Liquid ejection head and manufacturing method thereof

Abstract

To achieve both suppression of structural crosstalk and suppression of intrusion of moisture into an actuator storage chamber.SOLUTION: A head 1 comprises: a flow passage substrate 11 in which a plurality of individual flow passages 20 are formed; a plurality of actuators 12x fixed to a surface of the flow passage substrate 11; and a protection substrate 13 fixed to the surface of the flow passage substrate 11 and covering the plurality of actuators 12x. The protection substrate 13 has a wall part 13w for defining actuator storage chambers 12c storing the actuators 12x. The wall part 13w overlaps, in a vertical direction, with bulkheads 11b1 separating two pressure chambers 21 in the flow passage substrate 11 from each other and is made to adhere to the surface of the flow passage substrate 11 through an adhesion part A constituted of adhesives. A protection film C is formed in the protection substrate 13 and in a portion defining the actuator storage chambers 13c in the adhesion part A.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a liquid ejection head in which a protection substrate has walls for defining a plurality of actuator housing chambers, and to a method for manufacturing the same. [Background technology]

[0002] In Patent Document 1, the protection substrate has a support portion (wall portion) for defining an actuator accommodating chamber for each piezoelectric element (actuator). The support portion overlaps in the Z direction (orthogonal direction) with a partition wall separating two pressure chambers in the pressure chamber substrate, and is bonded to the pressure chamber substrate via an adhesive. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2020-032713 A Summary of the Invention [Problem to be solved by the invention]

[0004] According to Patent Document 1, the support portion (wall portion) of the protective substrate overlaps with the partition wall of the pressure chamber substrate in the Z direction (orthogonal direction), thereby suppressing structural crosstalk (the phenomenon in which vibration caused by deformation of an actuator is transmitted to another actuator adjacent to the actuator). However, moisture may enter the actuator accommodating chamber from the outside of the protective substrate through the adhesive between the wall portion of the protective substrate and the flow path substrate, and the actuator may be destroyed by the moisture.

[0005] An object of the present invention is to provide a liquid ejection head that can suppress both structural crosstalk and the intrusion of moisture into an actuator housing chamber, and a method for manufacturing the same. [Means for solving the problem]

[0006] The liquid ejection head according to the present invention comprises a flow path substrate on which a plurality of individual flow paths are formed, each of which includes a nozzle and a pressure chamber connected to the nozzle; a plurality of actuators fixed to a surface of the flow path substrate and overlapping with each of the pressure chambers of the plurality of individual flow paths in an orthogonal direction perpendicular to the surface; and a protective substrate fixed to the surface and covering the plurality of actuators, the protective substrate having a wall portion for defining a plurality of actuator accommodating chambers each accommodating one or more of the actuators, the wall portion overlapping with a partition wall separating two of the pressure chambers in the flow path substrate in the orthogonal direction and being adhered to the surface via an adhesive, and a protective film having a moisture permeability lower than the moisture permeability of the adhesive is formed in portions of the protective substrate and the adhesive portion defining each of the plurality of actuator accommodating chambers.

[0007] A method for manufacturing a liquid ejection head according to the present invention includes an actuator forming step of forming a plurality of actuators on a surface of a flow path substrate, and a protective substrate fixing step of fixing a protective substrate to the surface so as to cover the plurality of actuators after the actuator forming step, the protective substrate having a wall portion for defining a plurality of actuator housing chambers each housing one or more of the actuators, a first communication hole that connects at least one of the plurality of actuator housing chambers to the outside, and a second communication hole that connects the plurality of actuator housing chambers to each other, the protective substrate being fixed to the protective substrate. In the process, the wall portion is arranged so as to overlap a partition wall separating two pressure chambers in the flow path substrate in an orthogonal direction perpendicular to the surface, and is adhered to the surface via an adhesive portion, and after the protective substrate fixing process, a protective film forming process is provided in which a gas is injected from the outside to the inside of the protective substrate via the first communication hole, thereby forming a protective film having a moisture permeability lower than the moisture permeability of the adhesive in portions of the protective substrate and the adhesive portion that define each of the plurality of actuator accommodating chambers, and after the protective substrate forming process, a sealing process is provided in which the first communication hole is sealed with a sealing member. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a plan view of a printer 100 equipped with a head 1 according to a first embodiment of the present invention. [Diagram 2] FIG. [Diagram 3] 3 is a cross-sectional view of the head 1 taken along line III-III in FIG. 2. [Figure 4] 4 is a cross-sectional view of the head 1 taken along the line IV-IV in FIG. 2. [Diagram 5] 3 is a plan view corresponding to FIG. 2, illustrating the relationship between the protective substrate 13, the actuators 12x, and the individual flow paths 20. FIG. [Figure 6] 6 is a plan view showing a protection substrate 13 and corresponds to FIG. 5. FIG. [Figure 7] 3 is a flow diagram showing a manufacturing method of the head 1. FIG. [Figure 8] 7 is a plan view corresponding to FIG. 6 and showing a protection substrate 213 of a head according to a second embodiment of the present invention. FIG. [Figure 9] 7 is a plan view corresponding to FIG. 6 and showing a protection substrate 313 of a head according to a third embodiment of the present invention. FIG. [Figure 10] 4 is a cross-sectional view corresponding to the partially enlarged view of FIG. 3, showing a protection substrate 413 of a head according to a fourth embodiment of the present invention. [Figure 11] 5 is a cross-sectional view corresponding to FIG. 3 and showing a protection substrate 513 of a head according to a fifth embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] First Embodiment A head 1 according to a first embodiment of the present invention is provided in a printer 100, as shown in Fig. 1. The printer 100 includes a head unit 1x including four heads 1, a platen 3, a transport mechanism 4, and a control unit 5.

[0010] The head unit 1x is a line type that is elongated in the paper width direction (a direction perpendicular to the vertical direction) and ejects ink from nozzles 22 (see Figs. 2 and 3) onto paper 9 while being fixed in position. Each of the four heads 1 is elongated in the paper width direction and is arranged in a staggered pattern in the paper width direction.

[0011] The platen 3 is a flat member disposed below the head unit 1x, and a sheet of paper 9 is placed on the upper surface of the platen 3.

[0012] The transport mechanism 4 has two roller pairs 4a, 4b arranged in the transport direction (the direction perpendicular to the vertical direction and the paper width direction) with the platen 3 between them. When a transport motor (not shown) is driven under the control of the control unit 5, the roller pairs 4a, 4b rotate while holding the paper 9 therebetween, and the paper 9 is transported in the transport direction.

[0013] The control unit 5 has a ROM (Read Only Memory), a RAM (Random Access Memory), and an ASIC (Application Specific Integrated Circuit). The ASIC executes recording processing and the like according to a program stored in the ROM. In the recording processing, the control unit 5 controls a conveying motor (not shown) and a driver IC 19 (see FIG. 3) of each head 1 based on a recording command (including image data) input from an external device such as a PC, thereby causing the conveying mechanism 4 to convey the paper 9 and each head 1 to eject ink onto the paper 9, thereby recording an image on the paper 9.

[0014] Next, the configuration of the head 1 will be described.

[0015] The head 1 has a flow path substrate 11, an actuator substrate 12, a wiring substrate 18, and two protection substrates 13, as shown in FIGS.

[0016] The flow path substrate 11 is composed of four plates 11a to 11d that are stacked in the vertical direction (orthogonal direction) and bonded to each other. Of the four plates 11a to 11d, the uppermost plate 11a is formed by, for example, injection molding of resin, and has two common flow paths 31. The plates 11b to 11d are composed of, for example, resin (for example, LCP: liquid crystal polymer) or metal (for example, SUS: stainless steel), and have a plurality of individual flow paths 20 formed therein.

[0017] The individual flow paths 20 are arranged in the paper width direction (column direction) to form two individual flow path rows 20R. Each individual flow path row 20R is composed of a plurality of individual flow paths 20 arranged in the paper width direction. The two individual flow path rows 20R are aligned in the transport direction. The individual flow paths 20 are generally arranged in a staggered pattern in the paper width direction.

[0018] As shown in Fig. 2, the two common flow paths 31 each extend in the paper width direction and are aligned in the transport direction. A plurality of individual flow paths 20 are disposed between the two common flow paths 31 in the transport direction. The two common flow paths 31 each communicate with a sub-tank (not shown) via a supply port 31x. The sub-tank communicates with a main tank that stores ink, and stores ink supplied from the main tank. The ink in the sub-tank flows into the common flow path 31 from each supply port 31x when a pump (not shown) is driven under the control of the control unit 5.

[0019] Of the two common flow paths 31, the common flow path 31 on the left side in Fig. 2 communicates with the multiple individual flow paths 20 belonging to the individual flow path array 20R on the left side in Fig. 2 out of the two individual flow path arrays 20R. Of the two common flow paths 31, the common flow path 31 on the right side in Fig. 2 communicates with the multiple individual flow paths 20 belonging to the individual flow path array 20R on the right side in Fig. 2 out of the two individual flow path arrays 20R.

[0020] As shown in FIG. 2, each individual flow path 20 includes a pressure chamber 21, a nozzle 22, a connecting flow path 23, a narrow flow path 24, and a wide flow path 25.

[0021] The pressure chamber 21 has a generally rectangular shape that is elongated in the transport direction in a plane perpendicular to the vertical direction. One end of the pressure chamber 21 in the transport direction is connected to a connection flow path 23, and the other end of the pressure chamber 21 in the transport direction is connected to a narrow flow path 24.

[0022] The narrow flow passage 24 has a width smaller than the width (length in the paper width direction) of the pressure chamber 21, and functions as a throttle. The wide flow passage 25 has a width substantially the same as the width (length in the paper width direction) of the pressure chamber 21.

[0023] As shown in FIG. 3, the pressure chamber 21, the narrow flow passage 24, and the wide flow passage 25 are configured as through holes formed in the plate 11b.

[0024] The connection flow path 23 is constituted by a through hole formed in the plate 11c, and connects the pressure chamber 21 and the nozzle 22 to each other.

[0025] The nozzle 22 is configured as a through hole formed in the plate 11 d and opens to the lower surface of the flow path substrate 11 .

[0026] As shown in FIG. 2, ink flowing into the common flow path 31 from each supply port 31x is supplied to a plurality of individual flow paths 20 belonging to the corresponding individual flow path row 20R. In each individual flow path 20, ink from the common flow path 31 flows into the wide flow path 25, and then flows into the pressure chamber 21 through the narrow flow path 24. Then, as described below, the actuator 12x (see FIG. 3) is deformed and the volume of the pressure chamber 21 is reduced, so that pressure is applied to the ink in the pressure chamber 21, and ink is ejected from the nozzle 22 through the connection flow path 23. In addition, as ink is ejected from the nozzle 22, ink is supplied from the common flow path 31 to each individual flow path 20, and ink is supplied from the sub tank to the common flow path 31.

[0027] As shown in FIG. 3, the actuator substrate 12 is fixed to the upper surface of the plate 11b, and includes, from the bottom up, a vibration plate 12a, a common electrode 12b, a plurality of piezoelectric bodies 12c, and a plurality of individual electrodes 12d.

[0028] The vibration plate 12a and the common electrode 12b are disposed over the entire upper surface of the plate 11b, and cover all the pressure chambers 21 formed in the plate 11b. On the other hand, the piezoelectric body 12c and the individual electrode 12d are provided for each pressure chamber 21, and overlap the pressure chamber 21 in the vertical direction.

[0029] The actuator substrate 12 further includes an insulating film 12i and a plurality of wirings 12e.

[0030] The insulating film 12i is made of silicon dioxide (SiO2) or the like, and covers a portion of the upper surface of the common electrode 12b where the piezoelectric body 12c is not provided, the side surfaces of the piezoelectric body 12c, and the upper surfaces of the individual electrodes 12d. A through hole is provided in the insulating film 12i in a portion that vertically overlaps with the individual electrodes 12d.

[0031] The wiring 12e is provided for each individual electrode 12d, and is electrically connected to the individual electrode 12d by inserting an end of the wiring 12e into the through hole of the insulating film 12i.

[0032] The wiring board 18 is made of a COF (Chip On Film) or the like, and one end of the wiring board 18 is fixed to the center in the transport direction of the upper surface of the actuator substrate 12. The wiring board 18 has a plurality of individual wirings 18e electrically connected to the plurality of wirings 12e, respectively, and a common wiring (not shown) electrically connected to the common electrode 12b.

[0033] The other end of the wiring board 18 is connected to the control unit 5 (see FIG. 1). A driver IC 19 is mounted between one end and the other end of the wiring board 18.

[0034] The driver IC 19 is electrically connected to the individual electrode 12d via the individual wiring 18e, and is electrically connected to the common electrode 12b via a common wiring. The driver IC 19 maintains the potential of the common electrode 12b at the ground potential, while generating a drive signal based on a control signal from the control unit 5 and applying the drive signal to the individual electrode 12d, thereby changing the potential of the individual electrode 12d between a predetermined drive potential and the ground potential. At this time, a portion of the piezoelectric body 12c sandwiched between the individual electrode 12d and the common electrode 12b (actuator 12x) contracts in the planar direction due to the piezoelectric transverse effect. Accordingly, a portion of the actuator substrate 12 that vertically overlaps with the pressure chamber 21 deforms so as to be convex toward the pressure chamber 21, thereby reducing the volume of the pressure chamber 21 and applying pressure to the ink in the pressure chamber 21.

[0035] 3, the two protective substrates 13 are fixed to the upper surface of the actuator substrate 12. The protective substrate 13 is provided for each individual flow path array 20R, and covers the actuators 12x corresponding to that individual flow path array 20R.

[0036] Each protection substrate 13 has a wall portion 13w and a plate portion 13p.

[0037] The wall portion 13w corresponds to a side wall of the protection substrate 13. The lower end of the wall portion 13w is adhered to the upper surface of the actuator substrate 12 via an adhesive portion A made of an adhesive (for example, an epoxy-based or silicone-based adhesive).

[0038] The plate portion 13p corresponds to the upper wall of the protective substrate 13, and is connected to the upper end of the wall portion 13w. The plate portion 13p defines the outer shape of the protective substrate 13 shown in Fig. 5, has a rectangular shape that is elongated in the paper width direction in a plane perpendicular to the vertical direction, and overlaps in the vertical direction with the multiple actuators 12x corresponding to the individual flow path array 20R.

[0039] 5 and 6, the wall portion 13w includes a pair of first wall portions 13w1 each extending in the paper width direction, and a plurality of second wall portions 13w2 each extending in the transport direction. As shown in FIG. 4, each of the second wall portions 13w2 overlaps in the vertical direction with a partition wall 11b1 that separates the two pressure chambers 21 in the plate 11b.

[0040] The wall 13w is configured in such a way that a plurality of actuator housing chambers 13c are defined, each housing one actuator 12x. The actuator housing chambers 13c are arranged in the paper width direction, as shown in Fig. 5. The height (vertical length) H of each actuator housing chamber 13c is 100 µm or more (see Fig. 4).

[0041] A first communication hole 13x is formed in the center of the plate portion 13p in the transport direction and the paper width direction, as shown in Figures 5 and 6. The first communication hole 13x penetrates the plate portion 13p in the vertical direction and communicates one of the multiple actuator accommodating chambers 13c defined by the protection substrate 13 with the outside. The first communication hole 13x is sealed by a plate-shaped sealing member 14, as shown in Figure 5.

[0042] Each second wall portion 13w2 extends in the transport direction from one of the pair of first wall portions 13w1 (the first wall portion 13w1 that overlaps the wide flow path 25 in the vertical direction as shown in FIG. 5). The tip of each second wall portion 13w2 is not connected to the other of the pair of first wall portions 13w1. The space between the tip of each second wall portion 13w2 and the other of the pair of first wall portions 13w1 constitutes a second communication hole 13y that communicates the multiple actuator housing chambers 13c with each other. The second communication hole 13y is formed over the entire vertical length of the actuator housing chamber 13c as shown in FIG. 3, at a position that does not overlap with the actuator 12x in the paper width direction as shown in FIG. 5.

[0043] In such a configuration of the protective substrate 13, a protective film C is formed on the entire inner wall surface of the protective substrate 13 (see Figs. 3 and 4). The protective film C is made of a material (e.g., at least one of tantalum oxide, hafnium oxide, and aluminum oxide) having a lower moisture permeability than that of the adhesive constituting the adhesive portion A. The protective film C is formed on the protective substrate 13 and on the portions of the adhesive portion A that define the actuator accommodating chambers 13c, and is also formed on the upper surfaces of the individual electrodes 12d constituting each actuator 12x and on the side surfaces of the piezoelectric bodies 12c.

[0044] Next, a method for manufacturing the head 1 will be described with reference to FIG.

[0045] First, an actuator 12x is formed on the surface of a silicon single crystal substrate that will become the plate 11b (S1: actuator formation step). Specifically, a vibration plate 12a made of a silicon dioxide film is formed on the surface of the silicon single crystal substrate that will become the plate 11b by thermal oxidation or the like. Thereafter, a common electrode 12b is formed on the surface of the vibration plate 12a, a plurality of piezoelectric bodies 12c are formed on the surface of the common electrode 12b, and an individual electrode 12d is formed on the surface of each piezoelectric body 12c. Furthermore, an insulating film 12i and a plurality of wirings 12e are formed by sputtering, etching, or the like.

[0046] After S1, two protective substrates 13 are fixed to the surface of the silicon single crystal substrate that will become the plate 11b so as to cover the actuators 12x corresponding to the individual flow path arrays 20R (S2: protective substrate fixing step). Specifically, the lower end of the wall portion 13w is bonded to the surface of the silicon single crystal substrate that will become the plate 11b via the adhesive portion A made of adhesive, and the plate portion 13p is disposed so as to cover the actuators 12x.

[0047] After S2, the flow paths (common flow path 31 and individual flow paths 20) are formed in the flow path substrate 11 (S3). Specifically, the silicon single crystal substrate that becomes the plate 11b is polished to a predetermined thickness, and then etching is performed from the lower surface of the silicon single crystal substrate to form the pressure chambers 21, narrow flow paths 24, and wide flow paths 25 of each individual flow path 20. At this stage, the silicon single crystal substrate becomes the plate 11b. Thereafter, the plate 11c is bonded to the lower surface of the plate 11b, the plate 11d is bonded to the lower surface of the plate 11c, and the plate 11a is bonded to the upper surface of the plate 11c, thereby completing the flow path substrate 11 in which the common flow path 31 and the individual flow paths 20 are formed. At this time, the wall portion 13w is arranged so as to overlap the partition wall 11b1 in a direction perpendicular to the surface of the flow path substrate 11 (see FIG. 4).

[0048] After S3, the nozzles 22 formed on the lower surface of the flow path substrate 11 are sealed with a sealing member (a member different from the sealing member 14) (S4).

[0049] After S4, a protective film C is formed on the entire inner wall surface of the protective substrate 13 (S5: protective film forming step). Specifically, the members including the flow path substrate 11, the actuator substrate 12, and the protective substrate 13 formed in S1 to S4 are placed in a gas chamber, and gas is injected into the gas chamber using atomic layer deposition. As a result, gas is injected from the outside to the inside of the protective substrate 13 through the first communication hole 13x, and the gas spreads through the multiple actuator housing chambers 13c through the second communication hole 13y, so that the protective film C is formed on the protective substrate 13 and the portion of the adhesive portion A that defines each actuator housing chamber 13c, and on the upper surface of the individual electrode 12d and the side surface of the piezoelectric body 12c that constitutes each actuator 12x. At this time, the protective film C is not formed on the nozzle 22 because the nozzle 22 is sealed with a sealing member.

[0050] After S5, the first communication hole 13x is sealed with a sealing member 14 (S6: sealing step), thereby blocking communication between the actuator accommodating chamber 13c and the outside.

[0051] After S6, one end of the wiring board 18 is fixed to the surface of the flow path substrate 11 (S7). Specifically, one end of the wiring board 18 is placed on the surface of the flow path substrate 11 via a thermosetting adhesive, and the adhesive is cured by applying heat and pressure. This electrically connects the individual wiring 18e and the wiring 12e, and electrically connects the common wiring (not shown) and the common electrode 12b. This completes the head 1.

[0052] As described above, according to this embodiment, structural crosstalk (a phenomenon in which vibration caused by deformation of an actuator 12x is transmitted to another actuator 12x adjacent to the actuator 12x) can be suppressed by vertically overlapping the wall 13w of the protective substrate 13 with the partition wall 11b1 of the flow path substrate 11 as shown in Fig. 4. In addition, as shown in Fig. 3 and Fig. 4, a protective film C is formed on the protective substrate 13 and the portion of the adhesive portion A that defines each actuator accommodating chamber 13c, so that intrusion of moisture from the outside into the actuator accommodating chamber 13c through the adhesive portion A (and thus damage to the actuator 12x) can be suppressed.

[0053] 5 and 6, the protective substrate 13 is formed with a first communication hole 13x that connects the actuator housing chamber 13c to the outside, and a second communication hole 13y that connects the actuator housing chambers 13c to each other. 3 Even in the configuration in which the gap 13c is defined, in S5 (protective film forming step), gas is distributed through the actuator housing chambers 13c via the first communication hole 13x and the second communication hole 13y, and the protective film C can be efficiently formed. After S5 (protective film forming step), the first communication hole 13x is sealed with a sealing member 14 (S6). This makes it possible to prevent moisture from entering the actuator housing chambers 13c from the outside via the first communication hole 13x (and thus damage to the actuator 12x).

[0054] The second communication hole 13y is formed over the entire vertical length of the actuator housing chamber 13c as shown in Fig. 3 at a position where it does not overlap with the actuator 12x in the paper width direction as shown in Fig. 5. If the second communication hole 13y is formed over the entire vertical length of the actuator housing chamber 13c as shown in Fig. 3 at a position where it overlaps with the actuator 12x in the paper width direction, the binding force of the wall portion 13w on the partition wall 11b1 may be reduced, and the effect of suppressing structural crosstalk may be reduced. In contrast, in this configuration, since the second communication hole 13y does not overlap with the actuator 12x in the paper width direction, the binding force of the wall portion 13w on the partition wall 11b1 is not reduced, and the effect of suppressing structural crosstalk can be maintained. Furthermore, since the second communication hole 13y is formed over the entire vertical length of the actuator accommodating chamber 13c, in S5 (protective film forming process), gas can easily reach the multiple actuator accommodating chambers 13c through the second communication hole 13y, and the protective film C can be reliably formed for all actuator accommodating chambers 13c.

[0055] In S5 (protective film forming step), an atomic layer deposition method is used. In this case, the protective film C can be easily formed.

[0056] The protective film C is made of at least one of tantalum oxide, hafnium oxide, and aluminum oxide. In this case, the atomic layer deposition method can be effectively realized by using a material suitable for the atomic layer deposition method (and thus the protective film C can be easily formed).

[0057] The height (vertical length) H of the actuator housing chamber 13c is 100 μm or more (see FIG. 4). If the height of the actuator housing chamber 13c is less than 100 μm, the air resistance of the gas injected into the actuator housing chamber 13c by atomic layer deposition or the like increases, and the gas cannot be sufficiently distributed in the actuator housing chamber 13c in S5 (protective film forming step) (and thus it may be difficult to form the protective film C over the entire actuator housing chamber 13c). In contrast, in this configuration, since the height of the actuator housing chamber 13c is 100 μm or more, the air resistance of the gas injected into the actuator housing chamber 13c by atomic layer deposition or the like is low, and the gas can be sufficiently distributed in the actuator housing chamber 13c in S5 (protective film forming step) (and thus the protective film C can be formed over the entire actuator housing chamber 13c).

[0058] A protective film C is also formed on the surfaces of the actuators 12x (the upper surfaces of the individual electrodes 12d and the side surfaces of the piezoelectric bodies 12c) (see Figs. 3 and 4). In this case, even if moisture enters the actuator housing chamber 13c from the outside, damage to the actuators 12x can be suppressed. Note that the protective film C is thin and does not impede the deformation of the actuators 12x.

[0059] In S5 (protective film forming process), the nozzles 22 are sealed with a sealing member (a member different from the sealing member 14) when the gas is injected (see S4). If a protective film C is formed on the nozzles 22, problems may occur in the ejection of ink. In this configuration, by sealing the nozzles 22 when the gas is injected, it is possible to prevent the protective film C from being formed on the nozzles 22 (and thus to prevent problems in the ejection of ink).

[0060] <Second embodiment> Next, a second embodiment of the present invention will be described with reference to FIG.

[0061] In the first embodiment (FIG. 6), one first communication hole 13x is formed for one protection substrate 13, but in the second embodiment (FIG. 8), two first communication holes 13x are formed for one protection substrate 213. The two first communication holes 13x are spaced apart from each other in the paper width direction (column direction).

[0062] According to this embodiment, in S5 (protective film forming process), gas can be sufficiently distributed to the actuator housing chambers 13c located at the ends in the paper width direction (and thus, protective films C can be reliably formed in all actuator housing chambers 13c).

[0063] <Third embodiment> Next, a third embodiment of the present invention will be described with reference to FIG.

[0064] In the first embodiment (Figure 6), the second communication holes 13y are arranged in a row in the paper width direction in each protective substrate 13, but in the third embodiment (Figure 9), the second communication holes 13y are arranged in a staggered manner in the paper width direction (column direction) in each protective substrate 313, and two second communication holes 13y adjacent to each other in the paper width direction do not overlap each other in the paper width direction.

[0065] When two second communication holes 13y adjacent to each other in the paper width direction overlap each other in the paper width direction (see FIG. 6), the strength of the protective substrate 13 is locally reduced in the portion where the second communication holes 13y are formed, and the protective substrate 13 may be damaged in S2 (protective substrate fixing step). In contrast, in this embodiment, two second communication holes 13y adjacent to each other in the paper width direction do not overlap each other in the paper width direction, so that the local reduction in strength of the protective substrate 313 is suppressed, and the protective substrate 313 is less likely to be damaged in S2 (protective substrate fixing step).

[0066] Furthermore, according to this embodiment, the second communication holes 13y are arranged in a staggered pattern in the paper width direction, which further suppresses a decrease in the strength of the protective substrate 313, making the protective substrate 313 less susceptible to damage in S2 (protective substrate fixing step).

[0067] <Fourth embodiment> Next, a fourth embodiment of the present invention will be described with reference to FIG.

[0068] In the first embodiment, as shown in Fig. 6, the second wall portion 13w2 extends from one of the pair of first wall portions 13w1, the tip of the second wall portion 13w2 is not connected to the other of the pair of first wall portions 13w1, and the second communication hole 13y is formed by the space between the tip of the second wall portion 13w2 and the other of the pair of first wall portions 13w1. Also, as shown in Fig. 3, the second communication hole 13y is formed over the entire vertical length of the actuator accommodating chamber 13c.

[0069] In contrast, in the fourth embodiment, as shown in Fig. 10, the second wall portion 13w2 is connected to both of the pair of first wall portions 13w1, and the second communication hole 13y is formed by a through hole formed in the upper end of the second wall portion 13w2 (the other end opposite to the one end bonded to the upper surface of the flow path substrate 11). The second communication hole 13y is formed only in the upper part of the actuator accommodating chamber 13c in the vertical direction. Also, in the fourth embodiment, the second communication hole 13y is provided at each of one end and the other end of the second wall portion 13w2 in the transport direction.

[0070] If the second communication hole 13y is formed in a portion including the lower end of the wall portion 13w, the binding force of the wall portion 13w on the partition wall 11b1 (see FIG. 4) may be reduced, and the effect of suppressing structural crosstalk may be reduced. In contrast, in this embodiment, the second communication hole 13y is formed in a portion excluding the lower end of the wall portion 13w, so that the binding force of the wall portion 13w on the partition wall 11b1 is not reduced, and the effect of suppressing structural crosstalk can be maintained. In other words, the second communication hole 13y can communicate the multiple actuator accommodating chambers 13c (and thus the protective film C can be efficiently formed on the entire inner wall surface of the protective substrate 413 in S5 (protective film forming step)) while maintaining the effect of suppressing structural crosstalk.

[0071] <Fifth embodiment> Next, a fifth embodiment of the present invention will be described with reference to FIG.

[0072] In the first embodiment (FIG. 3), the wall portion 13w and the plate portion 13p of the protection substrate 13 are formed of a single member, but in the fifth embodiment (FIG. 11), the wall portion 13w and the plate portion 13p of the protection substrate 513 are formed of separate members.

[0073] In this embodiment, the wall portion 13w is made of a photosensitive adhesive that forms the adhesive portion A. The plate portion 13p is made of a plate-shaped member separate from the wall portion 13w. The plate portion 13p is connected to the upper end of the wall portion 13w and overlaps the multiple actuators 12x in the vertical direction (orthogonal direction).

[0074] In this embodiment, in S2 (protective substrate fixing step), first, a wall portion 13w made of a photosensitive adhesive is formed on the surface of a silicon single crystal substrate to be the plate 11b using a photomask. Then, a plate portion 13p is disposed so as to cover the actuators 12x and fixed to the upper end of the wall portion 13w.

[0075] According to this embodiment, since the wall portion 13w is made of a photosensitive adhesive, when the wall portion 13w is formed, patterning with high positional accuracy can be performed using a photomask.

[0076] Furthermore, since the wall portion 13w can be formed with high positional accuracy, high positional accuracy is not required for the plate portion 13p, so that the protection substrate 513 including the wall portion 13w and the plate portion 13p can be formed easily and with high accuracy.

[0077] <Modification> Although the preferred embodiments of the present invention have been described above, the present invention is not limited to the above-mentioned embodiments, and various design modifications are possible within the scope of the claims.

[0078] In the fourth embodiment (Figure 10), the second communication hole 13y is formed at the upper end of the second wall portion 13w2. However, if the second communication hole 13y is formed in a portion of the second wall portion 13w2 other than the lower end (for example, even if it is formed in a middle portion between the upper and lower ends of the second wall portion 13w2), the restraining force of the wall portion 13w on the partition 11b1 is not reduced, and the effect of suppressing structural crosstalk can be maintained.

[0079] Furthermore, when the second communication hole 13y is formed in a portion of the second wall portion 13w2 excluding the lower end as in the fourth embodiment (Figure 10), even if the second communication hole 13y overlaps with the actuator 12x in the paper width direction, the restraining force of the wall portion 13w on the partition 11b1 is difficult to reduce.

[0080] Although the first communication holes 13x are formed in the top surface of the protective substrate in the above-described embodiment (FIGS. 6 and 9), they may be formed in the side surface of the protective substrate (wall portion 13w that constitutes the outer surface of the protective substrate).

[0081] In the above embodiment (FIG. 7), the flow path is formed in the flow path substrate (S3) after S2 (protective substrate fixing step) and before S5 (protective film forming step), but this is not limited to this. For example, the flow path may be formed in the flow path substrate before S2 (protective substrate fixing step). Alternatively, the flow path may be formed in the flow path substrate after S5 (protective film forming step).

[0082] The liquid ejection head is not limited to the line type, but may be a serial type (a type in which liquid is ejected from nozzles onto an ejection target while moving in a scanning direction parallel to the paper width direction).

[0083] The ejection target is not limited to paper, but may be, for example, cloth, a substrate, etc.

[0084] The liquid ejected from the nozzles is not limited to ink, and may be any liquid (for example, a treatment liquid that aggregates or precipitates components in the ink, etc.).

[0085] The present invention is not limited to printers, but can also be applied to facsimiles, copy machines, multifunction machines, etc. The present invention can also be applied to liquid ejection devices used for purposes other than image recording (for example, liquid ejection devices that eject conductive liquid onto a substrate to form a conductive pattern). [Explanation of symbols]

[0086] 1 Head (liquid ejection head) 11 Flow channel substrate 11b1 Bulkhead 12x Actuator 13;213;313;413;513 Protection Board 13c Actuator Chamber 13p board part 13w wall 13x 1st communication hole 13y 2nd communication hole 14 Sealing member 20 Individual Channels 21 Pressure Chamber 22 Nozzle A Adhesive part C Protective film

Claims

1. a flow path substrate in which a plurality of individual flow paths are formed, each of which includes a nozzle and a pressure chamber communicating with the nozzle; a plurality of actuators fixed to a surface of the flow path substrate and overlapping with each of the pressure chambers of the plurality of individual flow paths in a direction perpendicular to the surface; a protection substrate fixed to the surface and covering the actuators; the protection substrate has a wall portion for defining a plurality of actuator accommodating chambers each accommodating one or more of the actuators; the wall portion overlaps a partition wall that separates the two pressure chambers in the flow path substrate in the perpendicular direction, and is adhered to the surface via an adhesive portion made of an adhesive, a protective film having a moisture permeability lower than that of the adhesive is formed on a portion of the protective substrate and the adhesive portion that defines each of the actuator housing chambers, a first communication hole that communicates at least one of the plurality of actuator housing chambers with the outside, and a second communication hole that communicates the plurality of actuator housing chambers with each other, are formed in the protection substrate; The liquid ejection head further comprises a sealing member that seals the first communication hole.

2. The actuator housing chambers are arranged in a column direction perpendicular to the orthogonal direction, The liquid ejection head according to claim 1 , wherein a plurality of the first communication holes are formed in the protection substrate so as to be spaced apart from one another in the column direction.

3. The actuator housing chambers are arranged in a column direction perpendicular to the orthogonal direction, The liquid ejection head according to claim 1 , wherein two of the second communication holes adjacent to each other in the column direction do not overlap each other in the column direction.

4. The liquid ejection head according to claim 3 , wherein the second communication holes are arranged in a staggered pattern in the column direction.

5. 5. The liquid ejection head according to claim 1, wherein the second communication hole is formed in a portion of the wall portion excluding one end that is bonded to the surface.

6. The actuator housing chambers are arranged in a column direction perpendicular to the orthogonal direction, A liquid ejection head as claimed in any one of claims 1 to 5, characterized in that the second communication hole is formed over the entire length of the multiple actuator accommodating chambers in the perpendicular direction, at a position that does not overlap with the actuators in the column direction.

7. 7. The liquid ejection head according to claim 1, wherein the protective film is made of at least one of tantalum oxide, hafnium oxide, and aluminum oxide.

8. 8. The liquid ejection head according to claim 1, wherein the length of the plurality of actuator housing chambers in the perpendicular direction is 100 μm or more.

9. 9. The liquid ejection head according to claim 1, wherein the protective film is also formed on the surfaces of the actuators.

10. 10. The liquid ejection head according to claim 1, wherein the wall portion is made of a photosensitive adhesive that constitutes the adhesive portion.

11. The liquid ejection head described in claim 10, characterized in that the protective substrate is a plate portion made of a separate material from the wall portion, connected to one end opposite to one end adhered to the surface of the wall portion, and overlapping with the multiple actuators in the perpendicular direction.

12. an actuator forming step of forming a plurality of actuators on a surface of a flow path substrate; a protective substrate fixing step of fixing a protective substrate to the front surface so as to cover the actuators after the actuator forming step, the protection substrate has a wall portion for defining a plurality of actuator accommodating chambers each accommodating one or more of the actuators; a first communication hole that communicates at least one of the plurality of actuator housing chambers with the outside, and a second communication hole that communicates the plurality of actuator housing chambers with each other, are formed in the protection substrate; In the protective substrate fixing step, the wall portion is adhered to the surface via an adhesive portion made of an adhesive; a protective film forming step of forming a protective film having a moisture permeability lower than that of the adhesive on portions of the protective substrate and the adhesive part that define the plurality of actuator housing chambers by injecting a gas from the outside to the inside of the protective substrate through the first communication hole after the protective substrate fixing step; a sealing step of sealing the first communication hole with a sealing member after the protective film forming step, A method for manufacturing a liquid ejection head, comprising: arranging the wall portion so as to overlap a partition wall separating two pressure chambers in the flow path substrate in a direction perpendicular to the surface.

13. The method for manufacturing a liquid ejection head according to claim 12, wherein an atomic layer deposition method is used in the protective film forming step.

14. 14. The method for manufacturing a liquid ejection head according to claim 13, wherein the protective film is made of at least one of tantalum oxide, hafnium oxide, and aluminum oxide.

15. Prior to the protective film forming step, a plurality of individual flow paths each including a nozzle and a pressure chamber communicating with the nozzle are formed in the flow path substrate; 15. The method for manufacturing a liquid ejection head according to claim 12, wherein in the protective film forming step, the nozzle is sealed with a different sealing member when the gas is injected.

16. A method for manufacturing a liquid ejection head as described in any one of claims 12 to 15, characterized in that in the protective substrate fixing process, after the wall portion made of photosensitive adhesive that constitutes the adhesive portion is formed on the surface, a plate portion of the protective substrate that overlaps with the multiple actuators in the perpendicular direction is connected to the other end of the wall portion opposite to the one end that is adhered to the surface.

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