Inkjet head for reducing variation in liquid ejection performance

An inkjet head comprises a pressure chamber; a nozzle plate including a first surface at the side of the pressure chamber, a second surface opposite to the first surface, a first nozzle formed into a frustum which penetrates the first surface and the second surface and the diameter of which decreases as it goes closer to the second surface, and a second nozzle formed into a frustum which is the same as the frustum of the first nozzle; and a driving element configured adjacent to the pressure chamber to eject droplets from the first nozzle and the second nozzle simultaneously; wherein the part of the first nozzle on the first surface is integrally connected to the part of the second nozzle on the first surface, and the part of the first nozzle on the second surface is separated from the part of the second nozzle on the second surface.

CROSS-REFERENCE TO RELATED APPLICATION

This application is based upon and claims the benefit of priority from Japanese Patent Application No. 2013-242094, filed Nov. 22, 2013, the entire contents of which are incorporated herein by reference.

FIELD

Embodiments described herein relate generally to an inkjet head which can eject ink to carry out printing.

BACKGROUND

An inkjet head used in an inkjet printer is provided with a nozzle plate including nozzles, a pressure chamber connected with the nozzles and a piezoelectric vibrator for ejecting liquid from the nozzles. When pressure fluctuation occurs in the pressure chamber through the operation of the piezoelectric vibrator, droplets are ejected from the nozzles.

DETAILED DESCRIPTION

In accordance with one embodiment, an inkjet head comprises a pressure chamber; a nozzle plate configured to include a first surface at the side of the pressure chamber, a second surface opposite to the first surface, a first nozzle formed into a frustum which penetrates the first surface and the second surface and the diameter of which decreases as it goes closer to the second surface, and a second nozzle formed into a frustum which penetrates the first surface and the second surface and the diameter of which decreases as it goes closer to the second surface; and a driving element configured adjacent to the pressure chamber to eject droplets from the first nozzle and the second nozzle simultaneously; wherein the part of the first nozzle on the first surface is integrally connected to the part of the second nozzle on the first surface, and the part of the first nozzle on the second surface is separated from the part of the second nozzle on the second surface.

Hereinafter, a first embodiment of the inkjet head is described with reference toFIG. 1-FIG. 9. The inkjet head, arranged in a printing apparatus, can print characters, images and the like on a print target such as paper with liquid (ink) supplied from the printing apparatus. The liquid (ink) used in the inkjet head further contains functional ink having various functions used for a purpose other than forming an image, in addition to various kinds of ink used to form an image.

An inkjet head11, arranged in an inkjet printer (printing apparatus), is connected with a tank (ink tank, liquid tank) arranged inside the inkjet printer through a tube and the like. The inkjet head11includes a head main body12, a unit part13and a pair of circuit substrates14.

The unit part13includes a manifold which forms one part of a path between the head main body12and the tank, and a member for connecting with the inkjet printer. The pair of circuit substrates14is arranged on the head main body12, respectively.

As shown inFIG. 1, the pair of circuit substrates14includes a substrate main body15and a pair of film carrier packages (FCP16), respectively. The substrate main body15is a rectangular printed wiring board. Various electronic components and connectors are arranged in the substrate main body15. Further, the pair of FCPs16is mounted to the substrate main body15, respectively.

The pair of FCPs16includes a flexible resin-made film in which a plurality of wiring is formed and ICs17connected with the plurality of wiring, respectively. The film is tape automated bonding (TAB). The IC17is a component for applying voltage to an electrode. The IC17is fixed onto the film through resin.

As shown inFIG. 2, the end of the FCP16is connected with a wiring pattern21on a baseplate through thermocompression bonding with an anisotropic conductive film (ACF). The plurality of wiring of the FOP is electrically connected with the wiring pattern21through the ACF.

The head main body12is a device for ejecting droplets (ink drops) to the print target. The head main body12is mounted onto the unit part13. As shown inFIG. 2, the head main body12includes a baseplate22, a nozzle plate23, a frame member24, and blocks25on which a plurality of driving elements31are arranged.

As shown inFIG. 2andFIG. 3, the baseplate22is, for example, a rectangular plate formed with ceramic such as alumina and the like. A plurality of supply holes26and a plurality of discharge holes27are arranged to penetrate the baseplate22.

The supply holes26are arrayed at substantially central portion of the baseplate22in the longitudinal direction of the baseplate22. The supply hole26is connected with an ink supply section28of the manifold of the unit part13. The supply hole26is connected with the tank through the ink supply section28.

The discharge holes27are arrayed at two sides of the baseplate22in the longitudinal direction with the supply holes26nipped therebetween. The discharge hole27is connected with an ink discharge section29of the manifold of the unit part13. The discharge hole27is connected with the tank through the ink discharge section29.

The frame member24is a rectangular frame formed by, for example, a nickel alloy and the like. The frame member24is arranged between the baseplate22and the nozzle plate23. The frame member24is adhered to amounting surface of the baseplate22and the nozzle plate23, respectively.

The driving elements31(the blocks25on which a plurality of driving elements are arranged) are formed by two plate-shaped piezoelectric bodies which are formed by, for example, lead zirconate titanate (PZT). The two piezoelectric bodies are bonded together in such a manner that the directions of polarization thereof are opposite in the thickness direction.

The block25on which the plurality of driving elements31are arranged is adhered to the mounting surface of the baseplate22. As shown inFIG. 2, the block25is formed in a shape of which the cross-section is trapezoidal. The top of the driving element31is adhered to the nozzle plate23.

As shown inFIG. 3, a plurality of grooves is formed on the block25. The grooves extend in a direction crossing the longitudinal direction (longitudinal direction of the inkjet head11) of the block25, respectively. The plate-shaped driving elements31are separated from each other by the grooves. The areas in the grooves serve as pressure chambers32which face later described first nozzles36and second nozzles37. The driving elements31can eject droplets from the later described first nozzle36and the second nozzle37simultaneously. As shown inFIG. 2, the nozzle plate23, the parts of the baseplate22nearby the supply holes26and the slope part of the block25constitute a common liquid chamber33for supplying liquid (ink) to each pressure chamber32. The common liquid chamber33is connected to each pressure chamber32.

As shown inFIG. 4, electrodes34are arranged at both sides of the driving element31. The electrodes34cover the bottom of the grooves (pressure chambers32) and the lateral sides of the driving elements31. The electrodes34are formed by, for example, laser patterning a nickel thin film.

As shown inFIG. 3, a plurality of wiring patterns21is arranged on the mounting surface of the baseplate22to extend in a direction crossing the longitudinal direction of the baseplate22from the plurality of driving elements31. The wiring pattern21is formed by, for example, laser patterning the nickel thin film formed on the baseplate22.

As shown inFIG. 3, the nozzle plate23, which is in a substantially rectangular shape, is formed by, for example, a polyimide film. The nozzle plate23faces the baseplate22. The nozzle plate23includes a first surface23A facing the pressure chambers32and a second surface23B opposite to the first surface23A.

As shown inFIG. 3, a plurality of integrated nozzles35penetrating the nozzle plate23is arranged on the nozzle plate23. The plurality of integrated nozzles35is arrayed along the longitudinal direction of the nozzle plate23.

As shown inFIG. 3andFIG. 5, each integrated nozzle35includes the first nozzle36and the second nozzle37. For example, the second nozzle37is arranged nearby the first nozzle36in a manner of being adjacent to the first nozzle36in a direction crossing the longitudinal direction of the nozzle plate23. The first nozzle36and the second nozzle37are arranged to face the same pressure chamber32(refer toFIG. 2).

As shown inFIG. 6, the shapes of the first nozzle36and the second nozzle37are almost the same. The first nozzle36and the second nozzle37are formed into, for example, a frustum of which the diameter decreases as it goes closer to the second surface23B, and the first nozzle36and the second nozzle37penetrate the first surface23A and the second surface23B. The first nozzle36includes a first opening section36A arranged on the first surface23A and a second opening section36B arranged on the second surface23B. The second nozzle37includes a third opening section37A arranged on the first surface23A and a fourth opening section37B arranged on the second surface23B.

As shown inFIG. 5, part of the first opening section36A is arranged to be overlapped with part of the third opening section37A. That is, the first opening section36A is arranged to be connected to the third opening section37A. Thus, as shown inFIG. 6, the part of the first nozzle36on the first surface23A is integrally connected to the part of the second nozzle37on the first surface23A, and these parts constitute a sharing part.

As shown inFIG. 7, the second opening section36B, though separated from the fourth opening section37B, is arranged nearby the fourth opening section37B. Thus, the part of the first nozzle36on the second surface23B is separated from the part of the second nozzle37on the second surface23B.

As shown inFIG. 6, a first peripheral surface36C (inner peripheral surface, lateral surface and slope) of the first nozzle36extends linearly from the second surface23B towards the first surface23A. The first peripheral surface36C (inner peripheral surface, lateral surface and slope) of the first nozzle36intersects, at the way from the second surface23B towards the first surface23A, with a second peripheral surface37C (inner peripheral surface, lateral surface and slope) of the second nozzle37which extends linearly from the second surface23B towards the first surface23A.

Next, the manufacturing process of the inkjet head11having the constitution described above is described.

First, the supply holes26and the discharge holes27are formed on the baseplate22constituted by an unfired ceramic sheet (ceramic green sheet) through press molding processing. Then the baseplate22is fired.

After the firing process is completed, as shown inFIG. 3, a pair of blocks25of piezoelectric bodies serving as the driving elements is adhered to the mounting surface of the baseplate22. At this time, the pair of blocks25is positioned against the baseplate22through a jig and adhered to the baseplate22.

Next, a so-called tapering processing (chamfering processing) is carried out at the corners of each block25adhered to the baseplate22. In this way, the cross-section of each block25is in a trapezoidal shape as shown inFIG. 2. Then a plurality of grooves (pressure chambers32) and the plate-shaped driving elements31are formed on the blocks25. The plurality of grooves is formed by, for example, a multi-cutter of a dicing saw used for cutting an IC wafer and the like.

Next, the nickel thin film is formed through, for example, electroless plating on the mounting surface of the baseplate22, the bottoms of the grooves (pressure chambers32) and the lateral sides of the plate-shaped driving elements31. The electrodes34and the wiring patterns21are formed by patterning the nickel thin film through laser irradiation. Further, the frame member24is adhered to the baseplate22and then the nozzle plate23is adhered to the frame member24. Then the integrated nozzles35(first nozzles36and second nozzles37) are formed by irradiating the nozzle plate23with laser. In addition, it is exemplified in the present embodiment that the integrated nozzles35are formed on the nozzle plate23through laser after the nozzle plate23is adhered to the frame member24; however, the nozzle forming method is not limited to this. It is also applicable that the integrated nozzles35are formed on the nozzle plate23through pressing process and the like in advance, and then the nozzle plate23is adhered to the frame member24.

At last, the pair of circuit substrates14is adhered to the baseplate22through an ACF, and in this way, the inkjet head11is completed.

Next, the liquid ejecting operation of the inkjet head11according to the present embodiment is described. The inkjet head11according to the present embodiment is a liquid (ink) circulation type inkjet head11, and the ink ejected from the tank is supplied to the pressure chamber32through the supply holes26and the common liquid chamber33. The ink that is not ejected and used in the pressure chamber32is collected to the tank from the discharge holes27. In this way, in the inkjet head11according to the present embodiment, the ink is circulated between the tank and the inkjet head11.

Herein, the liquid (ink) ejecting operation is described on the basis of the comparison with an inkjet head41(as shown inFIG. 8) in which the first nozzle36and the second nozzle37are independent and the pressure chamber32connected with these nozzles is also independent.

As shown inFIG. 8, in the conventional inkjet head41, the driving elements31are operated to increase or decrease the volume of the pressure chamber32when to eject liquid from the nozzle42. For example, if the volume of the pressure chamber32is decreased to a volume smaller than the original volume after being increased temporarily, the liquid in the pressure chamber32is pressurized, and droplets are ejected vigorously towards the print target from the nozzles42. The meniscus surface43protrudes outwards immediately before the liquid is ejected and is ejected to the print target as droplets as it is. After the droplets are ejected, the meniscus surface43is retracted backwards into the nozzle42. As stated above, the meniscus surface43vibrates in a direction indicated by an arrow under the pressure of the driving element31immediately before and after the printing. As a result, the liquid (ink) in the pressure chamber32also vibrates in the direction indicated by the arrow. At this time, as the first nozzle36and the pressure chamber32connected thereto are independent from the second nozzle37and the pressure chamber32connected thereto, thus, the vibration of the liquid inside the pressure chambers32is independent. Thus, difference occurs in the vibration of the liquid (meniscus surface43) due to the size variation of the first nozzles36and the second nozzles37and the volume variation of the pressure chambers32. As a result, a variation in the ejecting performance such as the liquid ejecting speed, liquid ejecting amount and the like is likely to occur between the first nozzle36and the second nozzle37.

FIG. 9is an enlarged diagram illustrating the parts surrounding the first nozzle36and the second nozzle37of the inkjet head11according to the present embodiment.

In the inkjet head11, the driving elements31are driven to increase or decrease the volume of the pressure chamber32when to eject liquid from the integrated nozzles35, similar to that shown inFIG. 8. For example, if the volume of the pressure chamber32is decreased to a volume smaller than the original volume after being increased temporarily, the liquid in the pressure chamber32is pressurized, and droplets are ejected simultaneously from the first nozzle36and the second nozzle37. The meniscus surfaces43of the first nozzle36and the second nozzle37protrude outwards immediately before the liquid is ejected and are ejected to the print target as droplets as it is. After the droplets are ejected, the meniscus surface43of the first nozzle36and the meniscus surface43of the second nozzle37are retracted backwards into the first nozzle36and the second nozzle37. As stated above, the meniscus surface43vibrates in a direction indicated by an arrow under the pressure of the driving element31immediately before and after the printing. As a result, the liquid in the parts of the first nozzle36and the second nozzle37nearby the pressure chambers32(the first surface23A side of the nozzle plate23) and the liquid (ink) in the pressure chamber32also vibrate in the direction indicated by the arrow.

In the present embodiment, as the first nozzle36, the second nozzle37and the pressure chambers32connected thereto are connected to each other, thus, the vibration of the liquid in these components are synchronous. As a result, it is possible to prevent the occurrence of difference in the vibration of the liquid (the vibration of the meniscus surfaces43) caused by the size variation of the first nozzle36and the second nozzle37. As a result, it is possible to prevent the occurrence of a variation in the ejecting performance such as the liquid ejecting speed, liquid ejecting amount and the like between the first nozzle36and the second nozzle37.

In accordance with the first embodiment, the inkjet head11comprises the pressure chamber32; the nozzle plate23including the first surface23A at the side of the pressure chamber32, the second surface23B opposite to the first surface23A, the first nozzle36formed into a frustum which penetrates the first surface23A and the second surface23B and the diameter of which decreases as it goes closer to the second surface23B, and the second nozzle37formed into a frustum which penetrates the first surface23A and the second surface23B and the diameter of which decreases as it goes closer to the second surface23B; and the driving element31which is arranged adjacent to the pressure chamber32to eject droplets from the first nozzle36and the second nozzle37simultaneously; wherein the part of the first nozzle36on the first surface23A is integrally connected to the part of the second nozzle37on the first surface23A, and the part of the first nozzle36on the second surface23B is separated from the part of the second nozzle37on the second surface23B.

In accordance with the constitution, the droplets can be ejected from the first nozzle36and the second nozzle37simultaneously, thus, there can be provided an inkjet head11that is capable of ejecting a large amount of droplets through one ejecting driving operation. Further, in accordance with the constitution, the part of the first nozzle36on the first surface23A can be integrally connected to the part of the second nozzle37on the first surface23A. In this way, it is possible to synchronize (share) the vibration of the meniscus surface43of the first nozzle36and the second nozzle37, which can reduce the variation in the liquid ejecting performance caused by the size variation of the first nozzles36and the second nozzles37.

The peripheral surface of the first nozzle36extends linearly from the second surface23B towards the first surface23A and intersects, at the way from the second surface23B towards the first surface23A, with the peripheral surface of the second nozzle37which extends linearly from the second surface23B towards the first surface23A. In accordance with the constitution, a part connected with the second nozzle37can be arranged at the peripheral surface of the first nozzle36at the way from the second surface23B towards the first surface23A. In this way, it is possible to arrange the part of the first nozzle36on the second surface23B more closer to the part of the second nozzle37on the second surface23B, which can make the synchronization of the vibration of the meniscus surface43between the two nozzles much more easier. Thus, it is possible to prevent the occurrence of the variation in the liquid ejecting performance caused by the size variation of the first nozzles36and the second nozzles37.

A Second Embodiment

Hereinafter, the second embodiment of the inkjet head11is described with reference toFIG. 10-FIG. 12. The inkjet head11described in the present embodiment is the same as that described in the first embodiment except that a sharing part of the first nozzle36-the fourth nozzle52is formed. Thus, the different part is mainly described and the same part is not shown or described repeatedly.

FIG. 10is a diagram of the nozzle plate23viewed from the pressure chamber32(first surface23A).FIG. 11is a cross-sectional view taken along a line F11-F11shown inFIG. 10.FIG. 12is a diagram of the nozzle plate23viewed from an outer side (second surface side).

A plurality of integrated nozzles35that penetrates the nozzle plate23is arranged on the nozzle plate23. Similar to those shown inFIG. 1, the plurality of integrated nozzles35is arranged along the longitudinal direction of the nozzle plate23.

As shown inFIG. 10, each integrated nozzle35includes the first nozzle36, the second nozzle37, a third nozzle51and a fourth nozzle52. The second nozzle37is arranged nearby the first nozzle36and is adjacent to the first nozzle36in, for example, a direction crossing the longitudinal direction of the nozzle plate23. The third nozzle51is arranged nearby the first nozzle36and is adjacent to the first nozzle36in, for example, the longitudinal direction of the nozzle plate23. The fourth nozzle52is arranged nearby the second nozzle37and is adjacent to the second nozzle37in, for example, the longitudinal direction of the nozzle plate23. As shown inFIG. 12, the first nozzle36is in diagonal to the fourth nozzle52, and the second nozzle37is in diagonal to the third nozzle51. The first nozzle36-fourth nozzle52are arranged to face the same pressure chamber32.

As shown inFIG. 11, the shapes of the first nozzle36-fourth nozzle52are almost the same. The first nozzle36-fourth nozzle52are formed into a frustum which penetrates the first surface23A and the second surface23B and the diameter of which decreases as it goes closer to the second surface23B. The first nozzle36includes the first opening section36A arranged on the first surface23A and the second opening section36B arranged on the second surface23B. The second nozzle37includes the third opening section37A arranged on the first surface23A and the fourth opening section37B arranged on the second surface23B.

As shown inFIG. 10andFIG. 12, the third nozzle51includes a fifth opening section51A arranged on the first surface23A and a sixth opening section51B arranged on the second surface23B. The fourth nozzle52includes a seventh opening section52A arranged on the first surface23A and an eighth opening section52B arranged on the second surface23B.

As shown inFIG. 10, part of the first opening section36A is arranged in a manner of being overlapped with part of the third opening section37A and the fifth opening section51A. Thus, the first opening section36A is connected to the third opening section37A and the fifth opening section51A. Similarly, part of the seventh opening section52A is arranged in a manner of being overlapped with part of the third opening section37A and the fifth opening section51A. Thus, the seventh opening section52A is connected to the third opening section37A and the fifth opening section51A.

Thus, in the present embodiment, the parts of the first nozzle36-fourth nozzle52on the first surface23A constitute the sharing part, that is, are integrally arranged.

As shown inFIG. 12, the second opening section36B, though separated from the fourth opening section37B and the sixth opening section51B, is arranged nearby the fourth opening section37B and the sixth opening section51B. Similarly, the eighth opening section52B, though separated from the fourth opening section37B and the sixth opening section51B, is arranged nearby the fourth opening section37B and the sixth opening section51B. Thus, the parts of the first nozzle36-fourth nozzle52on the second surface23B are separated from each other to constitute independent parts.

As shown inFIG. 11, the first peripheral surface36C (inner peripheral surface, lateral surface and slope) of the first nozzle36extends linearly from the second surface23B towards the first surface23A. The first peripheral surface36C of the first nozzle36intersects, at the way from the second surface23B towards the first surface23A, with the second peripheral surface37C (inner peripheral surface, lateral surface and slope) of the second nozzle37which extends linearly from the second surface23B towards the first surface23A. Similarly, as shown inFIG. 10andFIG. 12, the first peripheral surface36C (inner peripheral surface, lateral surface and slope) of the first nozzle36intersects, at the way from the second surface23B towards the first surface23A, with a third peripheral surface51C (inner peripheral surface, lateral surface and slope) of the third nozzle51which extends linearly from the second surface23B towards the first surface23A.

Further, a fourth peripheral surface52C (inner peripheral surface, lateral surface and slope) of the fourth nozzle52extends linearly from the second surface23B towards the first surface23A. The fourth peripheral surface52C of the fourth nozzle52intersects, at the way from the second surface23B towards the first surface23A, with the second peripheral surface37C of the second nozzle37and the third peripheral surface51C of the third nozzle51.

In the present embodiment, a pair of driving elements31between which the pressure chamber32is nipped can eject droplets from the first nozzle36, the second nozzle37, the third nozzle51and the fourth nozzle52simultaneously.

The manufacturing process of the inkjet head11according to the present embodiment is almost the same as that described in the first embodiment except that the number of the nozzles formed as the integrated nozzle35is different from that in the first embodiment.

In the present embodiment, the number of the nozzles included in the integrated nozzle35is different from that in the first embodiment, thus, the amount of the droplets (ink drops) that can be ejected by the inkjet head11according to the present embodiment through one ejecting driving operation is different from that of the inkjet head11described in the first embodiment. That is, the inkjet head11according to the present embodiment can eject twice as much droplets (ink drops) as the inkjet head11in the first embodiment. The other parts of the present embodiment have the same functions as those of the first embodiment.

In accordance with the present embodiment, the inkjet head11includes the pressure chamber32; the nozzle plate23including the first surface23A at the side of the pressure chamber32, the second surface23B opposite to the first surface23A, the first nozzle36formed into a frustum which penetrates the first surface23A and the second surface23B and the diameter of which decreases as it goes closer to the second surface23B, the second nozzle37formed into a frustum which penetrates the first surface23A and the second surface23B and the diameter of which decreases as it goes closer to the second surface23B, the third nozzle51formed into a frustum which penetrates the first surface23A and the second surface23B and the diameter of which decreases as it goes closer to the second surface23B, and the fourth nozzle52formed into a frustum which penetrates the first surface23A and the second surface23B and the diameter of which decreases as it goes closer to the second surface23B; and the driving element31which is arranged adjacent to the pressure chamber32to eject droplets from the first nozzle36, the second nozzle37, the third nozzle51and the fourth nozzle52simultaneously; wherein the parts of the first nozzle36-fourth nozzle52on the first surface23A are integrally connected to each other, and the parts of the first nozzle36-fourth nozzle52on the second surface23B are separated from each other.

In accordance with the constitution, the droplets can be ejected from the first nozzle36-fourth nozzle52simultaneously, thus, there can be provided an inkjet head11that is capable of ejecting a large amount of droplets through one ejecting driving operation. Further, in accordance with the constitution, there can be provided an inkjet head11in which the ejecting performance of the first nozzle36-fourth nozzle52is uniform.

A Third Embodiment

Hereinafter, the third embodiment of the inkjet head11is described with reference toFIG. 13-FIG. 15. Though the inkjet head11according to the present embodiment is the same as that described in the second embodiment in the point that the sharing part is formed at a certain position at the first surface23A of the first nozzle36-fourth nozzle52, the shape of the sharing part is different from that in the second embodiment. However, other parts of the third embodiment are the same as those of the second embodiment. Thus, the different part is mainly described and the same part is not shown or described repeatedly.

FIG. 13is a diagram of the nozzle plate23viewed from the pressure chamber32(first surface23A).FIG. 14is a cross-sectional view taken along a line F14-F14shown inFIG. 13.FIG. 15is a diagram of the nozzle plate23viewed from an outer side (second surface side).

A plurality of integrated nozzles35that penetrates the nozzle plate23is arranged on the nozzle plate23. Similar to those shown inFIG. 1, the plurality of integrated nozzles35is arranged along the longitudinal direction of the nozzle plate23at specific intervals. Each integrated nozzle35includes the first nozzle36, the second nozzle37, a third nozzle51and a fourth nozzle52. The second nozzle37is arranged nearby the first nozzle36and is adjacent to the first nozzle36in, for example, a direction crossing the longitudinal direction of the nozzle plate23. The third nozzle51is arranged nearby the first nozzle36and is adjacent to the first nozzle36in, for example, the longitudinal direction of the nozzle plate23. The fourth nozzle52is arranged nearby the second nozzle37and is adjacent to the second nozzle37in, for example, the longitudinal direction of the nozzle plate23. As shown inFIG. 15, the first nozzle36is in diagonal to the fourth nozzle52, and the second nozzle37is in diagonal to the third nozzle51. The first nozzle36-fourth nozzle52are arranged to face the same pressure chamber32.

The shapes of the first nozzle36-fourth nozzle52are almost the same. That is, each of the first nozzle36-fourth nozzle52is formed into, for example, a frustum. The first nozzle36includes the first opening section36A arranged on the first surface23A and the second opening section36B arranged on the second surface23B. The second nozzle37includes the third opening section37A arranged on the first surface23A and the fourth opening section37B arranged on the second surface23B. The third nozzle51includes the fifth opening section51A arranged on the first surface23A and the sixth opening section51B arranged on the second surface23B. The fourth nozzle52includes the seventh opening section52A arranged on the first surface23A and the eighth opening section52B arranged on the second surface23B.

In the present embodiment, the first opening section36A-seventh opening section52A constitute an integrated substantially-square sharing opening section. Thus, in the present embodiment, the parts of the first nozzle36-fourth nozzle52on the first surface23A constitute a substantially quadrangular sharing part, that is, are integrally arranged.

As shown inFIG. 15, the second opening section36B, though separated from the fourth opening section37B and the sixth opening section51B, is arranged nearby the fourth opening section37B and the sixth opening section51B. Similarly, the eighth opening section52B, though separated from the fourth opening section37B and the sixth opening section51B, is arranged nearby the fourth opening section37B and the sixth opening section51B. Thus, the parts of the first nozzle36-fourth nozzle52on the second surface23B are separated from each other to constitute independent parts.

As shown inFIG. 14, the first peripheral surface36C (inner peripheral surface, lateral surface and slope) of the first nozzle36extends linearly from the second surface23B towards the first surface23A. The first peripheral surface36C of the first nozzle36intersects, at the way from the second surface23B towards the first surface23A, with the second peripheral surface37C (inner peripheral surface, lateral surface and slope) of the second nozzle37which extends linearly from the second surface23B towards the first surface23A. Similarly, as shown inFIG. 13andFIG. 15, the first peripheral surface36C (inner peripheral surface, lateral surface and slope) of the first nozzle36intersects, at the way from the second surface23B towards the first surface23A, with a third peripheral surface51C (inner peripheral surface, lateral surface and slope) of the third nozzle51which extends linearly from the second surface23B towards the first surface23A.

Further, the fourth peripheral surface52C (inner peripheral surface, lateral surface and slope) of the fourth nozzle52extends linearly from the second surface23B towards the first surface23A. The fourth peripheral surface52C of the fourth nozzle52intersects, at the way from the second surface23B towards the first surface23A, with the second peripheral surface37C of the second nozzle37and the third peripheral surface51C of the third nozzle51.

In the present embodiment, a pair of driving elements31between which the pressure chamber32is nipped can eject droplets from the first nozzle36, the second nozzle37, the third nozzle51and the fourth nozzle52simultaneously.

The manufacturing process of the inkjet head11according to the present embodiment is almost the same as that described in the second embodiment. In the present embodiment, in the forming process of the integrated nozzle35, the parts of the first nozzle36-fourth nozzle52on the first surface23A are formed as a substantially-square sharing opening section. The integrated nozzle35may be formed through laser processing or pressing processing. In the present embodiment, the inkjet head11has almost the same functions as those in the second embodiment.

In accordance with the present embodiment, the droplets can be ejected from the first nozzle36-fourth nozzle52simultaneously, thus, there can be provided an inkjet head11that is capable of ejecting a large amount of droplets through one ejecting driving operation. Further, in accordance with the constitution, there can be provided an inkjet head11in which the ejecting performance of the first nozzle36-fourth nozzle52is uniform.

The first-third embodiments are described above, however, the components in these embodiments may be appropriately combined.