LIQUID EJECTING HEAD AND LIQUID EJECTING SYSTEM

A liquid ejecting head having a supply port to which a liquid is supplied and a discharge port from which the liquid is discharged includes a first flow path extending in a first axial direction between the supply port and the discharge port, and a nozzle that is provided to branch from the first flow path and that ejects the liquid along a second axial direction orthogonal to the first axial direction. The first flow path is provided with a protruding portion facing an opening, which opens to the first flow path, of the nozzle.

The present application is based on, and claims priority from JP Application Serial Number 2019-116206, filed Jun. 24, 2019, the disclosure of which is hereby incorporated by reference herein in its entirety.

BACKGROUND

1. Technical Field

The present disclosure relates to a liquid ejecting head and a liquid ejecting system that eject liquid from a nozzle, and more particularly, to an ink jet recording head and an ink jet recording system that eject ink as a liquid.

2. Related Art

There has been proposed a liquid ejecting system that circulates liquid inside a liquid ejecting head that ejects the liquid. The liquid ejecting system circulates the liquid to, for example, discharge bubbles contained in the liquid, suppress an increase in the viscosity of the liquid, and suppress settling of a component contained in the liquid in the liquid ejecting head (for example, refer to JP-A-2018-103602).

In the liquid ejecting head of JP-A-2018-103602, the liquid inside the liquid ejecting head is circulated through a branched flow path provided in the vicinity of the nozzles, thereby suppressing an increase in the viscosity caused by drying of the liquid not ejected from the nozzles.

However, there is a desire for a liquid ejecting head capable of more efficiently collecting the liquid in the vicinity of the nozzles.

This problem exists not only in an ink jet recording head but also similarly in a liquid ejecting head that ejects a liquid other than the ink.

SUMMARY

An advantage of some aspects of the present disclosure is to provide a liquid ejecting head and a liquid ejecting system capable of more efficiently collecting liquid in the vicinity of nozzles.

According to an aspect of the present disclosure, there is provided a liquid ejecting head having a supply port to which a liquid is supplied and a discharge port from which the liquid is discharged, the liquid ejecting head including a first flow path extending in a first axial direction between the supply port and the discharge port, and a nozzle that is provided to branch from the first flow path and that ejects the liquid along a second axial direction orthogonal to the first axial direction, in which the first flow path is provided with a protruding portion facing an opening, which opens to the first flow path, of the nozzle.

According to another aspect of the present disclosure, there is provided a liquid ejecting system including the liquid ejecting head and a mechanism configured to supply a liquid to the supply port, collect the liquid from the discharge port, and circulate the liquid.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

Hereinafter, the present disclosure will be described in detail based on the embodiments. However, the following description illustrates an embodiment of the present disclosure and may be optionally changed within the scope of the present disclosure. In the drawings, the same reference numerals denote the same members and the description thereof will be omitted as appropriate. In the drawings, X, Y, and Z represent three spatial axes orthogonal to each other. In the present specification, directions along these axes are defined as an X direction, a Y direction, and a Z direction. The directions of the arrows in the diagrams are illustrated as positive (+) directions and the directions opposite to the arrows are illustrated as negative (−) directions. The Z direction indicates a vertical direction, the +Z direction indicates vertically downward, and the −Z direction indicates vertically upward.

An ink jet recording head, which is an example of the liquid ejecting head of the present embodiment, will be described with reference toFIGS. 1 to 6.FIG. 1is a plan view of an ink jet recording head, which is an example of a liquid ejecting head according to Embodiment 1 of the present disclosure, as viewed from a nozzle surface side.FIG. 2is a sectional diagram taken along line II-II ofFIG. 1.FIG. 3is an enlarged view of the main parts ofFIG. 2.FIG. 4is a sectional diagram taken along line IV-IV ofFIG. 3.FIG. 5is a diagram for explaining the streamlines inside the flow path ofFIG. 3.FIG. 6is a diagram illustrating the streamlines inside the flow path of a comparative example.

As illustrated in the drawings, an ink jet recording head1(hereinafter, also simply referred to as a recording head1), which is an example of the liquid ejecting head of the present embodiment, is provided with members such as a flow path forming substrate10as flow path substrate, a communicating plate15, a nozzle plate20, a protection substrate30, a case member40, and a compliance substrate49.

The flow path forming substrate10is formed of a silicon single crystal substrate and a diaphragm50is formed at one surface of the flow path forming substrate10. The diaphragm50may be a single layer or a laminate selected from a silicon dioxide layer and a zirconium oxide layer.

The flow path forming substrate10is provided with pressure chambers12configuring individual flow paths200, the pressure chambers12being partitioned by partition walls. The pressure chambers12are arranged at a predetermined pitch along the X direction in which the nozzles21that discharge the ink are arranged. In the present embodiment, one row of the pressure chambers12is provided such that the pressure chambers12are arranged in the X direction. The flow path forming substrate10is disposed such that the in-plane direction includes the X direction and the Y direction. In the present embodiment, the portions between the pressure chambers12arranged in the X direction of the flow path forming substrate10are referred to as partition walls. The partition walls are formed along the Y direction. In other words, the partition walls refer to portions overlapping the pressure chambers12in the Y direction of the flow path forming substrate10.

Although the flow path forming substrate10is provided with only the pressure chambers12in the present embodiment, the flow path forming substrate10may be provided with a flow path resistance imparting portion having a narrower cross-sectional area crossing the flow paths than the pressure chambers12so as to impart the ink to be supplied to the pressure chambers12with a flow path resistance.

Piezoelectric actuators300are configured by forming the diaphragms50on one side of the flow path forming substrate10in the −Z direction and by laminating first electrodes60, piezoelectric layers70, and second electrodes80on the diaphragm50using film formation and lithography. In the present embodiment, the piezoelectric actuator300is an energy generating element that generates pressure changes in the ink inside the pressure chamber12. Here, the piezoelectric actuator300is also referred to as a piezoelectric element and refers to a portion including the first electrode60, the piezoelectric layer70, and the second electrode80. In general, one of the electrodes of the piezoelectric actuator300is used as a common electrode and the other electrode and the piezoelectric layer70are patterned for each pressure chamber12. In the present embodiment, although the first electrode60is used as the common electrode of the piezoelectric actuator300and the second electrode80is used as the individual electrode of the piezoelectric actuator300, there is no impediment to reversing this configuration in consideration of the drive circuit and wiring. In the example described above, although the diaphragm50and the first electrode60act as a diaphragm, the configuration is not limited thereto. For example, a configuration may be adopted in which the diaphragm50is not provided and only the first electrode60acts as a diaphragm. The piezoelectric actuator300itself may substantially serve as the diaphragm.

A respective lead electrode90is coupled to the second electrode80of each of the piezoelectric actuators300and a voltage is selectively applied to each of the piezoelectric actuators300via the lead electrodes90.

The protection substrate30is joined to the −Z direction surface of the flow path forming substrate10.

A piezoelectric actuator holding portion31having enough space to not hinder the motion of the piezoelectric actuator300is provided in a region of the protection substrate30facing the piezoelectric actuator300. The piezoelectric actuator holding portion31only needs to have enough space to not hinder the motion of the piezoelectric actuator300and the space may be sealed or not sealed. The piezoelectric actuator holding portion31is formed to have a size that integrally covers the row of the piezoelectric actuators300arranged in the X direction. Naturally, the piezoelectric actuator holding portion31is not particularly limited to this configuration, and may individually cover the piezoelectric actuators300, and may cover each group configured of two or more piezoelectric actuators300arranged in the X direction.

For the protection substrate30, it is preferable to use a material having substantially the same coefficient of thermal expansion as the flow path forming substrate10, for example, glass, ceramic material, or the like. In the present embodiment, a silicon single crystal substrate of the same material as the material of the flow path forming substrate10is used to form the protection substrate30.

The protection substrate30is provided with a through-hole32extending through the protection substrate30in the Z direction. The end portion of the lead electrode90extending from each of the piezoelectric actuators300is provided to extend so as to be exposed inside the through-hole32and is electrically coupled to a flexible cable120inside the through-hole32. The flexible cable120is a flexible wiring substrate, and in the present embodiment, a drive circuit121which is a semiconductor element is mounted to the flexible cable120. The lead electrode90and the drive circuit121may be electrically coupled to each other without being coupled via the flexible cable120. A flow path may be provided in the protection substrate30.

The case member40that partitions a supply flow path communicating with the pressure chambers12and that partitions the protection substrate30is fixed onto the protection substrate30. The case member40is joined to a surface of the protection substrate30on the side opposite from the flow path forming substrate10and is also joined to the communicating plate15(described later).

The case member40is provided with a first liquid chamber portion41that forms part of a first common liquid chamber101and a second liquid chamber portion42that forms part of a second common liquid chamber102. The first liquid chamber portion41and the second liquid chamber portion42are provided in the Y direction on both sides of one row of the pressure chambers12.

Each of the first liquid chamber portion41and the second liquid chamber portion42has a concave shape opened on the −Z side surface of the case member40and is provided continuously to extend over the pressure chambers12arranged in the X direction.

The case member40is provided with a supply port43that communicates with the first liquid chamber portion41to supply the ink to the first liquid chamber portion41and a discharge port44that communicates with the second liquid chamber portion42and discharges the ink from the second liquid chamber portion42.

Furthermore, the case member40is further provided with a coupling port45which communicates with the through-hole32of the protection substrate30and through which the flexible cable120is inserted.

On the other hand, the communicating plate15, the nozzle plate20, and the compliance substrate49are provided on the +Z side of the flow path forming substrate10which is the side opposite from the protection substrate30.

Nozzles21that eject the ink in the +Z direction are formed in the nozzle plate20. In the present embodiment, as illustrated inFIG. 1, the nozzles21are disposed in a straight line along the X direction, thereby forming one nozzle row22.

Each nozzle21includes a first nozzle21aand a second nozzle21bhaving different inner diameters disposed next to each other in the Z direction which is the plate thickness direction of the nozzle plate20. The first nozzle21ahas a smaller inner diameter than the second nozzle21b. The first nozzle21ais disposed outside, that is, on the +Z side of the nozzle plate20and ink is ejected to the outside as an ink droplet from the first nozzle21ain the +Z direction. In other words, the second axial direction in which the ink of the present embodiment is discharged is the Z direction in the present embodiment.

The second nozzle21bis disposed on the −Z side of the nozzle plate20and communicates with a first flow path201extending in the Y direction which is described later in detail. In other words, the first axial direction, which is the extending direction of the first flow path201, is the Y direction in the present embodiment. The Y direction which is the first axial direction and the Z direction which is the second axial direction are orthogonal to each other.

It is possible to improve the flow speed of the ink by providing the nozzle21with the first nozzle21ahaving a relatively small inner diameter and it is thus possible to improve the flight speed of the ink droplet ejected from the nozzle21. By providing the nozzle21with the second nozzle21bhaving a relatively large inner diameter, when so-called circulation is performed in which the ink inside the individual flow path200is caused to flow from the first common liquid chamber101toward the second common liquid chamber102(described in detail later), it is possible to reduce the portion of the nozzle21that is not influenced by the circulation flow inside the nozzle21. In other words, it is possible to generate an ink flow inside the second nozzle21bduring the circulation and it is possible to increase the velocity gradient of the ink inside the nozzle21to replace the ink inside the nozzle21with new ink supplied from upstream. However, when the inner diameter of the second nozzle21bis excessively large as compared with the inner diameter of the first nozzle21a, the ratio of the inertance between the second nozzle21band the first nozzle21aincreases, and the position of the meniscus of the ink inside the nozzle21is not stable when the ink droplets are continuously discharged. In other words, when the ratio of the inertance between the second nozzle21band the first nozzle21aincreases, the meniscus of the ink moves into the second nozzle21binstead of being retained inside the first nozzle21aand it is no longer possible to continue the stable discharging of the ink droplets.

When the inner diameter of the second nozzle21bis excessively small, the ink flow inside the second nozzle21bduring the circulation is less likely to occur. When the inner diameter of the second nozzle21bis excessively small, the flow path resistance from the pressure chamber12to the nozzle21increases and the pressure loss increases, and the weight of the ink droplet discharged from the nozzle21therefore decreases. As a result, the piezoelectric actuator300is to be driven at a higher drive voltage and the discharging efficiency is reduced. Accordingly, the sizes of the first nozzle21aand the second nozzle21bare determined, as appropriate, in consideration of the ink replacement performance during circulation, the discharging stability, the discharging efficiency, the flight speed of the ink droplet, and the like.

The first nozzle21aand the second nozzle21bare provided so that the opening shapes thereof are substantially the same in the Z direction. Accordingly, a level difference is formed between the first nozzle21aand the second nozzle21b. Naturally, the shapes of the first nozzle21aand the second nozzle21bare not limited thereto, and for example, the inner surface of the second nozzle21bmay be an inclined surface inclined with respect to the Z direction. In other words, the inner diameter of the second nozzle21bmay be provided so as to gradually decrease toward the first nozzle21a. Accordingly, for example, a level difference may not be formed between the first nozzle21aand the second nozzle21band a continuous inner surface may be formed. In this manner, when the inner surfaces of the first nozzle21aand the second nozzle21bare continuous, the first nozzle21arefers to a portion in which the opening shape is substantially the same in the Z direction.

The shape of the nozzle21when viewed in plan view in the Z direction is not particularly limited and may be a circle, an ellipse, a rectangle, a polygon, an egg shape, or the like.

It is possible to form the nozzle plate20by using, for example, a metal such as stainless steel (SUS), an organic material such as a polyimide resin, or a flat plate material such as silicon. The plate thickness of the nozzle plate20is preferably 60 μm to 100 μm. By using the nozzle plate20having such a plate thickness, it is possible to improve the handleability of the nozzle plate20and to improve the ease of assembly of the recording head1. Although it is possible to reduce the size of a portion of the nozzle21that is not influenced by the circulation flow inside the nozzle21during the circulation of the ink by reducing the length of the nozzle21in the Z direction, it is necessary to reduce the thickness of the nozzle plate20in the Z direction in order to reduce the length of the nozzle21in the Z direction. When the thickness of the nozzle plate20is reduced in this manner, there is an increase in the likelihood of the rigidity of the nozzle plate20being reduced and the deformation of the nozzle plate20causing variation in the discharging direction of the ink droplets, and an increase in the likelihood of a reduction in the handleability of the nozzle plate20causing a reduction in the ease of assembly to occur. In other words, by using the nozzle plate20having a certain degree of thickness as described above, it is possible to suppress a reduction in the rigidity of the nozzle plate20and it is possible to suppress the occurrence of variation in the discharging direction caused by the deformation of the nozzle plate20and a reduction in the ease of assembly caused by a reduction in the handleability.

The communicating plate15includes a first communicating plate151and a second communicating plate152in the present embodiment. The first communicating plate151and the second communicating plate152are laminated in the Z direction such that the first communicating plate151is on the −Z side and the second communicating plate152is on the +Z side.

The first communicating plate151and the second communicating plate152which form the communicating plate15may be made of a metal such as stainless steel, glass, a ceramic material, or the like. It is preferable that the communicating plate15be formed by using a material having substantially the same thermal expansion coefficient as that of the flow path forming substrate10. In the present embodiment, the communicating plate15is formed by using a silicon single crystal substrate of the same material as the material of the flow path forming substrate10.

The communicating plate15is provided with a first communicating portion16which communicates with the first liquid chamber portion41of the case member40to form a portion of the first common liquid chamber101, and a second communicating portion17and a third communicating portion18which communicate with the second liquid chamber portion42of the case member40to form a portion of the second common liquid chamber102. As will be described in detail later, the communicating plate15is provided with a flow path that communicates the first common liquid chamber101and the pressure chamber12with each other, a flow path that communicates the pressure chamber12and the nozzle21with each other, and a flow path that communicates the nozzle21with the second common liquid chamber102with each other. The flow paths provided in the communicating plate15form a portion of the individual flow path200.

The first communicating portion16is provided at a position overlapping the first liquid chamber portion41of the case member40in the Z direction and is provided to extend through the communicating plate15in the Z direction to be opened in both the +Z side surface and the −Z side surface of the communicating plate15. The first communicating portion16forms a first common liquid chamber101by communicating with the first liquid chamber portion41on the −Z side. In other words, the first common liquid chamber101is formed by the first liquid chamber portion41of the case member40and the first communicating portion16of the communicating plate15. The first communicating portion16extends in the −Y direction to a position overlapping the pressure chamber12in the Z direction on the +Z side. The first common liquid chamber101may be formed by the first liquid chamber portion41of the case member40without providing the first communicating portion16in the communicating plate15.

The second communicating portion17is provided at a position overlapping the second liquid chamber portion42of the case member40in the Z direction and is provided to be open on the −Z side surface of the first communicating plate151. The second communicating portion17is provided to widen toward the nozzle21in the +Y direction on the +Z side.

The third communicating portion18is provided to extend through the second communicating plate152in the Z direction such that one end of the third communicating portion18communicates with a portion of the second communicating portion17that is widened in the +Y direction. The opening on the +Z side of the third communicating portion18is covered by the nozzle plate20. In other words, by providing the second communicating portion17on the first communicating plate151, only the opening on the +Z side of the third communicating portion18may be covered by the nozzle plate20, and thus, it is possible to provide the nozzle plate20in a relatively small area and it is possible to reduce the cost.

The second common liquid chamber102is formed by the second communicating portion17and the third communicating portion18provided in the communicating plate15and the second liquid chamber portion42provided in the case member40. The second common liquid chamber102may be formed by the second liquid chamber portion42of the case member40without providing the second communicating portion17and the third communicating portion18in the communicating plate15.

The compliance substrate49including a compliance portion494is provided on a surface of the communicating plate15on the +Z side in which the first communicating portion16is opened. The compliance substrate49seals the opening of the first common liquid chamber101on a nozzle surface20aside.

In the present embodiment, the compliance substrate49includes a sealing film491formed of a thin flexible film and a fixed substrate492formed of a hard material such as a metal. Since the region of the fixed substrate492facing the first common liquid chamber101is an opening portion493completely removed in the thickness direction, a portion of the wall surface of the first common liquid chamber101is the compliance portion494which is a flexible portion sealed only by the flexible sealing film491. By providing the compliance portion494on a portion of the wall surface of the first common liquid chamber101in this manner, it is possible to absorb the pressure fluctuation of the ink inside the first common liquid chamber101by the compliance portion494being deformed.

The flow path forming substrate10, the communicating plate15, the nozzle plate20, the compliance substrate49, and the like which form the flow path substrate are provided with the individual flow paths200which communicate with the first common liquid chamber101and the second common liquid chamber102and through which the ink in the first common liquid chamber101flows to the second common liquid chamber102. Here, each of the individual flow paths200of the present embodiment is provided for corresponding one of the nozzles21in communication with the first common liquid chamber101and the second common liquid chamber102, and includes the nozzle21. The individual flow paths200are arranged along the X direction, which is the direction in which the nozzles21are arranged. Two of the individual flow paths200adjacent in the X direction, which is the direction in which the nozzles21are arranged, are provided to communicate with the first common liquid chamber101and the second common liquid chamber102, respectively. In other words, the individual flow paths200provided for the nozzles21are provided in communication only with the first common liquid chamber101and the second common liquid chamber102, respectively, and the individual flow paths200do not communicate with each other except by the first common liquid chamber101and the second common liquid chamber102. In other words, in the present embodiment, a flow path provided with one nozzle21and one pressure chamber12is referred to as the individual flow path200, and each of the individual flow paths200is provided to communicate with the other individual flow paths200only by the first common liquid chamber101and the second common liquid chamber102.

As illustrated inFIGS. 2 and 3, the individual flow path200includes the nozzle21, the pressure chamber12, the first flow path201, a second flow path202, and a supply path203.

The pressure chamber12is provided between the recessed portion provided in the flow path forming substrate10and the communicating plate15as described above and extends in the Y direction. In other words, the pressure chamber12is provided such that the supply path203is coupled to one end portion of the pressure chamber12in the Y direction, the second flow path202is coupled to the other end portion in the Y direction, and the ink flows inside the pressure chamber12in the Y direction. In other words, the direction in which the pressure chamber12extends refers to the direction in which the ink flows inside the pressure chamber12.

In the present embodiment, only the pressure chamber12is formed in the flow path forming substrate10. However, the configuration is not limited thereto, and the upstream end portion of the pressure chamber12, that is, the end portion in the +Y direction may be provided with the flow path resistance imparting portion having the cross-sectional area narrower than that of the pressure chamber12to impart flow path resistance.

The supply path203couples the pressure chamber12to the first common liquid chamber101and is provided to extend through the first communicating plate151in the Z direction. The supply path203communicates with the first common liquid chamber101at the end portion on the +Z side and communicates with the pressure chamber12at the end portion on the −Z side. In other words, the supply path203extends in the Z direction. Here, the direction in which the supply path203extends refers to the direction in which the ink flows inside the supply path203.

The first flow path201is provided to extend between the supply port43and the discharge port44in the Y direction. The direction in which the first flow path201extends refers to the direction in which the ink flows inside the first flow path201. In other words, the first axial direction in which the first flow path201extends is the Y direction in the present embodiment. The +Y direction end portion of the first flow path201communicates with the second flow path202and the −Y direction end portion of the first flow path201communicates with the third communicating portion18of the second common liquid chamber102.

The first flow path201of the present embodiment is provided to extend between the second communicating plate152and the nozzle plate20along the Y direction. Specifically, the first flow path201is formed by providing a recessed portion in the second communicating plate152and covering the opening of the recessed portion with the nozzle plate20. The first flow path201is not particularly limited to this configuration and a recessed portion may be provided in the nozzle plate20and the recessed portion of the nozzle plate20may be covered with the second communicating plate152, or alternatively, a recessed portion may be provided in both the second communicating plate152and the nozzle plate20.

In the present embodiment, the first flow path201is provided such that a cross-sectional area crossing the ink flowing through the flow path, that is, a cross-sectional area in the plane direction including the X direction and the Z direction has the same area over the Y direction. That is, the cross-sectional area of the first flow path201crossing the flow path is provided to have the same area in the Y direction refers to a portion excluding a protruding portion153described later in detail. The first flow path201may be provided such that the flow path-crossing cross-sectional area has a different area in the Y direction. The difference in the area crossing the first flow path201includes a case in which the height in the Z direction is different, a case in which the width in the X direction is different, and a case in which both are different.

The flow path-crossing cross-sectional shape of the first flow path201, that is, the cross-sectional shape in the plane direction including the X direction and the Z direction is rectangular. The flow path-crossing cross-sectional shape of the first flow path201is not particularly limited, and may be a trapezoid, a semicircle, a semi-ellipse, or the like.

The second flow path202is provided to extend between the pressure chamber12and the first flow path201in the Z direction. The direction in which the second flow path202extends is the direction in which the ink inside the second flow path202flows. In other words, in the present embodiment, the direction in which the second flow path202extends is the Z direction which is the same as the second axial direction. In the present embodiment, the second flow path202is provided to extend through the communicating plate15in the Z direction, communicates with the pressure chamber12at an end portion in the −Z direction, and communicates with the first flow path201at an end portion in the +Z direction.

The second flow path202refers to a portion formed in the communicating plate15. In other words, the second flow path202extends from the bottom surface of the pressure chamber12in the +Z direction to the portion covered by the nozzle plate20.

The nozzle21is disposed at a position communicating with the middle of the first flow path201. In other words, the nozzle21is provided to branch in the +Z direction from the first flow path201extending in the Y direction. Accordingly, ink droplets are ejected from the nozzle21in the +Z direction. In other words, the nozzle21is provided to extend through the nozzle plate20in the Z direction such that the end portion of the nozzle21in the −Z direction communicates with the middle of the first flow path201and the end portion of the nozzle21in the +Z direction opens to the nozzle surface20aof the nozzle plate20. Therefore, the second axial direction in which the nozzle21ejects ink droplets is the Z direction.

Here, the nozzle21being provided to branch from the first flow path201means that the nozzle21communicates with the middle of the first flow path201. The nozzle21communicating with the middle of the first flow path201means that the nozzle21is disposed at a position overlapping the first flow path201when viewed in plan view in the Z direction. When the nozzle21is disposed at a position overlapping the second flow path202when viewed in plan view in the Z direction, the nozzle21is not considered to be provided to communicate with the middle of the first flow path201. In other words, the first flow path201of the present embodiment is a portion that does not overlap the second flow path202when viewed in plan view in the Z direction.

It is preferable that the cross-sectional area crossing the ink flowing through the first flow path201with which the nozzle21communicates be smaller than the cross-sectional area crossing the ink flowing through the second flow path202. The cross-sectional area crossing the first flow path201is the area of a cross-section in the plane direction including the X direction and the Z direction. The cross-sectional area crossing the second flow path202is the area of a cross-section in the plane direction including the Y direction and the Z direction. In this manner, by making the cross-sectional area of the first flow path201relatively small, it is possible to dispose the individual flow paths200densely in the X direction to densely dispose the nozzles21in the X direction, and it is possible to suppress an increase in the size of the recording head1in the Z direction. By making the cross-sectional area of the second flow path202relatively large, it is possible to suppress a decrease in the flow path resistance from the pressure chamber12to the nozzle21to suppress reductions in the discharging properties of the liquid, in particular, in the weight of the droplets to be discharged. In particular, by widening the second flow path202in the Y direction to increase the cross-sectional area of the second flow path202, it is possible to reduce the flow path resistance in the second flow path202and it is possible to suppress a decrease in the density at which the individual flow paths200are disposed to dispose the individual flow paths200at a high density.

The first flow path201is provided with the protruding portion153facing the opening, which opens to the first flow path201, of the nozzle21. Here, the protruding portion153facing the opening, which opens to the first flow path201, of the nozzle21means that the protruding portion153is provided to protrude from the wall surface of the first flow path201that faces the opening, which opens to the first flow path201, of the nozzle21in the Z direction toward the nozzle21, that is, toward the +Z direction. In other words, a ceiling higher than the protruding portion153in the Z direction is provided upstream and downstream of the protruding portion153in the Y direction. A ceiling provided higher than the protruding portion153being provided only upstream of the protruding portion153, that is, a ceiling having the same height as the protruding tip surface of the protruding portion153downstream of the protruding portion153being provided is not referred to as the protruding portion153being provided. Similarly, a ceiling provided higher than the protruding portion153being provided only downstream of the protruding portion153, that is, a ceiling having the same height as the protruding tip surface of the protruding portion153upstream of the protruding portion153being provided is not referred to as the protruding portion153being provided. In other words, it is sufficient to provide a ceiling higher than the protruding tip surface of the protruding portion153both upstream and downstream of the protruding portion153in the Y direction, and the heights of the ceiling upstream and downstream of the protruding portion153may be different heights from each other.

The protruding portion153facing the opening, which opens to the first flow path201, of the nozzle21means that, when the protruding portion153is viewed in plan view in the Z direction as illustrated inFIG. 4, the protruding portion153includes a portion that overlaps with the opening of the second nozzle21bwhich is the opening, which opens to the first flow path201, of the nozzle21. In other words, the configuration includes a configuration in which the entirety of the protruding portion153in the Y direction is provided at a position overlapping the opening, which opens to the first flow path201, of the nozzle21when viewed in plan view in the Z direction and includes a configuration in which, when viewed in plan view in the Z direction, a portion of the protruding portion153in the Y direction overlaps the opening, which opens to the first flow path201, of the nozzle21and the other portion of the protruding portion153in the Y direction is provided to not overlap the opening of the nozzle21. Similarly, the configuration includes a configuration in which in the X direction, when viewed in plan view in the Z direction, the entirety of the protruding portion153in the X direction is provided at a position overlapping the opening, which opens to the first flow path201, of the nozzle21and includes a configuration in which, when viewed in plan view in the Z direction, a portion of the protruding portion153in the X direction overlaps the opening, which opens to the first flow path201, of the nozzle21and the other portion of the protruding portion153in the X direction is provided to not overlap the opening of the nozzle21.

The opening of the nozzle21that opens to the first flow path201is the opening of the second nozzle21bon the −Z side that is coupled to the first flow path201.

By providing the first flow path201with the protruding portion153facing the nozzle21in the Z direction, as illustrated inFIG. 5, it is possible to cause the ink flowing inside the first flow path201during the circulation to flow in the direction in which the protruding portion153projects, that is, to cause the ink inside the first flow path201to flow toward the +Z direction to enter the nozzle21and generate an ink flow inside the nozzle21, in particular, inside the second nozzle21b. By generating an ink flow inside the nozzle21, it is possible to increase the velocity gradient of the ink inside the nozzle21to replace the ink inside the nozzle21with new ink supplied from upstream. Therefore, the viscosity of the ink inside the nozzle21does not easily increase due to drying, and even if the ink inside the nozzle21increases in viscosity, since the ink flows downstream through the first flow path201, it is possible to suppress the occurrence of variation in the discharging direction of the ink droplets caused by the increased-viscosity ink remaining inside the nozzle21, and to suppress the displacement of the landing position of the ink droplets on the ejection target medium.

On the other hand, as illustrated inFIG. 6, when the ceiling of the first flow path201is rendered flat and the protruding portion153is not provided in the first flow path201, that is, when the wall surface mutually facing the nozzle21of the first flow path201in the −Z direction is formed to have the same height in the Z direction over the Y direction, it is difficult for the ink flowing inside the first flow path201flowing in the Y direction to enter the nozzle21and the ink is retained inside the nozzle21. When the ink is retained inside the nozzle21in this manner, the retained ink easily increases in viscosity due to drying. Therefore, the discharging direction of the ink droplet discharged from the nozzle21is varied due to the increased-viscosity ink and the landing position of the discharged ink droplet on the ejection target medium is easily displaced.

By providing the protruding portion153, it is possible to ensure the volume of the ink downstream of the nozzle21and to cause the dried ink inside the nozzle21to flow to a large volume downstream, it is possible to stabilize the concentration of the ink, and it is possible to improve the exchange efficiency of the dried ink inside the nozzle21. In other words, when the cross-sectional area of the first flow path201is different between the upstream and the downstream of the nozzle21and the protruding portion153is not provided, that is, when the cross-sectional area of the first flow path201upstream of the nozzle21is smaller than that on the downstream, the flow of the ink toward the nozzle21may not be generated inside the first flow path201, the exchange efficiency of the dried ink inside the nozzle21may not be improved, the flow path resistance from the pressure chamber12to the nozzle21increases, and there is an increase in pressure loss, thereby generating a reduction in the discharging efficiency, for example, the ink weight of the ink droplet decreases. When the cross-sectional area of the first flow path201downstream of the nozzle21is smaller than that of the upstream, even if it is possible to generate the ink flow toward the nozzle21inside the first flow path201, the dried ink inside the nozzle21may not flow to a large downstream volume, and the ink concentration may not be stabilized.

Here, as illustrated inFIG. 4, a length dimension L1in the Y direction of the protruding portion153, which is the first axial direction, is preferably less than or equal to two times a length dimension L2in the Y direction of the opening of the nozzle21that opens to the first flow path201, and the length is more preferably less than or equal to one times the length dimension L2in the Y direction of the opening of the nozzle21that opens to the first flow path201. In other words, L1≤L2×2 is preferable, and L1L2is more preferable. In the present embodiment, the length dimension L1of the protruding portion153in the Y direction is smaller than the length dimension L2of the opening of the nozzle21that opens to the first flow path201in the Y direction.

As illustrated inFIG. 3, the protruding portion153of the present embodiment is provided to have the same length in the Y direction over the Z direction. Therefore, the length dimension L1of the protruding portion153in the Y direction is the same length over the Z direction. The shape of the protruding portion153is not particularly limited thereto and the protruding portion153may be provided such that the length in the Y direction is different along the Z direction. Here,FIG. 7illustrates an example in which the protruding portion153is provided such that the length in the Y direction is different along the Z direction.FIG. 7is a sectional diagram illustrating a modification example of the protruding portion of the present embodiment.

As illustrated inFIG. 7, the protruding portion153includes side surfaces153ainclined with respect to the Y direction which is the first axial direction. In other words, in the protruding portion153, the side surfaces153aon both sides in the Y direction are inclined surfaces that are inclined with respect to the Y direction and the Z direction. In other words, the protruding portion153is provided such that the length dimension in the Y direction is gradually reduced toward the +Z direction.

By providing the side surfaces153ainclined with respect to the Y direction in the protruding portion153in this manner, portions where the ink flow stagnates are reduced and it is possible to improve the bubble discharging properties by suppressing the retaining of the bubbles contained in the ink flowing inside the first flow path201at corner portions formed between the side surfaces153aof the protruding portion153and the wall surfaces of the first flow path201. Therefore, it is possible to suppress the occurrence of ink droplet discharging faults or the like due caused by the bubbles being retained and growing and the grown bubbles entering the nozzle21or the like at unexpected timing.

When viewed in the Z direction, the side surfaces153aof the protruding portion153are provided at positions overlapping edges21cof the opening of the nozzle21that opens to the first flow path201. As described above, by providing the side surfaces153aat positions overlapping the edges21cof the opening of the nozzle21in the Z direction, it is possible to guide the ink flowing along the side surfaces153ainto the opening of the nozzle21and it is possible to generate an ink flow inside the nozzle21.

When the length of the protruding portion153in the Y direction is different along the Z direction, the length dimension L1in the Y direction of the protruding portion153defined with respect to the length dimension L2of the opening of the nozzle21in the Y direction is the longest portion of the protruding portion153, that is, the dimension at the end portions in the −Z direction of the side surfaces153a.

As illustrated inFIG. 4, the protruding portion153of the present embodiment is provided to have the same length in the Y direction over the X direction. Therefore, the length dimension L1of the protruding portion153in the Y direction is the same length over the X direction. The shape of the protruding portion153is not particularly limited thereto and the protruding portion153may be provided such that the length in the Y direction is different along the X direction. Here,FIG. 8illustrates an example in which the length of the protruding portion153in the Y direction is different along the X direction.FIG. 8is a sectional diagram illustrating a modification example of the protruding portion of the present embodiment.

As illustrated inFIG. 8, the protruding portion153is provided such that the length of the protruding portion153in the Y direction gradually decreases from the center portion in the X direction toward both end portions. In other words, the protruding portion153includes side surfaces153binclined with respect to the X direction, which is a third axial direction, on both sides in the Y direction.

By providing the side surfaces153binclined with respect to the X direction in the protruding portion153in this manner, portions where the ink flow stagnates are reduced and it is possible to improve the bubble discharging properties by suppressing the retaining of the bubbles contained in the ink flowing inside the first flow path201at corner portions formed between the side surfaces153bof the protruding portion153and the wall surfaces of the first flow path201. Therefore, it is possible to suppress the occurrence of ink droplet discharging faults or the like due caused by the bubbles being retained and growing and the grown bubbles entering the nozzle21or the like at unexpected timing.

When viewed in the Z direction, the side surfaces153bof the protruding portion153are provided at positions overlapping edges21cof the opening of the nozzle21that opens to the first flow path201.

When the length of the protruding portion153in the Y direction is different along the X direction, the length dimension L1in the Y direction of the protruding portion153defined with respect to the length dimension L2of the opening of the nozzle21in the Y direction is the longest portion of the protruding portion153, that is, the dimension at the center portion of the side surfaces153b.

The protruding portion153may be provided with side surfaces that are inclined with respect to the Y direction and that are inclined with respect to the X direction.

As illustrated inFIG. 4, the nozzle21of the present embodiment is provided to have a shape having a circular opening when viewed in plan view in the Z direction. Therefore, the length dimension L2in the Y direction of the opening of the nozzle21that opens to the first flow path201is a diameter r of the second nozzle21b. Naturally, the shape of the nozzle21is not particularly limited thereto and may be elliptical, rectangular, polygonal, an egg shape, or the like in plan view in the Z direction. The length dimension L2of the opening of the nozzle21that opens to the first flow path201is the dimension of the longest portion in the Y direction in the opening of the first flow path201of the nozzle21.

As described above, by setting the length dimension L1of the protruding portion153to less than or equal to 2 times, more preferably, less than or equal to one times the length dimension L2of the opening of the nozzle21, it is possible to facilitate the ink flowing through the first flow path201in the Y direction is flowing into the nozzle21and to replace the ink inside the nozzle21with new ink supplied from upstream. When the length dimension L1of the protruding portion153is larger than 2 times the length dimension L2of the opening of the nozzle21that opens to the first flow path201, the flow of ink toward the nozzle21does not occur easily. In other words, when the length dimension L1in the Y direction of the protruding portion153is excessively long, the ink flowing through the first flow path201in the Y direction comes into contact with the side surfaces of the protruding portion153and a flow toward the +Z direction is generated at a position away from the nozzle21. When a flow in the +Z direction is generated at a position away from the nozzle21in the Y direction in this manner, the flow along the Y direction between the tip surface of the protruding portion153and the wall surface of the first flow path201is generated directly above the nozzle21in the −Z direction, and thus, the ink does not easily enter the nozzle21.

As illustrated inFIG. 4, a width dimension W1in the X direction, which is the third axial direction, of the protruding portion153is preferably more than or equal to ½ times a width dimension W2of the first flow path201in the X direction, and is more preferably more than or equal to 1 times. In other words, W1≥W2×½ is preferable and W1≥W2is more preferable.

The protruding portion153of the present embodiment is provided over the first flow path201in the X direction. Therefore, the protruding portion153is provided to have the same width in the X direction over the Y direction and the width dimension W1in the X direction is the same width as the width dimension W2of the first flow path201in the X direction, that is, W1=W2. The protruding portion153may be formed to have a width smaller than the width of the first flow path201in the X direction. Here, such an example is illustrated inFIG. 9.FIG. 9is a sectional diagram illustrating a modification example of the protruding portion153.

As illustrated inFIG. 9, the protruding portion153is formed to have a width smaller than the width of the first flow path201in the X direction. Therefore, since the first flow path201is not blocked at both end portions of the protruding portion153in the X direction, it is possible to suppress the retention of bubbles without forming corner portions between both end portions of the protruding portion153in the X direction and the wall surface of the first flow path201.

In the examples illustrated inFIGS. 4 and 9, although the protruding portion153is provided such that the width thereof in the X direction is the same width over the Y direction, the configuration is not particularly limited thereto and the protruding portion153may be formed such that the width thereof in the X direction is different along the Y direction. The width dimension W1of the protruding portion153in the X direction when the protruding portion153is provided such that the width thereof in the X direction is different along the Y direction refers to the width dimension of the widest portion in the X direction.

The first flow path201of the present embodiment is provided to have the same width in the X direction over the Y direction. The first flow path201may be provided to have a different width in the X direction along the Y direction. The width dimension W2of the first flow path201in the X direction is a dimension of the width of the first flow path201in the X direction at a portion where the nozzle21communicates with the first flow path201in the Y direction.

As described above, the width dimension W1of the protruding portion153in the X direction, which is the third axial direction, is more than or equal to ½ times and more preferably more than or equal to the width dimension W2of the first flow path201in the X direction. Therefore, the flow of ink passing through both sides of the protruding portion153in the X direction from upstream toward downstream of the protruding portion153in the Y direction is suppressed and it is possible to change the flow of the ink flowing inside the first flow path201into a flow toward the inside of the nozzle21.

As illustrated inFIG. 3, a height dimension H1of the protruding portion153in the Z direction is preferably more than or equal to ⅓ times a height dimension H2of the first flow path201in the Z direction and is more preferably more than or equal to ½ times the height dimension H2. In other words, H1≥H2×⅓ is preferable, and H1≥H2×½ is more preferable. Here, the height dimension H1of the protruding portion153in the Z direction is a height by which the protruding portion153protrudes in the +Z direction from the ceiling portion upstream and downstream of the protruding portion153in the Y direction. In the present embodiment, the height of the protruding portion153in the Z direction is the same height over the Y direction and the X direction, that is, the protruding tip surface of the protruding portion153is formed in the plane direction including the X direction and the Y direction. The protruding portion153may be formed to have a different height in the Z direction along the Y direction, or may be formed to have a different height along the X direction. The height dimension H1of the protruding portion153is a dimension in the Z direction of a portion at which the protruding amount is the largest.

The height of the first flow path201in the Z direction is the height between the portion of the nozzle21where the first flow path201is opened and the ceiling portion of the first flow path201where the protruding portion153is not provided. In the present embodiment, the first flow path201has the same height in the Z direction over the X and Y directions. The first flow path201is not particularly limited thereto, and may be formed such that the height in the Z direction is a different height along the X direction, or the first flow path201may be formed such that the height thereof is different along the Y direction. The height dimension H2of the first flow path201is the highest portion in the Z direction between the portion at which the nozzle21is opened and the portion facing the opening in the Z direction and where the protruding portion153is not provided.

As described above, the height dimension H1of the protruding portion153in the Z direction is preferably more than or equal to ⅓ times, more preferably more than or equal to ½ times the height dimension H2of the first flow path201, and thus, it is possible to direct the flow of the ink flowing through the first flow path201toward the nozzle21direction using the protruding portion153. When the height dimension H1of the protruding portion153is smaller than ⅓ times the height dimension H2of the first flow path201, the flow of the ink toward the inside of the nozzle21is not easily generated due to the protruding portion153and the flow of the ink into the nozzle21is not easily generated.

The height dimension H1of the protruding portion153in the Z direction is preferably less than or equal to 1 times, more preferably less than or equal to ⅔ times the height dimension H2of the first flow path201in the Z direction. In other words, H1H2is preferable, and H1H2×⅔ is more preferable.

Here,FIG. 10illustrates when the height dimension H1of the protruding portion153in the Z direction is the same as the height dimension H2of the first flow path201in the Z direction.

As illustrated inFIG. 10, the protruding tip surface of the protruding portion153is disposed to be flush with the wall surface of the first flow path201in which the nozzle21opens. The height dimension H1of the protruding portion153is more than the height dimension H2of the first flow path201when the protruding portion153is provided to enter the nozzle21.

The protruding portion153may be provided such that a height H1thereof in the Z direction is a different height along the X direction.FIG. 11illustrates such an example.

As illustrated inFIG. 11, the height dimension H1of the protruding portion153in the Z direction is the same height as the height dimension H2of the first flow path201in the Z direction. The protruding portion153is formed such that the height in the Z direction gradually decreases from both ends toward the center portion in the X direction. In other words, the tip surface of the protruding portion153is a concave curved surface when viewed in plan view in the Y direction.

In the protruding portion153, as the distance of the nozzle21from the opening in the X direction increases, the ink flowing through the first flow path201in the Y direction is blocked more by the protruding portion153, and thus, more ink flows easily toward the center portion in the X direction, that is, the center portion of the opening of the nozzle21. Therefore, it is possible to increase the amount of the ink flowing inside the nozzle21.

As described above, the height dimension H1of the protruding portion153is set to less than or equal to 1 times, more preferably less than or equal to ⅔ times the height dimension H2of the first flow path201, and thus, it is possible to suppress a decrease in the discharging efficiency caused by the protruding portion153increasing in the flow path resistance of the first flow path201.

When the height dimension H1of the protruding portion153is larger than the height dimension H2of the first flow path201, the flow path resistance from the pressure chamber12to the nozzle21increases and the pressure loss increases, and thus, the weight of the ink droplet discharged from the nozzle21is reduced.

Therefore, the piezoelectric actuator300is to be driven at a higher drive voltage and the discharging efficiency is reduced. By setting the height dimension H1of the protruding portion153to less than or equal to ⅔ times, more preferably less than or equal to the height dimension H2of the first flow path201, it is possible to suppress an increase in pressure loss, and to suppress a decrease in the weight of the ink droplet, and thus, it is possible to drive the piezoelectric actuator300at a lower drive voltage and it is possible to improve the discharging efficiency.

As illustrated inFIG. 4, the protruding portion153of the present embodiment is formed such that the range occupied by the protruding portion153in the Y direction when viewed in the Z direction, which is the second axial direction, is substantially symmetrical with respect to a center C of the opening of the nozzle21at the first flow path201.

Here, the center C of the opening of the nozzle21at the first flow path201is the center of the maximum inner dimension in the Y direction when the opening is non-circular. The fact that the range occupied by the protruding portion153in the Y direction is substantially symmetrical with respect to the center C of the opening of the nozzle21means that the protruding portion153has a deviation of 20% or less with respect to the length dimension L1of the protruding portion153in the Y direction. In other words, the center of the protruding portion153in the Y direction refers to a position of less than or equal to L1×0.2 in the −Y direction and less than or equal to L1×0.2 in the +Y direction with respect to the center C of the opening of the nozzle21.

As described above, by rendering the protruding portion153substantially symmetrical with respect to the center C of the opening of the nozzle21, even when the ink is circulated from the first common liquid chamber101toward the second common liquid chamber102, and even when the ink is circulated from the second common liquid chamber102toward the first common liquid chamber101, it is possible to generate the flow of the ink inside the nozzle21using the protruding portion153.

Furthermore, as illustrated inFIG. 4, when the diameter of the opening of the nozzle21at the first flow path201is r, it is preferable that the first flow path201extend over a range of a length more than or equal to 2r in both positive and negative directions of the Y direction from the center C of the opening of the nozzle21. Since the first flow path201is a portion that does not overlap the second flow path202in the Z direction, the end portion of the first flow path201in the +Y direction serves as the side surface of the second flow path202in the −Y direction. Since the first flow path201is a portion that does not overlap the second common liquid chamber102in the Z direction, the end portion of the first flow path201in the −Y direction serves as the side surface of the second common liquid chamber102in the +Y direction.

Therefore, the length dimension L3in the +Y direction from the center C of the opening of the nozzle21at the first flow path201to the end portion coupled to the second flow path202is a length that is more than or equal to 2 times the diameter r of the opening of the first flow path201of the nozzle21, that is, the first flow path201is provided at a length that satisfies L3≥2r. The length dimension L4in the −Y direction from the center C of the opening of the nozzle21of the first flow path201to the end portion coupled to the second common liquid chamber102is more than or equal to 2 times the diameter r of the opening of the nozzle21at the first flow path201, that is, the first flow path201is provided at a length that satisfies L4≥2r.

In the individual flow path200, so-called circulation is performed in which the liquid flows from the first common liquid chamber101, through the individual flow path200, to the second common liquid chamber102. A pressure change is generated in the ink inside the pressure chamber12by driving the piezoelectric actuator300and the ink droplet is discharged from the nozzle21to the outside in the +Z direction by increasing the pressure of the ink inside the nozzle21. When the ink flows from the first common liquid chamber101to the second common liquid chamber102through the individual flow path200, the piezoelectric actuator300may be driven, or the piezoelectric actuator300may be driven when the ink does not flow from the first common liquid chamber101to the second common liquid chamber102through the individual flow path200. The flow of the ink from the second common liquid chamber102to the first common liquid chamber101may be temporarily generated by a pressure change caused by the driving of the piezoelectric actuator300.

As described above, the ink jet recording head1which is an example of the liquid ejecting head of the present embodiment includes the supply port43and the discharge port44of the ink which is the liquid. The ink jet recording head1is provided with the first flow path201extending in the Y direction, which is the first axial direction, between the supply port43and the discharge port44, and the nozzle21which is provided to branch from the first flow path201and is the nozzle21which ejects the ink along the Z direction, which is the second axial direction orthogonal to the Y direction, in which the first flow path201is provided with the protruding portion153facing the opening of the nozzle21that opens to the first flow path201.

By causing the nozzle21to communicate with the middle of the first flow path201which extends in the Y direction in this manner, it is possible to dispose the nozzle21away from a portion at which the ink is retained, such as a corner portion between the second flow path202and the nozzle plate20, and the ink and air bubbles in which a component settles due to the retaining do not easily move to the nozzle21side. Therefore, it is possible to suppress clogging of the nozzle21caused by the ink or bubbles in which the component settles due to the retaining, variation in the components of ink droplets to be discharged from the nozzle21, and the like.

By causing the nozzle21to communicate with the middle of the first flow path201extending in the Y direction, it is possible to cause the air bubbles that enter from the nozzle21to flow toward the second common liquid chamber102on the downstream using the ink flowing through the first flow path201. Therefore, it is possible to prevent the bubbles that enter from the nozzle21from entering the pressure chamber12or the first common liquid chamber101side and to suppress ink droplet discharging faults caused by the pressure fluctuations of the ink inside the pressure chamber12being absorbed by the bubbles that enter the pressure chamber12. When the nozzle21is provided at a position communicating with the second flow path202, the bubbles entering from the nozzle21easily move to the pressure chamber12side against the flow of the ink due to buoyancy. When the bubbles enter the pressure chamber12from the nozzle21, there is a concern that the bubbles that enter the pressure chamber12may absorb pressure fluctuations of the ink inside the pressure chamber12and that ink droplet discharging faults may occur.

By providing the protruding portion153in the first flow path201, it is possible to change the flow of the ink flowing inside the first flow path201in the Y direction to a flow in the Z direction toward the nozzle21to generate a flow of the ink to the nozzle21and replace the ink inside the nozzle21with new ink supplied from upstream. Therefore, it is possible to suppress the ink being retained inside the nozzle21and it is possible to suppress the occurrence of discharging faults such as clogging of the nozzle21caused by an increase in the viscosity of the retained ink, displacement of the flight direction of the ink droplet discharged from the nozzle21, and the like.

By providing the nozzle21at a position communicating with the first flow path201, it is possible to raise the degree of freedom in the disposing of the nozzle21in the Y direction.

In the recording head1of the present embodiment, the length dimension L1of the protruding portion153in the Y direction, which is the first axial direction, is preferably less than or equal to 2 times, and more preferably less than or equal to the length dimension L2the opening of the nozzle21at the first flow path201in the Y direction. By setting the length dimension L1of the protruding portion153to less than or equal to 2 times, more preferably, less than or equal to the opening of the nozzle21, it is possible to allow the ink flowing through the first flow path201in the Y direction to easily flow into the nozzle21to replace the ink inside the nozzle21with new ink supplied from upstream.

In the recording head1of the present embodiment, the width dimension W1of the protruding portion153in the X direction, which is the third axial direction orthogonal to the Y direction, which is the first axial direction, and orthogonal to the Z direction, which is the second axial direction, is preferably at more than or equal to ½ times and more preferably more than or equal to the width dimension W2of the opening of the nozzle21at the first flow path201in the X direction. As described above, the width dimension W1of the protruding portion153in the X direction is more than or equal to ½ times and more preferably more than or equal to the width dimension W2of the first flow path201in the X direction. Therefore, the flow of ink passing through both sides of the protruding portion153in the X direction from upstream toward downstream of the protruding portion153in the Y direction is suppressed and it is possible to change the flow of the ink flowing inside the first flow path201into a flow toward the inside of the nozzle21.

In the recording head1of the present embodiment, as illustrated inFIG. 7, it is preferable that the protruding portion153include side surfaces153ainclined with respect to the Y direction which is the first axial direction. Accordingly, by inclining the side surfaces153aof the protruding portion153with respect to the Y direction, the ink is not easily retained at the corner portions between the side surfaces153aof the protruding portion153and the wall surface of the first flow path201and it is possible to improve the bubble discharging properties.

In the recording head1of the present embodiment, as illustrated inFIG. 7, it is preferable that the side surfaces153aoverlap the edges21cof the opening as viewed in the Z direction which is the second axial direction. Accordingly, the flow of the ink changed by the side surfaces153aeasily enters from the opening of the nozzle21and it is possible to reliably generate the flow of the ink inside the nozzle21.

In the recording head1of the present embodiment, the height dimension H1of the protruding portion153in the Z direction, which is the second axial direction, is preferably more than or equal to ⅓ times, and more preferably more than or equal to ½ times the height dimension H2of the first flow path201in the Z direction. As described above, the height dimension H1of the protruding portion153in the Z direction is preferably more than or equal to ⅓ times the height dimension H2of the first flow path201, more preferably more than or equal to ½ times the height dimension H2of the first flow path201, and thus, it is possible to direct the flow of the ink flowing through the first flow path201toward the nozzle21direction using the protruding portion153, and it is possible to reliably generate the flow of the ink inside the nozzle21.

In the recording head1of the present embodiment, the height dimension H1of the protruding portion153in the Z direction, which is the second axial direction, is preferably less than or equal to 1 times, and more preferably less than or equal to ⅔ times the height dimension H2of the first flow path201in the Z direction. As described above, the height dimension H1of the protruding portion153is set to less than or equal to 2 times, more preferably less than or equal to ⅔ times the height dimension H2of the first flow path201, and thus, it is possible to suppress a decrease in the discharging efficiency caused by the protruding portion153increasing in the flow path resistance of the first flow path201.

In the recording head1of the present embodiment, it is preferable that the protruding portion153be formed such that the range occupied by the protruding portion153in the Y direction, which is the first axial direction, when viewed in the Z direction, which is the second axial direction, be substantially symmetrical with respect to the center C of the opening of the nozzle21at the first flow path201. Accordingly, even if the flow of the ink flowing through the first flow path201is reversed, it is possible to generate the flow of the ink inside the nozzle21.

In the recording head1of the present embodiment, when the diameter of the opening of the nozzle21at the first flow path201is r, it is preferable that the first flow path201extend over a range of a length more than or equal to 2r toward each of both sides of the center C of the opening in the Y direction, which is the first axial direction. In other words, it is preferable to satisfy the length dimensions L3≥2r and L4≥2r.

Other Embodiments

Although the embodiments of the present disclosure are described above, the basic configuration of the present disclosure is not limited to the above-described embodiment.

For example, in the above-described embodiment, a configuration is exemplified in which the nozzles21are arranged in the X direction orthogonal to both the Y direction and the Z direction with the first axial direction as the Y direction and the second axial direction as the Z direction. However, the configuration is not particularly limited thereto. For example, the nozzles21, the pressure chambers12, and the like may be arranged side by side in a direction inclined with respect to the X direction in the in-plane direction of the nozzle surface20a.

In the present embodiment, although the first flow path201of the individual flow path200and the second common liquid chamber102are directly coupled, the configuration is not particularly limited thereto, and another flow path extending in the Z direction, which is the second axial direction, may be provided between the first flow path201and the second common liquid chamber102.

Here, an example of an ink jet recording apparatus, which is an example of the liquid ejecting apparatus of the present embodiment, will be described with reference toFIG. 12.FIG. 12is a perspective view illustrating a schematic configuration of the ink jet recording apparatus of the present disclosure.

As illustrated inFIG. 12, in an ink jet recording apparatus I, which is an example of a liquid ejecting apparatus, two or more recording heads1are mounted on a carriage3. The carriage3on which the recording heads1are mounted is provided on a carriage shaft5attached to an apparatus main body4to move freely in the axial direction. In the present embodiment, the moving direction of the carriage3is the Y direction, which is the first axial direction.

The apparatus main body4is provided with a tank2which is a storage unit in which ink is stored as a liquid. The tank2is coupled to the recording head1via a supply pipe2asuch as a tube and the ink from the tank2is supplied to the recording head1via the supply pipe2a. The recording head1and the tank2are coupled via a discharge pipe2bsuch as a tube and the ink discharged from the recording head1is returned to the tank2via the discharge pipe2b, that is, so-called circulation is performed. The tank2may be formed by two or more tanks.

The driving force of a drive motor7is transmitted to the carriage3via gears (not illustrated) and a timing belt7a, and thus, the carriage3on which the recording head1is mounted is moved along the carriage shaft5. On the other hand, the apparatus main body4is provided with a transport roller8which serves as a transport unit and a recording sheet S which is an ejection target medium such as paper is transported by the transport roller8. The transport unit that transports the recording sheet S is not limited to the transport roller8and may be a belt, a drum, or the like. In the present embodiment, the transport direction of the recording sheet S is the X direction.

In the ink jet recording apparatus I described above, a configuration is exemplified in which the recording head1is mounted on the carriage3and moves in a main scanning direction. However, the configuration is not particularly limited thereto, and for example, it is possible to apply the present disclosure to a so-called line type recording apparatus in which the recording head1is fixed and the printing is performed by only moving the recording sheet S such as paper in the sub-scanning direction.

In each embodiment, the ink jet recording head is described as an example of the liquid ejecting head and the ink jet recording apparatus is described as an example of the liquid ejecting apparatus. However, the present disclosure widely targets liquid ejecting heads and liquid ejecting apparatuses in general, and naturally, it is possible to apply the present disclosure to a liquid ejecting head or a liquid ejecting apparatus that ejects a liquid other than the ink. Examples of other liquid ejecting heads include various recording heads used in image recording apparatuses such as printers, color material ejecting heads used in manufacturing color filters of liquid crystal displays and the like, electrode material ejection heads used for forming electrodes of organic EL displays, FEDs (field emission displays), and the like, and biological organic material ejection heads used for manufacturing biochips, and it is also possible to apply the present disclosure to a liquid ejecting apparatus provided with such a liquid ejecting head.

Here, an example of the liquid ejecting system of the present embodiment will be described with reference toFIG. 13.FIG. 13is a block diagram illustrating the liquid ejecting system of the ink jet recording apparatus which is the liquid ejecting apparatus of the present disclosure.

As illustrated inFIG. 13, the liquid ejecting system includes the recording head1and, as a mechanism for supplying the ink as the liquid to the supply port43, collecting the ink from the discharge port44, and circulating the ink, includes a main tank500, a first tank501, a second tank502, a compressor503, a vacuum pump504, a first liquid pump505, and a second liquid pump506.

The recording head1and the compressor503are coupled to the first tank501, and the ink in the first tank501is supplied to the recording head1at a predetermined pressure by the compressor503.

The second tank502is coupled to the first tank501via the first liquid pump505, and the ink in the second tank502is pumped to the first tank501by the first liquid pump505.

The recording head1and the vacuum pump504are coupled to the second tank502, and the ink of the recording head1is discharged to the second tank502at a predetermined negative pressure by the vacuum pump504.

In other words, the ink is supplied from the first tank501to the recording head1and the ink is discharged from the recording head1to the second tank502. The ink is circulated by the ink being pumped from the second tank502to the first tank501by the first liquid pump505.

The main tank500is coupled to the second tank502via the second liquid pump506, and an amount of the ink corresponding to that consumed by the recording head1is replenished in the second tank502from the main tank500. The replenishment of the ink in the second tank502from the main tank500may be performed, for example, at a timing when the liquid level of the ink in the second tank502becomes lower than a predetermined height.