JP6922957B2 - Liquid discharge device - Google Patents

Description

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

Conventionally, a liquid injection head having a pressure chamber for accommodating a liquid, a piezoelectric film and a vibrating 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 done. The pressure chamber is partitioned by a bulkhead.

A groove is formed in the piezoelectric film at a portion corresponding to the partition wall, and the piezoelectric film is divided. Each partitioned piezoelectric membrane corresponds to each pressure chamber. The piezoelectric film deforms one surface of the pressure chamber, and droplets are ejected from the nozzle opening (see, for example, Patent Document 1).

Japanese Unexamined Patent Publication No. 2014-184603

In recent years, in order to realize high-definition recording, it is required to increase the density of the liquid injection head. When increasing the density of the head, it is necessary to reduce the width dimension of the pressure chamber, the nozzle opening, and the like. Here, if the thickness of the vibrating membrane is not changed, the thickness dimension of the vibrating membrane is large with respect to the width dimension of the pressure chamber, and the vibrating membrane is less likely to bend. Therefore, it is desirable to make the piezoelectric film and the vibrating film thin.

However, if the piezoelectric film is made thin, the reliability of the liquid injection head may decrease. For example, if a defect occurs during the production of the piezoelectric film, the thinness of the defect makes it difficult to repair the piezoelectric film. Further, as the thickness becomes thinner, the allowable voltage of the piezoelectric film also becomes smaller, but the voltage applied to the liquid injection head is determined according to the specifications of the main body (for example, the printer) to which the liquid injection head is attached. If the following settings cannot be made, the piezoelectric film may be damaged by high voltage.

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

The liquid discharge device according to the present invention intersects the vibrating membrane with a vibrating membrane constituting one surface of a pressure chamber in which the liquid is housed, a piezoelectric membrane provided on the opposite side of the pressure chamber in the vibrating membrane, and the vibrating membrane. Between the partition wall forming the side surface portion of the pressure chamber and the piezoelectric film and the vibrating membrane, the first electrode covered with the piezoelectric film and the piezoelectric film and the vibrating membrane are pressed against each other. It is provided with a second electrode that covers from the opposite side of the chamber, and is characterized in that the thickness of the connecting portion of the diaphragm with the partition wall is thinner than the thickness of the other portion of the diaphragm.

In the present invention, when the groove is formed, the connecting portion of the vibrating membrane with the partition wall is made thin. As a result, the vibrating film becomes easy to bend without thinning the entire piezoelectric film and the vibrating film. Further, by covering the first electrode with a piezoelectric film, the piezoelectric film is positioned between the first electrode and the second electrode to prevent a short circuit.

In the liquid discharge device according to the present invention, the vibrating membrane has 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 is deleted.

In the present invention, at least a part of the second layer is thinned or removed to make the vibrating membrane more flexible. Further, for example, when the first layer is composed of silicon dioxide and the second layer is composed 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 discharge device 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 discharge device 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 vibrating membrane is easily vibrated by locating the thin portion or the deleted portion of the vibrating membrane inside the pressure chamber with respect to the partition wall.

The liquid discharge device according to the present invention is characterized in that 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 side surface of the connecting portion thinner than the other portion is inclined to form a groove so as to form, for example, a rhombus in a plan view. The vibrating membrane is bent at the wide central portion to ensure the rigidity of the vibrating membrane at the narrow end portion.

The liquid discharge device 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, which is thinner than the other portion, is shallower than the depth of the central portion. The vibrating membrane is flexed at the central portion having a large depth, and the rigidity of the vibrating membrane is ensured at the end portion having a shallow depth.

In the liquid discharge device according to the present invention, the bottom surface and the side surface of the connecting portion have a depth of the central portion larger than the depth of the end portion in the width direction of the connecting portion intersecting the longitudinal direction of the connecting portion. As such, it is characterized by being 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 vibrating membrane is bent while ensuring the rigidity of the vibrating membrane.

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

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

The liquid discharge device according to the present invention is characterized in that 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 vibrating membrane.

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 vibrating membrane side to suppress stress concentration on the end portion in the width direction of the groove.

In the liquid discharge device according to the present invention, the connecting portion of the vibrating membrane with the partition wall is formed thinner inside the pressure chamber than the partition wall. As a result, the vibrating film becomes easy to bend without thinning the entire piezoelectric film and the vibrating film, and the decrease in reliability is suppressed. Further, a piezoelectric film can be positioned between the first electrode and the second electrode to prevent a short circuit.

It is a top view which shows the printer which concerns on Embodiment 1. It is a schematic cross-sectional view which made the line II-II shown in FIG. 1 a cutting line. It is a bottom view of an inkjet head. It is a top view of the head unit. Partial enlarged view illustrating the portion surrounded by the V line in FIG. FIG. 5 is a schematic cross-sectional view taken along the VI-VI line shown in FIG. 5 as a cutting line. FIG. 5 is a schematic cross-sectional view taken along the line VII-VII shown in FIG. 5 as a cutting line. It is a vertical cross-sectional view which shows schematic the piezoelectric element of the printer which concerns on Embodiment 2. FIG. It is a vertical cross-sectional view which shows schematic the piezoelectric element of the printer which concerns on Embodiment 3. FIG. It is a partially enlarged view which shows the part surrounded by X-ray of FIG. It is a vertical cross-sectional view which shows schematic the piezoelectric element of the printer which concerns on Embodiment 4. FIG. FIG. 5 is a schematic cross-sectional view taken along the line XII-XII shown in FIG. 11 as a cutting line.

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

In FIG. 1, the downstream side in the transport direction of the recording paper 100 is defined as the front side of the printer 1, and the upstream side in the transport direction is defined as the rear side of the printer 1. Further, the paper width direction parallel to the surface on which the recording paper 100 is conveyed (the surface parallel to the paper surface in FIG. 1) and orthogonal to the conveying direction is defined as the 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, the direction orthogonal to the transport surface of the recording paper 100 (the 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. In the following, the front, back, left, right, top and bottom will be described as appropriate.

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

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

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

For example, the control device 7 controls the motor that drives the transport rollers 5 and 6 to transport the recording paper 100 to the transport rollers 5 and 6 in the transport direction, and controls the inkjet head 4 toward the recording paper 100. Ink is ejected. As a result, the 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 side by side in the front-rear direction above the platen 3 and at a position between the two transport rollers 5 and 6. Each of the inkjet heads 4 is held by the head holding portion 8.

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

FIG. 2 is a schematic cross-sectional view taken along line II-II shown in FIG. 1 as a cutting line, 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-shaped holder 10 that is long in the paper width direction, and a plurality of (nine in this embodiment) head units 11 attached to the holder 10. And have.

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 arranged side by side along the paper width direction (arrangement direction), which is the longitudinal direction of the inkjet head 4, and form two rows of 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 displaced 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 pattern along the arrangement direction to form a front unit row consisting of four head units and a rear unit row consisting of five head units. Has been done. In the present embodiment, a plurality of head units 11 are arranged side by side along a direction orthogonal to the transport direction (paper width direction), but along a direction intersecting the transport direction at an angle other than 90 degrees. A plurality of head units 11 may be arranged diagonally, so to speak.

As shown in FIGS. 1 and 2, the reservoir 12 is provided above the plurality of head units 11. Note that 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 ink supplied from the ink tank is temporarily stored. The lower portion 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.

FIG. 4 is a plan view of the head unit 11, FIG. 5 is a partially enlarged view illustrating a portion surrounded by a V line in FIG. 4, and FIG. 6 is an abbreviation in which the VI-VI line shown in FIG. 5 is a cutting line. It is a sectional view shown.

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, the cover member 23 located above the piezoelectric actuator 22 is not shown in order to make it easier to understand the configuration of the piezoelectric actuator 22.

The flow path substrate 20 is composed of a silicon single crystal substrate. A plurality of rectangular pressure chambers 26 long in the transport direction are formed on the flow path substrate 20. As shown in FIG. 4, the plurality of pressure chambers 26 are arranged side by side in the paper width direction (arrangement direction) to form two rows of pressure chambers in the transport direction. A vibrating film 30 covering a plurality of pressure chambers 26 is formed on the flow path substrate 20.

The vibrating 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 30a is formed in a portion of the vibrating membrane 30 that overlaps with the inner end of each pressure chamber 26.

The nozzle plate 21 is joined to the lower surface of the flow path substrate 20. A plurality of nozzles 24 penetrating vertically are formed on the nozzle plate 21. The plurality of nozzles 24 are connected to each of the plurality of pressure chambers 26.

As shown in FIG. 4, each nozzle 24 is vertically overlapped in the corresponding pressure chamber 26. The plurality of nozzles 24 are arranged in the paper width direction (arrangement direction) corresponding to the plurality of pressure chambers 26, and form two rows of nozzles arranged in the transport direction. Between the two rows of nozzles, the positions of the nozzles 24 in the arrangement direction are shifted by half (P / 2) of the arrangement pitch P in each nozzle row. The material of the nozzle plate 21 is not particularly limited, but it can be a silicon single crystal substrate as in the flow path substrate 20. Alternatively, one made of synthetic resin may be adopted.

The piezoelectric actuator 22 applies 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 arranged corresponding to the plurality of pressure chambers 26 on the upper surface of the vibrating membrane 30.

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 vibrating film 30. By forming a film, a plurality of piezoelectric elements 39 are formed.

A plurality of lower electrodes 31 are formed on the upper surface of the vibrating film 30. The plurality of lower electrodes 31 are arranged side by side in the arrangement direction, and are provided for each of 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, but is made of, for example, platinum (Pt).

On the lower electrode 31, two piezoelectric films 32 are arranged corresponding to the two pressure chamber rows. The piezoelectric film 32 has a rectangular shape that is long in the arrangement direction, and is arranged so as to straddle a plurality of pressure chambers 26 that form a corresponding pressure chamber row. The piezoelectric film 32 is made of, for example, a piezoelectric material containing lead zirconate titanate (PZT), which is a mixed crystal of lead titanate and lead zirconate, as a main component.

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 a 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, which is a common electrode, facing one pressure chamber 26, the lower electrode 31, which is an individual electrode, and the portion of the piezoelectric film 32 facing one pressure chamber 26 Two piezoelectric elements 39 are configured. Further, in each piezoelectric element 39, the 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 in particular.

A wiring 35 is connected to the lower electrode 31 of each piezoelectric element 39. The wiring 35 is made 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 (rear) in the transport direction.

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

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

FIG. 7 is a schematic cross-sectional view taken along the line VII-VII shown in FIG. 5 as a cutting line. The pressure chamber 26 is partitioned by a plurality of partition walls 25 arranged side by side 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. The upper end of the partition wall 25 is connected to the vibrating membrane 20, and the lower end 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 vibrating film 30 includes a first layer 301 forming an upper surface portion of the pressure chamber 26 and a second layer 302 provided above the first layer 301. The first layer 301 contains silicon dioxide (SiO ₂ ) or silicon nitride (SiN _x ), and the second layer 302 contains 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 arranged between the central portion of the lower surface of the piezoelectric film 32 in the arrangement direction and the central portion 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 array direction. The thickness of the piezoelectric film 32 is, for example, 1 micrometer.

Between the piezoelectric elements 39 adjacent to each other in the arrangement direction, a rectangular groove 34 in a plan view extending in the front-rear direction is formed in the second layer 302 and the piezoelectric film 32 on the upper side of the first layer 301. There is. In other words, a groove 34 is formed at the upper end of the partition wall 25 and the connecting portion of the vibrating film 30. The upper electrode 33 is formed on the upper side of 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-back dimension) of the groove 34 is about 300 μm.

Since the piezoelectric film 32 is provided between both ends of the lower electrode 31 in the arrangement direction and the upper electrode 33, and between the lower electrode 31 and the upper electrode 33 in the vertical direction, the lower electrode 31 and the upper electrode 33 can be separated from each other. 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 (dimensions 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 vibrating film 30 is thinner in the vicinity of the partition wall 25 than the thickness of other portions. Therefore, the vibrating film 30 is easily bent.

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, the thin portion of the second layer 302 near 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 film 30 and the partition wall 25 is formed thinner inside the pressure chamber 26 than the partition wall 25. .. As a result, the vibrating film 30 is easily bent and the decrease in reliability is suppressed without thinning the entire piezoelectric film 32 and the vibrating film 30. 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 to make the vibrating film 30 more flexible. Further, for example, when the first layer 301 is composed of silicon dioxide or silicon nitride and the second layer 302 is composed of zirconium oxide, the first layer 301 is used as an etching stop layer and the second layer 302 is thinned. Or it can be deleted.

Further, the vibrating film 30 can be easily vibrated by locating the thin portion or the deleted portion of the vibrating 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 the printer 1 according to the second embodiment. FIG. 8 is a vertical cross-sectional view illustrating the piezoelectric element 39. The cutting position in FIG. 8 corresponds to FIG. 7. In the second embodiment, the same components as those in the first embodiment are designated by the same reference numerals, and detailed description thereof will be omitted.

In the second embodiment, the first layer 301 of the vibrating film 30 is thinner than the other portions in the vicinity of the partition wall 25. 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 to the left and right.

Since not only the second layer 302 but also the first layer 301 is thinned, the vibrating film 30 becomes more flexible.

(Embodiment 3)
Hereinafter, the present invention will be described with reference to the drawings showing the printer 1 according to the third embodiment. FIG. 9 is a vertical cross-sectional view illustrating the piezoelectric element 39, and FIG. 10 is a partially enlarged view illustrating a portion surrounded by X-rays in FIG. The cutting position in FIG. 9 corresponds to FIG. 7. In the third embodiment, the same components as those in the first embodiment are designated by the same reference numerals, and detailed description thereof will be omitted.

A groove 342 is formed between adjacent piezoelectric elements 39. When the groove 342 is cut by a plane parallel to the arrangement direction, the cross-sectional shape of the groove 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, in the width direction (arrangement 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 the side surface of the groove in the central portion in the width direction.

In the third embodiment, the groove 342 is formed in a V-shaped or U-shaped cross section to make the vibrating film 30 easy to bend while ensuring the rigidity of the vibrating film 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 the side surface of the groove 342 in the central portion in the width direction. 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 vibrating film 30, stress concentration on the widthwise end of the groove 342 can be suppressed.

(Embodiment 4)
Hereinafter, the present invention will be described with reference to the drawings showing the printer 1 according to the fourth embodiment. FIG. 11 is a vertical cross-sectional view illustrating the piezoelectric element 39, and FIG. 12 is a schematic cross-sectional view taken along the line XII-XII shown in FIG. 11 as a cutting line. The cutting position in FIG. 11 corresponds to FIG. 7. In the fourth embodiment, the same components as those in the first embodiment are designated by the same reference numerals, and detailed description thereof will be omitted.

As shown in FIG. 11, a groove 343 is formed between adjacent piezoelectric elements 39. The groove 343 has a plan-viewed rhombus shape extending in the front-rear direction (transportation 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 the 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 33a is formed in the upper electrode 33 on the upper side of the groove 343. That is, the groove 343 is not covered by the upper electrode 33 by the opening 33a. The groove 343 may have another shape, for example, an elliptical shape in a plan view or a hexagonal shape.

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

In the fourth embodiment, the bottom surface of the groove 343 is inclined so that the depths of the front end portion and the rear end portion of the groove 343 are shallower than the depth of the central portion. Therefore, the vibrating film 30 can be flexed at the central portion where the groove 343 is deep, and the rigidity of the vibrating film 30 can be ensured at the shallow front end portion and the rear end portion.

Further, the left and right side surfaces of the groove 343 are inclined to form the groove 343 so as to form, for example, a rhombic shape extending in the front-rear direction. Therefore, the vibrating film 30 can be flexed at the central portion having a wide width of the groove 343, and the rigidity of the vibrating film 30 can be ensured at the front end portion and the rear end portion having a narrow width of the groove 343. Further, since the groove 343 is not covered by the upper electrode 33, the thickness in the vicinity of the groove 343 is thinner than the other portions, and the groove 343 is easily bent.

In the fourth embodiment, the left-right side surface and the bottom surface of the groove 343 are inclined, but either the left-right side surface or the bottom surface of the groove 343 may be formed straight or flat.

The printer 1 in each of the above-described embodiments may be provided with a carriage that moves in the left-right direction, and the inkjet head 4 may be provided on the carriage. Also in the first to third embodiments, it is not necessary to form the upper electrode 33 on the upper side of the grooves 34, 341, 342 as in the fourth embodiment.

The embodiments disclosed this time should be considered to be exemplary in all respects and not restrictive. The technical features described in each example can be combined with each other and the scope of the invention is intended to include all modifications within the claims and scope equivalent to the claims. Will be done.

1 Printer 24 Nozzle 25 Partition wall 26 Pressure chamber 30 Vibrating membrane 301 1st layer 302 2nd layer 31 Lower electrode (1st electrode)
32 Piezoelectric film 33 Upper electrode (second electrode)
34, 341, 342, 343 grooves (connecting part)

Claims (7)

The vibrating membrane that constitutes one side of the pressure chamber in which the liquid is stored,
A piezoelectric film provided on the opposite side of the pressure chamber in the vibrating film and
A partition wall that intersects and is connected to the vibrating membrane and constitutes a side surface portion of the pressure chamber.
Between the piezoelectric film and the vibrating film, the first electrode covered with the piezoelectric film and
A second electrode that covers the piezoelectric film and the vibrating film from the opposite side of the pressure chamber is provided.
On the partition wall, a groove extending along the partition wall is formed in the piezoelectric film and the vibration film.
The groove is also formed at one end of the first electrode in the longitudinal direction .
The vibrating membrane is
First layer and
With the second layer provided on the opposite side of the pressure chamber in the first layer
Have,
A liquid discharge device, characterized in that at least a part of the second layer is thinner or deleted than other parts of the second layer. The vibrating membrane that constitutes one side of the pressure chamber in which the liquid is stored,
A piezoelectric film provided on the opposite side of the pressure chamber in the vibrating film and
A partition wall that intersects and is connected to the vibrating membrane and constitutes a side surface portion of the pressure chamber.
Between the piezoelectric film and the vibrating film, the first electrode covered with the piezoelectric film and
A second electrode that covers the piezoelectric film and the vibrating film from the opposite side of the pressure chamber is provided.
On the partition wall, a groove extending along the partition wall is formed in the piezoelectric film and the vibration film.
The second electrode has an opening formed on the partition wall .
The vibrating membrane is
First layer and
With the second layer provided on the opposite side of the pressure chamber in the first layer
Have,
A liquid discharge device, characterized in that at least a part of the second layer is thinner or deleted than other parts of the second layer. The liquid discharge device according to claim 1 or 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 liquid discharge device according to any one of claims 1 to 3, wherein a part of the first layer corresponding to the part of the second layer is thinner than the other part of the first layer. .. The liquid discharge device according to any one of claims 1 to 4 , wherein at least a part of the groove is located inside the pressure chamber with respect to the partition wall. The liquid discharge device according to any one of claims 1 to 5 , wherein the width of the central portion in the longitudinal direction of the groove is the widest in the longitudinal direction. The liquid discharge device according to claim 6 , wherein the groove has a rhombic shape in a plan view.

Images