Head chip, liquid jet head, liquid jet recording device, and method for manufacturing head chip

Abstract

A head chip according to an aspect of the present disclosure comprises: a chip body having a plurality of pressure chambers that are formed in line in a first direction and in which a liquid is accommodated, and drive units that are disposed separately at portions facing the pressure chambers; a first drive electrode that is formed in the drive units; and a sheet-shaped protective film that is formed following the drive unit while covering the first drive electrode. Formed in the chip body is an air vent passage that connects between the pressure chambers and the outside of the chip body, and in which communication between the pressure chamber and the outside of the chip body is blocked by the protective film.

Description

Head chip, liquid jet head, liquid jet recording apparatus, and method of manufacturing head chip

[0001] This application claims priority to Japanese Patent Application No. 2023-215736, filed on December 21, 2023, the contents of which are incorporated herein by reference.

[0002] An inkjet head ejects ink onto a recording medium through a head chip. The head chip includes an actuator plate in which ejection channels are formed, and a cover plate overlaid on the actuator plate. Electrodes are formed on the inner surfaces of the ejection channels in the actuator plate. For example, Patent Document 1 listed below discloses a configuration in which the electrodes are protected by a deposited film. The deposited film is formed of an insulating material such as a paraxylylene-based resin material (e.g., Parylene (registered trademark)).

[0003] Japanese Patent Application Publication No. 2002-127431

[0004] However, in the above-mentioned conventional techniques, the deposited film is formed by a film formation method such as chemical vapor deposition (CVD). Therefore, if a film formation defect (e.g., a pinhole) occurs in the deposited film, a discontinuity is formed in the deposited film. In this case, ink may enter between the deposited film and the inner surface of the ejection channel through the discontinuity, which may cause a short circuit or corrosion of the electrode. In order to reduce the risk of film formation defect, it is necessary to ensure the thickness of the deposited film or strictly control the film formation state, which leads to a decrease in manufacturing efficiency and an increase in material costs.

[0005] The present disclosure provides a head chip, a liquid jet head, a liquid jet recording apparatus, and a method for manufacturing the head chip, which are capable of protecting electrodes while improving manufacturing efficiency and reducing costs.

[0006] In order to solve the above problems, the present disclosure employs the following aspects: (1) A head chip according to one aspect of the present disclosure comprises a chip body having a plurality of pressure chambers formed side by side in a first direction and each pressure chamber containing a liquid, and drive units each arranged in a portion facing the pressure chamber, a first drive electrode formed in the drive unit, and a sheet-like protective film formed in accordance with the drive unit while covering the first drive electrode, wherein the chip body has an air vent passage formed in the chip body that connects the inside of the pressure chamber to the outside of the chip body and whose communication between the inside of the pressure chamber and the outside of the chip body is blocked by the protective film.

[0007] According to this aspect, by covering the drive unit with a sheet-like protective film, the occurrence of discontinuities such as pinholes can be suppressed, unlike conventional configurations in which a deposited film made of a paraxylylene-based resin material (e.g., Parylene (registered trademark)) or the like is formed by a film-forming method such as CVD. This prevents liquid from reaching the first drive electrodes formed on the drive unit. This suppresses short circuits and corrosion of the first drive electrodes, providing a highly reliable head chip. Furthermore, by employing a sheet-like protective film, a simpler and less costly protective film can be provided compared to configurations in which a deposited film is formed by CVD or the like. As a result, the manufacturing efficiency of the head chip can be improved, and the cost of the head chip 32 can be reduced.

[0008] However, if there is a location where the protective film and the drive unit are not in close contact, deformation of the drive unit at the location is not easily transmitted to the liquid via the protective film. In response to this, in the head chip of this embodiment, the chip body is configured to have an air vent passage that connects the pressure chamber to the outside of the chip body and that blocks communication between the pressure chamber and the outside of the chip body via the protective film. With this configuration, since the air vent passage connects the pressure chamber to the outside of the chip body, air remaining in the pressure chamber can be efficiently discharged to the outside of the chip body during the protective film formation process. This makes it easier to generate negative pressure within the pressure chamber and draw the protective film into the pressure chamber. As a result, it is easier to adhere the protective film to the desired position (drive unit) of the pressure chamber. In this case, deformation of the drive unit is easily transmitted to the liquid via the protective film, ensuring the desired pressure generation within the pressure chamber and suppressing the degradation of ejection performance associated with the formation of the protective film.

[0009] (2) In the head chip according to the above aspect (1), it is preferable that the air vent passage extends so as to straddle the pressure chambers. According to this aspect, air can be efficiently discharged from each pressure chamber through the air vent passage. As a result, it becomes easier to adhere the protective film to the desired position (drive unit) of the pressure chamber.

[0010] (3) In the head chip according to the above aspect (2), it is preferable that an air chamber that does not contain liquid is formed in a portion of the chip body located between adjacent pressure chambers in the first direction, the protective film is provided so as to straddle the pressure chamber and the air chamber in the first direction, and the air vent passage extends so as to straddle the pressure chamber and the air chamber. According to this aspect, air can be efficiently discharged from each pressure chamber and air chamber through the air vent passage. As a result, the protective film can be easily drawn to the chip body, and the protective film can be provided at a desired position with high precision.

[0011] (4) In the head chip according to the above aspect (3), it is preferable that a second drive electrode that generates a potential difference between the air chamber and the first drive electrode is formed on the inner surface of the air chamber, a wiring hole that opens into the air chamber is formed in the chip body, and a through-wire connected to the second drive electrode is formed on the inner surface of the wiring hole. According to this aspect, the pressure chamber is also connected to the outside of the chip body through the air vent passage, the air chamber, and the wiring hole. That is, in the protective film formation process, air in the pressure chamber or the air chamber can also be discharged through the wiring hole. This simplifies the air vent passage and allows the protective film to be provided at the desired position with high precision.

[0012] (5) In the head chip according to any one of the above aspects (1) to (4), it is preferable that the pressure chamber extends in the chip body with a longitudinal direction in a second direction intersecting the first direction, and the air vent passage is connected to a central portion of the pressure chamber in the second direction. According to this aspect, in the protective film forming process, air can be vented from the central portion of the pressure chamber in the second direction. This allows air to be effectively vented throughout the entire pressure chamber, thereby preventing poor adhesion of the protective film.

[0013] (6) In the head chip according to aspect (5), it is preferable that the head chip further includes an ejection hole plate having an ejection hole formed therein and communicating with the pressure chamber, the pressure chamber opening on an opening surface of the chip body facing a third direction intersecting the second direction as viewed from the first direction, the ejection hole plate being provided on the opening surface of the chip body so as to close the opening of the pressure chamber, and the air vent passage being provided in a position of the pressure chamber overlapping the ejection hole as viewed from the third direction. According to this aspect, since the air vent passage is provided in a position overlapping the ejection hole as viewed from the third direction, the portion of the protective film covering the air vent passage elastically displaces in response to pressure fluctuations in the pressure chamber during liquid ejection. Therefore, pressure fluctuations in the pressure chamber can be alleviated during liquid ejection, making it easier to reduce variations in generated pressure between the pressure chambers.

[0014] (7) In the head chip according to any one of the above aspects (1) to (6), it is preferable that the chip body includes an actuator plate having the pressure chambers and the drive unit, and a cover plate superimposed on the actuator plate, and the air vent passage is formed in the actuator plate. According to this aspect, forming the air vent passage in the actuator plate improves the degree of freedom in designing the cover plate.

[0015] (8) In the head chip according to any one of aspects (1) to (7) above, it is preferable that the chip body includes an actuator plate having the pressure chamber and the drive unit, and a cover plate superimposed on the actuator plate, and the air vent passage is formed in the cover plate. According to this aspect, since the air vent passage is formed in the cover plate, the degree of freedom in designing the actuator plate can be improved. Furthermore, unlike when the air vent passage is formed in the actuator plate, the reduction in the surface area of ​​the drive unit due to the formation of the air vent passage can be suppressed. Therefore, it is possible to provide the air vent passage while maintaining the ejection performance.

[0016] (9) In the head chip according to any one of (1) to (7) above, the chip body includes a flow path member in which the pressure chambers are formed, and an actuator plate overlaid on the pressure chambers and having the drive unit. The drive unit has a first recess opening toward the flow path member. A second recess opening toward the opposite side of the flow path member is formed in a portion of the actuator plate located between adjacent pressure chambers in the first direction. The first drive electrode is formed on the inner surface of the first recess. The protective film is provided in the drive unit following the inner surface of the first recess. The air vent passage is preferably formed to connect the first recess and the second recess. According to this aspect, forming the first drive electrode following the inner surface of the first recess ensures a sufficient surface area for the first drive electrode. This increases the electric field generated in the actuator plate, thereby improving the pressure generated in the pressure chamber during liquid ejection. Furthermore, forming the first recess in the actuator plate increases the rigidity of the actuator plate in the Z direction. Furthermore, because the second recess is formed in the actuator plate, when the actuator plate deforms, the second recess functions as a relief portion that allows deformation of the actuator plate. This makes it easier to ensure the amount of deformation of the actuator plate. Furthermore, because the air vent passage is formed to connect the first recess and the second recess, air can be effectively discharged from within the first recess during the protective film formation process. This makes it easier to adhere the protective film to the inner surface of the first recess.

[0017] (10) A liquid jet head according to an aspect of the present disclosure preferably includes the head chip according to any one of the above aspects (1) to (9). According to this aspect, since the liquid jet head includes the head chip according to the above aspect, it is possible to provide a liquid jet head with excellent reliability.

[0018] (11) A liquid jet recording apparatus according to an aspect of the present disclosure preferably includes the liquid jet head according to aspect (10). According to this aspect, since the liquid jet recording apparatus includes the head chip according to the aspect, it is possible to provide a highly reliable liquid jet recording apparatus.

[0019] (12) A method for manufacturing a head chip according to one aspect of the present disclosure includes a chip body having a plurality of pressure chambers formed in a first direction and containing liquid, and drive units each arranged on a portion facing the pressure chamber, a first drive electrode formed on the drive unit, and a sheet-like protective film formed to conform to the drive unit while covering the first drive electrode, wherein the chip body has an air vent passage formed therein that connects the pressure chamber to the outside of the chip body and blocks communication between the pressure chamber and the outside of the chip body by the protective film, and the method includes a protective film forming step of applying negative pressure to the pressure chamber through the air vent passage in a space on the opposite side of the protective film from the pressure chamber, thereby adhering the protective film to the drive unit.

[0020] According to one aspect of the present disclosure, it is possible to protect the first drive wiring while improving manufacturing efficiency and reducing costs.

[0021] 6 is a schematic diagram of an inkjet printer according to a first embodiment. FIG. 6 is a schematic diagram of an inkjet head and an ink circulation mechanism according to the first embodiment. FIG. 6 is an exploded perspective view of a discharge unit according to the first embodiment. FIG. 6 is an exploded perspective view of a head chip according to the first embodiment. FIG. 6 is a bottom view of an actuator plate according to the first embodiment. FIG. 6 is a plan view of an actuator plate according to the first embodiment. FIG. 6 is a cross-sectional view corresponding to line VII-VII in FIG. 5. FIG. 6 is a cross-sectional view corresponding to line VIII-VIII in FIG. 5. FIG. 6 is a bottom view of a cover plate according to the first embodiment. FIG. 6 is a plan view of a cover plate according to the first embodiment. FIG. 6 is a cross-sectional view corresponding to line XI-XI in FIG. 6. FIG. 6 is a cross-sectional view corresponding to line XII-XII in FIG. 6. FIG. 6 is a flowchart for explaining a method of manufacturing a discharge unit according to the first embodiment. FIG. 6 is a process diagram for explaining a method of manufacturing a discharge unit according to the first embodiment. FIG. 6 is a process diagram for explaining a method of manufacturing a discharge unit according to the first embodiment. FIG. 6 is a process diagram for explaining a method of manufacturing a discharge unit according to the first embodiment. FIG. 6 is a process diagram for explaining a method of manufacturing a discharge unit according to the first embodiment. 27. A process diagram for explaining a method for manufacturing a discharge unit according to the first embodiment. A process diagram for explaining a method for manufacturing a discharge unit according to the first embodiment. A process diagram for explaining a method for manufacturing a discharge unit according to the first embodiment. A cross-sectional view of a head chip according to a modified example. A cross-sectional view of a head chip according to a second embodiment. A cross-sectional view corresponding to line XXVIII-XXVIII in FIG. 27. A cross-sectional view corresponding to line XXIX-XXIX in FIG. 27. A plan view of an actuator plate according to the second embodiment. A bottom view of an actuator plate according to the second embodiment. An exploded perspective view of a head chip according to a third embodiment. A cross-sectional view corresponding to line XXXIII-XXXIII in FIG. 32.33. A cross-sectional view corresponding to line XXXIV-XXXIV in Fig. 33. A bottom view of an actuator plate according to a third embodiment. A plan view of an actuator plate according to a third embodiment. A plan view of a cover plate according to the third embodiment. A bottom view of an actuator plate according to a modified example. A bottom view of an actuator plate according to a modified example. A cross-sectional view of a head chip according to a modified example. A cross-sectional view of a head chip according to a fourth embodiment. A bottom view of an actuator plate according to the fourth embodiment. A plan view of an actuator plate according to the fourth embodiment. A bottom view of an actuator plate according to the fourth embodiment.

[0022] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In the embodiments and modified examples described below, corresponding components may be designated by the same reference numerals and their description may be omitted. In the following description, expressions indicating relative or absolute arrangements, such as "parallel," "orthogonal," "center," and "coaxial," not only strictly refer to such arrangements, but also refer to a state in which there is a relative displacement with a tolerance or an angle or distance that provides the same function. In the following embodiment, an inkjet printer (hereinafter simply referred to as a printer) that records on a recording medium using ink (liquid) will be described as an example. In the drawings used in the following description, the scale of each component has been appropriately changed to make each component recognizable.

[0023] (First embodiment) [Printer 1] Fig. 1 is a schematic diagram of a printer 1. The printer (liquid jet recording apparatus) 1 shown in Fig. 1 includes a pair of transport mechanisms 2 and 3, an ink tank 4, an inkjet head (liquid jet head) 5, an ink circulation mechanism 6, and a scanning mechanism 7.

[0024] In the following description, an X, Y, Z Cartesian coordinate system will be used as necessary. In this case, the X direction corresponds to the transport direction (sub-scanning direction) of the recording medium P (e.g., paper, etc.). The Y direction corresponds to the scanning direction (main scanning direction) of the scanning mechanism 7. The Z direction indicates the height direction (direction of gravity) perpendicular to the X and Y directions. In the following description, of the X, Y, and Z directions, the arrows in the figures are defined as the plus (+) side, and the opposite side to the arrows is defined as the minus (-) side. In this specification, the +Z side corresponds to the upward direction in the direction of gravity, and the -Z side corresponds to the downward direction in the direction of gravity.

[0025] The transport mechanisms 2 and 3 transport the recording medium P to the +X side. Each of the transport mechanisms 2 and 3 includes a pair of rollers 11 and 12 extending in the Y direction, for example. The ink tanks 4 each contain four colors of ink, for example, yellow, magenta, cyan, and black. Each inkjet head 5 is configured to be able to eject the four colors of ink, yellow, magenta, cyan, and black, depending on the ink tank 4 connected to it.

[0026] 2 is a schematic diagram of the inkjet head 5 and the ink circulation mechanism 6. As shown in FIGS. 1 and 2, the ink circulation mechanism 6 circulates ink between the ink tank 4 and the inkjet head 5. Specifically, the ink circulation mechanism 6 includes a circulation flow path 23 having an ink supply pipe 21 and an ink discharge pipe 22, a pressure pump 24 connected to the ink supply pipe 21, and a suction pump 25 connected to the ink discharge pipe 22.

[0027] The pressure pump 24 pressurizes the ink supply pipe 21 and sends ink through the ink supply pipe 21 to the inkjet head 5. As a result, the ink supply pipe 21 side is under positive pressure relative to the inkjet head 5. The suction pump 25 reduces the pressure inside the ink discharge pipe 22 and sucks ink from the inkjet head 5 through the ink discharge pipe 22. As a result, the ink discharge pipe 22 side is under negative pressure relative to the inkjet head 5. By driving the pressure pump 24 and the suction pump 25, the ink can be circulated between the inkjet head 5 and the ink tank 4 through the circulation flow path 23.

[0028] 1, the scanning mechanism 7 causes the inkjet head 5 to scan back and forth in the Y direction. The scanning mechanism 7 includes a guide rail 28 extending in the Y direction, and a carriage 29 movably supported on the guide rail 28.

[0029] <Inkjet head 5> The inkjet head 5 is mounted on a carriage 29. In the illustrated example, a plurality of inkjet heads 5 are mounted side by side in the Y direction on one carriage 29. The inkjet head 5 includes a discharge unit 30 (see FIG. 2 ), an ink supply unit (not shown) that connects the ink circulation mechanism 6 and the discharge unit 30, and a control unit (not shown) that applies a drive voltage to the discharge unit 30.

[0030] [Ejection unit 30] Figure 3 is an exploded perspective view of the ejection unit 30. The ejection unit 30 shown in Figure 3 is a so-called circulation side chute type ejection unit 30. The ejection unit 30 circulates ink between the ink tank 4 and the ejection unit 30, and ejects ink from the center of the ejection channel 51 (described later) in the extension direction (Y direction). The ejection unit 30 includes a flow path plate 31, a head chip 32, a flow path cover 34, and a flexible printed circuit board 35 (see Figure 7).

[0031] <Flow path plate 31> The flow path plate 31 is formed in a rectangular frame shape with the thickness direction in the Z direction and the longitudinal direction in the X direction. The flow path plate 31 partitions a chip storage section 31a, an inlet common flow path 31b, and an outlet common flow path 31c. The chip storage section 31a, the inlet common flow path 31b, and the outlet common flow path 31c penetrate the flow path plate 31 in the Z direction while communicating with each other.

[0032] The chip accommodating section 31a is formed in the center of the flow channel plate 31 in the Y direction. The chip accommodating section 31a is formed in the shape of an elongated hole with the X direction as the longitudinal direction in a plan view. The inlet common flow channel 31b is formed in a portion of the flow channel plate 31 located on the +Y side of the chip accommodating section 31a. The inlet common flow channel 31b is formed in the shape of an elongated hole with the X direction as the longitudinal direction, similar to the chip accommodating section 31a. The +X side end of the inlet common flow channel 31b protrudes in the X direction relative to the chip accommodating section 31a. The outlet common flow channel 31c is formed in a portion of the flow channel plate 31 located on the -Y side of the chip accommodating section 31a. The outlet common flow channel 31c is formed in the shape of an elongated hole with the X direction as the longitudinal direction, similar to the inlet common flow channel 31b. The -X side end of the outlet common flow channel 31c protrudes in the X direction relative to the chip accommodating section 31a.

[0033] <Head chip 32> Fig. 4 is an exploded perspective view of the head chip 32. Fig. 5 is a bottom view of the actuator plate 41. Fig. 6 is a plan view of the actuator plate 41. Fig. 7 is a cross-sectional view of the discharge unit 30 corresponding to line VII-VII in Fig. 5. Fig. 8 is a cross-sectional view of the discharge unit 30 corresponding to line VIII-VIII in Fig. 5. As shown in Figs. 4 to 8, the head chip 32 includes a drive head 37 and a nozzle plate 44.

[0034] <Drive Head 37> The drive head 37 is formed in a block shape with its thickness in the Z direction and its length in the X direction. The drive head 37 is fitted into the chip accommodating portion 31a. The drive head 37 has the same thickness in the Z direction as the channel plate 31 and the same shape in plan view as the chip accommodating portion 31a. The drive head 37 has its +X side end face fixed by adhesive or the like to the inner surface of the chip accommodating portion 31a facing the -X side, and its -X side end face fixed by adhesive or the like to the inner surface of the chip accommodating portion 31a facing the +X side. Within the channel plate 31, the inlet common channel 31b and the outlet common channel 31c are blocked by the drive head 37. In the first embodiment, the back surface of the drive head 37 is arranged flush with the back surface of the channel plate 31. Meanwhile, the front surface of the drive head 37 is arranged flush with the front surface of the channel plate 31.

[0035] The drive head 37 includes an actuator plate 41, a cover plate 42, and a protective film 43. In the following description, in the Z direction, the direction from the actuator plate 41 toward the cover plate 42 (+Z side) may be referred to as the front side, and the direction from the cover plate 42 toward the actuator plate 41 (-Z side) may be referred to as the back side. In the first embodiment, the actuator plate 41 and the cover plate 42 constitute the chip body 40.

[0036] <Actuator Plate 41> The actuator plate 41 is made of a piezoelectric material such as PZT (lead zirconate titanate). The actuator plate 41 is a so-called chevron substrate. A chevron substrate is a substrate formed by stacking two piezoelectric plates whose polarization directions are different in the Z direction, for example. However, the actuator plate 41 may also be a so-called monopole substrate. A monopole substrate is a substrate whose polarization direction is unidirectional throughout the entire Z direction.

[0037] A channel row 46 is formed in the actuator plate 41. The channel row 46 has ejection channels 51 that are filled with ink and non-ejection channels 52 that are not filled with ink. The channels 51, 52 are arranged alternately in the actuator plate 41 with a gap between them in the X direction. In the head chip 32 of the first embodiment, the ejection channels 51 that serve as pressure chambers and the non-ejection channels 52 that serve as air chambers are formed in the actuator plate 41 itself. In the first embodiment, a configuration will be described in which the channel extension direction coincides with the Y direction, but the channel extension direction may also intersect with the Y direction.

[0038] 5 to 7, the discharge channels 51 penetrate the actuator plate 41 in the Z direction and extend linearly in the Y direction over the entire length of the actuator plate 41. The +Y side opening of each discharge channel 51 communicates with the inlet common flow path 31b. The -Y side opening of each discharge channel 51 communicates with the outlet common flow path 31c. The inlet common flow path 31b and the outlet common flow path 31c communicate with each discharge channel 51.

[0039] 4 and 8 , the non-ejection channels 52 extend linearly in the Y direction in the portions of the actuator plate 41 that are located between adjacent ejection channels 51. The portions of the actuator plate 41 that are located between adjacent ejection channels 51 and non-ejection channels 52 each form a drive wall (drive portion) 53 that faces the ejection channel 51. The channels 51 and 52 are surrounded on both sides in the X direction by a pair of drive walls 53.

[0040] Both ends of the non-ejection channel 52 in the Y direction are located inside the actuator plate 41. The non-ejection channel 52 does not communicate with the inlet common flow path 31b and the outlet common flow path 31c. The non-ejection channel 52 is formed in an arc shape that convex downward when viewed from the X direction. That is, the dimension of the non-ejection channel 52 in the Y direction gradually decreases from the +Z side to the -Z side. Specifically, the non-ejection channel 52 has a through portion 52a located in the center in the Y direction and raised portions 52b that continue on both sides of the through portion 52a in the Y direction.

[0041] The through portion 52a penetrates the actuator plate 41 in the Z direction. The raised portion 52b opens at the surface of the actuator plate 41. The dimension of the raised portion 52b in the Z direction gradually decreases with increasing distance from the through portion 52a in the Y direction. The +Z side opening of the non-ejection channel 52 is formed by the through portion 52a and the raised portion 52b. The -Z side opening of the non-ejection channel 52 is formed by the through portion 52a. The bottom surface of the raised portion 52b is formed in an arc shape with a uniform radius of curvature. A dividing groove 52c is formed in the center of the bottom surface of each raised portion 52b in the X direction. The dividing groove 52c is recessed relative to the bottom surface of each raised portion 52b over the entire length in the Y direction. The dividing groove 52c extends concentrically with the raised portion 52b in a side view.

[0042] In the following description, the portion of the actuator plate 41 that is located between adjacent ejection channels 51 and on the +Y side of the non-ejection channels 52 is referred to as a first tail portion 41a. The portion of the actuator plate 41 that is located between adjacent ejection channels 51 and on the -Y side of the non-ejection channels 52 is referred to as a second tail portion 41b.

[0043] 4, 7, and 8, the cover plate 42 is used to connect the head chip 32 and the flexible printed circuit board (external wiring) 35. In the illustrated example, the Z-direction dimension of the cover plate 42 is larger than that of the actuator plate 41. The cover plate 42 is formed from, for example, a piezoelectric material such as PZT, glass, silicon, a resin material, or other non-conductive material. The cover plate 42 may be formed by using a conductive material such as a metal material as a base with a non-conductive material coated on the outer surface of the base.

[0044] The outer shape of the cover plate 42 in a plan view is the same as that of the actuator plate 41. The cover plate 42 is overlaid on the entire surface of the actuator plate 41. The cover plate 42 is bonded to the surface of the actuator plate 41 with an adhesive or the like.

[0045] FIG. 9 is a bottom view of the cover plate 42. FIG. 10 is a plan view of the cover plate 42. As shown in FIGS. 4 and 8 to 10, the cover plate 42 is formed with a common hole 42a, a first individual hole 42b, and a second individual hole 42c. Each of the holes 42a to 42c is formed with a tapered shape, with the inner diameter gradually decreasing from the +Z side to the −Z side. The inner diameter of each of the holes 42a to 42c may be uniform throughout the Z direction. The planar shape of each of the holes 42a to 42c can be modified as appropriate, such as a rectangular shape, a circular shape, an oval shape, or a polygonal shape. The common hole 42a, the first individual hole 42b, and the second individual hole 42c may have the same shape or different shapes.

[0046] The common hole 42a penetrates in the Z direction through a portion of the cover plate 42 that overlaps with the second tail portion 41b in a plan view. The common hole 42a is provided between adjacent ejection channels 51 in the X direction.

[0047] The first individual holes 42b and the second individual holes 42c are provided on the +Y side of the non-ejection channels 52. The first individual holes 42b are portions of the cover plate 42 that overlap with the first tail portion 41a in plan view, and penetrate in the Z direction through portions located on the +X side of the dividing grooves 52c. The second individual holes 42c are portions of the cover plate 42 that overlap with the first tail portion 41a in plan view, and penetrate in the Z direction through portions located on the -X side of the dividing grooves 52c. The first individual holes 42b and the second individual holes 42c are provided for each non-ejection channel 52 in portions that overlap with the first tail portion 41a in plan view.

[0048] Fig. 11 is a cross-sectional view corresponding to line XI-XI in Fig. 6. As shown in Fig. 11, each of the individual holes 42b and 42c overlaps a portion of the non-ejection channel 52 in plan view. The inside of the non-ejection channel 52 communicates with the outside of the chip body 40 through each of the individual holes 42b and 42c.

[0049] Next, a description will be given of the various wirings formed on the head chip 32. As shown in Figures 4 to 8, the actuator plate 41 is formed with common wirings 61 and individual wirings 62 as drive wirings.

[0050] As shown in FIGS. 5 to 7 , the common wiring 61 includes a common electrode 65, a common output wiring 66, and a common back surface wiring 67. The common electrodes 65 are formed on the inner surfaces of the ejection channels 51 that face each other in the X direction. Each common electrode 65 is formed on the inner surface of the ejection channel 51 over the entire area in the Y and Z directions. As shown in FIG. 6 , the common output wiring 66 extends in a strip shape in the X direction on the surface of the second tail portion 41b. The common output wiring 66 connects the common electrodes 65 that face each other in the X direction, with the non-ejection channel 52 sandwiched between them, at the +Z-side opening edges of the ejection channels 51 that face each other in the X direction, with the non-ejection channel 52 sandwiched between them. As shown in FIG. 5 , the common back surface wiring 67 extends in the X direction on the back surfaces of each of the tail portions 41a, 41b. Each common back surface wiring 67 connects common electrodes 65 that face each other in the X direction with a non-ejection channel 52 therebetween at the -Z side opening edges of the ejection channels 51 that face each other in the X direction with a non-ejection channel 52 therebetween.

[0051] 5, 6, and 8, the individual wiring 62 includes individual electrodes 68 and individual lead-out wiring 69. The individual electrodes 68 include a first individual electrode 68a formed on at least the inner surface facing the -X side of the inner surface of the non-ejection channel 52, and a second individual electrode 68b formed on at least the inner surface facing the +X side. Each individual electrode 68 is formed over the entire Y-direction on the inner surface of the non-ejection channel 52, and is also formed on the bottom surface of the cut-up portion 52b. The first individual electrodes 68a and the second individual electrodes 68b formed in the same non-ejection channel 52 are separated from each other by a separating groove 52c.

[0052] 12 is a cross-sectional view corresponding to line XII-XII in FIG. 6. As shown in FIGS. 8 and 12, the individual electrodes 68 are formed on the entire inner surface of the non-ejection channel 52 in the Z direction, except for the -Z side end. That is, the -Z side edge of the individual electrode 68 is retracted to the +Z side with respect to the -Z side opening edge of the non-ejection channel 52. The -Z side end of the inner surface of the non-ejection channel 52 constitutes a non-forming region Q where no individual electrode 68 is formed. The dimension of the non-forming region Q in the Z direction is preferably 2% to 10% of the dimension of the non-ejection channel 52 in the Z direction.

[0053] 6 , the individual output wiring 69 includes a first individual output wiring 69a and a second individual output wiring 69b. The first individual output wiring 69a is formed on the surface of the first tail portion 41a in a portion located on the +X side of the separating groove 52c. The first individual output wiring 69a is connected to a first individual electrode 68a at the +Z side opening edge of the non-ejection channel 52. The second individual output wiring 69b is formed on the surface of the first tail portion 41a in a portion located on the −X side of the separating groove 52c. The second individual output wiring 69b is connected to a second individual electrode 68b at the +Z side opening edge of the non-ejection channel 52.

[0054] 4, 9, and 10, common connection wiring 71 and individual connection wiring 72 are formed on the cover plate 42 as connection wiring. The common connection wiring 71 includes a common through wiring 75 and a common pad 76. The common through wiring 75 is formed on the inner surface of the common hole 42a. Specifically, the common through wiring 75 is formed around the entire inner surface of the common hole 42a and is formed over the entire Z direction. The common through wiring 75 is connected to the common extraction wiring 66 at the opening edge on the -Z side of the common hole 42a.

[0055] The common pads 76 are formed on the surface of the cover plate 42. The common pads 76 are formed on portions of the surface of the cover plate 42 that are located between adjacent common through-wires 75. The common pads 76 are connected to adjacent common through-wires 75 at the +Z side opening edge of the common hole 42a, and protrude toward the +Y side of the common hole 42a. In other words, the common pads 76 and the common through-wires 75 are arranged alternately on the surface of the cover plate 42.

[0056] The individual connection wiring 72 includes a first individual through wiring 81, a second individual through wiring 82, and an individual pad 83. The first individual through wiring 81 is formed on the inner surface of the first individual hole 42b. The first individual through wiring 81 is formed around the entire inner surface of the first individual hole 42b and is formed over the entire Z direction. The first individual through wiring 81 is connected to the first individual output wiring 69a at the -Z side opening edge of the first individual hole 42b. The second individual through wiring 82 is formed on the inner surface of the second individual hole 42c. The second individual through wiring 82 is formed around the entire inner surface of the second individual hole 42c and is formed over the entire Z direction. The second individual through wiring 82 is connected to the second individual output wiring 69b at the -Z side opening edge of the second individual hole 42c.

[0057] The individual pads 83 are formed on a portion of the surface of the cover plate 42 that is located on the −Y side with respect to the individual holes 42b and 42c. The individual pads 83 connect a first individual through wiring 81 that is located on the −X side with respect to one ejection channel 51 and a second individual through wiring 82 that is located on the +X side with respect to one ejection channel 51. Specifically, the −X side end of the individual pad 83 is connected to the first individual through wiring 81 at the +Z side opening edge of the first individual hole 42b. The +X side end of the individual pad 83 is connected to the second individual through wiring 82 at the +Z side opening edge of the second individual hole 42c. This connects the individual electrodes 68a, 68b that face each other in the X direction with one ejection channel 51 between them (the second individual electrode 68b of the non-ejection channel 52 that is located on the +X side with respect to one ejection channel 51, and the first individual electrodes 68a of the non-ejection channel 52 that is located on the −X side with respect to one ejection channel 51). In the illustrated example, the common pad 76 and the individual pad 83 are provided at the same position in the X direction.

[0058] <Protective film 43> As shown in Figures 7, 8, 11, and 12, the protective film 43 is formed integrally in a sheet (film) shape. The protective film 43 is a so-called skin pack. The protective film 43 is adhered to the outer surface of the chip body 40 via adhesive 45 (see Figure 12). The protective film 43 includes an ejection channel covering portion 43a, a back surface covering portion 43b, a non-ejection channel covering portion 43c, and a side surface covering portion 43d.

[0059] The ejection channel covering portion 43a is provided within the ejection channel 51, folded back in the Z direction when viewed from the Y direction. The ejection channel covering portion 43a is in direct or indirect contact with the inner surface of the ejection channel 51, covering the entire inner surface of the ejection channel 51. That is, the ejection channel covering portion 43a is in direct contact with the top surface of the ejection channel 51 (the portion of the back surface of the cover plate 42 exposed within the ejection channel 51). The ejection channel covering portion 43a is indirectly in contact with the inner surface of the ejection channel 51 (the portion of the driving wall 53 exposed within the ejection channel 51) via a common electrode 65. As a result, the ejection channel covering portion 43a continuously covers the top surface and inner surface of the ejection channel 51. FIG. 7 shows the layered structure on the driving wall 53 with a partial cutaway. Specifically, the inside of the cutaway line shows the ejection channel covering portion 43a formed on the outermost layer, and the outside of the cutaway line shows the common electrode 65 covered by the ejection channel covering portion 43.

[0060] The back surface covering portion 43b covers the entire back surface of the actuator plate 41 where the channels 51 and 52 are not open. The back surface covering portion 43b covers the common back surface wiring 67 from the -Z side. The back surface covering portion 43b is in direct or indirect contact with the back surface of the actuator plate 41 where the channels 51 and 52 are not open. The back surface covering portion 43b is integrally connected to the ejection channel covering portion 43a at the -Z side opening edge of the ejection channel 51.

[0061] 8 and 12, the non-ejection channel covering portion 43c closes the -Z side opening of the non-ejection channel 52. Specifically, the non-ejection channel covering portion 43c is provided so as to straddle the entire -Z side opening of the non-ejection channel 52. The outer periphery of the non-ejection channel covering portion 43c is integrally connected to the back surface covering portion 43b. A part of the non-ejection channel covering portion 43c may extend into the non-ejection channel 52 through the -Z side opening of the non-ejection channel 52. Even if the non-ejection channel covering portion 43c extends into the non-ejection channel 52, it is preferable that the non-ejection channel covering portion 43c does not contact the individual electrode 68 (that is, be located within the range of the non-forming region Q in the Z direction).

[0062] As shown in Figures 7 and 8, the side surface covering portion 43d is integrally connected to the outer periphery of the ejection channel covering portion 43a and the back surface covering portion 43b. The side surface covering portion 43d covers the side surface of the chip body 40 (the surface facing the X direction or the Y direction). Specifically, the side surface covering portion 43d covers the entire periphery of the side surface of the chip body 40 except for the +Y side opening and the -Y side opening of the ejection channel 51. The side surface covering portion 43d is integrally connected to the outer periphery of the back surface covering portion 43b at the -Z side edge of the side surface of the chip body 40. The side surface covering portion 43d is integrally connected to the ejection channel covering portion 43a at the +Y side opening edge and the -Y side opening edge of the ejection channel 51. It is preferable that the side surface covering portion 43d is formed extending in the X direction on at least the side surface of the chip body 40 facing the Y direction. However, the side surface covering portion 43d is not an essential component.

[0063] As shown in FIG. 12 , the protective film 43 is stretched and adhered to the chip body 40 in the protective film forming step S50 (described later), resulting in a thickness thinner than the original thickness of the protective film 43 (e.g., 30 μm to 300 μm). In particular, the ejection channel covering portion 43 a is the minimum thickness of the protective film 43 because the displacement of the protective film 43 is restricted by the rear surface of the actuator plate 41. In this case, the thickness of the ejection channel covering portion 43 a is, for example, 10 μm to 60 μm. The thickness of the portions of the protective film 43 other than the ejection channel covering portion 43 a (the rear surface covering portion 43 b, the non-ejection channel covering portion 43 c, and the side surface covering portion 43 d) is approximately 10 μm to 200 μm. Furthermore, the width of the ejection channels 51 in the X direction is preferably between two and 20 times the original thickness of the protective film 43. The width of the non-ejection channels 52 in the X direction is preferably less than twice the original thickness of the protective film 43, more preferably less than twice the minimum thickness. The width of the ejection channel 51 in the X direction is preferably at least twice the width of the non-ejection channel 52 in the X direction. In this case, the width of the ejection channel 51 in the X direction is set to, for example, about 100 μm. The width of the non-ejection channel 52 in the X direction is set to about 40 μm.

[0064] The protective film 43 of the first embodiment is preferably made of a thermoplastic resin material that has excellent insulating properties and ink resistance and a softening point (Vicat softening temperature according to JIS K7206) of 120°C or less, preferably 100°C or less. In the first embodiment, the protective film 43 is made of a single-layer film or a laminated film such as an ionomer (softening point of 57°C to 80°C) or low-density polyethylene (softening point of 85°C to 97°C). When a laminated film is used for the protective film 43, it is preferable to use a material with excellent flexibility (e.g., ionomer) as a base layer and a material with excellent ink resistance (e.g., low-density polyethylene) as an upper layer.

[0065] As shown in FIGS. 7 to 9 , an air vent passage 70 is formed in the cover plate 42. The air vent passage 70 is a groove that opens on the back surface of the cover plate 42 and extends along the X direction. The air vent passage 70 extends over the entire length of the cover plate 42 in the X direction. The air vent passage 70 opens on the side surface of the cover plate 42 facing the X direction. The air vent passage 70 is formed in a position that overlaps the center of each channel 51, 52 in the Y direction when viewed from the Z direction. The center of the Y direction is, for example, a 1 / 3 region located in the center of the entire length of the discharge channel 51. In the illustrated example, the air vent passage 70 is formed in a position that includes the center of each channel 51, 52 in the Y direction. However, the air vent passage 70 may be formed in a region other than the center of each channel 51, 52 in the Y direction when viewed from the Z direction.

[0066] The air vent passage 70 crosses between adjacent ejection channels 51 and non-ejection channels 52 in the X direction. The air vent passage 70 connects each channel 51, 52 to the outside of the chip body 40. The portion of the air vent passage 70 that overlaps with the ejection channel 51 when viewed from the Z direction is covered by the ejection channel covering portion 43a, thereby blocking communication between the interior of the ejection channel 51 and the outside of the chip body 40 through the air vent passage 70. The air vent passage 70 is closed by the ejection channel covering portion 43a, thereby blocking communication between the interior of the ejection channel 51 and the non-ejection channel 52 through the air vent passage 70. The portion of the air vent passage 70 that overlaps with the non-ejection channel 52 when viewed from the Z direction connects the interior of the non-ejection channel 52 to the outside of the chip body 40 through the air vent passage 70. In the first embodiment, connecting the ejection channel 51 to the outside of the chip body 40 means that the ejection channel 51 is indirectly connected to the ejection channel 51, for example, via the ejection channel covering portion 43a, while communication between the inside of the ejection channel 51 and the inside of the air vent passage 70 is blocked.

[0067] The position and number of the air vent passages 70 can be changed as appropriate. In the first embodiment, the air vent passages 70 are described as being formed in a straight line, but the present invention is not limited to this configuration. The air vent passages 70 may be formed in a curved line, for example. The ends of the air vent passages 70 may be located inside the cover plate 42 (they do not have to open on the side surfaces of the cover plate 42) as long as they connect the channels 51 and 52.

[0068] <Nozzle Plate 44> As shown in FIGS. 4 and 7 , the nozzle plate 44 blocks the −Z side openings of the ejection channels 51 and the non-ejection channels 52. The nozzle plate 44 covers the back surface of the actuator plate 41 and the back surface of the flow path plate 31 collectively. The nozzle plate 44 is bonded to the back surface covering portion 43b via an adhesive, thereby covering the back surface of the actuator plate 41, and is also bonded to the back surface of the flow path plate 31 via an adhesive or the like, thereby covering the back surface of the flow path plate 31. As a result, the nozzle plate 44 blocks the −Z side openings of the inlet common flow path 31b and the outlet common flow path 31c, as well as the −Z side openings of each of the channels 51 and 52 collectively. The nozzle plate 44 is formed of a resin material (such as polyimide). However, the nozzle plate 44 may have a single-layer structure or a laminated structure made of a metal material (such as SUS or Ni—Pd), a resin material (such as polyimide), glass, silicon, or the like.

[0069] As shown in Figures 7 and 12, a plurality of nozzle holes 44a are formed in the nozzle plate 44. The nozzle holes 44a penetrate the nozzle plate 44 in the Z direction. For example, the nozzle holes 44a are formed in a tapered shape such that the inner diameter gradually decreases from the +Z side to the -Z side. The nozzle holes 44a are arranged at intervals in the X direction. Each nozzle hole 44a is individually connected to a corresponding ejection channel 51. In the illustrated example, the +Z side opening of each nozzle hole 44a overlaps with the portion of the air vent passage 70 exposed in the ejection channel 51 at the center of the ejection channel 51 in the Y direction, as viewed from the Z direction. The nozzle holes 44a may be provided at a position offset in the Y direction with respect to the air vent passage 70.

[0070] <Flow Channel Cover 34> As shown in Figures 3 and 7, the flow channel cover 34 sandwiches the flow channel plate 31 and the head chip 32 between itself and the nozzle plate 44. The flow channel cover 34 includes a cover base 95, an inlet port 96, and an outlet port 97. The cover base 95 is rectangular plate-shaped. The outer shape of the cover base 95 in a plan view is formed to be the same as the outer shape of the flow channel plate 31. The cover base 95 is overlaid on the surfaces of the flow channel plate 31 and the head chip 32. The cover base 95 is bonded to the surfaces of the flow channel plate 31 and the head chip 32 via an adhesive or the like, and is fastened to the flow channel plate 31 with screws or the like. The cover base 95 closes the upper end openings of the inlet common flow channel 31b and the outlet common flow channel 31c.

[0071] A slit 95a is formed in the center of the cover base 95 in the Y direction. The slit 95a penetrates the cover base 95 in the Z direction and extends in the X direction. The slit 95a is formed at a position overlapping the center of the head chip 32 (excluding the outer periphery) in a plan view. That is, the dimension of the slit 95a in the Y direction is smaller than the dimension of the head chip 32 in the Y direction. The dimension of the slit 95a in the X direction is smaller than the dimension of the head chip 32 in the X direction. The slit 95a exposes at least a portion of each pad 76, 83 on the surface of the cover plate 42.

[0072] The inlet port 96 is located at the end of the cover base 95 on the +Y side and the +X side. The inlet port 96 protrudes from the cover base 95 on the +Z side. The inlet port 96 is connected to the inlet common flow path 31b through the +X side end (the portion protruding relative to the chip housing portion 31a) of the inlet common flow path 31b. Ink flowing through the ink supply tube 21 is supplied to the inlet common flow path 31b through the inlet port 96. The outlet port 97 is located at the end of the cover base 95 on the -Y side and the -X side. The outlet port 97 protrudes from the cover base 95 on the +Z side. The outlet port 97 is connected to the outlet common flow path 31c through the -X side end (the portion protruding relative to the chip housing portion 31a) of the outlet common flow path 31c. Ink flowing through the outlet common flow path 31c is discharged to the ink discharge tube 22 through the outlet port 97.

[0073] 7, the flexible printed circuit board 35 is pressure-bonded to the surface of the cover plate 42 through the slit 95a. The flexible printed circuit board 35 is connected to each of the pads 76 and 83 on the surface of the cover plate 42. The flexible printed circuit board 35 is drawn out to the +Z side and then connected to the control unit.

[0074] [Operation Method of Printer 1] Next, a case where characters, figures, etc. are recorded on a recording medium P using the printer 1 configured as described above will be described below. In the initial state, it is assumed that the four ink tanks 4 shown in Fig. 1 are each filled with a sufficient amount of ink of a different color. The ink in the ink tanks 4 is then filled into the inkjet head 5 via the ink circulation mechanism 6.

[0075] When the printer 1 is operated in an initial state, the recording medium P is conveyed in the +X direction while being sandwiched between the rollers 11 and 12 of the conveyance mechanisms 2 and 3. Simultaneously with the conveyance of the recording medium P, the carriage 29 moves in the Y direction, causing the inkjet heads 5 mounted on the carriage 29 to move back and forth in the Y direction. While the inkjet heads 5 move back and forth, ink is ejected from each inkjet head 5 appropriately onto the recording medium P. This allows characters, images, etc. to be recorded on the recording medium P.

[0076] The operation of each inkjet head 5 will now be described in detail. In a circulation-type side-chute inkjet head 5 such as that of the first embodiment, the pressure pump 24 and the suction pump 25 shown in FIG. 2 are first operated to circulate ink through the circulation flow path 23. In this case, ink circulating through the ink supply pipe 21 is supplied into the inlet common flow path 31b through the inlet port 96. The ink supplied to the inlet common flow path 31b is distributed to each ejection channel 51 through the +Y side openings of each ejection channel 51, and then circulates through each ejection channel 51 to the -Y side. The ink is then discharged into the outlet common flow path 31c through the -Y side openings of each ejection channel 51. The ink discharged into the outlet common flow path 31c flows into the ink discharge pipe 22 through the outlet port 97 and is returned to the ink tank 4. This allows ink to circulate between the inkjet head 5 and the ink tank 4.

[0077] When the inkjet head 5 begins to reciprocate due to the movement of the carriage 29 (see FIG. 1 ), a drive voltage is applied between the common electrode 65 and the individual electrodes 68 via the flexible printed circuit board 35. At this time, the drive voltage is applied with the common electrode 65 at a reference potential GND and the individual electrodes 68 at a drive potential Vdd. This generates a potential difference in the X direction between the common electrode 65 and the individual electrode 68, which face each other across the drive wall 53. This potential difference in the X direction generates an electric field in the actuator plate 41 in a direction perpendicular to the polarization direction (Z direction). As a result, the actuator plate 41 undergoes thickness-slip deformation in the Z direction due to shear mode. Specifically, thickness-slip deformation occurs in the two drive walls 53 that define the ejection channel 51, and these two drive walls 53 deform so as to protrude toward the non-ejection channel 52 side. That is, the actuator plate 41 of the first embodiment is made up of two laminated piezoelectric substrates polarized in the thickness direction (Z direction), and therefore, when a drive voltage is applied, the actuator plate 41 bends and deforms in a V shape around the middle position in the Z direction of the drive wall 53. This causes the ejection channel 51 to deform as if it were expanding.

[0078] Thereafter, when the driving voltage is set to zero, the actuator plate 41 restores its original shape, causing the volume within the ejection channel 51 to return to its original state. As the actuator plate 41 restores its original shape, the pressure within the ejection channel 51 increases, causing the ink within the ejection channel 51 to be ejected to the outside through the nozzle hole 44a. The ink ejected to the outside lands on the recording medium P, thereby recording print information on the recording medium P.

[0079] <Manufacturing Method of Discharge Unit 30> Next, a manufacturing method of the above-described discharge unit 30 will be described. FIG. 13 is a flowchart for explaining the manufacturing method of the discharge unit 30. FIGS. 14 to 25 are process diagrams for explaining the manufacturing method of the discharge unit 30. As shown in FIG. 13, the manufacturing method of the discharge unit 30 includes an actuator processing step S10, a cover plate processing step S20, a grinding step S30, an electrode removal step S40, a protective film forming step S50, an assembly step S60, and a nozzle bonding step S70. Of the manufacturing steps of the discharge unit 30, the actuator processing step S10, the cover plate processing step S20, the grinding step S30, the electrode removal step S40, the protective film forming step S50, and the nozzle bonding step S70 correspond to the manufacturing steps of the head chip 32. For convenience, the following description will be given taking as an example a case where the head chip 32 is manufactured at the chip level.

[0080] As shown in FIG. 14 , in the actuator processing step S10, first, the formation regions of the ejection channels 51 and non-ejection channels 52 in the actuator plate 41 are processed by a first dicer 110 (channel formation step). The first dicer 110 is formed in a disk shape when viewed from the X direction. In the channel formation step, the travel distance of the first dicer 110 in the Y direction is reduced in the formation regions of the non-ejection channels 52 compared to the formation regions of the ejection channels 51. As a result, when viewed from the X direction, the bottom surfaces of the non-ejection channels 52 are formed in arc shapes convex toward the −Z side (see FIG. 19 ), and the bottom surfaces of the ejection channels 51 are formed in linear shapes. The penetration distance of the first dicer 110 in the Z direction is set to be greater than the post-processing dimension of the actuator plate 41 but smaller than the pre-processing dimension of the actuator plate 41. In other words, after the channel formation step, neither the ejection channels 51 nor the non-ejection channels 52 penetrate the actuator plate 41.

[0081] 15 , common wiring 61 and individual wiring 62 as drive wiring are formed on the actuator plate 41 (first wiring formation process). Specifically, an electrode material (for example, TiAu) is formed as a film by oblique deposition or the like from the surface side of the actuator plate 41. As a result, a common electrode 65 is formed on the inner surface of each ejection channel 51, and individual electrodes 68 are formed on the inner surface of each non-ejection channel 52. In addition, a common output wiring 66 and individual output wiring 69 are formed on the surface of the actuator plate 41. In the first wiring formation process, the electrode material can be formed by sputtering, ion plating, plating, or the like, in addition to oblique deposition.

[0082] 16 , the individual electrodes 68 a, 68 b formed in one non-ejection channel 52 are divided (dividing process). Specifically, a second dicer 115 is advanced into the center of the non-ejection channel 52 in the X direction. At this time, the dimension of the second dicer 115 in the X direction is smaller than the dimension of the non-ejection channel 52 in the X direction. Therefore, the individual electrodes 68 a, 68 b are divided at the bottom surface of the non-ejection channel 52.

[0083] As shown in Fig. 17 , in the cover plate processing step S20, an air vent passage 70 is formed in the back surface of the cover plate 42 (air vent passage forming step). The air vent passage 70 can be formed by dicer processing, sandblasting, or the like. Next, as shown in Fig. 18 , a common hole 42a and individual holes 42b, 42c are formed in the cover plate 42 (hole forming step). Specifically, a laser beam is irradiated from the front surface side of the cover plate 42 to penetrate the cover plate 42. The order of the air vent passage forming step and the hole forming step may be reversed.

[0084] Subsequently, as shown in FIG. 19, the cover plate 42 is attached to the surface of the actuator plate 41 (bonding step).

[0085] 20 , common connection wiring 71 and individual connection wiring 72 are formed on the cover plate 42 as connection wiring (second wiring formation process). Specifically, a film of electrode material is formed by vapor deposition or the like from the surface side of the cover plate 42 through a mask pattern (not shown). As a result, a common through wiring 75 is formed in the common hole 42a, and individual through wirings 81, 82 are formed in the individual holes 42b, 42c. In addition, a common pad 76 and individual pads 83 are formed on the surface of the cover plate 42.

[0086] 21, the rear surface of the actuator plate 41 is ground (grinding step S30). Specifically, the actuator plate 41 is ground until the ejection channels 51 and the non-ejection channels 52 are opened on the rear surface of the actuator plate 41.

[0087] 22, a non-forming region Q is formed on the inner surface of the non-ejection channel 52 (electrode removal step S40). Specifically, the -Z side end of the individual electrode 68 is removed by laser processing, dicer processing, or the like through the -Z side opening of the non-ejection channel 52. Note that, in order to form the non-forming region Q, for example, the -Z side end of the non-ejection channel 52 may be formed in advance to have a stepped shape. In this case, the non-forming region Q can be formed by removing the individual electrode 68 formed in the stepped portion. In this way, the chip body 40 is completed.

[0088] 23, in the protective film forming step S50, a protective film 43 is formed on the chip body 40. In the protective film forming step S50, the chip body 40 and the protective film 43 are set in a state where they face each other inside the chamber 120. Specifically, first, adhesive 45 (see FIG. 12) is applied to the region of the chip body 40 where the protective film 43 is to be formed.

[0089] Next, the chip body 40 is set on the stage 121 in the chamber 120 via the base film 122, with the back surface of the actuator plate 41 facing upward. The base film 122 is formed of a material that can be peeled off from both the actuator plate 41 and the protective film 43. The protective film 43 is set at a distance from the chip body 40 in the chamber 120. The portion of the protective film 43 that is outside the chip body 40 in a plan view is held by a holder or the like (not shown). In other words, the portion of the protective film 43 that is located outside the chip body 40 also functions as a gripping margin for gripping the protective film 43 in the chamber 120.

[0090] With the chip body 40 and protective film 43 set in the chamber 120, the chamber 120 is heated so that the protective film 43 reaches or exceeds the softening point, but is below the Curie point of the actuator plate 41 (the temperature at which polarization breakdown occurs). Then, a first space S1 (lower space) located on the chip body 40 side of the protective film 43 within the chamber 120 is set at a negative pressure relative to a second space S2 (upper space) located on the opposite side of the protective film 43 from the chip body 40. Air present in the chip body 40 is then discharged through the openings of the channels 51, 52, the air vent passage 70, and the individual holes 42b, 42c that open on the outer surface of the chip body 40. In particular, in the first embodiment, the air vent passage 70 is connected to the center of each channel 51, 52 in the Y direction, so that the air in each channel 51, 52 is discharged directly from the air vent passage 70, or indirectly through the non-ejection channel 52 or individual holes 42b, 42c via the air vent passage 70.

[0091] 24, the pressure difference between the first space S1 and the second space S2 causes the protective film 43 to approach the chip body 40. Thereafter, the protective film 43 contacts the chip body 40 and is stretched and deformed to conform to the outer surface shape of the chip body 40. The protective film 43 contacts the back surface of the chip body 40, restricting downward displacement. Then, a portion of the protective film 43 enters the ejection channel 51 while being stretched, thereby adhering to the inner surface of the ejection channel 51. Therefore, the portion of the air vent passage 70 exposed within the ejection channel 51 is blocked by the protective film 43 (ejection channel covering portion 43a). A portion of the protective film 43 is stretched and wraps around the side surface of the chip body 40, thereby adhering to the side surface of the chip body 40. The width of the non-ejection channel 52 in the X direction is set to be less than twice the original thickness of the protective film 43. Therefore, in the protective film forming step S50, the protective film 43 is unlikely to enter the non-ejection channels 52. Therefore, the non-ejection channel covering portions 43c close the −Z side openings of the non-ejection channels 52 on the back surface of the chip body 40. In this way, the protective film 43 is formed on the chip body 40.

[0092] 25 , after protective film 43 is formed, chamber 120 is cooled so that protective film 43 becomes below its softening point, and then head chip 32 is removed from chamber 120. Specifically, protective film 43 and base film 122 are cut around chip body 40, and head chip 32 is removed together with base film 122. Thereafter, base film 122 is peeled off from head chip 32.

[0093] When the chip bodies 40 are manufactured at the wafer level, a stack of an actuator plate wafer and a cover plate wafer is formed. Thereafter, the wafer stack is divided into individual chip bodies 40, and then the protective film 43 may be formed on each chip body 40, or the protective film 43 may be formed on the entire wafer stack, and then the wafer stack is divided into individual head chips 32.

[0094] Thereafter, in an assembly step S60, the head chip 32 is assembled to the flow path plate 31. Specifically, the head chip 32 is fitted into the chip accommodating portion 31a so that the back surface of the flow path plate 31 and the back surface of the head chip 32 are flush with each other.

[0095] Next, in a nozzle bonding process S70, a nozzle plate 44 is attached so as to cover the rear surface of the flow path plate 31 and the rear surface of the head chip 32. Thereafter, a flow path cover 34 is attached to the front surface of the flow path plate 31. With the above steps, the ejection unit 30 is completed.

[0096] As described above, the head chip 32 of the first embodiment includes a chip body 40 having ejection channels (pressure chambers) 51 for storing ink and drive walls (drive units) 53 arranged separately facing the ejection channels 51; a common electrode (first drive electrode) 65 formed on the drive wall; and a sheet-like protective film formed to conform to the drive wall 53 while covering the common electrode 65. According to this configuration, covering the drive wall 53 with the sheet-like protective film 43 can prevent the occurrence of discontinuities such as pinholes, unlike conventional configurations in which a deposited film made of a paraxylylene-based resin material (e.g., Parylene (registered trademark)) is formed by a film formation method such as CVD. This prevents ink from reaching the common electrode 65 formed on the drive wall 53. This prevents short circuits and corrosion of the common electrode 65, providing a highly reliable head chip 32. Furthermore, the use of the sheet-like protective film 43 allows for a simpler and less costly protective film 43 compared to configurations in which a deposited film is formed by CVD or the like. As a result, the manufacturing efficiency of the head chip 32 can be improved, and the cost of the head chip 32 can be reduced.

[0097] However, if there is a location where the protective film 43 and the driving wall 53 are not in good contact with each other, deformation of the driving wall 53 at the location of the poor contact is not easily transmitted to the ink via the protective film 43. In contrast, in the head chip 32 of the first embodiment, the chip body 40 is configured to have an air vent passage 70 that connects the inside of the ejection channel 51 to the outside of the chip body 40 and blocks communication between the inside of the ejection channel 51 and the outside of the chip body 40 by the protective film 43. With this configuration, since the air vent passage 70 connects the inside of the ejection channel 51 to the outside of the chip body 40, air remaining in the ejection channel 51 can be efficiently discharged to the outside of the chip body 40 in the protective film forming step S50. This makes it easier to generate negative pressure in the ejection channel 51 and draw the protective film 43 into the ejection channel 51. As a result, it is easier to adhere the protective film 43 to the entire inner surface of the ejection channel 51 (the driving wall 53). In this case, the deformation of the drive wall 53 is easily transmitted to the ink via the protective film 43, so that the desired pressure is generated within the ejection channel 51 and the decrease in ejection performance due to the formation of the protective film 43 can be suppressed.

[0098] In the head chip 32 of the first embodiment, the air vent passage 70 is configured to extend across the plurality of ejection channels 51. With this configuration, air can be efficiently discharged from within each ejection channel 51 through the air vent passage 70. As a result, it becomes easier to adhere the protective film 43 to the entire inner surface of the ejection channel 51 (drive wall 53).

[0099] In the head chip 32 of the first embodiment, non-ejection channels (air chambers) that do not contain ink are formed in the chip body 40 in portions located between adjacent ejection channels 51 in the X direction. The protective film 43 is provided so as to straddle each of the ejection channels 51 and non-ejection channels 52 in the X direction. The air vent passage 70 extends so as to straddle the ejection channel 51 and non-ejection channel 52 chambers. With this configuration, air can be efficiently discharged from inside each ejection channel 51 and non-ejection channel 52 through the air vent passage 70. As a result, the protective film 43 can be easily drawn to the chip body 40, and the protective film 43 can be provided at a desired position with high precision.

[0100] In the head chip 32 of the first embodiment, an individual electrode (second drive electrode) 68 that generates a potential difference between the non-ejection channel 52 and the common electrode 65 is formed on the inner surface of the non-ejection channel 52. In the chip body 40, individual through-wires (through-wires) 81, 82 connected to the individual electrode 68 are formed on the inner surfaces of individual holes (wiring holes) 42b, 42c that open into the non-ejection channel 52. This configuration allows the inside of the ejection channel 51 to be connected to the outside of the chip body 40 through the air vent passage 70, the non-ejection channel 52, and the individual holes 42b, 42c. That is, in the protective film forming step S50, air in the ejection channel 51 and the non-ejection channel 52 can also be discharged through the individual holes 42b, 42c. This simplifies the air vent passage 70 and allows the protective film 43 to be provided at a desired position with high precision.

[0101] In the head chip 32 of the first embodiment, the ejection channel 51 extends in the Y direction (second direction) in the chip body 40. The air vent passage 70 is connected to the center of the ejection channel 51 in the Y direction. With this configuration, air can be vented from the center of the ejection channel 51 in the Y direction in the protective film forming step S50. This allows air to be effectively vented throughout the entire ejection channel 51, thereby preventing poor adhesion of the protective film 43.

[0102] In the head chip 32 of the first embodiment, the ejection channels 51 are open on the back surface (opening surface facing the third direction) of the chip body 40. A nozzle plate (ejection hole plate) 44 is provided on the back surface of the chip body 40. The nozzle plate 44 closes the openings of the ejection channels 51 and has nozzle holes (ejection holes) 44a that communicate with the ejection channels 51. The air vent passage 70 is provided at a position in the ejection channel 51 that overlaps with the nozzle hole 44a when viewed from the Z direction. With this configuration, the air vent passage 70 is provided at a position that overlaps with the nozzle hole 44a when viewed from the Z direction, so that the portion of the protective film 43 that covers the air vent passage 70 elastically displaces in response to pressure fluctuations in the ejection channels 51 during ink ejection. Therefore, pressure fluctuations in the ejection channels 51 can be alleviated during ink ejection, making it easier to reduce variations in generated pressure among the ejection channels 51.

[0103] In the head chip 32 of the first embodiment, the chip body 40 includes an actuator plate 41 having an ejection channel 51 and a drive wall 53, and a cover plate 42 superimposed on the actuator plate 41. The air vent passage 70 is formed in the cover plate 42. With this configuration, the air vent passage 70 is formed in the cover plate 42, which improves the design freedom of the actuator plate 41. Furthermore, unlike when the air vent passage 70 is formed in the actuator plate 41, it is possible to prevent the surface area of ​​the drive wall 53 from being reduced due to the formation of the air vent passage 70. Therefore, it is possible to provide the air vent passage 70 while maintaining ejection performance.

[0104] The printer 1 and inkjet head 5 of the first embodiment include the head chip 32 described above, and therefore can provide a printer 1 and inkjet head 5 with excellent reliability.

[0105] In the first embodiment described above, the protective film 43 is configured to include the ejection channel covering portion 43a, the back surface covering portion 43b, the non-ejection channel covering portion 43c, and the side surface covering portion 43d. However, the present invention is not limited to this configuration. The protective film 43 may be configured to include at least the ejection channel covering portion 43a. For example, the protective film 43 may not include the non-ejection channel covering portion 43c, or may be configured to include at least any of the back surface covering portion 43b, the non-ejection channel covering portion 43c, and the side surface covering portion 43d.

[0106] In the first embodiment described above, a configuration in which the non-forming region Q of the individual electrodes 68 is formed on the inner surface of the non-ejection channel 52 has been described, but the present invention is not limited to this configuration. The individual electrodes 68 may be formed over the entire area in the Z direction on the inner surface of the non-ejection channel 52.

[0107] (Modification) In the above-described embodiment, a configuration in which the air vent passage 70 is formed in the cover plate 42 has been described, but this configuration is not limited thereto. For example, as shown in FIG. 26 , the air vent passage 70 may be formed in the actuator plate 41. The air vent passage 70 is a groove that opens on the surface of the actuator plate 41 and extends along the X direction. The air vent passage 70 extends over the entire length of the actuator plate 41 in the X direction. Therefore, the air vent passage 70 opens on the side surface of the actuator plate 41 facing the X direction. The air vent passage 70 is formed in a position that overlaps with the center of each channel 51, 52 in the Y direction when viewed from the Z direction.

[0108] The air vent passage 70 crosses between adjacent ejection channels 51 and non-ejection channels 52 in the X direction. The air vent passage 70 overlaps with portions of the channels 51 and 52 when viewed from the Y direction. That is, the portions of the air vent passage 70 that overlap with the channels 51 and 52 when viewed from the Z direction are exposed within the channels 51 and 52. The air vent passage 70 connects each of the channels 51 and 52 to the outside of the chip body 40. The portions of the air vent passage 70 that overlap with the ejection channel 51 when viewed from the Z direction are covered by the ejection channel covering portion 43a, thereby blocking communication between the interior of the ejection channel 51 and the outside of the chip body 40 through the air vent passage 70. The portions of the air vent passage 70 that overlap with the non-ejection channel 52 when viewed from the Z direction connect the interior of the non-ejection channel 52 and the outside of the chip body 40 through the air vent passage 70.

[0109] As in this modified example, by forming the air vent passage 70 in the actuator plate 41, the degree of freedom in designing the cover plate 42 can be improved.

[0110] In the first embodiment and the modified example described above, a configuration in which the air vent passage is formed in either the actuator plate 41 or the cover plate 42 has been described, but this configuration is not limiting. The air vent passage may be formed in both the actuator plate 41 and the cover plate 42. In the above-described embodiment, a configuration in which the ejection channels 51 and the non-ejection channels 52 are alternately arranged has been described, but this configuration is not limiting. For example, the present disclosure may be applied to a so-called three-cycle type head chip 32 in which ink is ejected sequentially from all channels.

[0111] Second Embodiment A head chip 32 according to a second embodiment differs from the first embodiment in that the ejection channels 51 do not penetrate the actuator plate 41 in the Z direction. Fig. 27 is a cross-sectional view of the head chip 32 according to the second embodiment. Fig. 28 is a cross-sectional view corresponding to line XXVIII-XXVIII in Fig. 27.

[0112] 27 and 28 , the ejection channel 51 opens on the rear surface of the actuator plate 41 and penetrates the actuator plate 41 in the Y direction. The depth of the ejection channel 51 in the Z direction is shallower than the thickness of the actuator plate 41 in the Z direction. Therefore, the top surface of the ejection channel 51 is formed by the actuator plate 41. The common electrode 65 is formed over the entire inner surface (inner side surface and top surface) of the ejection channel 51. Therefore, the ejection channel covering portion 43 a is in direct or indirect contact with the top surface and inner side surface of the ejection channel 51, thereby continuously covering the entire ejection channel 51 via the common electrode 65.

[0113] Fig. 29 is a cross-sectional view corresponding to line XXIX-XXIX in Fig. 27. Fig. 30 is a plan view of the actuator plate 41. Fig. 31 is a bottom view of the actuator plate 41. As shown in Figs. 29 to 31, common through holes 200 are formed in the actuator plate 41 in portions located on both sides in the Y direction of the non-ejection channels 52. The common through holes 200 penetrate the actuator plate 41 in the Z direction.

[0114] As shown in Figures 27 and 30, the common wiring 61 includes a common surface wiring 210 and a common lead-out wiring 211. The common surface wiring 210 extends in the X direction on portions of the surface of the actuator plate 41 that are located on both sides of the non-ejection channels 52 in the Y direction. Each common surface wiring 210 crosses the common through hole 200 in the X direction. The common lead-out wiring 211 is formed on the inner surface of the common through hole 200. The common lead-out wiring 211 is formed around the entire inner surface of the common through hole 200 and is formed over the entire Z direction. The common lead-out wiring 211 is connected to the common back surface wiring 67 at the opening edge on the -Z side of the common through hole 200. The common lead-out wiring 211 is connected to the common surface wiring 210 at the opening edge on the +Z side of the common through hole 200.

[0115] As shown in Figures 28 and 30, the individual wiring 62 includes an individual surface electrode 220 and a connection wiring 221. The individual surface electrode 220 is formed on the surface of the actuator plate 41 in a portion that overlaps with the ejection channel 51 when viewed from the Z direction. The individual surface electrode 220 is formed in a strip shape extending in the Y direction. The individual surface electrode 220 has the same width as the ejection channel 51. The connection wiring 221 extends in the X direction through the center of the surface of the actuator plate 41 in the Y direction. The connection wiring 221 connects the individual electrodes 68 that face each other in the X direction, with one ejection channel 51 sandwiched between them, at the +Z-side opening edge of the non-ejection channel 52. The connection wiring 221 is connected to the individual surface electrode 220 on the surface of the actuator plate 41.

[0116] 27, 28, and 29, the air vent passage 230 is a groove that opens on the surface of the actuator plate 41 and extends along the X direction. The air vent passage 230 extends over the entire length of the actuator plate 41 in the X direction. The air vent passage 230 opens on the side surface of the actuator plate 41 facing the X direction. When viewed from the Z direction, the air vent passage 230 is formed at a position that overlaps with the center portion of each channel 51, 52 in the Y direction. The air vent passage 230 divides the individual surface electrodes 220 and the connection wiring 221 at their centers in the Y direction.

[0117] The air vent passage 230 crosses between adjacent ejection channels 51 and non-ejection channels 52 in the X direction. The air vent passage 230 overlaps with portions of the channels 51 and 52 when viewed in the Y direction. The portions of the air vent passage 230 that overlap with the channels 51 and 52 when viewed in the Z direction are exposed within the channels 51 and 52. The air vent passage 230 connects the channels 51 and 52 to the outside of the chip body 40. The portions of the air vent passage 230 that overlap with the ejection channel 51 when viewed in the Z direction are covered by an ejection channel covering portion 43a, thereby blocking communication between the interior of the ejection channel 51 and the outside of the chip body 40 through the air vent passage 230. As the air vent passage 230 is closed by the ejection channel covering portion 43a, communication between the interior of the ejection channel 51 and the interior of the non-ejection channel 52 through the air vent passage 230 is also blocked. In the portion of the air vent passage 230 that overlaps with the non-ejection channel 52 when viewed from the Z direction, the inside of the non-ejection channel 52 communicates with the outside of the tip body 40 through the air vent passage 230 .

[0118] The overlap amount between the air vent passage 230 and the discharge channel 51 in the Z direction (the distance between the bottom surface of the air vent passage 230 and the top surface of the discharge channel 51 in the Z direction) is preferably as small as possible, and is preferably 2% to 15% of the dimension of the discharge channel 51 in the Z direction. By making the overlap amount between the air vent passage 230 and the discharge channel 51 in the Z direction 2% or more of the dimension of the discharge channel 51 in the Z direction, the interior of the discharge channel 51 and the interior of the air vent passage 70 can be more reliably connected. By making the overlap amount between the air vent passage 230 and the discharge channel 51 in the Z direction 15% or less of the dimension of the discharge channel 51 in the Z direction, a reduction in the area of ​​the common electrode 65 due to the formation of the air vent passage 230 can be suppressed.

[0119] In the head chip 32 according to the second embodiment, the individual holes 231 are formed in the cover plate 42 at the center in the Y direction of the individual surface electrodes 220 when viewed from the Z direction, at a position overlapping with the air vent passage 230. The air vent passage 230 is in communication with the outside of the chip body 40 through the individual holes 231. An individual through wire 232 is formed on the inner surface of the individual holes 231. The individual through wire 232 is formed around the entire inner surface of the individual holes 231 and is formed over the entire Z direction. The individual through wire 232 is connected to portions of the individual surface electrodes 220 located on both sides of the air vent passage 230 in the Y direction at the -Z side opening edge of the individual holes 231. The individual through wire 232 is connected to individual pads 83 at the +Z side opening edge of the individual holes 231.

[0120] In the head chip 32 according to the second embodiment, during ink ejection, a potential difference in the X direction is generated between the portion of the common electrode 65 formed on the inner surface of the ejection channel 51 and the individual electrode 68, thereby deforming the actuator plate 41 (drive wall 53) in the X direction in shear mode. Furthermore, a potential difference in the Z direction is generated between the portion of the common electrode 65 formed on the top surface of the ejection channel 51 and the individual surface electrode 220, thereby deforming the portion of the actuator plate 41 located between the top surface of the ejection channel 51 and the surface of the actuator plate 41 (top drive wall 240) in the Z direction in bend mode. That is, in the second embodiment, the drive wall 53 and the top drive wall 240 constitute the drive unit according to the present disclosure. Furthermore, a potential difference can be generated in the Z direction between the portion of the individual electrode 68 located on the +Z side of the top surface of the ejection channel 51 and the portion of the common electrode 65 formed on the top surface of the ejection channel 51. Therefore, the actuator plate 41 can be deformed in a direction that expands the volume of the ejection channel 51 in shear mode and bend mode. In this way, by deforming the actuator plate 41 in both the X and Z directions, it is easy to ensure the elastic energy of the actuator plate 41 when a voltage is applied, which makes it easy to ensure the pressure generated in the ejection channel 51 when ejecting ink, thereby achieving the desired ejection performance.

[0121] In the head chip 32 according to the second embodiment, the air vent passage 230 is formed in the actuator plate 41, so there is no need to process the cover plate 42 in relation to the air vent passage 230. This improves the design freedom for the cover plate 42. In the head chip 32 according to the second embodiment, by deforming the actuator plate 41 in the shear mode and bend mode as described above, it is possible to suppress a decrease in generated pressure due to a reduction in the area of ​​the common electrode 65 and individual electrodes 68 caused by the formation of the air vent passage 230 in the actuator plate 41.

[0122] Third Embodiment A head chip 300 of the third embodiment differs from the above-described embodiments in that it employs a so-called roof chute type. FIG. 32 is an exploded perspective view of the head chip 300. FIG. 33 is a cross-sectional view corresponding to line XXXIII-XXXIII in FIG. 32. FIG. 34 is a cross-sectional view corresponding to line XXXIV-XXXIV in FIG. 33. As shown in FIGS. 32 to 34, the head chip 300 includes a nozzle plate 301, a flow path member 302, a protective film 303, an actuator plate 304, a film 305, and a cover plate 306. The actuator plate 304, the film 305, and the cover plate 306 constitute a chip body 308 in the third embodiment.

[0123] The flow path member 302 is plate-shaped with its thickness direction in the Z direction. The flow path member 302 is made of a material that is resistant to ink. Examples of such materials that can be used include metal, metal oxide, glass, resin, and ceramics. The flow path member 302 is formed with a flow path 310 through which ink flows, and a plurality of pressure chambers 311 that communicate with the flow path 310 and contain ink. The flow path 310 and the pressure chambers 311 penetrate the flow path member 302 in the Z direction.

[0124] 32 , the pressure chambers 311 are arranged at intervals in the X direction. Each pressure chamber 311 is formed as a groove that extends linearly in the Y direction. Each pressure chamber 311 penetrates the flow path member 302 over the entire area in the Y direction. However, the pressure chamber 311 may penetrate the flow path member 302 only partially in the Y direction. In a plan view, each pressure chamber 311 is partitioned by a partition wall 312.

[0125] The flow paths 310 include an inlet-side common flow path 314, an inlet-side communication path 315, an outlet-side common flow path 316, and an outlet-side communication path 317. The inlet-side common flow path 314 extends in the X direction from a portion of the flow path member 302 that is located on the +Y side of each pressure chamber 311. The inlet-side communication paths 315 branch off from portions of the inlet-side common flow path 314 that overlap with each pressure chamber 311 when viewed from the Y direction toward the -Y side, thereby connecting the inlet-side common flow path 314 and each pressure chamber 311.

[0126] The outlet-side common flow path 316 extends in the X direction from a portion of the flow path member 302 that is located on the −Y side of each pressure chamber 311. The outlet-side communication paths 317 branch off from portions of the outlet-side common flow path 316 that overlap with each pressure chamber 311 when viewed from the Y direction toward the +Y side, thereby connecting the outlet-side common flow path 316 and each pressure chamber 311.

[0127] 32 and 33, the nozzle plate 301 is fixed to the rear surface of the flow path member 302 by adhesive or the like. The nozzle plate 301 closes the flow paths 310 and the -Z side openings of the pressure chambers 311. The nozzle plate 301 is formed with a plurality of nozzle holes 301a that penetrate the nozzle plate 301 in the Z direction. The nozzle holes 301a are arranged at intervals in the X direction. Each nozzle hole 301a is connected to a corresponding pressure chamber 311 at the center in the X and Y directions.

[0128] The protective film 303 is interposed between the flow path member 302 and the actuator plate 304. Details of the protective film 303 will be described later.

[0129] The actuator plate 304 is provided on the protective film 303 with its thickness direction in the Z direction. The outer shape of the actuator plate 304 in a plan view is the same as the outer shape of the flow path member 302 in a plan view. The actuator plate 304 is overlaid on the entire flow path member 302 with the protective film 303 sandwiched therebetween. The actuator plate 304 faces each pressure chamber 311 in the Z direction with the protective film 303 sandwiched therebetween. The portion of the actuator plate 304 that faces the pressure chamber 311 constitutes the driving unit in the third embodiment. The actuator plate 304 (driving unit) is not limited to a configuration in which it covers all of the pressure chambers 311 collectively, and may be provided individually for each pressure chamber 311.

[0130] As shown in Fig. 33, the actuator plate 304 is set so that its polarization direction faces one direction on the +Z side. Drive wiring 325 is formed on both sides of the actuator plate 304. The actuator plate 304 is configured to be deformable in the Z direction when an electric field is generated by a voltage applied by the drive wiring 325. The actuator plate 304 expands or contracts the volume of the pressure chambers 311 by deformation in the Z direction, thereby ejecting ink from the pressure chambers 311. The configuration of the drive wiring will be described later.

[0131] A first recess 326 is formed in a portion of the actuator plate 304 that faces each pressure chamber 311. The first recess 326 is recessed toward the +Z side with respect to the rear surface of the actuator plate 304. The first recess 326 is formed in a portion that is located at the center of the pressure chamber 311 in the X direction in a plan view. The first recess 326 is formed in a rectangular shape when viewed from the Y direction.

[0132] Second recesses (air chambers) 327 are formed in portions of the actuator plate 304 located on both sides of the first recess 326 in the X direction. The second recesses 327 overlap portions of the flow path member 302 located between adjacent pressure chambers 311 in a plan view. The second recesses 327 are recessed relative to the surface of the actuator plate 304. The second recesses 327 extend in the Y direction along the first recess 326. In the illustrated example, the bottom surface of the second recess 327 (the surface located on the -Z side) is located on the -Z side of the top surface of the first recess 326 (the surface located on the +Z side).

[0133] The film 305 is fixed to the surface of the actuator plate 304 by adhesive or the like. In the third embodiment, the film 305 covers the entire surface of the actuator plate 304. The film 305 is made of an insulating and elastically deformable material. The second film 55 is not an essential component.

[0134] The cover plate 306 is fixed to the surface of the film 305 by adhesive or the like, with the Z direction being the thickness direction.

[0135] Next, the structure of the drive wiring 325 will be described. FIG. 35 is a bottom view of the actuator plate 304. FIG. 36 is a plan view of the actuator plate 304. The drive wiring 325 is provided corresponding to each pressure chamber 311. The drive wirings 325 corresponding to adjacent pressure chambers 311 have the same configuration. In the following description, the drive wiring 325 provided corresponding to one of the multiple pressure chambers 311 will be described as an example, and description of the drive wirings 325 corresponding to the other pressure chambers 311 will be omitted as appropriate. As shown in FIGS. 33 , 35 , and 36 , the drive wiring 325 includes a common wiring 331 and individual wiring 332.

[0136] The common wiring 331 includes a first common electrode 331a, a second common electrode 331b, a third common electrode 331c, a -Y side connection wiring 331d, a central connection wiring 331e, a +Y side connection wiring 331f, a common pad 331g, and a common through wiring 331h. As shown in Figures 33 to 35, the first common electrodes 331a are formed on the rear surface of the actuator plate 304 at positions overlapping with the partition walls 312 when viewed from the Z direction. Each first common electrode 331a extends linearly in the Y direction with a length equal to that of the pressure chamber 311.

[0137] As shown in Figures 33 and 36, the second common electrode 331b is arranged on the surface of the actuator plate 304 at a position that overlaps the corresponding pressure chamber 311 when viewed from the Z direction, but does not overlap the first common electrode 331a when viewed from the Z direction. In the example shown, the second common electrode 331b is formed in a region that includes the center of the pressure chamber 311 in the X direction. The second common electrode 331b extends linearly in the Y direction with a length equal to that of the pressure chamber 311. The third common electrode 331c is formed over the entire inner surface of each second recess 327. The third common electrode 331c is arranged on both sides of the second common electrode 331b in the X direction. It is sufficient that the third common electrode 331c is formed on at least a portion of the inner surface of the second recess 327.

[0138] 36 , the −Y side connection wiring 331d connects the −Y side ends of the second common electrode 331b and the third common electrode 331c on the surface of the actuator plate 304. The central connection wiring 331e connects the Y direction central parts of the second common electrode 331b and the third common electrode 331c on the surface of the actuator plate 304. The +Y side connection wiring 331f connects the +Y side ends of the second common electrode 331b and the third common electrode 331c on the surface of the actuator plate 304.

[0139] Fig. 37 is a plan view of the cover plate 306. As shown in Fig. 37, the common pad 331g is formed on the surface of the cover plate 306 in a portion that overlaps with the pressure chamber 311 when viewed from the Z direction.

[0140] The through wiring 331h connects the first common electrode 331a, the -Y side connection wiring 331d, and the common pad 331g. The common through wiring 331h is provided penetrating the actuator plate 304, the film 305, and the cover plate 306 in the Z direction. Specifically, a common wiring hole 341 is formed in the portions of the actuator plate 304, the film 305, and the cover plate 306 that are located on the -Y side of the second recess 327. The common wiring hole 341 is formed individually for each partition wall 312. The common wiring hole 341 communicates with the inside of the second recess 327. The common through wiring 331h is formed on the inner surface of the common wiring hole 341 over the entire area in the Z direction. The -Y side edges of the first common electrode 331a, the -Y side connection wiring 331d, and the common pad 331g are connected to the common through wiring 331h at the opening edge of the common wiring hole 341.

[0141] As shown in FIGS. 33 to 35 , the individual wiring 332 includes an individual electrode (first drive electrode) 332a, an individual pad 332b, and an individual through-wire 332c. The individual electrode 332a generates a potential difference between itself and the first common electrode 331a, and also generates a potential difference between itself and the second common electrode 331b and between itself and the third common electrode 331c. At least a portion of the individual electrode 332a overlaps with the second common electrode 331b when viewed from the Z direction. The individual electrodes 332a extend in the Y direction while being spaced apart from each first common electrode 331a in the X direction. The individual electrodes 332a are formed on the inner surface of the first recess 326. In the illustrated example, the individual electrodes 332a are formed over the entire length of the first recess 326, covering the entire top surface and inner surface of the first recess 326. However, it is sufficient that the individual electrode 332 a is formed on at least a part of the inner surface of the first recess 326 .

[0142] 37, the individual pads 332b are formed on the surface of the cover plate 306. The individual pads 332b extend in the Y direction on a portion of the surface of the cover plate 306 that overlaps with the pressure chamber 311 when viewed from the Z direction.

[0143] As shown in Figures 34, 35, and 37, the individual through wires 332c connect the corresponding individual electrodes 332a and individual pads 332b. The individual through wires 332c are provided to penetrate the actuator plate 304 in the Z direction. Specifically, individual wiring holes 343 are formed in portions of the actuator plate 304, the film 305, and the cover plate 306 that are located on the +Y side of the individual electrodes 332a. The individual wiring holes 343 are formed individually for each pressure chamber 311 at positions offset in the X direction from the common wiring holes 341. The individual through wires 332c are formed on the inner surfaces of the individual wiring holes 343 over the entire area in the Z direction. The +Y side edges of the corresponding individual electrodes 332a and individual pads 332b are connected to the individual through wires 332c at the opening edges of the individual wiring holes 343.

[0144] As shown in Figures 32 to 34, the protective film 303 is adhered to the outer surface of the chip body 308 via an adhesive 309. The protective film 303 includes a recess covering portion 303a, a back surface covering portion 303b, and a side surface covering portion 303c. The recess covering portion 303a is provided following the shape of the inner surface of the first recess 326. The recess covering portion 303a is in close contact with the individual electrode 332a and continuously covers the inner surface of the first recess 326. The back surface covering portion 303b continuously covers the entire back surface of the actuator plate 304, including the first common electrode 331a. The back surface covering portion 303b is integrally connected to the recess covering portion 303a at the opening edge on the -Z side of the first recess 326. The side surface covering portion 303c is integrally connected to the outer peripheral edge of the back surface covering portion 303b. The side surface covering portion 303 c continuously covers the entire side surface (surface facing the X direction or Y direction) of the chip body 308 .

[0145] 33 , the portions of the drive wiring formed on the surface of the actuator plate 304 are covered with a film 305. Specifically, of the drive wiring, the second common electrode 331b, the third common electrode 331c, the −Y side connection wiring 331d, the central connection wiring 331e, and the +Y side connection wiring 331f are covered with the film 305.

[0146] 33, 34, and 36, an air vent passage 350 is formed in the actuator plate 304. The air vent passage 350 is a groove that opens on the surface of the actuator plate 304 and extends in the X direction. The air vent passage 350 extends over the entire length of the actuator plate 304 in the X direction, crossing between adjacent pressure chambers 311 when viewed from the Z direction. The air vent passage 350 opens on the side surface of the actuator plate 304 facing the X direction. The opening of the air vent passage 350 on the side surface of the actuator plate 304 is closed by the side surface covering portion 303c.

[0147] The air vent passage 350 is formed at a position overlapping the center of the pressure chamber 311 in the Y direction when viewed from the Z direction. The air vent passage 350 overlaps with the nozzle hole 301a when viewed from the Z direction. The air vent passage 350 divides the central connecting wiring 331e in the Y direction.

[0148] The bottom surface of air vent passage 350 is located between the top surface of first recess 326 and the bottom surface of second recess 327 in the Z direction. Air vent passage 350 communicates with the outside of tip body 308 through second recess 327. Air vent passage 350 is connected to the inside of pressure chamber 311 through first recess 326. The portion of air vent passage 350 exposed inside first recess 326 is blocked by recess covering portion 303 a, thereby blocking communication between the outside of tip body 308 and the inside of pressure chamber 311 through air vent passage 350.

[0149] The air vent passage 350 is formed by performing dicing or sandblasting on the surface of the actuator plate 304 after forming drive wiring on both sides of the actuator plate 304 and before laminating the film 305 and cover plate 306. The protective film 303 is formed on the chip body 308, which is made up of the laminated actuator plate 304, film 305, and cover plate 306, by performing a protective film formation step S50. In this case, air within the first recess 326 is discharged to the outside of the chip body 308 directly through the air vent passage 350, or from the air vent passage 350 through the second recess 327, the common wiring hole 341, etc. This allows the protective film 303 (recess covering portion 303a) to be tightly attached to the inner surface of the first recess 326 as well.

[0150] In the head chip 300 of the third embodiment, application of a drive voltage generates a potential difference in the X direction between the first common electrode 331a and the individual electrode 332a. The potential difference in the X direction causes the actuator plate 304 to undergo thickness sliding deformation in the Z direction due to shear mode. Meanwhile, a potential difference in the Z direction occurs between the second common electrode 331b and the individual electrode 332a and between the third common electrode 331c and the individual electrode 332a. The potential difference in the Z direction causes the actuator plate 304 to expand and contract in the Z direction due to bend mode. In other words, in the head chip 300 of the third embodiment, the deformations of the actuator plate 304 due to shear mode and bend mode both extend in the Z direction. In other words, application of a drive voltage causes the actuator plate 304 to deform in a direction away from the pressure chamber 311. This causes the volume within the pressure chamber 311 to expand. Subsequently, when the drive voltage is reduced to zero, the actuator plate 304 returns to its original state, and the volume within the pressure chamber 311 attempts to return to its original state. In the process of the actuator plate 304 restoring to its original state, the pressure in the pressure chamber 311 increases, and the ink in the pressure chamber 311 is ejected to the outside through the nozzle hole 301a.

[0151] In the head chip 300 of the third embodiment, a first recess 326 opening toward the flow path member 302 is formed in the actuator plate 304. A second recess 327 opening toward the opposite side of the flow path member 302 is formed in a portion of the actuator plate 304 located between adjacent pressure chambers 311. An individual electrode (first drive electrode) 322a is formed on the inner surface of the first recess 326. The protective film 303 is provided following the inner surface of the first recess 326. The air vent passage 350 is formed to connect the first recess 326 and the second recess 327. With this configuration, by forming the individual electrode 332a following the inner surface of the first recess 326, the surface area of ​​the individual electrode 332a can be secured. As a result, the electric field generated in the actuator plate 304 can be increased, thereby improving the pressure generated in the pressure chamber 311 during ink ejection. Furthermore, by forming the first recess 326 in the actuator plate 304, the rigidity of the actuator plate 304 in the Z direction can be increased. Furthermore, because the second recess 327 is formed in the actuator plate 304, the second recess 327 functions as a relief portion that allows deformation of the actuator plate 304 when the actuator plate 304 deforms in the Z direction. This makes it easier to ensure the amount of deformation of the actuator plate 304. Furthermore, because the air vent passage 350 is formed to connect the first recess 326 and the second recess 327, air can be effectively discharged from within the first recess 326 in the protective film forming step S50. This makes it easier to adhere the protective film 303 to the inner surface of the first recess 326.

[0152] In the third embodiment, a single air vent passage 350 is provided in the center in the Y direction, but the present invention is not limited to this configuration. For example, as shown in Fig. 38, the air vent passage 350 may be provided in portions located on both sides of the central connecting wiring 331e in the Y direction. For example, as shown in Fig. 39, three or more air vent passages 350 may be provided spaced apart in the Y direction.

[0153] In the third embodiment, a configuration in which the air vent passage 350 is formed only in the actuator plate 41 has been described, but the present invention is not limited to this configuration. For example, as shown in Figure 40, the air vent passage 350 may be formed so as to penetrate the film 305 and the cover plate 306 and to be recessed relative to the surface of the actuator plate 304. In this case, the air vent passage 350 can be formed after the chip body 308 has been formed and before the protective film forming step S50.

[0154] (Fourth Embodiment) A head chip 300 according to the fourth embodiment differs from the third embodiment in that an air vent passage 350 is formed on the back surface of the actuator plate 304. FIG. 41 is a cross-sectional view of a head chip 400 according to the fourth embodiment. FIG. 42 is a bottom view of the actuator plate 304. FIG. 43 is a plan view of the actuator plate 304. In the head chip 400 shown in FIGS. 41 to 43, the common wiring 331 includes a first common electrode 331a, a second common electrode 331b, a third common electrode 331c, a −Y-side connection wiring 331d, a central connection wiring 331e, a +Y-side connection wiring 331f, a common pad 331g, a common through wiring 331h, as well as a back-surface routing wiring 331j, a front-surface routing wiring 331k, and a side-surface routing wiring 331m.

[0155] The rear surface lead-out wiring 331j extends in the X direction along the +Y side edge on the rear surface of the actuator plate 304. The rear surface lead-out wiring 331j connects adjacent first common electrodes 331a to each other. The front surface lead-out wiring 331k extends in the Y direction in a portion of the front surface of the actuator plate 304 that is located between adjacent individual wiring holes 343. The -Y side end of the front surface lead-out wiring 331k is connected to the third common electrode 331c at the +Z side opening edge of the second recess 327. The +Y side end of the front surface lead-out wiring 331k reaches the +Y side edge on the front surface of the actuator plate 304.

[0156] The side surface lead-out wiring 331m is formed on the side surface facing the +Y side of the side surface of the actuator plate 304. The side surface lead-out wiring 331m connects between the back surface lead-out wiring 331j and the front surface lead-out wiring 331k. The side surface lead-out wiring 331m is preferably covered by the side surface covering portion 303c.

[0157] The air vent passage 402 is a groove that opens on the back surface of the actuator plate 304 and extends in the X direction. The air vent passage 402 extends over the entire length of the actuator plate 304 in the X direction, crossing between adjacent pressure chambers 311 when viewed from the Z direction. Therefore, the air vent passage 402 opens on the side surface of the actuator plate 304 facing the X direction.

[0158] The air vent passage 402 is formed at a position overlapping the center of the pressure chamber 311 in the Y direction when viewed from the Z direction. The top surface of the air vent passage 402 (the surface located on the +Z side) is located on the -Z side of the top surface of the first recess 326 and on the +Z side of the bottom surface of the second recess 327 in the Z direction. Therefore, the air vent passage 402 communicates with the outside of the tip body 308 through the second recess 327. The air vent passage 402 is connected to the inside of the pressure chamber 311 through the first recess 326. The portion of the air vent passage 350 exposed in the first recess 326 is blocked by the recess covering portion 303a, thereby blocking communication between the outside of the tip body 308 and the inside of the pressure chamber 311 through the air vent passage 350.

[0159] In the fourth embodiment, the first common electrode 331a is divided in the Y direction by the air vent passage 402. However, the portion of the first common electrode 331a located on the -Y side of the air vent passage 402 is connected to the -Y side connection wiring 331d through the common through wiring 331h. The portion of the first common electrode 331a located on the +Y side of the air vent passage 402 is connected to the front surface lead-out wiring 331k through the back surface lead-out wiring 331j and the side surface lead-out wiring 331m. Therefore, the common wiring 331 is integrally connected on the front and back surfaces of the actuator plate 304. At least a portion of the portion of the individual electrode 332a located on the inner surface of the first recess 326 is divided in the Y direction by the air vent passage 402. The portion of the individual electrode 332a located on the top surface of the first recess 326 is located on the +Z side of the air vent passage 402, and therefore extends continuously along the entire length of the top surface of the recess 326 in the Y direction.

[0160] According to the configuration of the fourth embodiment, the air vent passage 402 can be formed after forming various wirings on the front and back surfaces of the actuator plate 304. As a result, there is no need to form various wirings on the back surface of the actuator plate 304, while the front and back surfaces of the actuator plate 304 are in communication through the air vent passage 402 and the second recess 327. This makes it possible to prevent the various wirings formed on the front and back surfaces of the actuator plate 304 from being connected through the air vent passage 402. As a result, a head chip 400 with excellent reliability can be provided.

[0161] In the fourth embodiment described above, a configuration has been described in which the dimension of the first recess 326 in the Y direction is equal to that of the pressure chamber 311, but this configuration is not limiting. As shown in Fig. 44 , the first recess 326 may extend to a position where it overlaps with the common flow paths 314, 316 when viewed from the Z direction.

[0162] (Other Modifications) The technical scope of the present disclosure is not limited to the above-described embodiments, and various modifications may be made without departing from the spirit and scope of the present disclosure. For example, in the above-described embodiments, an inkjet printer 1 was described as an example of a liquid jet recording apparatus, but the present disclosure is not limited to a printer. For example, a fax machine, an on-demand printer, or the like may also be used. In the above-described embodiments, a configuration in which an inkjet head moves relative to a recording medium during printing (a so-called shuttle machine) was described as an example, but the present disclosure is not limited to this configuration. The configuration according to the present disclosure may also be adopted in a configuration in which the inkjet head is fixed and the recording medium moves relative to the inkjet head (a so-called fixed head machine). In the above-described embodiments, the recording medium P is described as paper, but the present disclosure is not limited to this configuration. The recording medium P is not limited to paper, but may be a metal material, a resin material, or even food. In the above-described embodiments, a configuration in which a liquid jet head is mounted on a liquid jet recording apparatus was described, but the present disclosure is not limited to this configuration. In other words, the liquid sprayed from the liquid spray head is not limited to liquid that lands on a recording medium, but may also be, for example, a medicinal liquid to be mixed into a prescription, a food additive such as a seasoning or fragrance to be added to food, or an air freshener to be sprayed into the air.

[0163] In the above-described embodiment, the Z direction is aligned with the direction of gravity, but the present invention is not limited to this configuration, and the Z direction may be aligned with the horizontal direction. In the above-described embodiment, the protective film is heated in the protective film forming step S50, but the present invention is not limited to this configuration. The protective film forming step S50 may be performed at room temperature.

[0164] In the above-described embodiment, a side-chute type head chip has been described as an example, but this configuration is not limited to this. For example, the configuration according to the present disclosure may be adopted in a so-called edge-chute type head chip that ejects ink from the end of the ejection channel in the extension direction. In the above-described embodiment, a configuration in which the air vent passage extends so as to straddle multiple pressure chambers has been described, but this configuration is not limited to this. The air vent passage may be connected individually to each pressure chamber. In the above-described embodiment, a configuration in which the air vent passage extends so as to straddle a pressure chamber and an air chamber has been described, but this configuration is not limited to this. The air vent passage may be connected only to the pressure chamber or only to the air chamber.

[0165] In addition, within the scope of the present disclosure, the components in the above-described embodiments may be replaced with well-known components as appropriate, and the above-described modified examples may be combined as appropriate.

[0166] DESCRIPTION OF SYMBOLS 1: Printer (liquid jet recording apparatus) 5: Inkjet head (liquid jet head) 32: Head chip 40: Chip body 41: Actuator plate 42: Cover plate 42b: First individual hole (wiring hole) 42c: Second individual hole (wiring hole) 43: Protective film 44: Nozzle plate (ejection hole plate) 51: Ejection channel (pressure chamber) 52: Non-ejection channel (air chamber) 53: Driving wall (driving section) 65: Common electrode (first driving electrode) 68: Individual electrode (second driving electrode) 70: Air vent passage 81: First individual through wire (through wire) 82: Second individual through wire (through wire) 120: Chamber 230: Air vent passage 231: Individual hole (wiring hole) 240: Top driving wall (driving section) 300: Head chip 302: Flow path member 303: Protective film 304: Actuator plate 308: Chip body 311: Pressure chamber 326: First recess 327: Second recess (second recess) 332a: Individual electrode (first drive electrode) 350: Air vent passage 400: Head chip 402: Air vent passage S50: Protective film forming step

Claims

1. A head chip comprising: a chip body having a plurality of pressure chambers formed in a first direction and containing liquid, and drive units each arranged on a portion facing the pressure chamber; a first drive electrode formed on the drive unit; and a sheet-like protective film formed in accordance with the drive unit while covering the first drive electrode, wherein the chip body has an air vent passage formed therein that connects the inside of the pressure chamber to the outside of the chip body and whose communication between the pressure chamber and the outside of the chip body is blocked by the protective film.

2. The head chip according to claim 1, wherein the air vent passage extends so as to straddle a plurality of the pressure chambers.

3. A head chip as described in claim 2, wherein an air chamber not containing liquid is formed in a portion of the chip body located between adjacent pressure chambers in the first direction, the protective film is arranged so as to straddle both the pressure chamber and the air chamber in the first direction, and the air vent passage extends so as to straddle between the pressure chamber and the air chamber.

4. A head chip as described in claim 3, wherein a second drive electrode for generating a potential difference between the first drive electrode and the inner surface of the air chamber is formed, a wiring hole opening into the air chamber is formed in the chip body, and a through wiring connected to the second drive electrode is formed on the inner surface of the wiring hole.

5. A head chip described in any one of claims 1 to 4, wherein the pressure chamber extends in the chip body with a second direction intersecting the first direction as its longitudinal direction, and the air vent passage is connected to a central portion of the pressure chamber in the second direction.

6. A head chip as described in claim 5, comprising an injection hole plate having an injection hole communicating with the pressure chamber, the pressure chamber opening on an opening surface of the chip body facing a third direction intersecting the second direction when viewed from the first direction, the injection hole plate closing the opening of the pressure chamber and being provided facing the opening surface of the chip body, and the air vent passage being provided at a position of the pressure chamber overlapping with the injection hole when viewed from the third direction.

7. A head chip described in any one of claims 1 to 6, wherein the chip body comprises an actuator plate having the pressure chamber and the driving section, and a cover plate superimposed on the actuator plate, and the air vent passage is formed in the actuator plate.

8. A head chip described in any one of claims 1 to 7, wherein the chip body comprises an actuator plate having the pressure chamber and the driving section, and a cover plate overlaid on the actuator plate, and the air vent passage is formed in the cover plate.

9. A head chip as claimed in any one of claims 1 to 7, wherein the chip body comprises: a flow path member in which the pressure chambers are formed; and an actuator plate overlaid on the pressure chambers and having the drive unit, wherein a first recess is formed in the drive unit and opens toward the flow path member, and a second recess is formed in a portion of the actuator plate located between adjacent pressure chambers in the first direction and opens toward the side opposite the flow path member, the first drive electrode is formed on the inner surface of the first recess, the protective film is provided in the drive unit following the inner surface of the first recess, and the air vent passage is formed to connect between the first recess and the second recess.

10. A liquid jet head comprising the head chip according to any one of claims 1 to 9.

11. A liquid jet recording apparatus comprising the liquid jet head according to claim 10.

12. A method for manufacturing a head chip comprising: a chip body having a plurality of pressure chambers formed in a first direction and containing liquid, and drive units each arranged on a portion facing the pressure chamber; a first drive electrode formed on the drive unit; and a sheet-like protective film formed to model the drive unit while covering the first drive electrode, wherein the chip body has an air vent passage formed therein that connects the pressure chamber to the outside of the chip body and blocks communication between the pressure chamber and the outside of the chip body on the drive unit by the protective film, the method comprising a protective film formation step of applying negative pressure to the pressure chamber through the air vent passage in a space on the opposite side of the protective film from the pressure chamber, thereby adhering the protective film to the drive unit.

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