JP7474661B2 - HEAD CHIP, LIQUID JET HEAD AND LIQUID JET RECORDING APPARATUS - Google Patents

Description

The present disclosure relates to a head chip, a liquid jet head, and a liquid jet recording device.

Liquid jet recording devices equipped with liquid jet heads are used in a variety of fields, and various types of liquid jet heads have been developed (see, for example, Patent Document 1). In addition, such liquid jet heads are provided with a head chip that ejects ink (liquid).

JP 2015-178209 A

For such head chips and the like, it is generally required to suppress manufacturing costs, reduce power consumption, and improve print image quality. It is desirable to provide a head chip, liquid ejection head, and liquid ejection recording device that can reduce power consumption and improve print image quality while suppressing the manufacturing costs of the head chip.

A head chip according to an embodiment of the present disclosure includes an actuator plate having a plurality of ejection grooves arranged in a predetermined direction and a plurality of electrodes individually provided on the side walls of the ejection grooves and extending along the extension direction of the ejection grooves, and a cover plate having a wall portion covering the ejection grooves, a first through hole formed on one side of the wall portion along the extension direction of the ejection grooves and for allowing liquid to flow into the ejection grooves, and a second through hole formed on the other side of the wall portion along the extension direction of the ejection grooves and for allowing liquid to flow out from the ejection grooves. The plurality of nozzle holes include a plurality of first nozzle holes arranged offset toward the first through hole side along the extension direction of the ejection grooves with respect to a center position along the extension direction of the ejection grooves, and a plurality of second nozzle holes arranged offset toward the second through hole side along the extension direction of the ejection grooves with respect to a center position along the extension direction of the ejection grooves. In the first ejection groove, which is an ejection groove communicating with the first nozzle hole, the first cross-sectional area, which is the cross-sectional area of the liquid flow path in the portion communicating with the first through hole, is smaller than the second cross-sectional area, which is the cross-sectional area of the liquid flow path in the portion communicating with the second through hole, and in the second ejection groove, which is an ejection groove communicating with the second nozzle hole, the second cross-sectional area is smaller than the first cross-sectional area. In addition, the positions of both ends of the ejection groove in the electrode along the extension direction are aligned with each other in the multiple electrodes along the predetermined direction.

The liquid jet head according to one embodiment of the present disclosure is equipped with a head chip according to one embodiment of the present disclosure.

A liquid jet recording device according to one embodiment of the present disclosure is equipped with the liquid jet head according to the above-described one embodiment of the present disclosure.

The head chip, liquid jet head, and liquid jet recording device according to one embodiment of the present disclosure make it possible to reduce power consumption and improve print image quality while keeping manufacturing costs of the head chip low.

1 is a schematic perspective view illustrating an example of a schematic configuration of a liquid jet recording apparatus according to an embodiment of the present disclosure. 4 is a schematic bottom view illustrating an example of the configuration of a liquid jet head with a nozzle plate removed. FIG. 3 is a schematic diagram illustrating an example of a cross-sectional configuration taken along line III-III shown in FIG. 2. 4 is a schematic diagram illustrating an example of a cross-sectional configuration taken along line IV-IV shown in FIG. 2. 5 is a schematic diagram illustrating an example of a planar configuration of the liquid ejecting head on the upper surface side of the cover plate illustrated in FIGS. 3 and 4 . FIG. 5 is a schematic diagram illustrating an example of a planar configuration near an end of the actuator plate illustrated in FIGS. 3 and 4. FIG. 5 is a schematic diagram illustrating a detailed configuration example in the vicinity of a discharge channel in the cross-sectional configuration example illustrated in FIG. 3 and FIG. 4. 8A to 8C are schematic diagrams illustrating an example of a method for forming the common electrode illustrated in FIG. 7 . 11 is a schematic bottom view illustrating a configuration example of a liquid jet head according to Comparative Example 1 in a state where a nozzle plate is removed. FIG. FIG. 10 is a schematic diagram illustrating an example of a cross-sectional configuration taken along line XX illustrated in FIG. 9. 11 is a schematic diagram illustrating an example of a cross-sectional configuration near an ejection channel in a liquid jet head according to Comparative Example 2. FIG. 13 is a schematic diagram illustrating an example of a planar configuration of an upper surface side of a cover plate in a liquid jet head according to Comparative Example 3. FIG. 13 is a schematic diagram illustrating an example of a cross-sectional configuration near an ejection channel in a liquid jet head according to Comparative Example 3. FIG. 10A and 10B are schematic diagrams illustrating an example of a cross-sectional configuration of a liquid jet head according to a first modified example. 11A and 11B are schematic diagrams illustrating another example of a cross-sectional configuration of the liquid jet head according to the first modification. 16 is a schematic diagram illustrating another example of the cross-sectional configuration of the head chip illustrated in FIG. 14 and FIG. 15. 11 is a schematic cross-sectional view showing an example of the positional relationship between a nozzle hole and an extended flow path portion according to Modification 1 and the like. FIG. 13A and 13B are schematic cross-sectional views showing other examples of the positional relationship between the nozzle hole and the extended flow path portion according to Modification 1 and the like. 11 is a schematic cross-sectional view showing an example of the positional relationship between a nozzle hole and an extended flow path portion according to Modification 2 and the like. FIG. 13A and 13B are schematic cross-sectional views showing other examples of the positional relationship between the nozzle holes and the extended flow path portion according to Modification 2 and the like.

Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. The description will be made in the following order.
1. Embodiment (Example of a case where nozzle holes are arranged in a staggered fashion and ejection grooves and common electrodes are arranged in a single row)
2. Modifications Modification 1 (Example in which an alignment plate having an extended flow path portion is further provided)
Modification 2 (example in which the center position of the expanded flow passage portion coincides with the center position of the nozzle hole)
3. Other Modifications

1. Preferred embodiment
[A. Overall Configuration of Printer 1]
1 is a schematic perspective view showing an example of the general configuration of a printer 1 as a liquid jet recording device according to an embodiment of the present disclosure. The printer 1 is an inkjet printer that uses ink 9, which will be described later, to record (print) images, characters, and the like on recording paper P as a recording medium. Note that this recording medium is not limited to paper, and includes materials that can be recorded on, such as ceramics and glass.

As shown in FIG. 1, the printer 1 comprises a pair of transport mechanisms 2a, 2b, an ink tank 3, an inkjet head 4, a circulation flow path 50, and a scanning mechanism 6. Each of these components is housed in a housing 10 having a predetermined shape. Note that in each of the drawings used in the description of this specification, the scale of each component has been appropriately changed so that each component is of a recognizable size.

Here, the printer 1 corresponds to a specific example of a "liquid jet recording device" in this disclosure, and the inkjet head 4 (inkjet heads 4Y, 4M, 4C, and 4K described below) corresponds to a specific example of a "liquid jet head" in this disclosure. Also, the ink 9 corresponds to a specific example of a "liquid" in this disclosure.

As shown in FIG. 1, each of the transport mechanisms 2a and 2b transports the recording paper P along the transport direction d (X-axis direction). Each of the transport mechanisms 2a and 2b has a grid roller 21, a pinch roller 22, and a drive mechanism (not shown). This drive mechanism rotates the grid roller 21 around its axis (in the Z-X plane), and is composed of, for example, a motor.

(Ink Tank 3)
The ink tanks 3 are tanks that contain ink 9. In this example, as shown in Fig. 1, four types of ink tanks 3 are provided, each of which contains four colors of ink 9: yellow (Y), magenta (M), cyan (C), and black (K). That is, an ink tank 3Y that contains yellow ink 9, an ink tank 3M that contains magenta ink 9, an ink tank 3C that contains cyan ink 9, and an ink tank 3K that contains black ink 9 are provided. These ink tanks 3Y, 3M, 3C, and 3K are arranged side by side along the X-axis direction within the housing 10.

Ink tanks 3Y, 3M, 3C, and 3K are identical in configuration except for the color of the ink 9 they contain, so in the following description they will be collectively referred to as ink tank 3.

(Inkjet head 4)
The inkjet head 4 is a head that ejects (discharges) droplets of ink 9 from a plurality of nozzles (nozzle holes H1, H2) to be described later onto the recording paper P to record (print) images, characters, and the like. In this example, as shown in FIG. 1, the inkjet head 4 is provided with four types of heads that eject the four colors of ink 9 contained in the ink tanks 3Y, 3M, 3C, and 3K, respectively. That is, the inkjet head 4Y that ejects the yellow ink 9, the inkjet head 4M that ejects the magenta ink 9, the inkjet head 4C that ejects the cyan ink 9, and the inkjet head 4K that ejects the black ink 9 are provided. These inkjet heads 4Y, 4M, 4C, and 4K are arranged side by side along the Y-axis direction within the housing 10.

In addition, the inkjet heads 4Y, 4M, 4C, and 4K each have the same configuration except for the color of the ink 9 that they use, so they will be collectively referred to as inkjet head 4 below. An example of the detailed configuration of the inkjet head 4 will be described later (Figures 2 to 6).

(Circulation flow path 50)
1, the circulation flow path 50 has flow paths 50a and 50b. The flow path 50a is a flow path that leads from the ink tank 3 to the inkjet head 4 via a liquid feed pump (not shown). The flow path 50b is a flow path that leads from the inkjet head 4 to the ink tank 3 via a liquid feed pump (not shown). In other words, the flow path 50a is a flow path through which the ink 9 flows from the ink tank 3 to the inkjet head 4. The flow path 50b is a flow path through which the ink 9 flows from the ink tank 3 to the inkjet head 4.

In this manner, in this embodiment, the ink 9 is circulated between the ink tank 3 and the inkjet head 4. Each of these flow paths 50a, 50b (ink 9 supply tubes) is formed, for example, from a flexible hose.

(Scanning mechanism 6)
The scanning mechanism 6 is a mechanism for scanning the inkjet head 4 along the width direction (Y-axis direction) of the recording paper P. As shown in Fig. 1, the scanning mechanism 6 has a pair of guide rails 61a, 61b extending along the Y-axis direction, a carriage 62 movably supported on these guide rails 61a, 61b, and a drive mechanism 63 for moving the carriage 62 along the Y-axis direction.

The drive mechanism 63 has a pair of pulleys 631a, 631b arranged between the guide rails 61a, 61b, an endless belt 632 wound between these pulleys 631a, 631b, and a drive motor 633 that rotates and drives the pulley 631a. In addition, the four types of inkjet heads 4Y, 4M, 4C, and 4K described above are arranged on the carriage 62 in a line along the Y-axis direction.

The scanning mechanism 6 and the transport mechanisms 2a and 2b described above constitute a movement mechanism that moves the inkjet head 4 and the recording paper P relative to one another. Note that the movement mechanism is not limited to this type of mechanism, and may be, for example, a method in which the inkjet head 4 and the recording medium are moved separately by fixing the inkjet head 4 and moving only the recording medium (the recording paper P) (the so-called "single pass method").

[B. Detailed configuration of inkjet head 4]
Next, a detailed configuration example of the inkjet head 4 (head chip 41) will be described with reference to FIGS. 2 to 6 in addition to FIG.

Figure 2 is a schematic bottom view (X-Y bottom view) of an example of the configuration of the inkjet head 4 with the nozzle plate 411 (described later) removed. Figure 3 is a schematic cross-sectional view (Y-Z cross-sectional view) of the inkjet head 4 taken along line III-III in Figure 2. Similarly, Figure 4 is a schematic cross-sectional view (Y-Z cross-sectional view) of the inkjet head 4 taken along line IV-IV in Figure 2. Figure 5 is a schematic planar view (X-Y planar view) of the inkjet head 4 on the upper surface side of the cover plate 413 (described later) shown in Figures 3 and 4. Figure 6 is a schematic planar view (X-Y planar view) of the actuator plate 412 (described later) shown in Figures 3 and 4 near the end along the Y-axis direction.

Note that, for convenience, in Figures 3 to 6, of the ejection channels C1e and C2e and the nozzle holes H1 and H2 described later, the ejection channel C1e and the nozzle hole H1 arranged corresponding to the nozzle row An1 described later are shown as representatives. In other words, the ejection channel C2e and the nozzle hole H2 arranged corresponding to the nozzle row An2 described later have the same configuration, so they are not shown.

The inkjet head 4 of this embodiment is a so-called side shoot type inkjet head that ejects ink 9 from the center of the extension direction (Y axis direction) of multiple channels (multiple channels C1 and multiple channels C2) in the head chip 41 described below. In addition, this inkjet head 4 is a circulation type inkjet head that circulates ink 9 between the ink tank 3 by using the circulation flow path 50 described above.

As shown in Figures 3 and 4, the inkjet head 4 includes a head chip 41. The inkjet head 4 also includes a circuit board and a flexible printed circuit board (Flexible Printed Circuits: FPC) as a control mechanism (mechanism for controlling the operation of the head chip 41) (not shown).

The circuit board is a board that carries a drive circuit (electrical circuit) for driving the head chip 41. The flexible printed circuit board is a board that electrically connects the drive circuit on this circuit board to the drive electrodes Ed (described later) on the head chip 41. In addition, multiple extraction electrodes are printed and wired on such a flexible printed circuit board.

As shown in Figures 3 and 4, the head chip 41 is a member that ejects ink 9 along the Z-axis direction, and is constructed using various plates. Specifically, as shown in Figures 3 and 4, the head chip 41 mainly comprises a nozzle plate (ejection hole plate) 411, an actuator plate 412, and a cover plate 413. The nozzle plate 411, actuator plate 412, and cover plate 413 are each attached to one another using, for example, an adhesive, and are stacked in this order along the Z-axis direction. In the following description, the cover plate 413 side along the Z-axis direction will be referred to as the upper side, and the nozzle plate 411 side will be referred to as the lower side.

(Nozzle plate 411)
The nozzle plate 411 is made of a film material such as polyimide having a thickness of about 50 μm, and is adhered to the lower surface of the actuator plate 412 as shown in Figures 3 and 4. However, the constituent material of the nozzle plate 411 is not limited to a resin material such as polyimide, and may be, for example, a metal material.

As shown in FIG. 2, the nozzle plate 411 is provided with two nozzle rows (nozzle rows An1, An2) that each extend along the X-axis direction. These nozzle rows An1, An2 are arranged at a predetermined distance from each other along the Y-axis direction. In this way, the inkjet head 4 (head chip 41) of this embodiment is a two-row type inkjet head (head chip).

Nozzle row An1, details of which will be described later, has a plurality of nozzle holes H1 arranged at a predetermined interval along the X-axis direction. Each of these nozzle holes H1 penetrates the nozzle plate 411 along its thickness direction (Z-axis direction), and as shown in Figures 3 and 4, for example, each nozzle hole H1 is individually connected to an ejection channel C1e in the actuator plate 412, which will be described later. The formation pitch of the nozzle holes H1 along the X-axis direction is the same as the formation pitch of the ejection channel C1e along the X-axis direction (same pitch). From the nozzle holes H1 in such nozzle row An1, details of which will be described later, ink 9 supplied from the ejection channel C1e is ejected (sprayed).

Nozzle row An2, as described in detail below, similarly has a plurality of nozzle holes H2 arranged at a predetermined interval along the X-axis direction. Each of these nozzle holes H2 also penetrates the nozzle plate 411 in its thickness direction, and is individually connected to an ejection channel C2e in the actuator plate 412, as described in detail below. The formation pitch of the nozzle holes H2 along the X-axis direction is the same as the formation pitch of the ejection channels C2e along the X-axis direction. As described in detail below, ink 9 supplied from the ejection channel C2e is also ejected from the nozzle holes H2 in such nozzle row An2.

As shown in FIG. 2, each nozzle hole H1 in nozzle row An1 and each nozzle hole H2 in nozzle row An2 are arranged in a staggered manner along the X-axis direction. Therefore, in the inkjet head 4 of this embodiment, the nozzle holes H1 in nozzle row An1 and the nozzle holes H2 in nozzle row An2 are arranged in a staggered pattern (staggered arrangement). Note that each of these nozzle holes H1 and H2 is a tapered through hole whose diameter gradually decreases as it extends downward (see FIGS. 3 and 4).

Here, in the nozzle plate 411 of the present embodiment, as shown in FIG. 2, among the multiple nozzle holes H1 in the nozzle row An1, the nozzle holes H1 adjacent to each other along the X-axis direction are arranged in a shifted manner along the extension direction (Y-axis direction) of the ejection channel C1e. That is, the multiple nozzle holes H1 in the nozzle row An1 are arranged in a staggered manner along the X-axis direction. Specifically, as shown in FIG. 2, the multiple nozzle holes H1 in the nozzle row An1 include multiple nozzle holes H11 belonging to the nozzle row An11 extending along the X-axis direction and multiple nozzle holes H12 belonging to the nozzle row An12 extending along the X-axis direction. In addition, each nozzle hole H11 is arranged in a shifted manner on the positive side of the Y-axis direction (the first supply slit Sin1 side described later) based on the center position along the extension direction (Y-axis direction) of the ejection channel C1e. On the other hand, each nozzle hole H12 is positioned offset to the negative side in the Y-axis direction (the side of the first exhaust slit Sout1 described later) with respect to the center position along the extension direction of the ejection channel C1e.

Similarly, in this nozzle plate 411, as shown in FIG. 2, among the multiple nozzle holes H2 in the nozzle row An2, the nozzle holes H2 adjacent to each other along the X-axis direction are arranged in a shifted manner along the extension direction (Y-axis direction) of the ejection channel C2e. That is, the multiple nozzle holes H2 in the nozzle row An2 are arranged in a staggered manner along the X-axis direction. Specifically, as shown in FIG. 2, the multiple nozzle holes H2 in the nozzle row An2 include multiple nozzle holes H21 belonging to the nozzle row An21 extending along the X-axis direction and multiple nozzle holes H22 belonging to the nozzle row An22 extending along the X-axis direction. In addition, each nozzle hole H21 is arranged in a shifted manner on the negative side of the Y-axis direction (the second supply slit side described later) with respect to the center position along the extension direction (Y-axis direction) of the ejection channel C2e. On the other hand, each nozzle hole H22 is arranged in a shifted manner on the positive side of the Y-axis direction (the second discharge slit side described later) with respect to the center position along the extension direction of the ejection channel C2e.

The detailed arrangement of the nozzle holes H1 (H11, H12) and H2 (H21, H22) will be described later.

(Actuator plate 412)

The actuator plate 412 is a plate made of a piezoelectric material such as PZT (lead zirconate titanate). As shown in Figs. 3 and 4, the actuator plate 412 is made by stacking two piezoelectric substrates having different polarization directions along the thickness direction (Z-axis direction) (so-called chevron type). However, the configuration of the actuator plate 412 is not limited to this chevron type. That is, for example, the actuator plate 412 may be made of one (single) piezoelectric substrate whose polarization direction is set in one direction along the thickness direction (Z-axis direction) (so-called cantilever type).

As shown in FIG. 2, the actuator plate 412 is provided with two channel rows (channel rows 421 and 422) that each extend along the X-axis direction. These channel rows 421 and 422 are disposed at a predetermined interval along the Y-axis direction.

As shown in FIG. 2, in such an actuator plate 412, an ejection area (jetting area) for ink 9 is provided in the center along the X-axis direction (area where the channel rows 421 and 422 are formed). On the other hand, in the actuator plate 412, non-ejection areas (non-jetting areas) for ink 9 are provided at both ends along the X-axis direction (areas where the channel rows 421 and 422 are not formed). These non-ejection areas are located on the outside along the X-axis direction with respect to the above-mentioned ejection areas. Note that, as shown in FIG. 2, both ends along the Y-axis direction of the actuator plate 412 each constitute a tail portion 420.

The above-mentioned channel row 421 has a plurality of channels C1, as shown in FIG. 2. These channels C1 extend along the Y-axis direction within the actuator plate 412, as shown in FIG. 2. Furthermore, these channels C1 are arranged in parallel to each other at a predetermined interval along the X-axis direction, as shown in FIG. 2. Each channel C1 is defined by a driving wall Wd made of a piezoelectric body (actuator plate 412), and forms a concave groove portion when viewed in the Z-X cross section.

Similarly, as shown in FIG. 2, the channel row 422 has a plurality of channels C2 extending along the Y-axis direction. As shown in FIG. 2, these channels C2 are arranged in parallel to each other at a predetermined interval along the X-axis direction. Each channel C2 is also defined by the driving wall Wd described above, and is a concave groove portion when viewed in the Z-X cross section.

As shown in Figures 2 to 6, the channel C1 includes ejection channels C1e (ejection grooves) for ejecting ink 9, and dummy channels C1d (non-ejection grooves) that do not eject ink 9. Each ejection channel C1e communicates with a nozzle hole H1 in the nozzle plate 411 (see Figures 3 and 4), while each dummy channel C1d does not communicate with the nozzle hole H1 and is covered from below by the upper surface of the nozzle plate 411.

The multiple ejection channels C1e are arranged in parallel such that at least a portion of them overlap each other along a predetermined direction (X-axis direction). In particular, in the example of FIG. 2, the multiple ejection channels C1e are arranged in their entirety so as to overlap each other along the X-axis direction. As a result, as shown in FIG. 2, the multiple ejection channels C1e are arranged in a row along the X-axis direction. Similarly, the multiple dummy channels C1d are arranged in parallel along the X-axis direction. In the example of FIG. 2, the multiple dummy channels C1d are arranged in their entirety in a row along the X-axis direction. In addition, in this channel row 421, such ejection channels C1e and dummy channels C1d are arranged alternately along the X-axis direction (see FIG. 2).

As shown in Figures 2 to 4, the channel C2 includes ejection channels C2e (ejection grooves) for ejecting ink 9, and dummy channels C2d (non-ejection grooves) that do not eject ink 9. Each ejection channel C2e communicates with a nozzle hole H2 in the nozzle plate 411, while each dummy channel C2d does not communicate with the nozzle hole H2 and is covered from below by the upper surface of the nozzle plate 411 (see Figures 3 and 4).

The multiple ejection channels C2e are arranged in parallel such that at least a portion of them overlap one another along a predetermined direction (the X-axis direction). In particular, in the example of FIG. 2, the multiple ejection channels C2e are arranged in their entirety so as to overlap one another along the X-axis direction. As a result, as shown in FIG. 2, the multiple ejection channels C2e are arranged in a row along the X-axis direction. Similarly, the multiple dummy channels C2d are arranged in parallel along the X-axis direction. In the example of FIG. 2, the multiple dummy channels C2d are arranged in their entirety in a row along the X-axis direction. In addition, in this channel row 422, the ejection channels C2e and dummy channels C2d are arranged alternately along the X-axis direction (see FIG. 2).

Each of these ejection channels C1e and C2e corresponds to a specific example of an "ejection groove" in this disclosure. The X-axis direction corresponds to a specific example of a "predetermined direction" in this disclosure, and the Y-axis direction corresponds to a specific example of an "extension direction of the ejection groove" in this disclosure.

As shown in Figures 2 to 4, the ejection channel C1e in the channel row 421 and the dummy channel C2d in the channel row 422 are arranged in a straight line along the extension direction (Y-axis direction) of these ejection channels C1e and dummy channels C2d. Also, as shown in Figure 2, the dummy channel C1d in the channel row 421 and the ejection channel C2e in the channel row 422 are arranged in a straight line along the extension direction (Y-axis direction) of these dummy channels C1d and ejection channels C2e.

Furthermore, as shown in FIG. 4, for example, each ejection channel C1e has an arc-shaped side surface in which the cross-sectional area of each ejection channel C1e gradually decreases from the cover plate 413 side (upper side) toward the nozzle plate 411 side (lower side). Similarly, each ejection channel C2e has an arc-shaped side surface in which the cross-sectional area of each ejection channel C2e gradually decreases from the cover plate 413 side toward the nozzle plate 411 side. Note that the arc-shaped side surfaces of such ejection channels C1e, C2e are each formed by cutting using, for example, a dicer.

The detailed configuration of the vicinity of the discharge channel C1e (and the vicinity of the discharge channel C2e) shown in Figures 3 and 4 will be described later.

As shown in Figures 3, 4, and 6, the inner surfaces of the driving wall Wd facing each other along the X-axis direction are provided with driving electrodes Ed extending along the Y-axis direction. The driving electrodes Ed include a common electrode Edc provided on the inner surface facing the ejection channels C1e and C2e, and an individual electrode (active electrode) Eda provided on the inner surface facing the dummy channels C1d and C2d. The driving electrodes Ed (common electrode Edc and individual electrode Eda) are formed on the inner surface of the driving wall Wd over the entire depth direction (Z-axis direction) (see Figures 3 and 4).

A pair of common electrodes Edc that face each other in the same ejection channel C1e (or ejection channel C2e) are electrically connected to each other at a common terminal (common wiring) not shown. In addition, a pair of individual electrodes Eda that face each other in the same dummy channel C1d (or dummy channel C2d) are electrically isolated from each other. On the other hand, a pair of individual electrodes Eda that face each other across the ejection channel C1e (or ejection channel C2e) are electrically connected to each other at an individual terminal (individual wiring) not shown.

Here, the aforementioned flexible printed circuit board is mounted on the aforementioned tail portion 420 (near the end portion along the Y-axis direction of the actuator plate 412) to electrically connect the drive electrodes Ed and the aforementioned circuit board. The wiring pattern (not shown) formed on this flexible printed circuit board is electrically connected to the aforementioned common wiring and individual wiring. This allows a drive voltage to be applied to each drive electrode Ed from the drive circuit on the aforementioned circuit board via the flexible printed circuit board.

In addition, in the tail portion 420 of the actuator plate 412, the ends of each of the dummy channels C1d, C2d along their extension direction (Y-axis direction) are configured as follows.

That is, first, in each of the dummy channels C1d and C2d, one side along the extension direction is an arc-shaped side surface in which the cross-sectional area of each of the dummy channels C1d and C2d gradually decreases toward the nozzle plate 411 side (see FIGS. 3 and 4). Note that, like the arc-shaped side surfaces of the ejection channels C1e and C2e described above, the arc-shaped side surfaces of the dummy channels C1d and C2d are also formed by, for example, cutting processing using a dicer. In contrast, in each of the dummy channels C1d and C2d, the other side (tail portion 420 side) along the extension direction is open up to the end of the actuator plate 412 along the Y-axis direction (see symbol P2 shown by the dashed line in FIGS. 3, 4, and 6). Also, as shown in, for example, FIGS. 3, 4, and 6, each of the individual electrodes Eda arranged opposite to each other on both sides along the X-axis direction in each of the dummy channels C1d and C2d also extends up to the end of the actuator plate 412 along the Y-axis direction.

The processing slits SL shown in FIG. 6 are slits formed along the Y-axis direction to separate the individual electrodes Eda and the common electrodes Edc on the surface of the actuator plate 412, and are formed, for example, as follows. That is, each of these processing slits SL is formed, for example, by a predetermined laser processing when the actuator plate 412 is formed. In addition, the individual electrodes Eda and the common electrodes Edc each include an individual electrode pad Pda and a common electrode pad Pdc, which are pad portions electrically connected to these electrodes and electrically connected to the flexible printed circuit board described above (see FIG. 6). In addition, the grooves D (see FIG. 6) that isolate the common electrode pads Pdc and individual electrode pads Pda between these pads are formed by cutting with a dicer after the above-mentioned predetermined laser processing.

(Cover plate 413)
3 to 5, the cover plate 413 is disposed so as to close the channels C1, C2 (the channel rows 421, 422) in the actuator plate 412. Specifically, the cover plate 413 is bonded to the upper surface of the actuator plate 412 and has a plate-like structure.

As shown in Figures 3 to 5, the cover plate 413 is formed with a pair of inlet common flow paths Rin1 and Rin2, a pair of outlet common flow paths Rout1 and Rout2, and wall portions W1 and W2.

The wall portion W1 is arranged to cover the upper sides of the discharge channel C1e and the dummy channel C1d, and the wall portion W2 is arranged to cover the upper sides of the discharge channel C2e and the dummy channel C2d (see Figures 3 and 4).

The inlet common flow paths Rin1, Rin2 and the outlet common flow paths Rout1, Rout2 each extend along the X-axis direction, as shown in FIG. 5, and are arranged parallel to each other at a predetermined interval along the X-axis direction. Of these, the inlet common flow path Rin1 and the outlet common flow path Rout1 are each formed in an area corresponding to the channel row 421 (multiple channels C1) in the actuator plate 412 (see FIGS. 3 to 5). On the other hand, the inlet common flow path Rin2 and the outlet common flow path Rout2 are each formed in an area corresponding to the channel row 422 (multiple channels C2) in the actuator plate 412 (see FIGS. 3 and 4).

The inlet common flow path Rin1 is formed near the end of each channel C1 on the inner side (one side of the wall W1) along the Y axis direction, and is a concave groove (see Figures 3 to 5). In the inlet common flow path Rin1, a first supply slit Sin1 is formed in the area corresponding to each ejection channel C1e, penetrating the cover plate 413 along its thickness direction (Z axis direction) (see Figures 3 to 5). Similarly, the inlet common flow path Rin2 is formed near the end of each channel C2 on the inner side (one side of the wall W2) along the Y axis direction, and is a concave groove (see Figures 3 and 4). In the inlet common flow path Rin2, a second supply slit (not shown) is also formed in the area corresponding to each ejection channel C2e, penetrating the cover plate 413 along its thickness direction.

Note that each of the first supply slit Sin1 and the second supply slit corresponds to a specific example of a "first through hole" in this disclosure.

The outlet side common flow path Rout1 is formed near the end of the outer side (the other side of the wall portion W1) along the Y axis direction of each channel C1, and is a concave groove portion (see Figures 3 to 5). In this outlet side common flow path Rout1, a first exhaust slit Sout1 is formed in the area corresponding to each discharge channel C1e, penetrating the cover plate 413 along its thickness direction (see Figures 3 to 5). Similarly, the outlet side common flow path Rout2 is formed near the end of the outer side (the other side of the wall portion W2) along the Y axis direction of each channel C2, and is a concave groove portion (see Figures 3 and 4). In this outlet side common flow path Rout2, a second exhaust slit (not shown) is also formed in the area corresponding to each discharge channel C2e, penetrating the cover plate 413 along its thickness direction.

Note that each of the first exhaust slit Sout1 and the second exhaust slit corresponds to a specific example of a "second through hole" in this disclosure.

Here, as shown in FIG. 5, for example, a first slit pair Sp1 is formed by the first supply slit Sin1 and the first exhaust slit Sout1 for each discharge channel C1e. In this first slit pair Sp1, the first supply slit Sin1 and the first exhaust slit Sout1 are arranged side by side along the extension direction (Y-axis direction) of the discharge channel C1e. Similarly, a second slit pair (not shown) is formed by the second supply slit and the second exhaust slit for each discharge channel C2e. In this second slit pair, the second supply slit and the second exhaust slit are arranged side by side along the extension direction (Y-axis direction) of the discharge channel C2e.

In this way, the inlet common flow path Rin1 and the outlet common flow path Rout1 are connected to each ejection channel C1e via the first supply slit Sin1 and the first exhaust slit Sout1, respectively (see Figures 3 to 5). That is, the inlet common flow path Rin1 is a common flow path that is connected to each of the first supply slits Sin1 for each of the first slit pairs Sp1 described above, and the outlet common flow path Rout1 is a common flow path that is connected to each of the first exhaust slits Sout1 for each of the first slit pairs Sp1 (see Figure 5). The first supply slit Sin1 and the first exhaust slit Sout1 are each a through hole through which the ink 9 flows between the ejection channel C1e. In detail, as shown by the dashed arrows in Figures 3 and 4, the first supply slit Sin1 is a through hole for allowing the ink 9 to flow into the ejection channel C1e, and the first exhaust slit Sout1 is a through hole for allowing the ink 9 to flow out from the ejection channel C1e. On the other hand, each dummy channel C1d is not connected to either the inlet side common flow path Rin1 or the outlet side common flow path Rout1. Specifically, each dummy channel C1d is blocked by the bottoms of the inlet side common flow path Rin1 and the outlet side common flow path Rout1.

Similarly, the inlet common flow path Rin2 and the outlet common flow path Rout2 are connected to each ejection channel C2e via the second supply slit and the second exhaust slit, respectively. That is, the inlet common flow path Rin2 is a common flow path connected to each of the second supply slits of each of the second slit pairs, and the outlet common flow path Rout2 is a common flow path connected to each of the second exhaust slits of each of the second slit pairs. The second supply slit and the second exhaust slit are each a through hole through which the ink 9 flows between the ejection channel C2e. In detail, the second supply slit is a through hole for allowing the ink 9 to flow into the ejection channel C2e, and the second exhaust slit is a through hole for allowing the ink 9 to flow out from the ejection channel C2e. On the other hand, neither the inlet common flow path Rin2 nor the outlet common flow path Rout2 is connected to each of the dummy channels C2d (see Figures 3 and 4). Specifically, each dummy channel C2d is blocked by the bottoms of the inlet common flow path Rin2 and the outlet common flow path Rout2 (see Figures 3 and 4).

[C. Detailed configuration of the vicinity of the discharge channels C1e and C2e]
Next, the detailed configuration of the nozzle holes H1, H2 and the cover plate 413 in the vicinity of the ejection channels C1e, C2e will be described with reference to FIGS.

First, in the head chip 41 of this embodiment, as described above, the multiple nozzle holes H1 include two types of nozzle holes H11 and H12, and the multiple nozzle holes H2 also include two types of nozzle holes H21 and H22 (see Figure 2).

Here, the center position Pn11 of each nozzle hole H11 is shifted to the positive side of the Y axis direction (the first supply slit Sin1 side) based on the center position Pc1 (= the center position of the wall portion W1 along the Y axis direction) along the extension direction (Y axis direction) of the ejection channel C1e (see Figures 3 and 5). Similarly, the center position of each nozzle hole H21 is shifted to the negative side of the Y axis direction (the second supply slit side) based on the center position (= the center position of the wall portion W2 along the Y axis direction) along the extension direction (Y axis direction) of the ejection channel C2e (see Figure 2).

On the other hand, the center position Pn12 of each nozzle hole H12 is shifted to the negative side in the Y-axis direction (toward the first exhaust slit Sout1) with respect to the center position Pc1 along the extension direction of the ejection channel C1e (see Figures 4 and 5). Similarly, the center position of each nozzle hole H22 is shifted to the positive side in the Y-axis direction (toward the second exhaust slit) with respect to the center position along the extension direction (Y-axis direction) of the ejection channel C2e (see Figure 2).

Therefore, in the ejection channel C1e (C1e1) communicating with each nozzle hole H11, the cross-sectional area of the ink 9 flow path in the portion communicating with the first supply slit Sin1 (first inlet side flow path cross-sectional area Sfin1) is smaller than the cross-sectional area of the ink 9 flow path in the portion communicating with the first exhaust slit Sout1 (first outlet side flow path cross-sectional area Sfout1) (Sfin1 < Sfout1: see FIG. 3). Similarly, in the ejection channel C2e communicating with each nozzle hole H21, the cross-sectional area of the ink 9 flow path in the portion communicating with the second supply slit (second inlet side flow path cross-sectional area Sfin2) is smaller than the cross-sectional area of the ink 9 flow path in the portion communicating with the second exhaust slit (second outlet side flow path cross-sectional area Sfout2) (Sfin2 < Sfout2).

On the other hand, in the discharge channel C1e (C1e2) communicating with each nozzle hole H12, the first outlet side flow path cross-sectional area Sfout1 is smaller than the first inlet side flow path cross-sectional area Sfin1 (Sfout1 < Sfin1: see FIG. 4). Similarly, in the discharge channel C2e communicating with each nozzle hole H22, the second outlet side flow path cross-sectional area Sfout2 is smaller than the second inlet side flow path cross-sectional area Sfin2 (Sfout2 < Sfin2).

In addition, in the ejection channel C1e1, the cross-sectional area (wall position flow path cross-sectional area Sf5) of the ink 9 flow path at a position corresponding to the wall surface of the wall W1 on the first supply slit Sin1 side is smaller than the cross-sectional area (wall position flow path cross-sectional area Sf6) of the ink 9 flow path at a position corresponding to the wall surface of the wall W1 on the first exhaust slit Sout1 side (Sf5<Sf6: see FIG. 3). Similarly, in the ejection channel C2e communicating with each nozzle hole H21, the cross-sectional area (wall position flow path cross-sectional area Sf5) of the ink 9 flow path at a position corresponding to the wall surface of the wall W2 on the second supply slit side is smaller than the cross-sectional area (wall position flow path cross-sectional area Sf6) of the ink 9 flow path at a position corresponding to the wall surface of the wall W2 on the second exhaust slit side.

On the other hand, in the above-mentioned discharge channel C1e2, the wall position flow path cross-sectional area Sf6 is smaller than the wall position flow path cross-sectional area Sf5 (Sf6<Sf5: see FIG. 4). Similarly, in the discharge channel C2e that communicates with each nozzle hole H22, the wall position flow path cross-sectional area Sf6 is smaller than the wall position flow path cross-sectional area Sf5.

In addition, in Figures 3 and 4, the end of the pump chamber has a cut-up shape at a position corresponding to one of the wall position flow path cross-sectional areas Sf5 and Sf6 described above, and the end of the pump chamber has a straight shape at a position corresponding to the other, but this is not limited to this example. In other words, as long as the relationship in size between the wall position flow path cross-sectional areas Sf5 and Sf6 is as described above, for example, both ends of the pump chamber may have a cut-up shape.

Here, the above-mentioned discharge channel C1e1 and the discharge channel C2e communicating with the nozzle hole H21 each correspond to a specific example of the "first discharge groove" in this disclosure. Similarly, the above-mentioned discharge channel C1e2 and the discharge channel C2e communicating with the nozzle hole H22 each correspond to a specific example of the "second discharge groove" in this disclosure. Also, the above-mentioned first inlet side flow path cross-sectional area Sfin1 and the second inlet side flow path cross-sectional area each correspond to a specific example of the "first cross-sectional area" in this disclosure. Similarly, the above-mentioned first outlet side flow path cross-sectional area Sfout1 and the second outlet side flow path cross-sectional area each correspond to a specific example of the "second cross-sectional area" in this disclosure. Also, the above-mentioned wall surface position flow path cross-sectional area Sf5 corresponds to a specific example of the "fifth cross-sectional area" in this disclosure. Similarly, the above-mentioned wall surface position flow path cross-sectional area Sf6 corresponds to a specific example of the "sixth cross-sectional area" in this disclosure. Furthermore, the center position Pn11 of the nozzle hole H11 and the center position of the nozzle hole H21 each correspond to a specific example of a "first center position" in this disclosure. Similarly, the center position Pn12 of the nozzle hole H12 and the center position of the nozzle hole H22 each correspond to a specific example of a "second center position" in this disclosure.

In addition, in this head chip 41, the first pump length Lw1 (see Figures 3 and 4), which is the distance between the first supply slit Sin1 and the first exhaust slit Sout1 in the first slit pair Sp1 described above, is the same in all first slit pairs Sp1 (see Figure 5). Similarly, the second pump length, which is the distance between the second supply slit and the second exhaust slit in the second slit pair described above, is also the same in all second slit pairs.

In this head chip 41, the size relationship between the length in the Y-axis direction of the first supply slit Sin1 (first supply slit length Lin1) and the length in the Y-axis direction of the first exhaust slit Sout1 (first exhaust slit length Lout1) alternates between the first slit pairs Sp1 adjacent to each other along the X-axis direction (see FIG. 5). That is, for example, when the size relationship of (Lin1>Lout1) is satisfied in a certain first slit pair Sp1, the size relationship of (Lin1<Lout1) is satisfied in the first slit pairs Sp1 located on both sides of the first slit pair Sp1, respectively. Also, for example, when the size relationship of (Lin1<Lout1) is satisfied in a certain first slit pair Sp1, the size relationship of (Lin1>Lout1) is satisfied in the first slit pairs Sp1 located on both sides of the first slit pair Sp1, respectively.

Similarly, the relationship in magnitude between the length of the second supply slit in the Y-axis direction (second supply slit length) and the length of the second exhaust slit in the Y-axis direction (second exhaust slit length) also alternates between pairs of second slits adjacent to each other along the X-axis direction, as described above.

Furthermore, in this head chip 41, the length in the Y-axis direction of the inlet side common flow channel Rin1 (first inlet side flow channel width Win1) is constant along the extension direction (X-axis direction) of this inlet side common flow channel Rin1 (see FIG. 5). Also, the length in the Y-axis direction of the outlet side common flow channel Rout1 (first outlet side flow channel width Wout1) is constant along the extension direction (X-axis direction) of this outlet side common flow channel Rout1 (see FIG. 5).

Similarly, the length in the Y-axis direction of the inlet-side common flow passage Rin2 (second inlet-side flow passage width) is also constant along the extension direction (X-axis direction) of this inlet-side common flow passage Rin2. In addition, the length in the Y-axis direction of the outlet-side common flow passage Rout2 (second outlet-side flow passage width) is also constant along the extension direction (X-axis direction) of this outlet-side common flow passage Rout2.

[D. Detailed configuration of the common electrode Edc]
Next, a detailed configuration example of the vicinity of the above-mentioned ejection channel C1e (C1e1, C1e2) (a detailed configuration example of the above-mentioned common electrode Ed) will be described with reference to Figures 3, 4, 7 and 8. Note that the detailed configuration example of the common electrode Ed in the above-mentioned ejection channel C2e is similar to the detailed configuration example of the common electrode Ed in the ejection channel C1e (C1e1, C1e2) described below, and therefore the description thereof will be omitted.

Figure 7 is a schematic diagram showing a detailed configuration example near the ejection channel C1e in the cross-sectional configuration example shown in Figures 3 and 4. Specifically, Figure 7(A) shows a detailed configuration example near the ejection channel C1e1 in the cross-sectional configuration example shown in Figure 3, and Figure 7(B) shows a detailed configuration example near the ejection channel C1e2 in the cross-sectional configuration example shown in Figure 4. Also, Figure 8 (Figures 8(A) and 8(B)) is a schematic diagram showing an example of a method for forming the common electrode Edc shown in Figures 7(A) and 7(B).

First, as shown in FIG. 7(A) and FIG. 7(B), in the inkjet head 4 (head chip 41) of this embodiment, the positions of both ends of the common electrode Edc along the extension direction (Y-axis direction) of the ejection channel C1e are aligned with each other for the multiple common electrodes Edc along the X-axis direction. That is, as described above, even in the ejection channels C1e1 and C1e2 in which the nozzle holes H11 and H12 are arranged in a shifted manner along the Y-axis direction (staggered arrangement), the positions of both ends of each common electrode Edc are aligned and are not shifted along the Y-axis direction. In other words, in the multiple ejection channels C1e arranged in parallel along the X-axis direction, the corresponding multiple common electrodes Edc are arranged in a line along the X-axis direction (not in a staggered arrangement). Note that such a line arrangement of the common electrodes Edc is also the same for the multiple ejection channels C2e arranged in parallel along the X-axis direction.

Specifically, each common electrode Edc includes a first portion Edc1 provided on the side wall of the nozzle plate 411 side (lower side) in the ejection channel C1e, C2e, and a second portion Edc2 provided on the side wall of the cover plate 413 side (upper side) (see FIG. 7(A) and FIG. 7(B)). In addition, the length (electrode length Le2) of the second portion Edc2 along the extension direction (Y-axis direction) of the ejection channel C1e, C2e is smaller than the length (electrode length Le1) of the first portion Edc1 along the Y-axis direction (Le2<Le1). That is, each common electrode Edc has a two-stage structure including such a first portion Edc1 and a second portion Edc2. In addition, the positions of both ends along the Y-axis direction in each of the first portion Edc1 and the second portion Edc2 are aligned (matched) with each other among the multiple common electrodes Edc along the X-axis direction. That is, as shown in Figures 7(A) and 7(B), the end positions Pe1a and Pe1b in the first portion Edc1 are aligned with the ejection channels C1e1 and C1e2, respectively, and the end positions Pe2a and Pe2b in the second portion Edc2 are aligned with the ejection channels C1e1 and C1e2, respectively. Note that the alignment of both end positions of the first portion Edc1 and the second portion Edc2 is also the case for the multiple ejection channels C2e arranged side by side along the X-axis direction.

Here, the first part Edc1 described above corresponds to a specific example of the "first part" in this disclosure. Also, the second part Edc2 described above corresponds to a specific example of the "second part" in this disclosure.

The common electrode Edc including such a first portion Edc1 and a second portion Edc2 can be formed, for example, by the method shown in Figures 8(A) and 8(B) (vacuum deposition method using two-stage oblique deposition).

That is, first, as shown in FIG. 8A, for example, vacuum deposition is performed to form the first portion Edc1 in a state where each ejection channel C1e (C1e1, C1e2) in the actuator plate 412 is formed. Specifically, as shown in FIG. 8A, a first stage of oblique deposition is performed at a predetermined angle in the deposition direction Ev2 toward the upward side through the opening Ap1 located below each ejection channel C1e1, C1e2. As a result, the first portion Edc1 is formed on the lower side of each ejection channel C1e1, C1e2, having a length (the electrode length Le1 described above) approximately equal to the width of the opening Ap1.

Next, as shown in FIG. 8B, for example, a mask M having a predetermined opening Ap2 (e.g., rectangular) is used to perform vacuum deposition to form the second portion Edc2. Specifically, as shown in FIG. 8B, a second stage of oblique deposition is performed through the opening Ap2 of the mask M at a predetermined angle in a deposition direction Ev2 toward the lower side (inside each ejection channel C1e1, C1e2). As a result, the second portion Edc2 is formed on the upper side (above the first portion Edc1) of each ejection channel C1e1, C1e2, with a length (the electrode length Le2 described above) approximately equal to the width of the opening Ap2.

By performing the above-described two-stage oblique deposition vacuum deposition, the common electrode Edc including the first portion Edc1 and the second portion Edc2 is formed. In addition, as will be described in detail later, in this embodiment, the common electrode Edc in both the ejection channels C1e1 and C1e2 can be formed at the same time using the mask M having the above-described opening Ap2.

[Actions, actions and effects]
(A. Basic Operation of Printer 1)
In this printer 1, a recording operation (printing operation) of images, characters, etc. on recording paper P is performed as follows. Note that, in the initial state, each of the four types of ink tanks 3 (3Y, 3M, 3C, 3K) shown in Fig. 1 is fully filled with ink 9 of the corresponding color (four colors). The ink 9 in the ink tanks 3 is filled in the inkjet head 4 via the circulation flow path 50.

When the printer 1 is operated in this initial state, the grid rollers 21 in the transport mechanisms 2a and 2b rotate, transporting the recording paper P between the grid rollers 21 and the pinch rollers 22 along the transport direction d (X-axis direction). Simultaneously with this transport operation, the drive motor 633 in the drive mechanism 63 rotates the pulleys 631a and 631b, respectively, to operate the endless belt 632. As a result, the carriage 62 reciprocates along the width direction (Y-axis direction) of the recording paper P while being guided by the guide rails 61a and 61b. At this time, the inkjet heads 4 (4Y, 4M, 4C, 4K) eject ink 9 of four colors onto the recording paper P as appropriate, thereby recording images, characters, etc. onto the recording paper P.

(B. Detailed Operation of Inkjet Head 4)
Next, a detailed description will be given of the operation (jetting operation of the ink 9) of the inkjet head 4. That is, in this inkjet head 4 (side shoot type), the ink 9 is jetted in a shear mode as follows.

First, when the carriage 62 (see FIG. 1) starts to reciprocate, the drive circuit on the circuit board applies a drive voltage to the drive electrodes Ed (common electrode Edc and individual electrodes Eda) in the inkjet head 4 via the flexible printed circuit board. Specifically, the drive circuit applies a drive voltage to each drive electrode Ed arranged on a pair of drive walls Wd that define the ejection channels C1e and C2e. This causes the pair of drive walls Wd to deform so as to protrude toward the dummy channels C1d and C2d adjacent to the ejection channels C1e and C2e.

Since the actuator plate 412 has the chevron type configuration described above, when a drive voltage is applied by the drive circuit described above, the drive wall Wd is bent and deformed into a V shape around the midpoint of the drive wall Wd in the depth direction. This bending and deformation of the drive wall Wd causes the ejection channels C1e and C2e to deform as if they are bulging.

Incidentally, if the actuator plate 412 is not of this chevron type but of the cantilever type described above, the driving wall Wd bends and deforms in a V shape as follows. That is, in the case of this cantilever type, the driving electrode Ed is attached by oblique deposition up to the upper half in the depth direction, so that the driving force acts only on the part where the driving electrode Ed is formed, causing the driving wall Wd to bend and deform (at the depth direction end of the driving electrode Ed). As a result, even in this case, the driving wall Wd bends and deforms in a V shape, so that the ejection channels C1e and C2e deform as if they are bulging.

In this way, the volume of the ejection channels C1e and C2e increases due to the bending deformation caused by the piezoelectric thickness slip effect at the pair of drive walls Wd. As the volume of the ejection channels C1e and C2e increases, the ink 9 stored in the inlet common flow paths Rin1 and Rin2 is guided into the ejection channels C1e and C2e.

Next, the ink 9 guided into the ejection channels C1e, C2e in this manner becomes a pressure wave and propagates inside the ejection channels C1e, C2e. Then, at the timing (or at a timing close to the timing) when this pressure wave reaches the nozzle holes H1, H2 of the nozzle plate 411, the drive voltage applied to the drive electrode Ed becomes 0 (zero) V. This causes the drive wall Wd to recover from the bent and deformed state described above, and the volume of the ejection channels C1e, C2e, which had increased once, returns to its original volume.

In this way, as the volumes of the ejection channels C1e and C2e return to their original volumes, the pressure inside the ejection channels C1e and C2e increases, and the ink 9 inside the ejection channels C1e and C2e is pressurized. As a result, droplets of ink 9 are ejected through the nozzle holes H1 and H2 to the outside (towards the recording paper P) (see Figures 3 and 4). In this way, the ink 9 is ejected (ejected) from the inkjet head 4, and as a result, images, characters, etc. are recorded on the recording paper P.

(C. Circulation Operation of Ink 9)
Next, the circulation operation of the ink 9 through the circulation flow path 50 will be described in detail with reference to FIGS.

In this printer 1, the ink 9 is sent from the ink tank 3 to the flow path 50a by the aforementioned liquid feed pump. Also, the ink 9 flowing in the flow path 50b is sent into the ink tank 3 by the aforementioned liquid feed pump.

At this time, in the inkjet head 4, the ink 9 flowing from the ink tank 3 through the flow path 50a flows into the inlet-side common flow paths Rin1 and Rin2. The ink 9 supplied to these inlet-side common flow paths Rin1 and Rin2 is supplied to each ejection channel C1e and C2e in the actuator plate 412 through the first supply slit Sin1 or the second supply slit (see Figures 3 and 4).

The ink 9 in each ejection channel C1e, C2e flows into the outlet-side common flow paths Rout1, Rout2 via the first discharge slit Sout1 or the second discharge slit (see Figures 3 and 4). The ink 9 supplied to these outlet-side common flow paths Rout1, Rout2 is discharged into the flow path 50b, and flows out of the inkjet head 4. The ink 9 discharged into the flow path 50b is then returned to the ink tank 3. In this way, the ink 9 is circulated via the circulation flow path 50.

When using ink that dries quickly in a non-circulating inkjet head, the ink may dry out near the nozzle holes, causing the ink to become locally viscous or solidify, which may result in ink not being ejected. In contrast, in the inkjet head 4 of this embodiment (a circulating inkjet head), fresh ink 9 is always supplied near the nozzle holes H1 and H2, which avoids the above-mentioned ink not being ejected.

(D. Actions and Effects)
Next, the operation and effects of the inkjet head 4 of this embodiment will be described in detail while comparing it with comparative examples (Comparative Examples 1 to 4).

(D-1. Comparative Example 1)
Fig. 9 is a schematic bottom view (X-Y bottom view) of an example of the configuration of the inkjet head 104 according to Comparative Example 1 with the nozzle plate 101 (described later) according to Comparative Example 1 removed. Fig. 10 is a schematic view of a cross-sectional configuration example (Y-Z cross-sectional configuration example) of the inkjet head 104 according to Comparative Example 1 taken along line X-X shown in Fig. 9.

As shown in Figures 9 and 10, in the inkjet head 104 (head chip 100) of Comparative Example 1, the arrangement of the nozzle holes H1, H2 is different from that of the inkjet head 4 (head chip 41) of this embodiment. Also, in the cover plate 103 of this head chip 100, unlike the cover plate 413 of the head chip 41, the first inlet side flow path cross-sectional area Sfin1 and the first outlet side flow path cross-sectional area Sfout1 described above are equal to each other (Sfin1 = Sfout1: see Figure 10).

Specifically, in the nozzle plate 101 of this comparative example 1, unlike the nozzle plate 411 of the present embodiment, the nozzle holes H1 and H2 in each nozzle row An101 and 102 are arranged in a row along the extension direction (X-axis direction) of each nozzle row An101 and 102 (see FIG. 9). In other words, unlike the above-described case of the present embodiment, in this comparative example 1, the center position Pn1 of each nozzle hole H1 is aligned with the center position Pc1 (= the center position of the wall part W1 along the Y-axis direction) along the extension direction (Y-axis direction) of the ejection channel C1e (see FIG. 10). Similarly, in this comparative example 1, the center position of each nozzle hole H2 is aligned with the center position (= the center position of the wall part W2 along the Y-axis direction) along the extension direction (Y-axis direction) of the ejection channel C2e.

In Comparative Example 1, as described above, the nozzle holes H1 and H2 are arranged in a row along the X-axis direction. Therefore, if the distance between adjacent nozzle holes H1 or the distance between adjacent nozzle holes H2 becomes smaller, for example, due to higher resolution of print pixels, there is a risk of the following: In other words, in such a case, the distance between droplets that are ejected at the same time and fly toward the recording medium (recording paper P, etc.) decreases, and there are cases where the droplets flying between the nozzle holes H1 and H2 and the recording medium are locally concentrated. This increases the effect on each flying droplet (generation of air currents), which may result in wood grain density unevenness on the recording medium and a decrease in print image quality.

(D-2. Comparative Example 2)
11A and 11B are schematic diagrams showing an example of a cross-sectional configuration near the ejection channel C1e in the inkjet head 204 according to Comparative Example 2. Specifically, Fig. 11A shows an example of a detailed configuration near the ejection channel C1e1, and Fig. 11B shows an example of a detailed configuration near the ejection channel C1e2.

In the inkjet head 204 (head chip 200) of this comparative example 2, the arrangement positions of each common electrode Edc are different from those of the inkjet head 4 (head chip 41) of this embodiment. Specifically, the common electrodes Edc (parts) are arranged in a staggered manner in the Y-axis direction between the ejection channels C1e1 and C1e2 in the actuator plate 202, and are arranged in a staggered manner similar to the nozzle holes H11 and H12 (see Figures 11(A) and 11(B)). In detail, in this example, for the first portion Edc1 of the common electrode Edc, the end positions Pe1a and Pe1b are aligned between the ejection channels C1e1 and C1e2, respectively. On the other hand, for the second portion Edc2, the end positions Pe2a and Pe2b are not aligned between the ejection channels C1e1 and C1e2 (they are offset from each other along the Y-axis direction).

In such Comparative Example 2, for example, the opening Ap2 (see FIG. 8A) of the mask M used when forming each common electrode Edc by the above-mentioned method (vacuum deposition) becomes complicated in shape. Specifically, as described above, in Comparative Example 2, the common electrodes Edc (parts) are arranged in a shifted manner between the ejection channels C1e1 and C1e2 (staggered arrangement), so that, for example, the opening Ap2 of the mask M also needs to be arranged in a staggered manner. And when the opening Ap2 of the mask M is arranged in a staggered manner, it becomes difficult to align the opening Ap2 of the mask M with the ejection channels C1e1 and C1e2, so it becomes difficult to form the common electrodes Edc in both the ejection channels C1e1 and C1e2 at the same time. As a result, in Comparative Example 2, it may be difficult to form each common electrode Edc.

(D-3. Comparative Examples 3 and 4)
Fig. 12 is a schematic diagram showing an example of a planar configuration (example of an XY planar configuration) of the upper surface side of the cover plate 303 in the inkjet head 304 according to Comparative Example 3. Fig. 13 is a schematic diagram showing an example of a cross-sectional configuration near the ejection channel C1e in the inkjet head 304 according to Comparative Example 3. Specifically, Fig. 13A shows an example of a detailed configuration near the ejection channel C1e1, and Fig. 13B shows an example of a detailed configuration near the ejection channel C1e2.

As shown in Figure 13, the inkjet head 304 of Comparative Example 3 corresponds to the inkjet head 4 of the embodiment (see Figures 3, 4, and 7) in which head chip 300 is provided instead of head chip 41. Also, the head chip 300 of Comparative Example 3 corresponds to the head chip 41 in which actuator plate 302 and cover plate 303, which will be described below, are provided instead of actuator plate 412 and cover plate 413, respectively, and other configurations are basically the same.

Specifically, as shown in Figs. 12 and 13, in the actuator plate 302 of Comparative Example 3, unlike the actuator plate 412 of the embodiment (see Fig. 5), the arrangement of the ejection channels C1e and C2e is as follows. That is, in the actuator plate 302, unlike the actuator plate 412, the multiple ejection channels C1e as a whole (and the multiple ejection channels C2e as a whole) are arranged in a staggered manner along the X-axis direction (alternately offset along the Y-axis direction) (see Fig. 12).

Furthermore, in the cover plate 303 of this comparative example 3, similar to the cover plate 413 of the embodiment (see FIG. 5), the first pump length Lw1 and the second pump length described above are the same for all first slit pairs Sp1 and second slit pairs, respectively (see FIG. 12).

On the other hand, in the cover plate 303, unlike the cover plate 413, the first supply slit length Lin1 and the second supply slit length, and the first exhaust slit length Lout1 and the second exhaust slit length are the same as each other (see FIG. 12: Lin1=Lout1, second supply slit length=second exhaust slit length). And, in the cover plate 303, unlike the cover plate 413, the first supply slit Sin1 and the second supply slit, and the first exhaust slit Sout1 and the second exhaust slit are staggered along the extension direction (X-axis direction) of the inlet side common flow paths Rin1, Rin2 and the outlet side common flow paths Rout1, Rout2, respectively (see FIG. 12).

As shown in FIG. 13(A) and FIG. 13(B), in this Comparative Example 3, the ejection channels C1e1 and C1e2 are arranged in a staggered manner as described above, but unlike the above-mentioned Comparative Example 2, the arrangement positions of each common electrode Edc are as follows. That is, in this Comparative Example 3, due to the ejection channels C1e1 and C1e2 being arranged in a staggered manner, for the first portion Edc1 of the common electrode Edc, the end positions Pe1a and Pe1b are not aligned with the ejection channels C1e1 and C1e2 (they are offset from each other along the Y-axis direction). On the other hand, for the second portion Edc2, the end positions Pe2a and Pe2b are aligned with the ejection channels C1e1 and C1e2.

For these reasons, in this Comparative Example 3, unlike the above-mentioned Comparative Example 2, the openings Ap2 of the mask M used when forming each common electrode Edc can be made to have a simple shape (e.g., rectangular) in the same manner as in this embodiment (see FIG. 8(B)). In other words, it is no longer necessary to arrange the openings Ap2 of the mask M in a staggered manner as in Comparative Example 2, for example, and it is possible to form the common electrodes Edc in both the ejection channels C1e1 and C1e2 at the same time. Therefore, in this Comparative Example 3, as in this embodiment, it is easier to form each common electrode Edc compared to Comparative Example 2.

However, in this comparative example 3, as described above, the end positions Pe1a and Pe1b of the first portion Edc1 are offset from each other in the ejection channels C1e1 and C1e2, while the end positions Pe2a and Pe2b of the second portion Edc2 are aligned with each other in the ejection channels C1e1 and C1e2, resulting in the following. That is, in this comparative example 3, it becomes difficult to make the length along the extension direction (Y-axis direction) of each common electrode Edc (electrode length Le2 of the second portion Edc2 in the example of Figures 13(A) and 13(B)) longer. Specifically, compared to the case of the present embodiment shown in Figures 7(A) and 7(B), the electrode length Le2 of the second portion Edc2 becomes shorter. This is because if the end positions Pe2a and Pe2b of the second portion Edc2 are located outside the end positions Pe1a and Pe1b of the first portion Edc1, burrs are more likely to occur when forming the common electrode Edc. In this way, in Comparative Example 3, it is difficult to increase the length of each common electrode Edc along its extension direction, and as a result, the area of each common electrode Edc is reduced, which may result in a decrease in voltage efficiency when driving the head chip 300.

Incidentally, in the configuration of Comparative Example 3, if the pump length in each ejection channel C1e, C2e is made wider than that in Comparative Example 3 in order to ensure the length along the extension direction of each common electrode Edc (Comparative Example 4), the result will be as follows. That is, in the configuration of Comparative Example 4, the first pump length Lw1 in each ejection channel C1e (and the pump length in each ejection channel C2e) becomes relatively long, and the value of the on-pulse peak (AP) specified in each ejection channel C1e, C2e also becomes large. This AP corresponds to a period of 1/2 the natural vibration period of the ink 9 in each ejection channel C1e, C2e (1AP = (natural vibration period of the ink 9) / 2), and corresponds to the drive pulse width for maximizing the ejection speed of the ink 9. In this way, in Comparative Example 4, since the value of this AP becomes large, the drive waveform per droplet becomes long, and it may become difficult to drive the head chip at a high frequency.

(D-4. This embodiment)
In contrast to this, the inkjet head 4 (head chip 41) of this embodiment differs from, for example, the comparative examples 1 to 4 and has the following configuration.

First, in this embodiment, unlike Comparative Example 1, among the multiple nozzle holes H1, H2, the nozzle holes H1 adjacent to each other along the X-axis direction (and the nozzle holes H2 adjacent to each other along the X-axis direction) are arranged to be shifted from each other along the extension direction (Y-axis direction) of the ejection channels C1e, C2e. Specifically, the center position Pn11 of the nozzle hole H11 is arranged to be shifted toward the first supply slit Sin1 side based on the center position Pc1 along the extension direction (Y-axis direction) of the ejection channel C1e, and the center position Pn12 of the nozzle hole H12 is arranged to be shifted toward the first exhaust slit Sout1 side based on the above-mentioned center position Pc1. Similarly, the center position of the nozzle hole H21 is arranged to be shifted toward the second supply slit side based on the center position along the extension direction (Y-axis direction) of the ejection channel C2e, and the center position of the nozzle hole H22 is arranged to be shifted toward the second exhaust slit side based on the center position along the extension direction of the ejection channel C2e.

As a result, in this embodiment, compared to Comparative Example 1, the following occurs. That is, the distance between adjacent nozzle holes H1 (and the distance between adjacent nozzle holes H2) is greater than when the nozzle holes H1 and H2 are arranged in a row along the X-axis direction (Comparative Example 1). As a result, the distance between droplets that are ejected at the same time and flying toward the recording medium (recording paper P, etc.) increases, and it is possible to mitigate local concentration of flying droplets between the nozzle holes H1 and H2 and the recording medium. As a result, in this embodiment, the effect on each flying droplet (generation of airflow) is suppressed, and as a result, the occurrence of wood grain density unevenness on the recording medium as described above is suppressed compared to Comparative Example 1.

In addition, in this embodiment, the entirety of the multiple ejection channels C1e (and the entirety of the multiple ejection channels C2e) are arranged in a row along the X-axis direction within the actuator plate 412. As a result, in this embodiment, the existing structure is maintained throughout the multiple ejection channels C1e (and throughout the multiple ejection channels C2e), making it easier to form each ejection channel C1e (and each ejection channel C2e).

Furthermore, in this embodiment, in the ejection channel C1e1, the first inlet side flow path cross-sectional area Sfin1 is smaller than the first outlet side flow path cross-sectional area Sfout1, and in the ejection channel C1e2, the first outlet side flow path cross-sectional area Sfout1 is smaller than the first inlet side flow path cross-sectional area Sfin1. And in this embodiment, even in such a case, the positions of both ends of the common electrode Edc along the extension direction (Y-axis direction) of the ejection channel C1e are aligned with each other for multiple common electrodes Edc along the X-axis direction, so that the following occurs.

That is, first, in this embodiment, compared to the case of Comparative Example 2 described above, for example, the openings Ap2 of the mask M used when forming each common electrode Edc can be made to have a simple shape (e.g., rectangular). In other words, it is no longer necessary to arrange the openings Ap2 of the mask M in a staggered pattern as in Comparative Example 2, for example, and it is possible to form the common electrodes Edc in both the ejection channels C1e1 and C1e2 at the same time. Therefore, in this embodiment, it is easier to form each common electrode Edc than in Comparative Example 2.

In addition, in this embodiment, the length along the extension direction (Y-axis direction) of each common electrode Edc (e.g., electrode length Le2 of second portion Edc2) can be made larger compared to Comparative Example 3 described above. As a result, the area of each common electrode Edc is increased in this embodiment compared to Comparative Example 3, and the voltage efficiency when driving the head chip 41 is improved.

Furthermore, in this embodiment, unlike Comparative Example 4 described above, there is no need to widen the pump length in each discharge channel C1e, C2e, which results in the following: In other words, in this embodiment, compared to Comparative Example 4, the AP value described above is smaller, which makes it easier to drive the head chip 41 at a high frequency.

As a result, in this embodiment, it is possible to easily form each ejection channel C1e, C2e, while improving the voltage efficiency when driving the head chip 41, and suppressing the occurrence of wood grain density unevenness on the recording medium. Therefore, in the inkjet head 4 (head chip 41) of this embodiment, it is possible to reduce power consumption and improve print image quality while suppressing the manufacturing cost of the head chip 41. Furthermore, in this embodiment, as described above, it is possible to realize high frequency driving and eject highly viscous ink 9 (high viscosity ink).

In addition, in this embodiment, the positions of both ends (the end positions Pe1a, Pe1b, Pe2a, and Pe2b described above) in each of the first portion Edc1 and the second portion Edc2 of the common electrode Edc are aligned with each other in the multiple common electrodes Edc along the X-axis direction, so that the following occurs. That is, even when each common electrode Edc has a structure (two-stage structure) including such a first portion Edc1 and a second portion Edc2, the formation of each common electrode Edc is easy. Also, since the above-mentioned electrode length Le2 in the second portion Edc2 is smaller than the above-mentioned electrode length Le1 in the first portion Edc1, the following occurs. That is, for example, conversely, burrs are less likely to occur when forming the common electrode Edc compared to a case in which the electrode length Le2 of the second portion Edc2 is larger than the electrode length Le1 of the first portion Edc1. Therefore, the burr removal process can be omitted, and the number of processes can be reduced. As a result, this embodiment makes it possible to further reduce the manufacturing costs of the head chip 41.

In addition, in this embodiment, in the ejection channel C1e1 of the ejection channels C1e, the wall position flow path cross-sectional area Sf5 described above is smaller than the wall position flow path cross-sectional area Sf6 described above, and in the ejection channel C1e2, the wall position flow path cross-sectional area Sf6 is smaller than the wall position flow path cross-sectional area Sf5. The same size relationship is also observed in the ejection channel C2e. As a result, in this embodiment, the length along the extension direction of each common electrode Edc (for example, the electrode length Le1 and electrode length Le2 described above) can be further increased compared to the case where, for example, these wall position flow path cross-sectional areas Sf5 and Sf6 are equal to each other. Therefore, the area of each common electrode Edc is further increased, and the voltage efficiency when driving the head chip 41 is further improved, which makes it possible to further reduce power consumption.

Furthermore, in this embodiment, as described above, while maintaining the existing structure in the entirety of the multiple ejection channels C1e (and the entirety of the multiple ejection channels C2e), the structure in which adjacent nozzle holes H1 (and adjacent nozzle holes H2) along the X-axis direction are shifted from each other along the Y-axis direction can be similar to the existing structure as follows. That is, the first pump length Lw1 and the second pump length described above can be made the same (common) in all first slit pairs Sp1 and all second slit pairs. As a result, in this embodiment, the variation in ejection characteristics between adjacent nozzle holes H1 (and adjacent nozzle holes H2) is suppressed, and the print image quality can be further improved. In addition, in this embodiment, compared to the case of the above-mentioned comparative example 2 (in which the first supply slit Sin1 and the second supply slit, and the first exhaust slit Sout1 and the second exhaust slit are staggered along the X-axis direction), the following is true. That is, first, in the case of Comparative Example 2, the entire plurality of ejection channels C1e (and the entire plurality of ejection channels C2e) are also arranged in a staggered arrangement along the X-axis direction (see FIG. 12). On the other hand, in this embodiment, the entire plurality of ejection channels C1e (and the entire plurality of ejection channels C2e) can be formed (processed) without a staggered arrangement, as in the existing structure (see FIG. 5), which improves the processability of the head chip 41 (it can be processed while maintaining the existing manufacturing process). As a result, in this embodiment, it is also possible to simplify the manufacturing process of the head chip 41.

In addition, in this embodiment, the flow path widths in the inlet side common flow paths Rin1, Rin2 (first inlet side flow path width Win1 and second inlet side flow path width) and the flow path widths in the outlet side common flow paths Rout1, Rout2 (first outlet side flow path width Wout1 and second outlet side flow path width) are constant along the extension direction (X-axis direction) of each common flow path, as follows. In other words, it is possible to maintain the existing structure for each of these inlet side common flow paths Rin1, Rin2 and outlet side common flow paths Rout1, Rout2.

In addition, in this embodiment, one side of each of the dummy channels C1d and C2d along the extension direction (Y-axis direction) is the side surface described above, and the other side along this extension direction is open up to the end of the actuator plate 412 along the Y-axis direction, so that the following is true. That is, as described above, in a structure in which adjacent nozzle holes H1 (and adjacent nozzle holes H2) along the X-axis direction are shifted from each other along the Y-axis direction, it is possible to arrange the nozzle holes H1 and H2 in the nozzle plate 411 at a high density without changing the size of the entire head chip 41 (chip size). In addition, since the other side of each of the dummy channels C1d and C2d is open up to the end, the individual electrodes Eda individually arranged in each of the dummy channels C1d and C2d can be formed separately (electrically insulated) from the common electrodes Edc arranged in each of the ejection channels C1e and C2d (see FIG. 6). From these points, in this embodiment, it is possible to realize a simplified manufacturing process for the head chip 41 while miniaturizing the chip size in the head chip 41.

2. Modified Examples
Next, modified examples (modifications 1 and 2) of the above embodiment will be described. Note that the same components as those in the embodiment will be given the same reference numerals, and the description will be omitted as appropriate.

[Modification 1]
(overall structure)
Fig. 14 and Fig. 15 each show a schematic cross-sectional configuration example (Y-Z cross-sectional configuration example) of inkjet head 4a according to Modification 1. Specifically, Fig. 14 shows a cross-sectional configuration example corresponding to Fig. 3 in the embodiment, and Fig. 15 shows a cross-sectional configuration example corresponding to Fig. 4 in the embodiment. Fig. 16 shows another cross-sectional configuration example (Z-X cross-sectional configuration example) of head chip 41a shown in Figs. 14 and 15.

As shown in Figures 14 and 15, the inkjet head 4a of this modified example 1 corresponds to the inkjet head 4 of the embodiment (see Figures 3 and 4) in which a head chip 41a is provided instead of the head chip 41. The head chip 41a of this modified example 1 corresponds to the head chip 41 in which an alignment plate 415, which will be described below, is further provided, and the other configurations are basically the same. Note that this inkjet head 4a corresponds to one specific example of a "liquid jet head" in this disclosure.

As shown in Figures 14 to 16, the alignment plate 415 is disposed between the actuator plate 412 and the nozzle plate 411. This alignment plate 415 has a number of openings H31, H32 for each nozzle hole H1 (H11, H12) and H2 (H21, H22) to align each nozzle hole H1, H2 during the manufacture of the head chip 41a. Specifically, an opening H31 is disposed for each nozzle hole H11, H21, and an opening H32 is disposed for each nozzle hole H21, H22 (see Figures 14 to 16).

These openings H31 and H32 communicate between the nozzle holes H11, H12, H21, and H22 and the ejection channels C1e1 and C1e2, respectively, and are substantially rectangular openings on the XY plane. The length in the Y-axis direction (opening length) of each opening H31 and H32 is greater than the length in the Y-axis direction of each nozzle hole H11, H12, H21, and H22 (see Figures 14 and 15). Also, the length in the X-axis direction of each opening H31 and H32 is greater than the length in the X-axis direction of each nozzle hole H11, H12, H21, and H22, and the length in the X-axis direction of each ejection channel C1e and C2e (see Figure 16). That is, for example, as shown in Figure 16, such openings H31 and H32 allow a small amount of positional deviation (positional deviation in the XY plane) in the nozzle holes H1 and H2, and prevent such positional deviation. The provision of such an alignment plate 415 makes it easy to align the actuator plate 412 and the nozzle plate 411 when manufacturing the head chip 41a.

Each of these openings H31 and H32 corresponds to a specific example of a "third through hole" in this disclosure.

Here, in the head chip 41a of this modified example 1, the following extended flow passage sections 431, 432 are formed to include the openings H31, H32 in the alignment plate 415.

The expanded flow path section 431 is formed near the nozzle holes H11 and H21, and as described in detail below, serves as a flow path that widens the cross-sectional area of the flow path of the ink 9 near the nozzle holes H11 and H21 (flow path cross-sectional area Sf3 near the nozzle holes) (see FIG. 14, for example). Similarly, the expanded flow path section 432 is formed near the nozzle holes H12 and H22, and as described in detail below, serves as a flow path that widens the cross-sectional area of the flow path of the ink 9 near the nozzle holes H12 and H22 (flow path cross-sectional area Sf4 near the nozzle holes) (see FIG. 15, for example).

The expanded flow passage section 431 corresponds to a specific example of a "first expanded flow passage section" in this disclosure. Similarly, the expanded flow passage section 432 corresponds to a specific example of a "second expanded flow passage section" in this disclosure. Furthermore, the flow passage cross-sectional area Sf3 near the nozzle hole described above corresponds to a specific example of a "third cross-sectional area" in this disclosure. Similarly, the flow passage cross-sectional area Sf4 near the nozzle hole described above corresponds to a specific example of a "fourth cross-sectional area" in this disclosure.

(Detailed configuration of the extended flow passage sections 431, 432)
Next, the detailed configuration of the above-mentioned extended flow passage portions 431 and 432 will be described with reference to Figs. 14 and 15 as well as Figs. 17 and 18. Figs. 17 and 18 are schematic cross-sectional views (Y-Z cross-sectional views) showing an example of the positional relationship between the nozzle holes H1 and H2 and the extended flow passage portion according to Modification 1 and the like. Specifically, Fig. 17(A) shows an enlarged cross-sectional configuration near VII in Fig. 14, and Fig. 17(B) shows the cross-sectional configuration of an inkjet head 504 (head chip 500) according to Comparative Example 5, which will be described later, in comparison with Fig. 17(A). Also, Fig. 18(A) shows an enlarged cross-sectional configuration near VIII in Fig. 15, and Fig. 18(B) shows the cross-sectional configuration of an inkjet head 604 (head chip 600) according to Comparative Example 6, which will be described later, in comparison with Fig. 18(A).

First, in the head chip 41a of this modified example 1, both ends of these expansion flow passage sections 431, 432 (openings H31, H32) along the Y-axis direction are located inside (inside the so-called pump chamber) more than both ends of the wall section W1 (or wall section W2) along the Y-axis direction (see Figures 14 and 15).

Specifically, as shown in FIG. 14, the end of the first supply slit Sin1 side in the extended flow passage section 431 is disposed on the first exhaust slit Sout1 side from the reference position of the end of the first supply slit Sin1 side in the wall section W1. The end of the first exhaust slit Sout1 side in the extended flow passage section 431 is also disposed on the first supply slit Sin1 side from the reference position of the end of the first exhaust slit Sout1 side in the wall section W1. Similarly, the end of the second supply slit side in the extended flow passage section 431 is disposed on the second exhaust slit side from the reference position of the end of the second supply slit side in the wall section W2. The end of the second exhaust slit side in the extended flow passage section 431 is also disposed on the second supply slit side from the reference position of the end of the second exhaust slit side in the wall section W2.

On the other hand, as shown in FIG. 15, the end of the first exhaust slit Sout1 side of the extended flow passage section 432 is disposed on the first supply slit Sin1 side from the reference position of the end of the first exhaust slit Sout1 side of the wall W1. The end of the first supply slit Sin1 side of the extended flow passage section 432 is also disposed on the first exhaust slit Sout1 side from the reference position of the end of the first supply slit Sin1 side of the wall W1. Similarly, the end of the second exhaust slit side of the extended flow passage section 432 is disposed on the second supply slit side from the reference position of the end of the second exhaust slit side of the wall W2. The end of the second supply slit side of the extended flow passage section 432 is also disposed on the second exhaust slit side from the reference position of the end of the second supply slit side of the wall W2.

Also, as shown in FIG. 17A, in the head chip 41a of this modified example 1, the center position Ph31 along the Y axis direction of the expanded flow path section 431 is shifted toward the first supply slit Sin1 along the Y axis direction from the center position Pn11 of the nozzle hole H11. Similarly, in this head chip 41a, the center position Ph31 along the Y axis direction of the expanded flow path section 431 is shifted toward the second supply slit along the Y axis direction from the center position of the nozzle hole H21.

In contrast, in the head chip 500 of Comparative Example 5 shown in FIG. 17(B), the center position Ph31 along the Y axis direction of the expanded flow path section 501 is shifted conversely toward the first exhaust slit Sout1 along the Y axis direction from the center position Pn11 of the nozzle hole H11. Similarly, in the head chip 500 of Comparative Example 5, the center position Ph31 along the Y axis direction of the expanded flow path section 501 is shifted conversely toward the second exhaust slit along the Y axis direction from the center position of the nozzle hole H21.

On the other hand, as shown in FIG. 18(A), in the head chip 41a of this modified example 1, the center position Ph32 in the Y-axis direction of the expanded flow path section 432 is shifted toward the first exhaust slit Sout1 along the Y-axis direction from the center position Pn12 of the nozzle hole H12. Similarly, in this head chip 41a, the center position Ph32 in the Y-axis direction of the expanded flow path section 432 is shifted toward the second exhaust slit along the Y-axis direction from the center position of the nozzle hole H22.

In contrast to this, in the head chip 600 of Comparative Example 6 shown in FIG. 18(B), the center position Ph32 along the Y axis direction of the expanded flow path section 602 is shifted in the opposite direction to the first supply slit Sin1 side along the Y axis direction from the center position Pn12 of the nozzle hole H12. Similarly, in the head chip 600 of Comparative Example 6, the center position Ph32 along the Y axis direction of the expanded flow path section 602 is shifted in the opposite direction to the second supply slit side along the Y axis direction from the center position of the nozzle hole H22.

(Action and Effects)
Inkjet head 4a (head chip 41a) of modified example 1 having such a configuration can also basically achieve the same effects as inkjet head 4 (head chip 41) of the embodiment.

In particular, in this modified example 1, the expanded flow path sections 431 and 432 as described above are formed in the head chip 41a. Specifically, an expanded flow path section 431 is formed near the nozzle holes H11 and H21 to expand the cross-sectional area of the flow path of the ink 9 near these nozzle holes H11 and H21 (flow path cross-sectional area Sf3 near the nozzle holes) (see FIG. 14). In addition, an expanded flow path section 432 is formed near the nozzle holes H12 and H22 to expand the cross-sectional area of the flow path of the ink 9 near these nozzle holes H12 and H22 (flow path cross-sectional area Sf4 near the nozzle holes) (see FIG. 15).

As described above, in this modified example 1, the center position Ph31 along the Y axis direction of the expanded flow path section 431 is shifted toward the first supply slit Sin1 along the Y axis direction from the center position Pn11 of the nozzle hole H11 (see FIG. 17A). Similarly, the center position Ph31 along the Y axis direction of the expanded flow path section 431 is shifted toward the second supply slit along the Y axis direction from the center position of the nozzle hole H21. Also, the center position Ph32 along the Y axis direction of the expanded flow path section 432 is shifted toward the first exhaust slit Sout1 along the Y axis direction from the center position Pn12 of the nozzle hole H12 (see FIG. 18A). Similarly, the center position Ph32 along the Y axis direction of the expanded flow path section 432 is shifted toward the second exhaust slit along the Y axis direction from the center position of the nozzle hole H22.

In this modified example 1, the extended flow path sections 431, 432 are formed in such an arrangement position, and compared to the previously described embodiment (a configuration in which the alignment plate 415 having the extended flow path sections 431, 432 is omitted: see Figures 3 and 4), the following occurs.

That is, in this modified example 1, the difference in the first inlet side flow channel cross-sectional area Sfin1 between the ejection channels C1e1 and C1e2 is smaller than in the embodiment, and the pressure loss from the inflow side of the ink 9 to the nozzle holes H11 and H12 is also smaller. As a result, in this modified example 1, the difference in steady-state pressure near the nozzle holes H11 and H12 between the ejection channels C1e1 and C1e2 is smaller than in the embodiment, and the head value margin of the entire head chip 41a is increased, improving the ejection characteristics of the ink 9 in the inkjet head 4. This effect also occurs between the ejection channels C2e communicating with each nozzle hole H21 and the ejection channels C2e communicating with each nozzle hole H22.

Incidentally, if the above-mentioned pressure difference increases, specifically, for example, the ejection characteristics of the ink 9 may deteriorate in the following manner. That is, even if one of the ejection channels C1e1, C1e2 has a pressure at which an appropriate meniscus is formed, the pressure near the nozzle hole H11 or nozzle hole H12 may become too high at the other, causing the meniscus to break and the ink 9 to leak out. Conversely, if that pressure becomes too low, the meniscus may break and air bubbles may get into the ejection channel C1e1 or ejection channel C1e2, resulting in non-ejection of the ink 9.

In addition, the deterioration of the ejection characteristics of the ink 9 due to such pressure differences can also occur between the ejection channel C2e communicating with each nozzle hole H21 and the ejection channel C2e communicating with each nozzle hole H22.

By the way, in the case of the comparative examples 5 and 6 described above (see FIG. 17B and FIG. 18B), the arrangement positions of the expansion flow passage sections 501 and 602 are different from those of the above-mentioned modified example 1, so that the following occurs. That is, in the comparative example 5, for example, as described above, the center position Ph31 along the Y axis direction in the expansion flow passage section 501 is shifted conversely toward the first discharge slit Sout1 side along the Y axis direction from the center position Pn11 of the nozzle hole H11 (see FIG. 17B). Also, in the comparative example 6, for example, as described above, the center position Ph32 along the Y axis direction in the expansion flow passage section 602 is shifted conversely toward the first supply slit Sin1 side along the Y axis direction from the center position Pn12 of the nozzle hole H12 (see FIG. 18B). Therefore, in these comparative examples 5 and 6, for example, the difference in steady-state pressure near the nozzle holes H11 and H12 between the ejection channels C1e1 and C1e2 increases, and the head value margin described above decreases further, which may further deteriorate the ejection characteristics of the ink 9.

In addition, in this modified example 1, the extended flow path sections 431, 432 are each configured to include openings H31, H32 (openings for aligning the nozzle holes H1, H2) in the alignment plate 415, and so the following occurs. That is, the above-mentioned extended flow path sections 431, 432 can each be formed simply and accurately using the existing openings H31, H32 in the alignment plate 415. This makes it possible to further reduce the manufacturing costs of the head chip 41a while further improving the ejection characteristics of the ink 9 and further improving the print image quality.

Furthermore, in this modified example 1, as described above, both ends along the Y-axis direction of the extended flow path sections 431, 432 (openings H31, H32) are located on the inside (inside the pump chamber) of both ends along the Y-axis direction of the wall section W1 (or wall section W2) (see Figures 14 and 15), resulting in the following. That is, for example, the non-uniformity of the pressure characteristics is reduced inside the ejection channels C1e1, C1e2, respectively, and the ejection characteristics of the ink 9 are further improved, making it possible to further improve the print image quality.

[Modification 2]
(composition)
19 and 20 are schematic cross-sectional views (Y-Z cross-sectional views) showing an example of the positional relationship between the nozzle holes H1, H2 and the extended flow path section according to the modified example 2 and the like. Specifically, FIG. 19(A) shows the cross-sectional configuration of the extended flow path section 431b and the like in the inkjet head 4b (head chip 41b) according to the modified example 2. FIG. 19(B) and FIG. 19(C) show the cross-sectional configurations (the cross-sectional configurations shown in FIG. 17(A) and FIG. 17(B)) of the extended flow path section 431 and the like in the modified example 1 and the extended flow path section 501 and the like in the comparative example 5, respectively, in comparison with each other. Also, FIG. 20(A) shows the cross-sectional configuration of the extended flow path section 432b and the like in the inkjet head 4b (head chip 41b) according to the modified example 2. Figures 20(B) and 20(C) respectively show a comparison of the cross-sectional configurations (the cross-sectional configurations shown in Figures 18(A) and 18(B)) of the expanded flow path section 432 of the aforementioned modified example 1 and the expanded flow path section 602 of the comparative example 6.

As shown in Fig. 19(A) and Fig. 20(A), the inkjet head 4b of this modified example 2 corresponds to the inkjet head 4a of modified example 1, in which head chip 41b is provided instead of head chip 41a. Note that this type of inkjet head 4b corresponds to one specific example of the "liquid jet head" in this disclosure.

In this head chip 41b, the extended flow passage sections 431b and 432b described below are formed in place of the extended flow passage sections 431 and 432 in the head chip 41a (see Figures 19(A) and 20(A)).

The extended flow path section 431b corresponds to a specific example of a "first extended flow path section" in this disclosure. Similarly, the extended flow path section 432b corresponds to a specific example of a "second extended flow path section" in this disclosure.

As shown in FIG. 19(A), the center position Ph31 of the expanded flow path section 431b along the Y-axis direction coincides with the center position Pn11 of the nozzle hole H11. Similarly, the center position Ph31 of the expanded flow path section 431b along the Y-axis direction coincides with the center position of the nozzle hole H21.

Also, as shown in FIG. 20A, the center position Ph32 of the expanded flow path section 432b along the Y-axis direction coincides with the center position Pn12 of the nozzle hole H12. Similarly, the center position Ph32 of the expanded flow path section 432b along the Y-axis direction coincides with the center position of the nozzle hole H22.

(Action and Effects)
Inkjet head 4b (head chip 41b) of modified example 2 having such a configuration can basically achieve the same effects as inkjet head 4a (head chip 41a) of modified example 1.

Specifically, in this modified example 2, unlike modified example 1, as described above, the center position Ph31 along the Y-axis direction of the expanded flow path section 431b coincides with the center position Pn11 of the nozzle hole H11 and the center position of the nozzle hole H21, respectively. Similarly, as described above, the center position Ph32 along the Y-axis direction of the expanded flow path section 432b coincides with the center position Pn12 of the nozzle hole H12 and the center position of the nozzle hole H22, respectively. In this modified example 2, the head value margin of the entire head chip 41b increases due to the same action as in modified example 1, and the ejection characteristics of the ink 9 in the inkjet head 4b are improved. Therefore, in this modified example 2, as in modified example 1, it is possible to improve the print image quality while suppressing the manufacturing cost of the head chip 41b.

3. Other Modifications
While the present disclosure has been described above by way of embodiments and modified examples, the present disclosure is not limited to these embodiments and can be modified in various ways.

For example, in the above embodiments, specific configuration examples (shape, arrangement, number, etc.) of each component in the printer and inkjet head are given and described, but they are not limited to those described in the above embodiments, and other shapes, arrangements, numbers, etc. may be used. In addition, the values, ranges, magnitude relationships, etc. of the various parameters described in the above embodiments are not limited to those described in the above embodiments, and other values, ranges, magnitude relationships, etc. may be used.

Specifically, for example, in the above embodiment, an inkjet head 4 of a two-row type (having two nozzle rows An1 and An2) has been described, but this is not limited to the example. That is, for example, it may be an inkjet head of a single row type (having one nozzle row) or an inkjet head of a multiple-row type (having three or more nozzle rows) with three or more rows (e.g., three or four rows).

In addition, in the above embodiment, examples of the offset arrangement of the nozzle holes H1 (H11, H12) and H2 (H21, H22) (staggered arrangement) and configuration examples of the various plates (nozzle plate, actuator plate, cover plate, and alignment plate) have been specifically described, but the present invention is not limited to these examples. In other words, the offset arrangement of each nozzle hole and the configuration of the various plates may be other configuration examples.

In addition, in the above embodiments, the case where each ejection channel (ejection groove) and each dummy channel (non-ejection groove) extends along the Y-axis direction (a direction perpendicular to the direction in which each channel is arranged) within the actuator plate has been described as an example, but this is not limited to the example. That is, for example, each ejection channel and each dummy channel may extend along a diagonal direction (a direction that forms an angle with each of the X-axis direction and the Y-axis direction) within the actuator plate.

In the above embodiment, the shape of the common electrode Edc (two-stage structure including the first portion Edc1 and the second portion Edc2) is specifically described, but the shape of the common electrode Edc is not limited to this example. In the above embodiment, the electrode length Le2 of the second portion Edc2 in the common electrode Edc1 is smaller than the electrode length Le1 of the first portion Edc (Le2<Le1), but the shape is not limited to this example. That is, in some cases, for example, the electrode lengths Le1 and Le2 may be equal to each other (Le1=Le2), or conversely, the electrode length Le1 may be smaller than the electrode length Le2 (Le1<Le2).

Furthermore, for example, the cross-sectional shape of the nozzle holes H1, H2 is not limited to a circular shape as described in the above embodiment, and may be, for example, an elliptical shape, a polygonal shape such as a triangular shape, a star shape, etc. Also, in the above embodiment, the cross-sectional shapes of the ejection channels C1e, C2e and the dummy channels C1d, C2d are formed by cutting with a dicer, and an example is described in which the side surfaces are arc-shaped (curved), but this example is not limited. That is, for example, the cross-sectional shapes of the ejection channels C1e, C2e and the dummy channels C1d, C2d may be formed using a processing method other than cutting with a dicer (etching, blasting, etc.) to have various side shapes other than an arc shape.

In addition, in the above modified examples 1 and 2, the case where the extended flow passage sections 431, 432, 431b, and 432b are all configured to include the openings H31 and H32 in the alignment plate 415 has been described as an example, but this is not limited to the example. In other words, such extended flow passage sections 431, 432, 431b, and 432b may each be provided in, for example, the nozzle plate 411 or the actuator plate 412.

In addition, in the above embodiment and the like, a circulation type inkjet head in which ink 9 is circulated between the ink tank and the inkjet head has been described as an example, but the present disclosure is not limited to this example. That is, for example, in some cases, the present disclosure may be applied to a non-circulation type inkjet head in which ink 9 is used without being circulated.

In addition, various types of inkjet head structures can be applied. That is, for example, in the above embodiment, a so-called side shoot type inkjet head that ejects ink 9 from the center of the extension direction of each ejection channel in the actuator plate has been described as an example. However, this is not limited to this example, and the present disclosure may be applied to other types of inkjet heads.

Furthermore, the printer system is not limited to the system described in the above embodiment, and various systems, such as the MEMS (Micro Electro Mechanical Systems) system, can be applied.

The series of processes described in the above embodiments may be performed by hardware (circuits) or software (programs). When performed by software, the software is composed of a group of programs for causing a computer to execute each function. Each program may be, for example, pre-installed in the computer and used, or may be installed in the computer from a network or recording medium and used.

Furthermore, in the above embodiment, the printer 1 (inkjet printer) has been described as one specific example of the "liquid jet recording device" of the present disclosure, but the present disclosure is not limited to this example and can be applied to devices other than inkjet printers. In other words, the "liquid jet head" (inkjet head) of the present disclosure may be applied to devices other than inkjet printers. Specifically, for example, the "liquid jet head" of the present disclosure may be applied to devices such as facsimiles and on-demand printers.

In addition, the various examples described above may be applied in any combination.

Note that the effects described in this specification are merely examples and are not limiting, and other effects may also be present.

The present disclosure can also be configured as follows.
(1)
A head chip for ejecting liquid,
an actuator plate including a plurality of ejection grooves arranged in a predetermined direction, and a plurality of electrodes provided individually on side walls of the ejection grooves and extending in the direction in which the ejection grooves extend;
a nozzle plate having a plurality of nozzle holes each of which is in communication with the plurality of ejection grooves;
a cover plate including a wall portion covering the ejection groove, a first through hole formed on one side of the wall portion along the extension direction of the ejection groove, for allowing the liquid to flow into the ejection groove, and a second through hole formed on the other side of the wall portion along the extension direction of the ejection groove, for allowing the liquid to flow out from inside the ejection groove,
The plurality of nozzle holes include
a plurality of first nozzle holes arranged to be shifted toward the first through hole in the extension direction of the ejection groove with respect to a center position in the extension direction of the ejection groove;
a plurality of second nozzle holes arranged to be shifted toward the second through hole in the extension direction of the ejection groove, with respect to a center position in the extension direction of the ejection groove,
In a first ejection groove that is the ejection groove communicating with the first nozzle hole, a first cross-sectional area that is a cross-sectional area of a flow path of the liquid in a portion that communicates with the first through hole is smaller than a second cross-sectional area that is a cross-sectional area of the flow path of the liquid in a portion that communicates with the second through hole,
In the second ejection groove, which is the ejection groove communicating with the second nozzle hole, the second cross-sectional area is smaller than the first cross-sectional area,
the positions of both ends of the electrodes along the extension direction of the ejection grooves are aligned with each other in the plurality of electrodes aligned along the predetermined direction.
(2)
The electrode is
a first portion provided on the side wall of the ejection groove on the nozzle plate side;
a second portion provided on the side wall of the ejection groove on the cover plate side,
a length of the second portion along the extension direction of the ejection groove is smaller than a length of the first portion along the extension direction of the ejection groove;
The head chip according to (1) above, wherein the positions of both ends in the extension direction of the ejection groove in each of the first portion and the second portion are aligned with each other in the plurality of electrodes aligned in the predetermined direction.
(3)
a first expanded flow path portion is formed in the vicinity of the first nozzle hole to expand a third cross-sectional area which is a cross-sectional area of the flow path of the liquid in the vicinity of the first nozzle hole;
a second expanded flow path portion is formed in the vicinity of the second nozzle hole to expand a fourth cross-sectional area which is a cross-sectional area of the flow path of the liquid in the vicinity of the second nozzle hole,
a center position of the first expansion flow path portion along the extension direction of the ejection groove coincides with a first center position which is a center position of the first nozzle hole, or is shifted toward the first through hole side from the first center position along the extension direction of the ejection groove,
The head chip described in (1) or (2) above, wherein the center position along the extension direction of the ejection groove in the second expansion flow path section coincides with a second center position which is the center position of the second nozzle hole, or is shifted toward the second through hole side along the extension direction of the ejection groove from the second center position.
(4)
an alignment plate disposed between the actuator plate and the nozzle plate, the alignment plate having a third through hole for each of the nozzle holes for aligning the nozzle holes;
The head chip according to (3) above, wherein the first extended flow path portion and the second extended flow path portion each include the third through hole in the alignment plate.
(5)
In the first ejection groove, a fifth cross-sectional area which is a cross-sectional area of the flow path of the liquid at a position corresponding to a wall surface of the wall portion on the first through hole side is smaller than a sixth cross-sectional area which is a cross-sectional area of the flow path of the liquid at a position corresponding to a wall surface of the wall portion on the second through hole side,
The head chip according to any one of (1) to (4), wherein in the second ejection groove, the sixth cross-sectional area is smaller than the fifth cross-sectional area.
(6)
A liquid jet head comprising the head chip according to any one of (1) to (5) above.
(7)
A liquid jet recording apparatus comprising the liquid jet head according to (6) above.

1... printer, 10... housing, 2a, 2b... transport mechanism, 21... grid roller, 22... pinch roller, 3 (3Y, 3M, 3C, 3K)... ink tank, 4 (4Y, 4M, 4C, 4K), 4a, 4b... inkjet head, 41, 41a, 41b... head chip, 411... nozzle plate, 412... actuator plate, 413... cover plate, 415... alignment plate, 420... tail, 421, 422... channel row, 431, 431a, 431b, 432, 432a, 432b... extended flow path section, 50... Circulation flow path, 50a, 50b...flow path (supply tube), 6...scanning mechanism, 61a, 61b...guide rail, 62...carriage, 63...driving mechanism, 631a, 631b...pulley, 632...endless belt, 633...driving motor, 9...ink, P...recording paper, d...transport direction, H1, H11, H12, H2, H21, H22...nozzle hole, H31, H32...opening, An1, An11, An12, An2, An21, An22...nozzle row, C1, C2...channel, C1e (C1e1, C1e2), C2e...ejection channel, C1d, C2d... dummy channel (non-ejection channel), Wd... driving wall, Ed... driving electrode, Eda... individual electrode (active electrode), Edc... common electrode (common electrode), Edc1... first portion, Edc2... second portion, Pda... individual electrode pad, Pdc... common electrode pad, D... groove, Rin1, Rin2... inlet side common flow path, Rout1, Rout2... outlet side common flow path, Sin1... first supply slit, Sout1... first discharge slit, Sp1... first slit pair, W1, W2... wall portion, Lw1... first pump length, Lin1... first supply slit length, Lout1...first exhaust slit length, Le1, Le2...electrode length, Win1...first inlet side flow passage width, Wout1...first outlet side flow passage width, Sfin1...first inlet side flow passage cross-sectional area, Sfout1...first outlet side flow passage cross-sectional area, Sf3, Sf4...flow passage cross-sectional area near nozzle hole, Sf5, Sf6...wall position flow passage cross-sectional area, Pc1, Pn11, Pn12, Ph31, Ph32...center position, Pe1a, Pe1b, Pe2a, Pe2b...end position, M...mask, Ap1, Ap2...opening, Ev1, Ev2...evaporation direction, SL...machining slit.

Claims (7)

A head chip for ejecting liquid,
an actuator plate including a plurality of ejection grooves arranged in a predetermined direction, and a plurality of electrodes provided individually on side walls of the ejection grooves and extending in the direction in which the ejection grooves extend;
a nozzle plate having a plurality of nozzle holes each communicating with the plurality of ejection grooves;
a cover plate having a wall portion covering the ejection groove, a first through hole formed on one side of the wall portion along the extension direction of the ejection groove, for allowing the liquid to flow into the ejection groove, and a second through hole formed on the other side of the wall portion along the extension direction of the ejection groove, for allowing the liquid to flow out from inside the ejection groove,
The plurality of nozzle holes include
a plurality of first nozzle holes arranged to be shifted toward the first through hole in the extension direction of the ejection groove with respect to a center position in the extension direction of the ejection groove;
a plurality of second nozzle holes arranged to be shifted toward the second through hole in the extension direction of the ejection groove, with respect to a center position in the extension direction of the ejection groove,
In a first ejection groove that is the ejection groove communicating with the first nozzle hole, a first cross-sectional area that is a cross-sectional area of a flow path of the liquid in a portion that communicates with the first through hole is smaller than a second cross-sectional area that is a cross-sectional area of the flow path of the liquid in a portion that communicates with the second through hole,
In the second ejection groove, which is the ejection groove communicating with the second nozzle hole, the second cross-sectional area is smaller than the first cross-sectional area,
the positions of both ends of the electrodes along the extension direction of the ejection grooves are aligned with each other in the plurality of electrodes aligned in the predetermined direction. The electrode is
a first portion provided on the side wall of the ejection groove on the nozzle plate side;
a second portion provided on the side wall of the ejection groove on the cover plate side,
a length of the second portion along the extension direction of the ejection groove is smaller than a length of the first portion along the extension direction of the ejection groove;
The head chip according to claim 1 , wherein the positions of both ends in the extension direction of the ejection groove in each of the first portion and the second portion are aligned with each other in the plurality of electrodes aligned in the predetermined direction. a first expanded flow path portion is formed in the vicinity of the first nozzle hole to expand a third cross-sectional area which is a cross-sectional area of the flow path of the liquid in the vicinity of the first nozzle hole;
a second expansion flow path portion is formed in the vicinity of the second nozzle hole to expand a fourth cross-sectional area which is a cross-sectional area of the flow path of the liquid in the vicinity of the second nozzle hole,
a center position of the first expansion flow path portion along the extension direction of the ejection groove coincides with a first center position which is a center position of the first nozzle hole, or is shifted toward the first through hole side from the first center position along the extension direction of the ejection groove,
The head chip described in claim 1 or claim 2, wherein a center position of the second expansion flow path portion along the extension direction of the ejection groove coincides with a second center position which is the center position of the second nozzle hole, or is shifted toward the second through hole side along the extension direction of the ejection groove from the second center position. an alignment plate disposed between the actuator plate and the nozzle plate, the alignment plate having a third through hole for each of the nozzle holes for aligning the nozzle holes;
The head chip according to claim 3 , wherein the first extended flow path portion and the second extended flow path portion each include the third through hole in the alignment plate. In the first ejection groove, a fifth cross-sectional area which is a cross-sectional area of the flow path of the liquid at a position corresponding to a wall surface of the wall portion on the first through hole side is smaller than a sixth cross-sectional area which is a cross-sectional area of the flow path of the liquid at a position corresponding to a wall surface of the wall portion on the second through hole side,
5 . The head chip according to claim 1 , wherein in the second ejection groove, the sixth cross-sectional area is smaller than the fifth cross-sectional area. 6 . A liquid jet head comprising the head chip according to claim 1 . A liquid jet recording apparatus comprising the liquid jet head according to claim 6.

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