically connected to the ground wiring of the COF 50.

  A driver IC 51 is mounted on the COF 50. The COF 50 is connected to the control device 7 (see FIG. 1) of the printer 1, and the driver IC 51 is electrically connected to the control device 7 via wiring on the COF 50. The driver IC 51 generates and outputs a drive signal for driving the piezoelectric element 39 based on the control signal sent from the control device 7.

  The waveform shape of the drive signal is not particularly limited, and examples thereof include a rectangular pulse waveform that switches the potential between a low potential and a high potential. The drive signal output from the driver IC 51 is input to the drive contact portion 46 via the wiring 55 of the COF 50 and further supplied to the lower electrode 31 of the piezoelectric element 39 via the wiring 35. The upper electrode 33 is connected to the ground wiring of the COF 50 via the ground contact portion 47, and the potential of the upper electrode 33 is always maintained at the ground potential.

  7 is a schematic cross-sectional view taken along line VII-VII shown in FIG. The pressure chamber 26 is partitioned by a plurality of partition walls 25 arranged in parallel in the arrangement direction. The dimension between the partition walls 25 in the arrangement direction is, for example, 7.35 micrometers. The partition wall 25 extends in the transport direction. An upper end portion of the partition wall 25 is connected to the vibration film 20, and a lower end portion of the partition wall 25 is connected to the nozzle plate 21.

  In the arrangement direction, the piezoelectric element 39 and the nozzle 24 are located between the adjacent partition walls 25. In other words, the piezoelectric element 39 and the nozzle 24 are arranged in each pressure chamber 26 partitioned by the partition wall 25.

The vibration film 30 includes a first layer 301 that constitutes the upper surface portion of the pressure chamber 26, and a second layer 302 provided on the upper side of the first layer 301. The first layer 301 includes silicon dioxide (SiO ₂ ) or silicon nitride (SiN _x ), and the second layer 302 includes zirconium oxide (ZrO ₂ ). The thickness of the first layer 301 is, for example, 1.5 micrometers, and the thickness of the second layer 302 is, for example, 0.5 micrometers.

  A piezoelectric film 32 is provided above the second layer 302. The lower electrode 31 is disposed between the center of the lower surface of the piezoelectric film 32 in the arrangement direction and the center of the upper surface of the second layer 302 in the arrangement direction. The piezoelectric film 32 covers the upper surface of the lower electrode 31 and both ends in the arrangement direction. The thickness of the piezoelectric film 32 is, for example, 1 micrometer.

  Between the piezoelectric elements 39 adjacent in the arrangement direction, a rectangular groove 34 in plan view extending in the front-rear direction is formed in the second layer 302 and the piezoelectric film 32 above the first layer 301. Yes. In other words, the groove 34 is formed in the upper end portion of the partition wall 25 and the connecting portion of the vibration film 30. An upper electrode 33 is formed above the second layer 302, the piezoelectric film 32 and the groove 34. For example, the width (left-right dimension) of the groove 34 is 30 μm, and the length (front-rear dimension) of the groove 34 is about 300 μm.

  Since the piezoelectric film 32 is provided between both ends of the lower electrode 31 and the upper electrode 33 in the arrangement direction and between the lower electrode 31 and the upper electrode 33 in the vertical direction, the lower electrode 31 and the upper electrode 33 Short circuit is prevented.

  The groove 34 is located above the partition wall 25 and extends to the left and right sides of the partition wall 25 in the arrangement direction. That is, the width of the groove 34 (dimension along the arrangement direction) is larger than the width of the partition wall 25.

  Since the second layer 302 does not exist from the partition wall 25 to the inside of the pressure chamber 26, the thickness of the vibration film 30 is thinner in the vicinity of the partition wall 25 than the thickness of other portions. Therefore, the vibration film 30 is easily bent.

  Note that the second layer 302 may be formed in the vicinity of the partition wall 25 so as to be thinner than the other portions. In this case, a thin portion of the second layer 302 in the vicinity of the partition wall 25 is formed from the partition wall 25 to the inside of the pressure chamber 26 in the arrangement direction.

  In the inkjet head 4 of the printer 1 according to the first embodiment, when the groove 34 is formed, the connecting portion between the vibrating membrane 30 and the partition wall 25 is configured to be thinner inside the pressure chamber 26 than the partition wall 25. . As a result, the vibration film 30 is easily bent without reducing the entire thickness of the piezoelectric film 32 and the vibration film 30, and a decrease in reliability is suppressed. Further, the piezoelectric film 32 can be positioned between the lower electrode 31 and the upper electrode 33 to prevent a short circuit.

  Further, in the vicinity of the partition wall 25, the second layer 302 is thinned or deleted, so that the vibration film 30 is easily bent. For example, when the first layer 301 is made of silicon dioxide or silicon nitride and the second layer 302 is made of zirconium oxide, the first layer 301 is used as an etching stop layer, and the second layer 302 is thinned. Or can be deleted.

  Further, the vibration film 30 can be easily vibrated by positioning the thin part or the deleted part of the vibration film 30 inside the pressure chamber 26 with respect to the partition wall 25.

(Embodiment 2)
Hereinafter, the present invention will be described with reference to the drawings showing a printer 1 according to a second embodiment. FIG. 8 is a longitudinal sectional view schematically showing the piezoelectric element 39. The cutting position in FIG. 8 corresponds to FIG. In the second embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  In the second embodiment, in the vicinity of the partition wall 25, the first layer 301 of the vibration film 30 is thinner than other portions. In other words, the groove 341 is formed up to the first layer 301, and the thin portion of the first layer 301 extends from the partition wall 25 to the inside of the pressure chamber 26 in the arrangement direction from side to side.

  Since not only the second layer 302 but also the first layer 301 is made thin, the vibration film 30 is more easily bent.

(Embodiment 3)
Hereinafter, the present invention will be described with reference to the drawings showing a printer 1 according to a third embodiment. FIG. 9 is a longitudinal sectional view schematically showing the piezoelectric element 39, and FIG. 10 is a partially enlarged view schematically showing a portion surrounded by the X-ray in FIG. The cutting position in FIG. 9 corresponds to FIG. In the third embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  A groove 342 is formed between adjacent piezoelectric elements 39. When the grooves 342 are cut along a plane parallel to the arrangement direction, the cross-sectional shape of the grooves 342 is U-shaped or V-shaped. As shown in FIG. 10, the inclination b / a of the groove 342 in the piezoelectric film 32 is larger than the inclination d / c of the groove 342 in the second layer 302 (vibration film 30). For example, the slope b / a is 2 and the slope d / c is 1. In other words, the inclination of the end of the groove 342 in the width direction (arrangement direction) of the grooves 342 is larger than the inclination of the bottom surface or side surface of the groove at the center in the width direction.

  In the third embodiment, the groove 342 is formed in a V-shaped or U-shaped cross section, and the diaphragm 30 is easily bent while ensuring the rigidity of the diaphragm 30. Further, in the width direction of the groove 342, the inclination of the end portion of the groove 342 is larger than the inclination of the bottom surface or side surface of the groove 342 in the central portion in the width direction, so that the groove 342 is compared with the case where the bottom surface of the groove 342 is flat. It is possible to suppress stress concentration at the end in the width direction. Further, since the inclination of the groove 342 in the piezoelectric film 32 is larger than the inclination of the groove 342 in the vibration film 30, stress concentration on the end portion in the width direction of the groove 342 can be suppressed.

(Embodiment 4)
Hereinafter, the present invention will be described with reference to the drawings showing a printer 1 according to a fourth embodiment. 11 is a vertical cross-sectional view schematically showing the piezoelectric element 39, and FIG. 12 is a schematic cross-sectional view taken along line XII-XII shown in FIG. The cutting position in FIG. 11 corresponds to FIG. In the fourth embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  As shown in FIG. 11, a groove 343 is formed between adjacent piezoelectric elements 39. The groove 343 has a rhombus shape in plan view extending in the front-rear direction (conveying direction). That is, the left and right side surfaces of the groove 343 are inclined so that the width (dimension in the arrangement direction) of the front end portion or rear end portion of the groove 343 in the longitudinal direction of the groove 34 is narrower than the width of the central portion. An opening 33 a is formed in the upper electrode 33 on the upper side of the groove 343. That is, the groove 343 is not covered with the upper electrode 33 by the opening 33a. The groove 343 may have other shapes, for example, an elliptical shape or a hexagonal shape in plan view.

  As shown in FIG. 12, in the front-rear direction, the bottom surface of the groove 343 is inclined so that the depth (the vertical dimension) of the front end portion and the rear end portion is shallower than the depth of the center portion.

  In the fourth embodiment, the bottom surface of the groove 343 is inclined so that the depth of the front end portion and the rear end portion of the groove 343 is shallower than the depth of the central portion. Therefore, the diaphragm 30 can be bent at the center where the groove 343 is deep, and the rigidity of the diaphragm 30 can be secured at the shallow front end and rear end.

  Further, the right and left side surfaces of the groove 343 are inclined to form the groove 343 so as to have, for example, a rhombus shape in plan view extending in the front-rear direction. Therefore, the vibration film 30 can be bent at the wide center portion of the groove 343, and the rigidity of the vibration film 30 can be secured at the narrow front end portion and rear end portion of the groove 343. Further, since the groove 343 is not covered with the upper electrode 33, the thickness in the vicinity of the groove 343 is thinner than other portions and is easily bent.

  In Embodiment 4, the left and right side surfaces and the bottom surface of the groove 343 are inclined, but either the left or right side surface or the bottom surface of the groove 343 may be formed straight or flat.

  The printer 1 in each embodiment described above may be provided with a carriage that moves in the left-right direction, and the inkjet head 4 may be provided on the carriage. In the first to third embodiments, similarly to the fourth embodiment, the upper electrode 33 may not be formed above the grooves 34, 341, and 342.

  It should be thought that embodiment disclosed this time is an illustration and restrictive at no points. The technical features described in each embodiment can be combined with each other, and the scope of the present invention is intended to include all modifications within the scope of claims and the scope equivalent to the scope of claims. Is done.

DESCRIPTION OF SYMBOLS 1 Printer 24 Nozzle 25 Partition 26 Pressure chamber 30 Vibration film 301 1st layer 302 2nd layer 31 Lower electrode (1st electrode)
32 Piezoelectric film 33 Upper electrode (second electrode)
34, 341, 342, 343 Groove (connection part)

Claims (7)

A vibrating membrane constituting one surface portion of the pressure chamber in which the liquid is stored;
A piezoelectric film provided on the opposite side of the pressure chamber in the vibration film;
A partition wall that intersects and is connected to the vibration membrane, and forms a side surface of the pressure chamber;
A first electrode covered with the piezoelectric film between the piezoelectric film and the vibration film;
A second electrode that covers the piezoelectric film and the vibration film from the opposite side of the pressure chamber,
Next to the partition, a groove extending along the partition is formed in the piezoelectric film and the vibration film,
Rather thin than the thickness of the other portion of the vibration film thickness the vibrating membrane at the bottom of the groove,
Liquid discharge apparatus depth of the end portion in the longitudinal direction of the groove, characterized in shallow Ikoto than the depth of the central portion. A vibrating membrane constituting one surface portion of the pressure chamber in which the liquid is stored;
A piezoelectric film provided on the opposite side of the pressure chamber in the vibration film;
A partition wall that intersects and is connected to the vibration membrane, and forms a side surface of the pressure chamber;
A first electrode covered with the piezoelectric film between the piezoelectric film and the vibration film;
A second electrode that covers the piezoelectric film and the vibration film from the opposite side of the pressure chamber;
With
Next to the partition, a groove extending along the partition is formed in the piezoelectric film and the vibration film,
The thickness of the vibration film at the bottom of the groove is thinner than the thickness of the other part of the vibration film,
The bottom surface and the side surface of the groove are inclined or curved so that the depth of the central portion is larger than the depth of the end portion in the width direction of the groove intersecting the longitudinal direction of the groove,
The inclination of the end portion in the width direction of the groove is larger than the inclination of the bottom surface or side surface of the groove in the center portion in the width direction,
  The inclination of the side surface of the groove in the piezoelectric film is larger than the inclination of the side surface of the groove in the vibration film.
A liquid ejection apparatus characterized by the above. The liquid ejection apparatus according to claim 2 , wherein the depth of the end portion in the longitudinal direction of the groove is shallower than the depth of the central portion. The vibrating membrane is
The first layer;
A second layer provided on the opposite side of the pressure chamber in the first layer,
Liquid ejecting apparatus according to any one of claims 1 to 3, characterized in that it is thin or removed than other portions of the at least partially the second layer of the second layer. The liquid ejection apparatus according to claim 4 , wherein a part of the first layer corresponding to the part of the second layer is thinner than another part of the first layer. At least a portion of the liquid ejecting apparatus according to any one of claims 1 to 5, characterized in that located inside the pressure chamber than the partition wall of the groove. Liquid ejecting apparatus according to any one of the six claims 1 to width of the end portion in the longitudinal direction of the groove being narrower than the width of the central portion.

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