JP7400628B2 - Inkjet head, inkjet recording device, and inkjet head manufacturing method - Google Patents

Description

The present invention relates to an inkjet head, an inkjet recording apparatus, and a method for manufacturing an inkjet head.

2. Description of the Related Art Conventionally, there is an inkjet recording apparatus that forms an image on a recording medium by ejecting ink onto a recording medium from nozzles provided in an inkjet head and causing the ink to land in a desired pattern. An inkjet head used in an inkjet recording device includes a pressure chamber that communicates with a nozzle through an ink flow path, and a pressure variation element that varies the pressure of the ink within the pressure chamber. Ink is ejected from the nozzle according to fluctuations in the ink.

Inkjet heads are widely used that are constructed by bonding multiple substrates, such as a nozzle substrate with nozzles, a channel substrate with ink channels, and an element substrate with pressure variation elements. . An adhesive may be used to bond the substrates together. If excess adhesive overflows into the ink flow path when bonding substrates with adhesive, the adhesive will flow through the ink flow path, causing the adhesive to flow into the nozzle and clog the nozzle, or damage the pressure fluctuation element. The adhesive may adhere to a movable member (for example, a diaphragm) due to the pressure fluctuation, and an abnormality may occur in the pressure fluctuation of the ink caused by the pressure fluctuation element.

To solve this problem, Patent Document 1 discloses that by providing a convex portion at the end of the bonding surface of the substrate with adhesive, a gap is created in the bonding surface where the adhesive can stay, and the adhesive overflows into the ink flow path. Techniques for suppressing the occurrence of problems have been disclosed.

Japanese Patent Application Publication No. 2007-203483

However, even if a gap is provided in the joint surface, if the amount of adhesive applied is too large relative to the capacity of the gap, it is not possible to prevent the adhesive from overflowing into the ink flow path. In the above-mentioned conventional technology, once the adhesive overflows into the ink flow path, it is impossible to prevent the adhesive from flowing along the ink flow path toward the movable member such as the nozzle or the pressure variation element, which may cause the nozzle to become clogged. Problems such as abnormal pressure fluctuations may occur.

An object of the present invention is to provide an inkjet head, an inkjet recording device, and a method for manufacturing an inkjet head that can suppress the occurrence of problems caused by adhesive overflowing into an ink flow path.

In order to achieve the above object, the invention of an inkjet head according to claim 1,
A nozzle that ejects ink,
a flow path member provided with an ink flow path through which ink is supplied to the nozzle;
Equipped with
The flow path member includes a plurality of laminated plate members,
The plurality of plate-like members are arranged in a positional relationship such that through holes provided in each of the plurality of plate-like members communicate with each other,
At least a portion of the ink flow path is a through flow path made up of a plurality of the through holes that communicate across the plurality of plate-like members,
The through-holes provided in any two of the plurality of plate-like members that are not adjacent to each other among the plurality of plate-like members are called first through-holes, and one or more of the plates located between the two plate-like members When the through holes provided in each of the shaped members are used as second through holes,
In any cross section perpendicular to the bonding surface of the plurality of plate-like members passing through the through-flow path, the one side of the second through-hole with respect to the inner wall surface on one side of the first through-hole. a side inner wall surface protrudes toward the through-flow channel,
With respect to a direction parallel to the joint surface in the cross section, the center positions of the two first through holes in the cross section are shifted in the same direction with respect to the center position of the second through hole in the cross section.

The invention according to claim 2 is the inkjet head according to claim 1,
The plurality of plate-like members are arranged in such a positional relationship that the center of the through-hole provided in each plate-like member is shifted in a random direction parallel to the joint surface.

The invention according to claim 3 is the inkjet head according to claim 1 or 2,
When a step portion is defined as a portion where the inner wall surface of the second through hole protrudes toward the through flow path with respect to the inner wall surface of the first through hole when viewed from a direction perpendicular to the joint surface,
Any one of the plurality of stepped portions having different positions in the direction perpendicular to the joint surface is provided at an arbitrary position on the outer periphery of the through flow path when viewed from a direction perpendicular to the joint surface.

The invention according to claim 4 is the inkjet head according to any one of claims 1 to 3,
A portion where the inner wall surface of the second through hole protrudes toward the through flow path side with respect to the inner wall surface of the first through hole when viewed from a direction perpendicular to the joint surface is defined as a stepped portion, and When the amount of protrusion of the inner wall surface of the second through hole in the stepped portion from the inner wall surface of the first through hole is defined as the step difference in the direction toward the center of the through hole,
In the step portion, the maximum value of the step is 5 μm or more and 20 μm or less.

The invention according to claim 5 provides the inkjet head according to any one of claims 1 to 4,
An inner wall surface of at least some of the through holes of the plurality of plate members has a convex portion projecting toward the through flow path.

The invention according to claim 6 is the inkjet head according to claim 5,
The convex portion has a protrusion amount of 5 μm or more and 30 μm or less in a direction toward the center of the through hole.

The invention according to claim 7 is the inkjet head according to any one of claims 1 to 6,
When the maximum value of the width of each of the through holes in a plane parallel to the bonding surface is defined as the through hole width, and the maximum value of the through hole widths in the plurality of through holes is defined as the maximum through hole width,
The center of the through hole of the plate member at one end of the plurality of plate members and the center of the through hole of the plate member at the other end in a direction parallel to the joint surface. The distance is 1/3 or less of the maximum width of the through hole.

The invention according to claim 8 is the inkjet head according to any one of claims 1 to 7,
The flow path member includes a nozzle substrate provided with the nozzle that communicates with the ink flow path, and a device that varies the pressure of ink in a pressure chamber that communicates with the ink flow path in order to eject ink from the nozzle. At least one of the element substrates provided with the pressure variation element is bonded via an adhesive,
The adhesive is a material that does not swell upon contact with ink.

Further, in order to achieve the above object, the invention of an inkjet recording apparatus according to claim 9,
An inkjet head according to any one of claims 1 to 8 is provided.

Further, in order to achieve the above object, the invention of an inkjet head manufacturing method according to claim 10,
A method for manufacturing an inkjet head, comprising: a nozzle for ejecting ink; and a flow path member including a plurality of laminated plate-like members and provided with an ink flow path through which ink supplied to the nozzle flows. ,
a first step of forming a through hole in each of the plurality of plate-like members;
The plurality of plate-like members are stacked in a positional relationship such that the through-holes communicate with each other to form at least a part of the ink flow path, and the plurality of through-holes communicate across the plurality of plate-like members. a second step of forming a through flow path;
including;
In the second step, the through-holes provided in any two non-adjacent plate-like members among the plurality of plate-like members are called first through-holes, which are located between the two plate-like members. When the through-holes provided in one or more of the plate-like members are used as second through-holes,
In any cross section perpendicular to the bonding surface of the plurality of plate-like members passing through the through-flow path, the one side of the second through-hole with respect to the inner wall surface on one side of the first through-hole. a side inner wall surface protrudes toward the through-flow channel side, and
With respect to a direction parallel to the joint surface in the cross section, the center positions of the two first through holes in the cross section are shifted in the same direction with respect to the center position of the second through hole in the cross section, The plurality of plate members are stacked.

The invention according to claim 11 is the method for manufacturing an inkjet head according to claim 10, comprising:
In the first step, the plate-like members are etched from one side and the other side of each of the plurality of plate-like members, so that the inner wall surface has a convex portion protruding toward the through-flow channel side. The through hole is formed.

According to the present invention, it is possible to suppress the occurrence of problems caused by adhesive overflowing into the ink flow path.

1 is a diagram showing a schematic configuration of an inkjet recording apparatus. FIG. 2 is a perspective view showing the configuration of an inkjet head. FIG. 3 is a diagram showing the configuration of a head chip. FIG. 3 is an enlarged view of the end of the actuator board on the positive side in the X-axis direction. FIG. 3 is a diagram showing a cross section of the head chip perpendicular to the X axis. FIG. 3 is a diagram schematically showing an arrangement of nozzles on a nozzle substrate. FIG. 3 is a partial perspective view showing a cross section of the configuration near the pressure chamber of the head chip. It is a figure which expands and shows the cross section of a through flow path. FIG. 7 is a diagram showing a region where a stepped portion is formed in the through flow path when viewed from the negative side in the Z-axis direction. FIG. 6 is an enlarged view showing a cross section of a through flow path in a configuration in which the inner wall surface of the through hole has a convex portion. FIG. 3 is a cross-sectional view illustrating a method of forming a convex portion. It is a flowchart showing the procedure of a manufacturing process of an inkjet head.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of an inkjet head, an inkjet recording apparatus, and a method for manufacturing an inkjet head of the present invention will be described below with reference to the drawings.

FIG. 1 is a diagram showing a schematic configuration of an inkjet recording apparatus 100 according to an embodiment of the present invention.
The inkjet recording apparatus 100 includes a conveyance belt 101, a conveyance roller 102, a head unit 103, and the like.

The conveyance roller 102 rotates around a rotation shaft by driving a conveyance motor (not shown). The conveyance belt 101 is a ring-shaped belt whose inner side is supported by a pair of conveyance rollers 102, and moves around the pair of conveyance rollers 102 as the conveyance rollers 102 rotate. In the inkjet recording apparatus 100, the recording medium M is placed on the conveying belt 101, and the conveying belt 101 rotates at a speed corresponding to the rotational speed of the conveying roller 102, thereby transferring the recording medium M onto the conveying belt 101. Convey in the moving direction (Y-axis direction in FIG. 1).

The head unit 103 records an image on the recording medium M conveyed by the conveyance belt 101 by ejecting ink from nozzles 51 (see FIGS. 5 and 6, etc.) based on the image data. In the inkjet recording apparatus 100 of this embodiment, four head units 103 respectively corresponding to four color inks of yellow (Y), magenta (M), cyan (C), and black (K) are arranged in the transport direction of the recording medium M. They are arranged in order from the upstream side at predetermined intervals. The number of head units 103 may be three or less or five or more depending on the number of colors used for recording.

Each head unit 103 has a flat base 103a and a plurality of (seven in this case) inkjet heads 1 fixed to the base 103a while being engaged with a hole passing through the base 103a. The head unit 103 has a casing that stores components including a plurality of inkjet heads 1, but its illustration is omitted in FIG. 1.

In the inkjet head 1, a plurality of nozzles 51 that eject ink are arranged in a direction intersecting the transport direction of the recording medium M (in the present embodiment, the width direction perpendicular to the transport direction, that is, the X-axis direction in FIG. 1). . Furthermore, each inkjet head 1 is provided with four nozzle rows each consisting of nozzles 51 arranged one-dimensionally in the X-axis direction (see FIG. 6).
The inkjet head 1 is provided with a mechanism corresponding to each nozzle 51 for ejecting ink from the nozzle 51.

In the plurality of inkjet heads 1 in each head unit 103, the arrangement range of the nozzles 51 in the X-axis direction covers the width in the X-axis direction of the area where an image can be recorded on the recording medium M on the conveyor belt 101. They are arranged in a houndstooth pattern. By arranging the inkjet head 1 in this way, the inkjet recording apparatus 100 can convey ink by ejecting ink from the inkjet head 1 at an appropriate timing according to image data while the head unit 103 is fixed. Images can be recorded on the recording medium M. That is, the inkjet recording apparatus 100 records images using a single pass method.

FIG. 2 is a perspective view showing the configuration of the inkjet head 1.
FIG. 3 is a diagram showing the configuration of the head chip 13 included in the inkjet head 1.
As shown in FIG. 2, the inkjet head 1 includes a housing 10 and a head base 12. The housing 10 is removably attached to the head base 12.

The housing 10 is a rectangular box with an open bottom surface. A notch 10a connected to the inside is provided on the top surface of the casing 10, and a circuit board 11 is housed in the casing 10 via this notch 10a. A drive circuit for driving the actuator in the head chip 13 is mounted on the circuit board 11 . Circular holes 10b are provided on the X-axis positive side and the X-axis negative side of the notch 10a, respectively. The hole 10b is for guiding an ink supply tube (not shown) into the inside of the housing 10.

The head base 12 is a frame body having a rectangular opening 12a in the center that passes through the head base 12 vertically. A head chip 13 shown in FIG. 3 is provided at the lower end of the opening 12a. A circuit board 11 and an FPC (Flexible Printed Circuit) are electrically connected to the head chip 13 within the opening 12a.

As shown in FIG. 3, the head chip 13 has a structure in which an actuator substrate 30 (element substrate), a channel substrate 40 (channel member), and a nozzle substrate 50 are stacked in this order. The actuator substrate 30, the channel substrate 40, and the nozzle substrate 50 are rectangular parallelepiped plates, and have the same shape when viewed from the Z direction. The actuator substrate 30 and the flow path substrate 40 are bonded together with an adhesive. Further, the flow path substrate 40 and the nozzle substrate 50 are bonded together via an adhesive.

Four main channels 21 extending in the X-axis direction are formed in the channel substrate 40.
Four ink supply ports 30a are formed in line in the Y-axis direction at an end on the X-axis positive side and an end on the X-axis negative side of the actuator board 30, respectively. Each ink supply port 30a is connected to one main channel 21, respectively.

FIG. 4 is an enlarged view of the end of the actuator board 30 on the positive side in the X-axis direction.
A plurality of pressure chambers 22 are provided in the actuator substrate 30 along the main flow path 21. Specifically, a groove is formed on the back surface of the actuator substrate 30 at a position corresponding to the pressure chamber 22, and when the actuator substrate 30 is stacked on the channel substrate 40, the groove on the back surface of the actuator substrate 30 and the channel substrate A pressure chamber 22 is formed between the pressure chamber 22 and the upper surface of the pressure chamber 40 . The pressure chamber 22 is connected to the main flow path 21 via a communication flow path 23 (see FIG. 5) formed in the flow path substrate 40.

Note that terminal groups (not shown) for connecting the FPC of the circuit board 11 are provided at the Y-axis negative end and the Y-axis positive end of the top surface of the actuator board 30, respectively. This terminal group is for applying a voltage (drive signal) to the piezoelectric layer 34 (see FIG. 5) of the actuator substrate 30.

As described above, the end of the main flow path 21 is connected to the ink supply port 30a. A large number of pressure chambers 22 are arranged along the main flow path 21 , and each pressure chamber 22 is connected to the main flow path 21 by a communication flow path 23 .

Returning to FIG. 3, ink supply tubes (not shown) are connected to each of the eight ink supply ports 30a, and ink is supplied from the ink supply tubes. The ink supplied to the ink supply port 30a is supplied to the pressure chamber 22 through the main flow path 21 and the communication flow path 23. In this embodiment, ink of the same color is supplied to the four main channels 21. However, the invention is not limited to this, and inks of different colors may be supplied to each main flow path 21 so that one inkjet head 1 can eject four colors of ink.

FIG. 5 is a diagram showing a cross section of the head chip 13 perpendicular to the X axis.
As shown in FIG. 5, the flow path substrate 40 is provided with a main flow path 21, a communication flow path 23, and a through flow path 24. The communication channel 23 extends from the negative side of the main channel 21 in the Z-axis direction and is connected to the pressure chamber 22 . The through passage 24 penetrates the passage substrate 40 so as to connect the pressure chamber 22 and the nozzle 51 of the nozzle substrate 50 . The main flow path 21, the communication flow path 23, and the through flow path 24 correspond to "an ink flow path through which ink supplied to the nozzle flows."

A nozzle 51 that penetrates the nozzle substrate 50 is formed in the nozzle substrate 50 at a position corresponding to the through flow path 24 extending from the pressure chamber 22 in the positive direction of the Z-axis. The nozzle 51 has a shape whose diameter gradually decreases in the positive direction of the Z-axis, and the diameter is uniform near the exit. The material of the nozzle substrate 50 is not particularly limited, but may be silicon, for example.

The actuator substrate 30 includes a pressure chamber layer 31 in which the pressure chambers 22 are formed, a diaphragm 32 laminated on the top of the pressure chamber layer 31 (on the negative side in the Z-axis direction), an insulating layer 33, and a piezoelectric layer 34 ( pressure variation element) and an electrode layer 35. The diaphragm 32, the insulating layer 33, the piezoelectric layer 34, and the electrode layer 35 can be formed by a vacuum film forming technique such as a sputtering method. These layers may be formed by other film forming techniques such as coating. The pressure chamber layer 31 can be formed using a thick film forming technique such as a plating method or a metal plate etching method. The pressure chamber 22 is formed by bonding the channel substrate 40 to the lower surface of the pressure chamber layer 31. The diaphragm 32 is made of a conductive metal material and also serves as a lower electrode (common electrode) of the piezoelectric layer 34. The insulating layer 33 insulates the diaphragm 32 from the piezoelectric layer 34 . That is, the insulating layer 33 blocks voltage application to the piezoelectric layer 34 other than the piezoelectric functional region R1.

The piezoelectric layer 34 is made of, for example, lead zirconate titanate (PZT). The thickness of the piezoelectric layer 34 is approximately several μm. The electrode layer 35 is formed of a conductive material. The electrode layer 35 is made of, for example, titanium containing a noble metal. The thickness of the electrode layer 35 is approximately 0.2 μm.

By applying a voltage to the electrode layer 35, the piezoelectric layer 34 is deformed in the Z-axis direction in the piezoelectric functional region R1, and the diaphragm 32 is accordingly deformed. When the diaphragm 32 deforms downward in the piezoelectric functional region R1, the volume of the pressure chamber 22 decreases, and the pressure of the ink 60 filled in the pressure chamber 22 increases. Furthermore, when the diaphragm 32 deforms upward in the piezoelectric functional region R1, the volume of the pressure chamber 22 increases, and the pressure of the ink 60 filled in the pressure chamber 22 decreases. By varying the pressure of the ink 60 in a predetermined order (for example, by increasing the pressure after decreasing the pressure), droplets 61 of the ink 60 are ejected from the nozzle 51 that communicates with the pressure chamber 22 via the through flow path 24. be done.

Each of the pressure chamber layer 31, the diaphragm 32, the insulating layer 33, the piezoelectric layer 34, and the electrode layer 35 does not necessarily have to be a single layer, and may be formed of a plurality of layers. Furthermore, another layer may be arranged between each layer.

FIG. 6 is a diagram schematically showing the arrangement of the nozzles 51 on the nozzle substrate 50.
As shown in FIG. 6, a plurality of nozzles 51 are arranged in a line on the nozzle substrate 50. On the nozzle substrate 50, rows L1 to L4 of four nozzles 51 are arranged. For example, several hundred nozzles 51 are provided in each of the rows L1 to L4 at regular intervals. Moreover, each nozzle row is provided in a positional relationship in which the positions of the nozzles 51 in the X-axis direction are shifted from each other. The number of nozzles 51 in each row is not limited to this.

FIG. 7 is a partial perspective view showing a cross section of the structure of the head chip 13 near the pressure chamber 22. As shown in FIG.
As shown in FIG. 7, the channel substrate 40 has a plurality of (here, 11) plate-like members 401 to 411 stacked in order in the Z-axis direction. The plate members 401 to 411 have the same rectangular outer shape when viewed from the Z-axis direction, and have upper and lower surfaces parallel to the XY plane. The material of the plate members 401 to 411 is, for example, SUS (stainless steel), but is not limited to this. A plate-like member 401 is arranged at the end on the negative side in the Z-axis direction, and this plate-like member 401 is joined to the actuator substrate 30 via an adhesive. Further, a plate-like member 411 is arranged at the end on the positive side in the Z-axis direction, and this plate-like member 411 is joined to the nozzle substrate 50 via an adhesive.

Among the plate members 401 to 411, the third plate member 409 from the bottom is thinner than the other plate members, and functions as a damper for the main flow path 21. This damper is for absorbing pressure waves applied from the communication flow path 23 to the main flow path 21 when the actuator board 30 is driven and the diaphragm 32 is displaced in the Z-axis direction.
The thickness of the plate members 401 to 408, 410, and 411 excluding the plate member 409 is approximately 200 μm.

Through holes 401a to 411a, which become part of the through flow path 24, are formed in the plate members 401 to 411, respectively. The plate members 401 to 411 are arranged in a positional relationship such that the through holes 401a to 411a communicate with each other to form the through flow path 24. In other words, the through flow path 24 is constituted by the plurality of through holes 401a to 411a communicating across the plate members 401 to 411. The opening shape of the through holes 401a to 411a is circular with a diameter of about 160 μm.

Further, the plate members 401 to 411 are arranged in a positional relationship in which the centers of the plurality of through holes 401a to 411a are shifted in a random direction parallel to the joining surface S0 (a plane perpendicular to the Z axis) between the plate members. ing. However, the amount of deviation of the plate members 401 to 411 is within a range in which the through flow path 24 as a whole extends in the Z-axis direction. Specifically, the amount of deviation of the plate-like members 401 to 411 is determined by the difference between the center of the through hole 401a of the plate-like member 401 at the negative end in the Z-axis direction and the penetration of the plate-like member 411 at the positive end in the Z-axis direction. The distance from the center of the hole 411a in the XY plane (in a plane parallel to the bonding surface S0) is within a range of 1/3 or less of the maximum width of the through hole. Here, the maximum width of the through holes in the through holes 401a to 411a is defined as the maximum width of each through hole in a plane parallel to the joint surface S0 (diameter in this embodiment). This is the maximum width. In the present embodiment, the maximum width of the through hole is 168 μm due to variations in the shape of the through hole, and the above-mentioned “within a range of 1/3 or less of the maximum width of the through hole” corresponds to 56 μm or less. Further, the center of the through hole is the area center of gravity of the opening shape of the through hole when the through hole is viewed from the Z-axis direction. Since the centers of the through holes are shifted in random directions, the through flow path 24 has irregularities on its inner wall surface. This feature will be detailed later.

Holes 401b and 402b forming the communication channel 23 are formed in the plate members 401 and 402, respectively. The opening shape of the hole 401b is approximately circular. Further, the diameter of the hole 402b is smaller than the diameter of the hole 401b.

Openings 403b to 408b are formed in the plate members 403 to 408, respectively, in areas corresponding to the main flow path 21. In other words, the main flow path 21 is constituted by the communicating openings 403b to 408b.
Furthermore, an opening 410b having the same shape as the openings 403b to 408b is formed in the plate member 410. The space formed by the opening 410b forms an air chamber into which ink does not flow. This air chamber and the main flow path 21 are partitioned off by a plate member 409 (damper).

The plate members 401 to 411 are diffusion bonded by, for example, a thermal diffusion method. However, the present invention is not limited to this, and the plate-like members may be joined together with an adhesive.
By bonding the plate-like member 401 and the actuator substrate 30 with an adhesive, the communication channel 23 and the pressure chamber 22 communicate with each other, and the pressure chamber 22 and the through channel 24 communicate with each other. Moreover, by joining the plate member 411 and the nozzle substrate 50 with an adhesive, the through flow path 24 and the nozzle 51 are communicated with each other.

By the way, when the actuator substrate 30 and the nozzle substrate 50 are bonded to the flow path substrate 40 with an adhesive, excess adhesive may overflow into the through flow path 24. In the conventional configuration in which the inner wall surface of the through-flow channel 24 is not provided with unevenness, this adhesive flows along the through-flow path 24, and the adhesive flows into the nozzle 51, clogging the nozzle 51, or causing damage to the actuator. There is a problem in that the adhesive adheres to the diaphragm 32 of the substrate 30, causing abnormal pressure fluctuations of the ink within the pressure chamber 22.
Specifically, after bonding the nozzle substrate 50 to the channel substrate 40, when bonding the actuator substrate 30 from above with an adhesive with the nozzle substrate 50 at the lowest position in the vertical direction, the adhesive may not be applied to the through channel 24. If it overflows, this adhesive flows vertically downward toward the nozzle substrate 50 and reaches the nozzle 51.
Furthermore, after bonding the actuator substrate 30 to the channel substrate 40, when bonding the nozzle substrate 50 from above with an adhesive while the actuator substrate 30 is at the bottom in the vertical direction, the adhesive overflows into the through channel 24. Once released, this adhesive flows vertically downward toward the actuator board 30 and reaches the diaphragm 32.

In contrast, in the inkjet head 1 of the present embodiment, the centers of the through holes 401a to 411a forming the through channel 24 are shifted in random directions, so that the inner wall surface of the through channel 24 is uneven. ing. These irregularities block the adhesive and prevent it from reaching the nozzle 51 and the diaphragm 32.

FIG. 8 is an enlarged view showing a cross section of the through flow path 24. As shown in FIG.
The cross section in FIG. 8 is a cross section passing through the through flow path 24 and perpendicular to the joint surface S0 (here, a cross section perpendicular to the joint surface S0 and the X axis), and passing through the center of any one of the through holes 401a to 411a. It is a cross section.

As shown in FIG. 8, through holes 403a and 405a provided in two non-adjacent plate members 403 and 405 among the plate members 401 to 411 are defined as first through holes, and these plate members 403 and 405 When the through hole 404a provided in the plate-like member 404 located between the holes is used as the second through hole, the first through hole is The inner wall surface S2 of the one side of the second through hole protrudes toward the through flow path 24 side (the negative side in the Y-axis direction).

As a result, when viewed from the negative side in the Z-axis direction, the inner wall surface S2 of the through hole 404a as the second through hole is closer to the through flow path 24 than the inner wall surface S1 of the through hole 403a as the first through hole. By protruding to the side, a stepped portion A1 is formed. When the adhesive overflowing into the through flow path 24 flows to the positive side in the Z-axis direction, the adhesive is dammed up by this stepped portion A1.
Furthermore, when viewed from the positive side in the Z-axis direction, the inner wall surface S2 of the through hole 404a as the second through hole is on the through flow path 24 side with respect to the inner wall surface S1 of the through hole 405a as the first through hole. A stepped portion B1 is formed by protruding from the bottom. When the adhesive overflowing into the through flow path 24 flows to the negative side in the Z-axis direction, the adhesive is dammed up by this stepped portion B1.

In addition, in the direction parallel to the joint surface S0 in the cross section of FIG. 8, with respect to the center position C2 of the through hole 404a as the second through hole in the cross section, the through hole 403a as the first through hole in the cross section, The center position C1 of 405a is shifted in the same direction (positive side in the Y-axis direction). By stacking the plate-like members 403 to 405 in such a positional relationship, it is possible to provide the stepped portions A1 and B1 while suppressing the overall inclination of the through flow path 24 to facilitate ink flow. Here, the center positions C1 and C2 are the center positions of the gap formed by the through hole in the cross section of FIG. 8, and do not necessarily coincide with the center of the through hole as seen from the Z-axis direction.

Similarly, through holes 401a and 404a provided in two non-adjacent plate members 401 and 404 are defined as first through holes, and through holes 401a and 404a provided in plate members 402 and 403 between these plate members 401 and 404 are defined as first through holes. When the through-holes 402a and 403a are used as second through-holes, with respect to the inner wall surface S1 on one side (negative side in the Y-axis direction) of the first through-hole, the corresponding one side of the second through-hole An inner wall surface S2 protrudes toward the through flow path 24 side (positive side in the Y-axis direction).
As a result, when viewed from the negative side in the Z-axis direction, the inner wall surface S2 of the through holes 402a and 403a as the second through hole has a through flow relative to the inner wall surface S1 of the through hole 401a as the first through hole. By protruding toward the path 24 side, a stepped portion A2 is formed. When the adhesive overflowing into the through flow path 24 flows to the positive side in the Z-axis direction, the adhesive is dammed up by this stepped portion A2.
Also, when viewed from the positive side in the Z-axis direction, the inner wall surface S2 of the through holes 402a and 403a as the second through hole is the through flow path with respect to the inner wall surface S1 of the through hole 404a as the first through hole. By protruding toward the 24 side, a stepped portion B2 is formed. When the adhesive overflowing into the through flow path 24 flows to the negative side in the Z-axis direction, the adhesive is dammed up by the stepped portion B2.
Regarding the through holes 401a and 404a as the first through holes and the through holes 402a and 403a as the second through holes, the center position of the two first through holes is They are shifted in the same direction (here, the negative side in the Y-axis direction).

In FIG. 8, a cross section perpendicular to the joint surface S0 and the X-axis is illustrated, but in any cross section that passes through the through flow path 24 and is perpendicular to the joint surface S0, a stepped portion is formed at any position in the Z-axis direction. It would be fine if it had been done.
Further, the position in the Z-axis direction where the step portion is formed and the number of step portions are not limited to the example shown in FIG. 8 .

Furthermore, the adhesive used is a material that does not swell due to contact with ink. Thereby, it is possible to prevent the adhesive blocked at the stepped portion from swelling and obstructing the flow of ink in the through channel 24.
Further, it is desirable that the adhesive be made of a material that does not dissolve in the ink. Thereby, it is possible to suppress the occurrence of problems (deterioration of image quality, etc.) caused by the adhesive blocked at the stepped portion being dissolved and the quality of the ink being altered.

FIG. 9 is a diagram showing a region where a step portion is formed in the through flow path 24 when viewed from the negative side in the Z-axis direction. In the following, a plate-like member provided with a first through-hole is also referred to as a "first plate-like member", and a plate-like member provided with a second through-hole is referred to as a "second plate-like member". Also written as
The step portion includes, when viewed from the Z-axis direction, an inner wall surface S1 of the first through hole and a portion of the inner wall surface S2 of the second through hole that is exposed (projects) inside the first through hole. , is the area surrounded by . More specifically, the step portion is formed between the opening of the first through hole on the second plate-like member side and the opening of the second through-hole on the first plate-like member side, when viewed from the Z-axis direction. This is a region surrounded by a portion exposed (protruding) inside the first through hole. In other words, the stepped portion is located inside the second through hole when viewed from the Z-axis direction on the surface of the second plate-shaped member on the first plate-shaped member side (the surface perpendicular to the Z-axis). This is the exposed (protruding) part.
FIG. 9A is a diagram of the opening position of the through hole 401a of the plate member 401 viewed from the negative side in the Z-axis direction. A stepped portion A2 formed by protruding an inner wall surface S2 of the through hole 402a of the plate-like member 402 from an inner wall surface S1 of the through hole 401a is exposed in the opening of the through hole 401a. This stepped portion A2 is provided from the 5 o'clock direction to the 11 o'clock direction of the inner wall surface of the through flow path 24 in FIG. 9(a). The stepped portion A2 has a crescent shape surrounded by the inner wall surfaces S1 and S2 of the through holes 401a and 402a.

If the amount of protrusion of the inner wall surface S2 in the direction from each position of the inner wall surface S1 toward the center O of the through hole 402a as the second through hole is defined as the step of the stepped portion A2, the maximum value W of the step is: The thickness is 5 μm or more and 20 μm or less. Specifically, since the error in diameter that may occur when forming the through holes 401a to 411a (diameter 160 μm) is ±10 μm, and the amount of random positional deviation of the plate members 401 to 411 is 10 μm, the maximum value W of the step difference is is 20 μm or less.

FIG. 9B is a diagram of the opening position of the through hole 403a of the plate member 403 viewed from the negative side in the Z-axis direction. A stepped portion A1 formed by protruding an inner wall surface S2 of the through hole 404a of the plate-like member 404 from an inner wall surface S1 of the through hole 403a is exposed in the opening of the through hole 403a. This stepped portion A1 is provided from the 12 o'clock direction to the 6 o'clock direction on the inner wall surface of the through flow path 24 in FIG. 9(b). The maximum value of the step in the step A1 is also 5 μm or more and 20 μm or less, similar to the step A2.

FIG. 9(c) is a diagram of the opening position of the through hole 405a of the plate member 405 viewed from the negative side in the Z-axis direction. A stepped portion A3 formed by protruding the inner wall surface S2 of the through hole 406a of the plate-like member 406 from the inner wall surface S1 of the through hole 405a is exposed in the opening of the through hole 405a. This stepped portion A3 is provided from the 10 o'clock direction to the 4 o'clock direction on the inner wall surface of the through flow path 24 in FIG. 9(c). The maximum value of the level difference of the level difference part A3 is also 5 μm or more and 20 μm or less, similar to the level difference part A2.
In the cross section shown in FIG. 8, there is almost no deviation between the plate-like member 405 and the plate-like member 406 in the Y-axis direction, but as shown in FIG. The stepped portion A3 is formed by shifting the plate member 406 mainly in the X-axis direction. In this way, the deviation between the plate-shaped members forming the stepped portion (the deviation of the centers O of the through holes 401a to 411a) is not limited to one direction (for example, the Y-axis direction), but may be caused within the XY plane (parallel to the joint surface S0). Random directions within the plane) are included.

FIG. 9(d) is a diagram showing the stepped portions A1 to A3 superimposed.
Since the centers O of the through holes 401a to 411a are shifted in random directions within the XY plane, as shown in FIG. One of a plurality of step portions A1 to A3 having different positions (orientations) in the Z-axis direction is provided. Thereby, even if the adhesive overflows to any position on the outer periphery of the through-flow channel 24, the adhesive can be dammed up by one of the stepped portions.
Although the explanation has been given using an example in which the outer periphery of the through flow path 24 is covered by three stepped portions A1 to A3, the present invention is not limited to this, and two or four or more stepped portions having different positions in the Z-axis direction are used. The outer periphery of the through flow path 24 may be covered by the stepped portions A1 to A3.
Also, when viewed from the positive side in the Z-axis direction, it is desirable that the outer periphery of the through flow path 24 be covered by a plurality of step portions including step portions B1 and B2 shown in FIG. Thereby, the adhesive can be effectively dammed up even when the adhesive flows in any direction in the Z-axis direction.

In the example described above, the inner wall surfaces of the through holes 401a to 411a were smooth surfaces parallel to the Z-axis direction, but in order to more reliably dam up the adhesive, at least some of the inner walls of the through holes 401a to 411a were More preferably, the wall surface has a convex portion that protrudes toward the through channel 24 side.

FIG. 10 is an enlarged view showing a cross section of the through flow path 24 in a configuration in which the inner wall surface of the through hole has a convex portion.
In the example shown in FIG. 10, the inner wall surfaces of the through holes 401a to 411a of each of the plate members 401 to 411 have convex portions D that protrude toward the through flow path 24 side. However, since the plate member 409 is a thin plate that functions as a damper, the inner wall surface of the through hole 409a does not need to have the protrusion D. The convex portion D is provided over the entire circumference of the inner wall surface of each through hole. In the configuration having the convex portion D, the above-mentioned step is formed from the inner wall surface S1 of the first through hole (more specifically, the opening of the first through hole on the second plate member side) when viewed from the Z-axis direction. Since the convex part protrudes further in addition to the part, it becomes possible to dam the adhesive more reliably.
The projection D has a protrusion amount of 5 μm or more and 30 μm or less in the direction toward the center of the through hole of the plate-like member in which the projection D is provided. In addition, when the amount of protrusion of the convex portion D is not uniform over the entire circumference of the inner wall surface, a configuration may be adopted in which the maximum value of the amount of protrusion is 5 μm or more and 30 μm or less. By setting such a protrusion amount, it is possible to secure a flow area in which ink can flow properly in the through flow path 24 in a configuration in which the maximum value of the step of the step portion is 5 μm or more and 20 μm or less. Here, the standard for the amount of protrusion of the convex portion D can be the opening position of the through hole, that is, the position of the edge of the opening of the through hole on the surface of the plate-like member.

The convex portion D can be formed by etching the plate-like members 401 to 411 from one side and the other side, respectively.

FIG. 11 is a cross-sectional view illustrating a method of forming the convex portion D.
In FIG. 11, a case where a convex portion D is formed on a plate-like member 401 will be described as an example.
First, a resist 70 is formed on one side of the plate member 401 except for the area where the through hole 401a is formed (FIG. 11(a)). Although not shown, the resist 70 is formed in a region excluding the region where the hole 401b is formed.

Next, the plate member 401 is etched using a predetermined etching solution using the resist 70 as a mask (FIG. 11(b)). Here, the etching amount is about 1/2 of the thickness of the plate member 401.

Next, a resist 70 is formed on the other surface of the plate member 401 except for the area where the through hole 401a is formed (FIG. 11(c)), and using the resist 70 as a mask, a predetermined etching solution is used to form a plate. The member 401 is etched from the other side (FIG. 11(d)). As shown in FIGS. 11(b) and 11(d), in the etching of the plate-like member 401, the etching proceeds equidistantly from the edge of the resist 70, so that at the outer edge of the etched area, the plate-like shape after etching is The inner wall surface of the member becomes curved. Convex portions D are formed by curved surfaces formed by etching from each side of the plate member 401, respectively.
After the etching is completed, the resist 70 is removed to obtain a plate-like member 401 having a convex portion D on the inner wall surface of the through hole 401a.

Next, a method for manufacturing the inkjet head 1 will be described.
FIG. 12 is a flowchart showing the steps of the manufacturing process of the inkjet head 1.
In the manufacturing process of the inkjet head 1, first, the through holes 401a to 411a are formed in the plate members 401 to 411 by the method described using FIG. 11 (step S101: first step). In this step S101, holes 401b, 402b, and openings 403b to 408b, 410b are formed together with the through holes 401a to 411a.

Next, the plate-like members 401 to 411 are arranged in a positional relationship in which the through holes 401a to 411a communicate with each other and the centers of the through holes 401a to 411a are shifted in random directions, that is, in a positional relationship in which the step portion described above is formed. The flow path substrate 40 is formed by stacking (step S102: second process).

Next, the actuator substrate 30 created in advance is bonded to the plate member 401 of the channel substrate 40 via an adhesive (step S103). Further, the nozzle substrate 50 prepared in advance is bonded to the plate member 411 of the channel substrate 40 via an adhesive (step S104). This completes the head chip 13. Note that the order of steps S103 and S104 may be changed.

Finally, each component of the inkjet head 1 including the head chip 13 is assembled into the housing 10 and the head base 12 (step S105), and the inkjet head 1 is completed.

As described above, the inkjet head 1 according to the present embodiment includes the nozzle 51 for ejecting ink, and the channel substrate 40 provided with the ink channel through which the ink supplied to the nozzle 51 flows. The substrate 40 has stacked plate members 401 to 411, and the plate members 401 to 411 are arranged in a positional relationship such that through holes 401a to 411a provided in each of the plate members 401 to 411 communicate with each other. At least a part of the ink flow path is a through flow path 24 consisting of through holes 401a to 411a that communicate across the plate members 401 to 411, and any of the plate members 401 to 411 that are not adjacent The through holes provided in each of the two plate members are referred to as first through holes, and the through holes provided in each of one or more plate members located between the two plate members are referred to as second through holes. In this case, in any cross section that passes through the through flow path 24 and is perpendicular to the joining surface of the plate members 401 to 411, the second through hole is connected to the inner wall surface S1 on one side of the first through hole. The inner wall surface S2 on one side of the hole protrudes toward the through-flow path 24 side, and in the direction parallel to the joint surface S0 in the cross-section, the center position C2 of the second through-hole in the cross-section is 2. The center positions C1 of the two first through holes are shifted in the same direction.
According to such a configuration, a step portion is formed in a portion where the inner wall surface S2 of the second through hole protrudes toward the through flow path 24 side with respect to the inner wall surface S1 of the first through hole. Therefore, even if the adhesive overflows into the through-flow path 24 when bonding the actuator board 30 or the nozzle board 50 to the flow-path substrate 40 via an adhesive, the adhesive will flow along the inner wall surface of the through-flow path 24. The adhesive flowing in the Z-axis direction can be stopped by this stepped portion. Therefore, problems caused by the adhesive overflowing into the through flow path 24 coming into contact with the nozzle substrate 50 or the actuator substrate 30 (for example, the adhesive flowing into the nozzle 51 and clogging the nozzle 51, or the adhesive contacting the diaphragm 32) It is possible to suppress the occurrence of a problem in which an abnormality occurs in the pressure fluctuation of the ink due to the piezoelectric layer 34 due to contact. Furthermore, the plate-like members 401 to 411 are stacked in a positional relationship in which the center position C1 of the two first through holes is shifted in the same direction with respect to the center position C2 of the second through hole. Although the stepped portion is provided, the overall inclination of the through flow path 24 can be suppressed to facilitate ink flow.

Further, the plate-like members 401 to 411 are arranged in a positional relationship in which the center O of the through hole provided in each plate-like member is shifted in a random direction parallel to the joint surface S0. Thereby, the stepped portions can be formed evenly at each position on the outer periphery of the through flow path 24 when viewed from the Z-axis direction.

Further, when the step portion is a portion where the inner wall surface S2 of the second through hole protrudes toward the through flow path 24 side with respect to the inner wall surface S1 of the first through hole when viewed from the direction perpendicular to the joint surface S0. In addition, any one of a plurality of step portions having different positions in the direction perpendicular to the joint surface S0 is provided at an arbitrary position on the outer periphery of the through-flow channel 24 when viewed from the above direction. Thereby, even if the adhesive overflows to any position (orientation) on the outer periphery of the through-flow channel 24 as viewed from the Z-axis direction, the adhesive can be dammed up by one of the stepped portions.

In addition, in the direction toward the center O of the second through hole, if the amount of protrusion of the inner wall surface S2 of the second through hole at the step portion from the inner wall surface S1 of the first through hole is defined as the step difference, The maximum value of the step is 5 μm or more and 20 μm or less. By making the step difference 5 μm or more, the adhesive can be effectively blocked at the step portion. Further, by setting the level difference to 20 μm or less, smooth flow of ink in the through flow path 24 can be ensured.

Furthermore, the inner wall surfaces of at least some of the through holes 401a to 411a of the plate members 401 to 411 have convex portions D that protrude toward the through flow path 24 side. According to this, the adhesive overflowing into the through flow path 24 can also be dammed up by the convex portion D. Therefore, since the adhesive can be dammed up more reliably, it is possible to more effectively suppress the occurrence of problems caused by the adhesive.

Further, the protrusion amount of the convex portion D in the direction toward the center O of the through hole is 5 μm or more and 30 μm or less. By setting the protrusion amount of the convex portion D to 5 μm or more, the adhesive can be effectively dammed up at the convex portion D. Further, by setting the protrusion amount of the convex portion D to 30 μm or less, smooth flow of ink in the through flow path 24 can be ensured.

Further, when the maximum value of the width of each through hole in a plane parallel to the joint surface S0 is taken as the through hole width, and the maximum value of the through hole widths in the through holes 401a to 411a is taken as the through hole maximum width, the plate-like member The distance between the center of the through hole 401a of the plate member 401 at one end of 401 to 411 and the center of the through hole 411a of the plate member 411 at the other end in the direction parallel to the joint surface S0 is 1/3 or less of the maximum width of the through hole. Thereby, it is possible to suppress the overall inclination of the through flow path 24 and make it easier for the ink to flow.

Further, the flow path substrate 40 includes a nozzle substrate 50 provided with a nozzle 51 communicating with the ink flow path, and an actuator substrate provided with a pressure variation element that changes the pressure of ink in a pressure chamber communicating with the ink flow path. At least one of 30 is bonded via an adhesive, and the adhesive is a material that does not swell upon contact with ink. Thereby, it is possible to prevent the adhesive blocked at the stepped portion from swelling and obstructing the flow of ink in the through channel 24.

Furthermore, since the inkjet recording apparatus of this embodiment includes the inkjet head 1 described above, it is possible to suppress the occurrence of problems caused by the adhesive overflowing into the through flow path 24 of the inkjet head 1. Therefore, deterioration in image quality caused by the adhesive can be suppressed.

Further, the method for manufacturing the inkjet head 1 of the present embodiment includes a first step of forming through holes 401a to 411a in each of the plate members 401 to 411, and a position where the through holes communicate with the plate members 401 to 411. a second step of forming a through flow path 24 consisting of through holes 401a to 411a communicating across plate-like members 401 to 411 and forming at least a part of the ink flow path by laminating them in a relationship; In the second step, the through holes provided in any two of the plate members 401 to 411 that are not adjacent to each other are called the first through holes, and the through holes 1 or 2 between the two plate members are used as the first through holes. When the through holes provided in each of the above plate-like members are defined as second through-holes, in any cross section that passes through the through flow path 24 and is perpendicular to the joint surface of the plate-like members 401 to 411, the first through hole is With respect to the inner wall surface S1 on one side of the second through hole, the inner wall surface S2 on one side of the second through hole protrudes toward the through flow path 24 side, and in the direction parallel to the joint surface S0 in the above cross section, the above The plate members 401 to 411 are stacked such that the center position C1 of the two first through holes in the cross section is shifted in the same direction with respect to the center position C2 of the second through hole in the cross section.
As a result, a stepped portion can be formed on the inner wall surface of the through-flow path 24, so that the adhesive overflowing into the through-flow path 24 can be dammed up by the stepped portion. Therefore, it is possible to suppress the occurrence of problems caused by the adhesive overflowing into the through flow path 24 coming into contact with the nozzle substrate 50 or the actuator substrate 30. In addition, by stacking the plate members 401 to 411 in a positional relationship in which the center position C1 of the two first through holes is shifted in the same direction with respect to the center position C2 of the second through hole, the step While providing a portion, it is possible to suppress the overall inclination of the through flow path 24 and make it easier for ink to flow.

In addition, in the first step, by etching the plate-like members from one side and the other side of each of the plate-like members 401 to 411, the inner wall surface has a convex portion protruding toward the through flow path 24 side. A through hole is formed. Thereby, the protrusions D can be formed on the inner wall surfaces of the through holes 401a to 411a, and the adhesive overflowing into the through flow path 24 can also be dammed up by the protrusions D. Therefore, the adhesive can be blocked more reliably, and the occurrence of defects caused by the adhesive can be more effectively suppressed.

Note that the present invention is not limited to the above-described embodiment and each modification, and various changes are possible.
For example, the shape of the through holes 401a to 411a when viewed from the Z-axis direction is not limited to a circle, but may be other shapes such as an ellipse or a rectangle.

Further, in the above embodiment, as shown in FIG. 9(d), a plurality of steps having different positions in the Z-axis direction are provided at arbitrary positions (azimuths) on the outer periphery of the through flow path 24 when viewed from the Z-axis direction. Although the description has been given by taking as an example a configuration in which any one of the sections A1 to A3 is provided, the present invention is not limited to this, and a stepped section may be provided in a part of the outer periphery of the through flow path 24 when viewed from the Z-axis direction. Good too.

Moreover, although the through-flow path 24 is exemplified as one that directly connects the lower surface of the pressure chamber 22 and the nozzle 51, the arrangement position of the through-flow path 24 in the head chip 13 is not limited to this.

Further, in the above embodiment, the through-flow path 24 is explained using an example in which it penetrates all the plate-like members 401 to 411 that constitute the flow path substrate 40, but the present invention is not limited to this. The through flow path 24 may penetrate through some of the plate members that constitute the flow path substrate 40 . In this case, the part of the plate-like members corresponds to "a plurality of plate-like members".

Further, in the above embodiment, the maximum value of the step of the step portion is 5 μm or more and 20 μm or less, and the protrusion amount of the convex portion D is 5 μm or more and 30 μm or less. The numerical value may be exceeded as long as it does not interfere. For example, when the inner wall surface of the through-hole does not have the convex portion D, the ink flow area is secured accordingly, so that the maximum value of the step difference in the step portion can be set to a value larger than 20 μm.
Moreover, not all the step portions necessarily satisfy the condition that "the maximum value of the step is 5 μm or more and 20 μm or less." Furthermore, not all of the convex portions D need to satisfy the condition that "the amount of protrusion is 5 μm or more and 30 μm or less."

Furthermore, in the above embodiment, the plurality of plate-like members are stacked in a positional relationship in which the centers of the plurality of through-holes are shifted in a random direction parallel to the bonding surface S0 of the plate-like members, but the present invention is not limited to this. I can't. For example, the plurality of plate-like members may be stacked in a positional relationship in which the centers of the plurality of through holes are shifted from each other by a predetermined regularity in a shift amount and a shift direction.

Further, in the above embodiment, the single-pass type inkjet printing apparatus 100 has been described as an example, but the present invention may be applied to an inkjet printing apparatus that prints an image while scanning the printhead.

Although several embodiments of the present invention have been described, the scope of the present invention is not limited to the above-described embodiments, but includes the scope of the invention described in the claims and equivalents thereof. .

1 Inkjet head 10 Housing 11 Circuit board 12 Head base 13 Head chip 21 Main channel 22 Pressure chamber 23 Communication channel 24 Through channel 30 Actuator board (element board)
30a Ink supply port 31 Pressure chamber layer 32 Vibration plate 33 Insulating layer 34 Piezoelectric layer (pressure variation element)
35 Electrode layer 40 Channel substrate (channel member)
50 Nozzle substrate 51 Nozzle 60 Ink 61 Droplet 70 Resist 100 Inkjet recording device 101 Conveyance belt 102 Conveyance roller 103 Head units 401 to 411 Plate members 401a to 411a Through holes 401b, 402b Holes 403b to 408b, 410b Openings A1 to A3 , B1, B2 Step portions C1, C2 Center position D Convex portion M Recording medium O Center R1 Piezoelectric functional area S0 Joint surfaces S1, S2 Inner wall surface

Claims (11)

A nozzle that ejects ink,
a flow path member provided with an ink flow path through which ink is supplied to the nozzle;
Equipped with
The flow path member includes a plurality of laminated plate members,
The plurality of plate-like members are arranged in a positional relationship such that through holes provided in each of the plurality of plate-like members communicate with each other,
At least a portion of the ink flow path is a through flow path made up of a plurality of the through holes that communicate across the plurality of plate-like members,
The through-holes provided in any two of the plurality of plate-like members that are not adjacent to each other among the plurality of plate-like members are called first through-holes, and one or more of the plates located between the two plate-like members When the through holes provided in each of the shaped members are used as second through holes,
In any cross section perpendicular to the bonding surface of the plurality of plate-like members passing through the through-flow path, the one side of the second through-hole with respect to the inner wall surface on one side of the first through-hole. a side inner wall surface protrudes toward the through-flow channel,
With respect to a direction parallel to the joint surface in the cross section, the center positions of the two first through holes in the cross section are shifted in the same direction with respect to the center position of the second through hole in the cross section, inkjet head. The inkjet head according to claim 1, wherein the plurality of plate-like members are arranged in a positional relationship such that the center of the through hole provided in each plate-like member is shifted in a random direction parallel to the bonding surface. . When a step portion is defined as a portion where the inner wall surface of the second through hole protrudes toward the through flow path with respect to the inner wall surface of the first through hole when viewed from a direction perpendicular to the joint surface,
Any one of the plurality of stepped portions having mutually different positions in the direction perpendicular to the joint surface is provided at any position on the outer periphery of the through-flow channel when viewed from a direction perpendicular to the joint surface. Item 2. The inkjet head according to item 1 or 2. A portion where the inner wall surface of the second through hole protrudes toward the through flow path side with respect to the inner wall surface of the first through hole when viewed from a direction perpendicular to the joint surface is defined as a stepped portion, and When the amount of protrusion of the inner wall surface of the second through hole in the stepped portion from the inner wall surface of the first through hole is defined as the step difference in the direction toward the center of the through hole,
The inkjet head according to claim 1, wherein the step portion has a maximum value of 5 μm or more and 20 μm or less. Any one of claims 1 to 4, wherein an inner wall surface of at least some of the through holes of the plurality of plate-like members has a convex portion protruding toward the through flow path. The inkjet head described in section. The inkjet head according to claim 5, wherein the protrusion of the convex portion has a protrusion amount of 5 μm or more and 30 μm or less in a direction toward the center of the through hole. When the maximum value of the width of each of the through holes in a plane parallel to the bonding surface is defined as the through hole width, and the maximum value of the through hole widths in the plurality of through holes is defined as the maximum through hole width,
The center of the through hole of the plate member at one end of the plurality of plate members and the center of the through hole of the plate member at the other end in a direction parallel to the joint surface. The inkjet head according to any one of claims 1 to 6, wherein the distance is 1/3 or less of the maximum width of the through hole. The flow path member includes a nozzle substrate provided with the nozzle that communicates with the ink flow path, and a device that varies the pressure of ink in a pressure chamber that communicates with the ink flow path in order to eject ink from the nozzle. At least one of the element substrates provided with the pressure variation element is bonded via an adhesive,
The inkjet head according to any one of claims 1 to 7, wherein the adhesive is a material that does not swell upon contact with ink. An inkjet recording device comprising the inkjet head according to any one of claims 1 to 8. A method for manufacturing an inkjet head, comprising: a nozzle for ejecting ink; and a flow path member including a plurality of laminated plate-like members and provided with an ink flow path through which ink supplied to the nozzle flows. ,
a first step of forming a through hole in each of the plurality of plate-like members;
The plurality of plate-like members are stacked in a positional relationship such that the through-holes communicate with each other to form at least a part of the ink flow path, and the plurality of through-holes communicate across the plurality of plate-like members. a second step of forming a through flow path;
including;
In the second step, the through-holes provided in any two non-adjacent plate-like members among the plurality of plate-like members are called first through-holes, which are located between the two plate-like members. When the through-holes provided in one or more of the plate-like members are used as second through-holes,
In any cross section perpendicular to the bonding surface of the plurality of plate-like members passing through the through-flow path, the one side of the second through-hole with respect to the inner wall surface on one side of the first through-hole. a side inner wall surface protrudes toward the through-flow channel side, and
With respect to a direction parallel to the joint surface in the cross section, the center positions of the two first through holes in the cross section are shifted in the same direction with respect to the center position of the second through hole in the cross section, A method for manufacturing an inkjet head, comprising stacking the plurality of plate-like members. In the first step, the plate-like members are etched from one side and the other side of each of the plurality of plate-like members, so that the inner wall surface has a convex portion protruding toward the through-flow channel side. The method for manufacturing an inkjet head according to claim 10, wherein the through hole is formed.

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