Liquid discharge head and recording device

Abstract

This liquid discharge head comprises: a first member (2) having a pressure chamber (21), a vibration plate (23) located above the pressure chamber (21), and a piezoelectric element (24) located above the diaphragm (23) corresponding to the pressure chamber (21); and a second member (3) located above the first member (2) and having a supply path through which a liquid can be supplied to the pressure chamber (24). The first member (2) is provided with an amorphous silicon layer (29), and the first member (1) and the second member (3) are mutually joined with the amorphous silicon layer (29) therebetween.

Description

Liquid ejection head and recording apparatus

[0001] The present disclosure relates to a liquid ejection head and a recording apparatus.

[0002] Patent document 1 discloses a liquid ejection head that includes a first member having a pressure chamber and a second member having a supply path that can supply liquid to the pressure chamber, the first member and the second member being bonded to each other via a resin adhesive.

[0003] JP 2016-168806 A

[0004] A liquid ejection head according to one aspect of the present disclosure comprises a first member having a pressure chamber, a vibration plate located on the pressure chamber, and a piezoelectric element located on the vibration plate corresponding to the pressure chamber, and a second member located on the first member and having a supply path capable of supplying liquid to the pressure chamber, wherein the first member is provided with an amorphous silicon layer, and the first member and the second member are bonded to each other via the amorphous silicon layer.

[0005] FIG. 1 is a side view schematically showing a printer according to a first embodiment. FIG. 2 is a plan view schematically showing a printer according to the first embodiment. FIG. 3 is a plan view schematically showing a liquid ejection head according to the first embodiment. FIG. 4 is a side view of the liquid ejection head according to the first embodiment as viewed from the A direction. FIG. 5 is a plan view schematically showing a first member, a second member, and a third member according to the first embodiment. FIG. 6 is a cross-sectional view taken along line II in FIG. 5. FIG. 7 is a cross-sectional view taken along line II-II in FIG. 5. FIG. 8 is a plan view showing the pressure chambers, liquid chambers, individual electrode wiring, common electrode wiring, and amorphous silicon layer extracted from the first member according to the first embodiment. FIG. 9 is a plan view schematically showing a first member according to a second embodiment. FIG. 10 is a cross-sectional view taken along line III-III in FIG. 9.

[0006] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0007] Please note that the drawings used in the following explanation are schematic, and the dimensional ratios in the drawings do not necessarily correspond to the actual ones. Even among multiple drawings showing the same configuration, the dimensional ratios may not correspond to each other because the shapes and the like are exaggerated.

[0008] First Embodiment FIG. 1 is a side view that schematically shows a printer 10 according to this embodiment. FIG. 2 is a plan view that schematically shows the printer 10. The printer 10 is, for example, a color inkjet printer. For ease of understanding, FIG. 1 illustrates a three-dimensional Cartesian coordinate system that includes an X-axis with the positive direction toward the right of the page and a Y-axis with the positive direction toward the back of the page. This Cartesian coordinate system is also shown in other drawings that will be used in the following description.

[0009] In the following description, for convenience, the positive Z-axis direction may be referred to as "upper." The X-axis direction is the transport direction of the printing paper P. In addition, "planar view" refers to a view from the Z-axis direction.

[0010] The configuration of a printer 10 according to this embodiment will be described with reference to FIGS. 1 and 2. FIG.

[0011] Fig. 1 is a side view that schematically shows a printer 10 that includes a liquid ejection head 1 according to this embodiment. Fig. 2 is a plan view that schematically shows the printer 10. The printer 10 is, for example, a color inkjet printer.

[0012] As shown in FIG. 1, the printer 10 includes a paper feed roller 101, a guide roller 102, a transport roller 103, a recovery roller 104, a head case 105, a frame 106, a liquid ejection head 1, a dryer 107, a sensor unit 108, and a control unit 109.

[0013] The control unit 109 controls the operations of the paper feed roller 101 , the guide roller 102 , the transport roller 103 , the recovery roller 104 , the head case 105 , the frame 106 , the liquid ejection head 1 , the dryer 107 , and the sensor unit 108 .

[0014] The paper feed roller 101, guide roller 102, transport roller 103, and recovery roller 104 constitute a moving unit that moves the print paper P and the liquid ejection head 1 relative to one another. The print paper P is an example of a recording medium. The moving unit is controlled by a control unit 109. The print paper P passes from the paper feed roller 101 between two guide rollers 102A and is transported onto multiple transport rollers 103. The print paper P then passes between two guide rollers 102B and two guide rollers 102C and is transported to the recovery roller 104.

[0015] The head case 105 houses the transport roller 103, the frame 106, and the liquid ejection head 1. The head case 105 is connected to the outside in some areas, such as the area where the printing paper P enters and leaves, but the rest of the head case 105 is a space isolated from the outside. Control factors such as temperature, humidity, and air pressure in the internal space of the head case 105 are controlled by a control unit 109 as necessary.

[0016] The frame 106 is flat and positioned close to and above the print paper P being transported by the transport rollers 103. There are four frames 106 inside the head case 105, positioned at predetermined intervals along the transport direction of the print paper P. The number of frames 106 mounted on the printer 10 can be changed as appropriate depending on the object to be printed or the printing conditions.

[0017] The liquid ejection head 1 has an elongated shape extending vertically in the plane of FIG. 2 . As shown in FIG. 2 , five liquid ejection heads 1 are mounted on each frame 106. In each frame 106, the five liquid ejection heads 1 constitute a head module 100. In each frame 106, three liquid ejection heads 1 are aligned in a direction intersecting the transport direction of the print paper P, and the other two liquid ejection heads 1 are aligned at offset positions along the transport direction, one between each of the three liquid ejection heads 1. In each frame 106, the liquid ejection heads 1 are arranged so that they overlap in the transport direction of the print paper P. The number of liquid ejection heads 1 included in one frame 106 can be changed as appropriate depending on the printing target or printing conditions. The moving unit moves the print paper P and the head module 100 relative to each other, thereby moving the print paper P and the liquid ejection heads 1 relative to each other.

[0018] The liquid ejection head 1 according to this embodiment is fixed to the printer 10. In other words, the printer 10 is a line printer. However, the printer 10 is not limited to a line printer, and may be a so-called serial printer in which the liquid ejection head 1 is moved in a direction intersecting the transport direction of the printing paper P to eject liquid droplets and to transport the printing paper P alternately.

[0019] The liquid ejection head 1 is controlled by the control unit 109 based on data such as images or characters, and ejects liquid toward the printing paper P. The distance between the liquid ejection head 1 and the printing paper P is, for example, about 0.5 to 20 mm.

[0020] The liquid ejection heads 1 belonging to one head module 100 are supplied with the same color liquid, and four head modules 100 can print four colors of liquid. Each head module 100 may be provided with a reservoir substrate positioned over the five liquid ejection heads 1. This allows liquid to be supplied to the five liquid ejection heads 1 from the flow paths of the reservoir substrate. The colors of liquid ejected from the liquid ejection heads 1 of each head module 100 are, for example, magenta, yellow, cyan, and black. By causing such liquid to land on the printing paper P, the printer 10 can print color images. Note that the type of liquid color can be changed as appropriate. Alternatively, several colors of liquid may be supplied to the liquid ejection heads 1 belonging to one head module 100, allowing one head module 100 to print several colors of liquid.

[0021] Furthermore, in addition to printing colored liquids, the printer 10 may also print liquids such as coating agents uniformly or in a pattern using the liquid ejection head 1 in order to perform surface treatment on the printing paper P. Note that the printer 10 may also apply a coating agent from an applicator (not shown) instead of the liquid ejection head 1.

[0022] The dryer 107 dries the printing paper P. After passing through the two guide rollers 102B, the printing paper P is dried by the dryer 107. By drying in the dryer 107, the overlapping printing paper P wound up on the collection roller 104 is less likely to stick to each other, and the undried liquid is less likely to rub against each other.

[0023] The sensor unit 108 includes a position sensor, a speed sensor, a temperature sensor, etc. The control unit 109 can control each part of the printer 10 based on information from each sensor.

[0024] The printer 10 may be provided with a cleaning unit that cleans the liquid ejection head 1. The cleaning unit cleans the liquid ejection head 1 by, for example, wiping or capping.

[0025] The recording medium may be a roll of cloth in addition to printing paper P. The printer 10 may also transport the recording medium on a transport belt. In this way, the printer 10 can print sheets of paper, cut pieces of cloth, wood, tiles, or the like as recording media. Furthermore, the printer 10 may print wiring patterns for electronic devices by ejecting a liquid containing conductive particles from the liquid ejection head 1. Furthermore, the printer 10 may produce chemicals by ejecting a predetermined amount of liquid chemical or a liquid containing a chemical from the liquid ejection head 1 into a reaction vessel or the like, causing a reaction.

[0026] The configuration of the liquid ejection head 1 according to this embodiment will be described with reference to Figures 3 and 4. Figure 3 is a plan view that schematically shows the liquid ejection head 1 according to this embodiment. Figure 4 is a side view of the liquid ejection head 1 shown in Figure 3, as viewed from A. Note that the two wavy lines drawn vertically on the paper in Figure 3 represent omission lines.

[0027] The liquid ejection head 1 includes a first member 2 , a second member 3 , a third member 4 , and a fourth member 5 .

[0028] The first member 2 includes a single crystal silicon substrate 20, a vibration plate 23 located on the single crystal silicon substrate 20, and a plurality of piezoelectric elements 24 located on the vibration plate 23. The single crystal silicon substrate 20 is located on the third member 4. A plurality of pressure chambers 21 and a plurality of liquid chambers 22 are formed in the single crystal silicon substrate 20.

[0029] The multiple pressure chambers 21 are through-holes that penetrate the single-crystal silicon substrate 20 in the Z-axis direction and are respectively connected to multiple nozzles 41 provided in the third member 4. According to the present embodiment, the multiple pressure chambers 21 are each physically connected to the multiple nozzles 41, but this is not limiting. For example, the multiple pressure chambers 21 may each be fluidly connected to the multiple nozzles 41 via flow paths such as descenders. In other words, the concept of "connected" is not limited to physical connection, but also includes fluidic connection. The multiple pressure chambers 21 are located along the Y-axis direction. Furthermore, in a plan view, the multiple pressure chambers 21 are located such that their longitudinal direction is aligned with the X-axis direction and their lateral direction is aligned with the Y-axis direction. According to the present embodiment, the pressure chambers 21 have a substantially rectangular planar shape, but this is not limiting. For example, the pressure chambers 21 may have a diamond-shaped or circular planar shape. Liquid is stored in the pressure chambers 21. When pressure is applied to the liquid in the pressure chamber 21, the liquid is ejected from the nozzle 41 to the outside as droplets.

[0030] The multiple liquid chambers 22 are through holes that penetrate the single crystal silicon substrate 20 in the Z-axis direction, and are each connected to one longitudinal end of the multiple pressure chambers 21. The liquid chamber 22 connected to the pressure chamber 21 located on the positive X-axis side is connected to the end of the pressure chamber 21 on the negative X-axis side. The liquid chamber 22 connected to the pressure chamber 21 located on the negative X-axis side is connected to the end of the pressure chamber 21 on the positive X-axis side. Liquid is stored in the liquid chamber 22, just like in the pressure chamber 21. When viewed in a plane, the liquid chamber 22 includes a portion where the width in the Y-axis direction, i.e., the flow path width, is narrower than that of the pressure chamber 21, and therefore functions as a so-called throttle.

[0031] The diaphragm 23 is located on a single crystal silicon substrate 20. The diaphragm 23 may be made of a material such as Si or SiO. ２ Examples include:

[0032] The plurality of piezoelectric elements 24 are located on the vibration plate 23 corresponding to the plurality of pressure chambers 21. Here, in this specification, "corresponding" means, for example, that in the relationship between a certain component and another component, there is at least a portion that overlaps when viewed in a plan view, or that there is at least a portion that overlaps in the vertical direction when viewed in a cross section. The plurality of piezoelectric elements 24 are provided in a one-to-one relationship with the plurality of pressure chambers 21. When a voltage is applied to the piezoelectric element 24, the piezoelectric element 24 is displaced. As the piezoelectric element 24 displaces, the vibration plate 23 located above the pressure chamber 21 also displaces. As a result, pressure is applied to the liquid in the pressure chamber 21. This causes the liquid to be ejected from the pressure chamber 21 through the nozzle 41. The plurality of piezoelectric elements 24 are not located on the vibration plate 23 corresponding to the plurality of liquid chambers 22.

[0033] The second member 3 is located on the first member 2. The second member 3 has a predetermined thickness that is thicker in the Z-axis direction than the first member 2, and has the function of supporting the first member 2. The second member 3 includes a plurality of supply paths 31. The second member 3 is made of single crystal silicon.

[0034] The multiple supply paths 31 are through holes that pass through the second member 3 in the Z-axis direction, and are each connected to multiple liquid chambers 22. The multiple supply paths 31 are each connected to multiple pressure chambers 21 via multiple liquid chambers 22. Similar to the liquid chambers 22, the supply paths 31 function as so-called throttles. Furthermore, the multiple supply paths 31 are located in the center of the second member 3 in the X-axis direction when viewed in a plan view.

[0035] The third member 4 includes a plurality of nozzles 41. The third member 4 is made of single crystal silicon. The third member 4 is located below the first member 2. The third member 4 according to this embodiment has substantially the same shape as the first member 2 in plan view.

[0036] The plurality of nozzles 41 are through-holes that penetrate the third member 4 in the Z-axis direction. The plurality of nozzles 41 are positioned along the Y-axis direction and form a nozzle group. The liquid ejection head 1 according to this embodiment has two nozzle groups: a nozzle group on the positive X-axis direction side and a nozzle group on the negative X-axis direction side. Although the liquid ejection head 1 according to this embodiment has two nozzle groups, it may have only one nozzle group or three or more nozzle groups. The two nozzle groups according to this embodiment are configured parallel to each other. The distance between the nozzles 41 in each nozzle group is 84.6 μm. In other words, the resolution of the nozzles 41 in the nozzle groups is 300 dpi. The nozzles 41 in the nozzle group on the positive X-axis direction side are positioned between the nozzles 41 in the nozzle group on the negative X-axis direction side in the Y-axis direction. In other words, the nozzles 41 in the nozzle group on the positive X-axis direction and the nozzles 41 in the nozzle group on the negative X-axis direction are offset from each other in the Y-axis direction, and the combined resolution of the nozzles 41 in the two nozzle groups is 600 dpi. The distance between the nozzles 41 in each nozzle group may be set appropriately depending on the resolution.

[0037] The fourth member 5 is located on the second member 3. In a plan view, the fourth member 5 has substantially the same shape as the second member 3. The fourth member 5 includes a common flow path 51. The fourth member 5 is made of resin.

[0038] In a plan view, the common flow path 51 is located at the center of the fourth member 5 in the X-axis direction and is provided along the Y-axis direction. Therefore, the common flow path 51 is located above the plurality of supply paths 31 and is connected to the plurality of supply paths 31. Therefore, the common flow path 51 can supply liquid to the plurality of supply paths 31.

[0039] Liquid is filled in the pressure chamber 21, the liquid chamber 22, the supply path 31, and the common flow path 51. When pressure is applied to the pressure chamber 21 by the piezoelectric element 24, liquid is supplied from the pressure chamber 21 to the nozzle 41, and droplets are ejected from the nozzle 41. In addition, liquid is replenished into the pressure chamber 21 from the common flow path 51 via the liquid chamber 22 and the supply path 31.

[0040] In the liquid ejection head 1 according to this embodiment, two restrictions, that is, the liquid chamber 22 and the supply path 31, are provided between each pressure chamber 21 and the common flow path 51. This makes it possible to reduce so-called crosstalk, which is the propagation of a pressure wave generated in one pressure chamber 21 to another pressure chamber 21 via the common flow path 51.

[0041] 3 and 4 show an example of the configuration of the liquid ejection head 1, and the liquid ejection head 1 may further include members other than those shown in FIGS.

[0042] Furthermore, the common flow path 51 may have both a common supply flow path that supplies liquid to the pressure chambers 21 and a common recovery flow path that recovers liquid from the pressure chambers 21. This provides the liquid ejection head 1 with a circulation function that recovers a portion of the liquid that was not ejected from the nozzles 41.

[0043] The flexible substrate 6 is located on the end of the first member 2 in the negative direction of the X axis. The liquid ejection head 1 according to this embodiment has one flexible substrate 6, but is not limited to this. For example, the liquid ejection head 1 may have two or more flexible substrates 6. Here, one end of the flexible substrate 6 is electrically connected to the first member 2, and the other end of the flexible substrate 6 is drawn out above the second member 3 and the fourth member 5. The flexible substrate 6 is a flexible wiring board and has the function of transmitting a drive signal to the first member 2.

[0044] The driving IC 7 is mounted on the flexible substrate 6. The driving IC 7 is electrically connected to the control unit 109. Therefore, the driving IC 7 generates a driving signal based on a signal sent from the control unit 109. Furthermore, the driving IC 7 outputs this driving signal to the piezoelectric element 24 via the flexible substrate 6. This allows the driving IC 7 to control the driving of the liquid ejection head 1.

[0045] The first member 2, the second member 3, and the third member 4 will be described in detail with reference to Fig. 5. Fig. 5 is a plan view schematically showing the first member 2, the second member 3, and the third member 4 according to this embodiment. Fig. 6 is a cross-sectional view taken along line II shown in Fig. 5. Fig. 7 is a cross-sectional view taken along line II-II shown in Fig. 5. Note that the two wavy lines drawn in the vertical direction of the paper in Fig. 5 represent omission lines.

[0046] The first member 2 further includes an insulator 2N, individual electrode wiring 25, common electrode wiring 26, a protective film 27, a bonding layer 28, and an amorphous silicon layer 29. In Fig. 5, the bonding layer 28 and the amorphous silicon layer 29 are shown in gray.

[0047] The piezoelectric element 24 includes a common electrode 241, a piezoelectric body 242, and an individual electrode 243. In the piezoelectric element 24 according to this embodiment, the common electrode 241 is located on the diaphragm 23, the piezoelectric body 242 is located on the common electrode 241, and the individual electrode 243 is located on the piezoelectric body 242, but this is not limiting. For example, the order of the common electrode 241 and the individual electrodes 243 from the diaphragm 23 may be reversed. Specifically, the individual electrode 243, the piezoelectric body 242, and the common electrode 241 may be provided on the diaphragm 23 in this order.

[0048] The common electrode 241 according to this embodiment is provided in common to the multiple pressure chambers 21, but this is not limiting. For example, the common electrode 241 may be provided individually for each pressure chamber 21. The thickness of the common electrode 241 may be 0.05 μm or more and 1 μm or less. The common electrode 241 may be made of a metal material such as Pt, for example.

[0049] The piezoelectric body 242 according to this embodiment is provided individually corresponding to each pressure chamber 21, but this is not limiting. For example, the piezoelectric body 242 may be provided in common to a plurality of pressure chambers 21 in plan view. The piezoelectric body 242 is sandwiched between an individual electrode 243 and a common electrode 241. The thickness of the piezoelectric body 242 may be 1 μm or more and 10 μm or less. The constituent material of the piezoelectric body 242 is, for example, Pb(Zr,Ti)O ３ system, NaNbO ３ system, BaTiO３ system, (BiNa)NbO ３ system, BiNaNB ５ O １５ Examples of suitable materials include ceramic materials having ferroelectricity such as ferroelectric ceramics.

[0050] The individual electrodes 243 are individually provided corresponding to each pressure chamber 21. The individual electrodes 243 have substantially the same shape as the piezoelectric body 242. The thickness of the individual electrodes 243 may be 0.05 μm or more and 1 μm or less. Examples of materials that can be used to form the individual electrodes 243 include metal materials such as Pt.

[0051] The portion of the piezoelectric body 242 that is sandwiched between the individual electrode 243 and the common electrode 241 is polarized in the thickness direction, in the Z-axis direction. Therefore, for example, when a voltage is applied in the polarization direction of the piezoelectric body 242 by the individual electrode 243 and the common electrode 241, the piezoelectric body 242 contracts in a direction along the vibration plate 23. This contraction is regulated by the vibration plate 23. As a result, the piezoelectric body 242 is displaced so as to convex toward the pressure chamber 21. As the piezoelectric body 242 displaces, the vibration plate 23 located above the pressure chamber 21 is also displaced. As a result, pressure is applied to the liquid in the pressure chamber 21. When pressure is applied to the pressure chamber 21, liquid is ejected from the nozzle 41.

[0052] The insulator 2N is positioned so as to cover the diaphragm 23 and the common electrode 241. In addition, the insulator 2N is positioned so as to surround the individual electrode 243 in plan view. The thickness of the insulator 2N may be set to, for example, 0.1 μm or more and 1 μm or less. The constituent material of the insulator 2N is, for example, SiO ２ Examples include:

[0053] Furthermore, the insulators 2N are positioned so as to cover the ends of the piezoelectric bodies 242 and the ends of the individual electrodes 243. Here, the ends of the piezoelectric bodies 242 and the ends of the individual electrodes 243 include the ends in the X-axis direction and the ends in the Y-axis direction. By covering the ends of the piezoelectric bodies 242, the insulators 2N can reduce the possibility that the piezoelectric bodies 242 will peel off from the individual electrodes 243. By covering the ends of the individual electrodes 243, the insulators 2N can reduce the possibility that the individual electrodes 243 will peel off from the vibration plate 23. On the other hand, the insulators 2N are not positioned in the center of the piezoelectric elements 24 so as not to interfere with the displacement of the piezoelectric elements 24.

[0054] The piezoelectric element 2 includes a plurality of individual electrode wires 25. The plurality of individual electrode wires 25 are electrically connected to the individual electrodes 243, respectively. The number of individual electrode wires 25 is the same as the number of piezoelectric elements 24. The individual electrode wires 25 are drawn from the end of each individual electrode 243 on the negative X-axis direction side to the end of the first member 2 on the negative X-axis direction side. The individual electrode wires 25 are electrically connected to the flexible substrate 6 at the end of the first member 2 on the negative X-axis direction side. As a result, a drive signal is transmitted from the drive IC 7 to the individual electrodes 253 via the flexible substrate 6 and the individual electrode wires 25.

[0055] The individual electrode wiring 25 is located on the insulator 2N. That is, by having the insulator 2N between the individual electrode wiring 25 and the common electrode 241, it is possible to reduce the possibility of electrical conduction between the individual electrode wiring 25 and the common electrode 241. Furthermore, the individual electrode wiring 25 according to this embodiment passes over the insulator 2N that is located so as to cover the end of the piezoelectric body 242 and connects to the individual electrode 243, so it is also possible to reduce the possibility of electrical conduction to the piezoelectric body 242.

[0056] The thickness of the individual electrode wires 25 may be, for example, 0.1 μm to 1 μm, and the constituent material of the individual electrode wires 25 may be, for example, Au.

[0057] The common electrode wiring 26 is electrically connected to the common electrode 241. The common electrode wiring 26 is located above the common electrode 241 at the end of the common electrode 241 on the positive X-axis direction side. The common electrode wiring 26 is also drawn from the portion located above the common electrode 241 to the end of the first member 2 on the negative X-axis direction side. The common electrode wiring 26 passes on the positive Y-axis direction side of the common electrode 241 and on the positive and negative Y-axis directions side of the common electrode 241, and is drawn to the end of the first member 2 on the negative X-axis direction side. The common electrode wiring 26 is electrically connected to the flexible substrate 6 at the end of the first member 2 on the negative X-axis direction side. As a result, a ground potential is applied to the common electrode 241 from the driving IC 7 via the flexible substrate 6 and the common electrode wiring 26.

[0058] The common electrode wiring 26 according to this embodiment is located on the insulator 2N except for the portion located on the common electrode 241. The common electrode wiring 26 according to this embodiment is located on the insulator 2N, but may be located directly on the diaphragm 23. The thickness of the common electrode wiring 26 may be, for example, 0.1 μm or more and 1 μm or less. Examples of materials that make up the common electrode wiring 26 include Au.

[0059] The protective film 27 is located on the insulator 2N, the individual electrode wiring 25, and the common electrode wiring 26. In a plan view, the protective film 27 is not located at the end of the first member 2 on the negative X-axis direction side. As a result, the protective film 27 is not located on the individual electrode wiring 25 and the common electrode wiring 26 at the end of the first member 2 on the negative X-axis direction side, making it possible to connect the flexible substrate 6 to the individual electrode wiring 25 and the common electrode wiring 26.

[0060] Furthermore, the protective film 27 is positioned so as to cover the insulators 2N at the ends of each piezoelectric body 242 and at the ends of each individual electrode 243. By covering the insulators 2N at the ends of each piezoelectric body 242, the protective film 27 can further reduce the possibility of the piezoelectric body 242 peeling off from the individual electrode 243. By covering the insulators 2N at the ends of each individual electrode 243, the protective film 27 can further reduce the possibility of the individual electrode 243 peeling off from the vibration plate 23. On the other hand, like the insulators 2N, the protective film 27 is not positioned in the center of the piezoelectric element 24 so as not to interfere with the displacement of the piezoelectric element 24.

[0061] The thickness of the protective film 27 may be, for example, 0.1 μm to 1 μm, and the constituent material of the protective film 27 may be, for example, SiN.

[0062] The bonding layer 28 is located on the protective film 27. In addition, the bonding layer 28 is located so as to surround the plurality of piezoelectric elements 24 in a planar view. Since the bonding layer 28 is located so as to surround the plurality of piezoelectric elements 24 in a planar view, it is possible to seal the plurality of piezoelectric elements 24. In addition, the bonding layer 28 may be located so as to surround each piezoelectric element 24 individually in a planar view.

[0063] The thickness of the bonding layer 28 may be, for example, 2 μm or more and 10 μm or less. The bonding layer 28 may be made of, for example, SiO ２ , SiN, etc.

[0064] The amorphous silicon layer 29 is located on the bonding layer 28. The amorphous silicon layer 29 contains amorphous silicon. The amorphous silicon layer 29 may contain other atoms as impurities. In this embodiment, the amorphous silicon layer 29 is composed of at least 90% amorphous silicon. Amorphous silicon is non-crystalline silicon, in which silicon atoms are bonded together in a disordered manner. The amorphous silicon layer 29 according to this embodiment overlaps with the bonding layer 28 when viewed in plan.

[0065] In the liquid ejection head 1 according to this embodiment, an Ar ion beam is irradiated onto the second member 3 made of single crystal silicon under high vacuum, causing silicon atoms to scatter onto the bonding layer 28, thereby forming an activated amorphous silicon layer 29 on the bonding layer 28. Here, "under high vacuum" refers to a temperature of 1000°C or less. ―５ This refers to a vacuum level of 0.1 Pa or less. Furthermore, being activated means that the silicon atoms have dangling bonds. In the liquid ejection head 1 according to this embodiment, the amorphous silicon layer 29 is formed on the bonding layer 28 by irradiating the second member 3 with an Ar ion beam and scattering silicon atoms onto the bonding layer 28, but this is not limitative. For example, the amorphous silicon layer 29 may be formed on the bonding layer 28 by irradiating single crystal silicon other than the second member 3 with an Ar ion beam and scattering silicon atoms onto the bonding layer 28. In other words, other single crystal silicon may be used to form the amorphous silicon layer 29, not limited to the second member 3 used in the liquid ejection head 1.

[0066] The second member 3 is located on the amorphous silicon layer 29 and is bonded to the first member 2. Specifically, when silicon atoms are scattered from the second member 3 using the Ar ion beam described above under high vacuum, the surface of the second member 3 is activated. When an activated portion of single crystal silicon contained in the second member 3 is brought into contact with the activated amorphous silicon layer 29, dangling bonds in the amorphous silicon layer 29 and dangling bonds in the second member 3 bond to each other, and the first member 2 and the second member 3 are bonded to each other.

[0067] In the liquid ejection head 1 according to this embodiment, the first member 2 and the second member 3 are bonded together by bringing an activated portion of single crystal silicon contained in the second member 3 into contact with the activated amorphous silicon layer 29, but this is not limited to this. In the liquid ejection head 1 according to this embodiment, the first member 2 and the second member 3 may also be bonded together by scattering silicon atoms into the second member 3 to form activated amorphous silicon, and bringing the activated amorphous silicon into contact with the activated amorphous silicon layer 29 of the first member 2.

[0068] In the liquid ejection head 1 according to this embodiment, the first member 2 and the second member 3 are bonded to each other via an amorphous silicon layer 29. Amorphous silicon has excellent chemical stability and deteriorates more slowly due to the influence of liquid than, for example, resins used in resin adhesives. Examples of deterioration due to the influence of liquid include deterioration due to hydrolysis, elution, or swelling. Furthermore, resins have lower thermal stability than amorphous silicon, so as the temperature of the liquid increases, the likelihood of deterioration due to hydrolysis, elution, or swelling increases. Therefore, in the liquid ejection head 1 according to this embodiment, the first member 2 and the second member 3 are bonded to each other via the amorphous silicon layer 29, which has excellent chemical and thermal stability, thereby reducing the possibility of deterioration at the joint between the first member 2 and the second member 3 due to the influence of the supplied liquid. In the liquid ejection head 1 according to this embodiment, the first member 2 and the second member 3 are bonded via the amorphous silicon layer 29, so that the bonded portion between the first member 2 and the second member 3 overlaps the amorphous silicon layer 29 in a plan view. Furthermore, amorphous silicon is less susceptible to deterioration due to oxidation than metals used in metal bonding. Therefore, the liquid ejection head 1 according to this embodiment can also reduce the possibility of deterioration due to oxidation at the bonded portion between the first member 2 and the second member 3.

[0069] In the liquid ejection head 1 according to this embodiment, the first member 2 and the second member 3 are bonded together by bringing an activated portion of the single crystal silicon contained in the second member 3 into contact with the activated amorphous silicon layer 29. Alternatively, in the liquid ejection head 1 according to this embodiment, silicon atoms are scattered in the second member 3 to form activated amorphous silicon, and the activated amorphous silicon is brought into contact with the activated amorphous silicon layer 29 of the first member 2, thereby bonding the first member 2 and the second member 3. The first member 2 and the second member 3 can be bonded together at room temperature. Here, room temperature is 5 to 35 degrees, and in the liquid ejection head 1 according to this embodiment, the first member 2 and the second member 3 are bonded together at 25 degrees. Therefore, the first member 2 and the second member 3 do not need to be joined at high temperatures of 200 degrees or more, as in, for example, joining with a resin adhesive or metal diffusion bonding, and this reduces the possibility of damage to the first member 2, particularly the piezoelectric element 24, due to exposure to high temperatures during joining.

[0070] As described above, in the liquid ejection head 1 according to this embodiment, the amorphous silicon layer 29 is composed of 90% or more amorphous silicon. Therefore, in the liquid ejection head 1 according to this embodiment, the amorphous silicon layer 29 contains fewer impurities, which further reduces the possibility of deterioration occurring at the joint between the first member 2 and the second member 3. Furthermore, in a liquid ejection head 1 in which, for example, 99% or more of the amorphous silicon layer 29 is composed of amorphous silicon, the impurities are even fewer, which further reduces the possibility of deterioration occurring at the joint between the first member 2 and the second member 3.

[0071] Furthermore, the vibration plate 23 has a through hole 231 at a position corresponding to the supply channel 31 in a plan view. In other words, the vibration plate 23 has the through hole 231 at a position overlapping the supply channel 31 in a plan view. Therefore, in the liquid ejection head 1 according to this embodiment, liquid can be supplied to the pressure chamber 21 from the supply channel 31 and the through hole 231. The joint between the first member 2 and the second member 3, which is located between the supply channel 31 and the through hole 231, comes into contact with the liquid supplied from the supply channel 31 to the pressure chamber 21 and is therefore susceptible to the influence of the liquid. Therefore, in the liquid ejection head 1 according to this embodiment, the amorphous silicon layer 29 is located so as to surround the through hole 231 in a plan view. As a result, in the liquid ejection head 1 according to this embodiment, the joint between the first member 2 and the second member 3 near the through hole 231 can reduce the influence of the liquid supplied from the supply channel 31 to the pressure chamber 21.

[0072] The amorphous silicon layer 29 does not overlap the pressure chambers 21 in plan view. Because the first member 2 and the second member 3 are bonded via the amorphous silicon layer 29, the rigidity of the portion of the first member 2 that overlaps with the amorphous silicon layer 29 is increased. In the liquid ejection head 1 according to this embodiment, the amorphous silicon layer 29 does not overlap the pressure chambers 21 in plan view, so it is possible to reduce the possibility that the rigidity of the vibration plate 23 located above the pressure chambers 21 will increase. Therefore, the liquid ejection head 1 according to this embodiment can reduce the possibility that the displacement of the vibration plate 23 associated with the displacement of the piezoelectric element 24 will decrease.

[0073] On the other hand, when viewed from above, the amorphous silicon layer 29 partially overlaps with the liquid chamber 22. The liquid chamber 22 is connected to the pressure chamber 21. Furthermore, the liquid chamber 22 is located between the supply channel 31 and the pressure chamber 21. In the liquid ejection head 1 according to this embodiment, the amorphous silicon layer 29 partially overlaps with the liquid chamber 22, so that a portion of the amorphous silicon layer 29 is located above the liquid chamber 22. Since a portion of the amorphous silicon layer 29 is located above the liquid chamber 22, the rigidity of the diaphragm 23 overlapping with the amorphous silicon layer 29 is increased. Therefore, the liquid ejection head 1 according to this embodiment can reduce displacement of the diaphragm 23 overlapping with the amorphous silicon layer 29. Furthermore, the liquid chamber 22 includes a portion having a width smaller than the width of the pressure chamber 21. Therefore, the liquid ejection head 1 according to this embodiment can further reduce displacement of the diaphragm 23 located above the liquid chamber 22. Therefore, in the liquid ejection head 1 according to this embodiment, pressure waves are less likely to occur in the liquid chamber 22, and fluid crosstalk can be reduced.

[0074] The thickness of the amorphous silicon layer 29 may be, for example, 1 nm or more and 20 nm or less. By reducing the thickness of the amorphous silicon layer 29 to 20 nm or less, it is possible to reduce the thickness variation of the amorphous silicon layer 29. Therefore, the liquid ejection head 1 according to this embodiment can reduce the possibility of poor bonding between the first member 2 and the second member 3 due to the thickness variation of the amorphous silicon layer 29.

[0075] The amorphous silicon layer 29 is located above the piezoelectric elements 24 when viewed in cross section. In other words, the amorphous silicon layer 29 is located further toward the positive side of the Z axis than the piezoelectric elements 24 when viewed in cross section. Specifically, the amorphous silicon layer 29 is located further toward the positive side of the Z axis than the individual electrodes 243 of the piezoelectric elements 24 when viewed in cross section. In the liquid ejection head 1 according to this embodiment, the amorphous silicon layer 29 is located above the piezoelectric elements 24 when viewed in cross section, so that the second member 3 located on the amorphous silicon layer 29 can be reduced in possibility of coming into contact with the piezoelectric elements 24. Therefore, the liquid ejection head 1 according to this embodiment can reduce the possibility of interfering with the displacement of the piezoelectric elements 24.

[0076] In the liquid ejection head 1 according to this embodiment, the amorphous silicon layer 29 is located on the bonding layer 28, so even if the thickness of the amorphous silicon layer 29 is relatively small, the bonding layer 28 can ensure a sufficient thickness. In the liquid ejection head 1 according to this embodiment, the thickness of the bonding layer 28 is thicker than the thickness of the amorphous silicon layer 29. In the liquid ejection head 1 according to this embodiment, the amorphous silicon layer 29 is located on the bonding layer 28, so it is easy to form the amorphous silicon layer 29 above the piezoelectric elements 24, for example.

[0077] In the liquid ejection head 1 according to this embodiment, the upper surface of the bonding layer 28 is located higher than the piezoelectric elements 24 when viewed in cross section. In other words, the upper surface of the bonding layer 28 is located on the positive Z-axis direction side of the piezoelectric elements 24 when viewed in cross section. This means that the amorphous silicon layer 29 located on the bonding layer 28 is located higher than the piezoelectric elements 24. Therefore, the liquid ejection head 1 according to this embodiment can reduce the possibility that the second member 3 will come into contact with the piezoelectric elements 24 and interfere with the displacement of the piezoelectric elements 24.

[0078] The upper surface of the bonding layer 28 is planarized by CMP (Chemical Mechanical Polishing). CMP is a chemical and mechanical polishing process using a slurry containing chemicals and abrasives. Other polishing methods, such as chemical polishing, electrolytic polishing, buffing, and lapping, may also be used. In the liquid ejection head 1 according to this embodiment, the upper surface of the bonding layer 28 is planarized, and therefore the amorphous silicon layer 29 located on the bonding layer 28 is also planarized. Therefore, the liquid ejection head 1 according to this embodiment can reduce bonding defects between the first member 2 and the second member 3. The height difference of the upper surface of the bonding layer 28 is preferably smaller than the thickness of the amorphous silicon layer 29. Here, the height difference refers to the difference in position in the Z-axis direction when any point on the upper surface of the bonding layer 28 is taken. The height difference of the upper surface of the bonding layer 28 is preferably 20 nm or less.

[0079] The bonding layer 28 and the amorphous silicon layer 29 are positioned to surround the piezoelectric element 24 in plan view. As described above, the bonding layer 28 is made of SiO ２ Since the bonding layer 28 and the amorphous silicon layer 29 contain SiN, they have high moisture resistance, heat resistance, and insulating properties. Therefore, in the liquid ejection head 1 according to this embodiment, the bonding layer 28 and the amorphous silicon layer 29 are positioned to surround the piezoelectric element 24 in a plan view, thereby sealing the piezoelectric element 24. By sealing the piezoelectric element 24, it is possible to reduce the possibility of the piezoelectric element 24 being altered by moisture or oxidized by oxygen.

[0080] In the liquid ejection head 1 according to this embodiment, the bonding layer 28 and the amorphous silicon layer 29 are positioned to surround the plurality of piezoelectric elements 24. Therefore, in the liquid ejection head 1 according to this embodiment, the bonding layer 28 and the amorphous silicon layer 29 can seal the plurality of piezoelectric elements 24 collectively, and the plurality of piezoelectric elements 24 can be placed closer to each other than when each piezoelectric element 24 is surrounded individually. This allows the liquid ejection head 1 to be made smaller.

[0081] The bonding layer 28 and the amorphous silicon layer 29 may be positioned so as to individually surround each of the plurality of piezoelectric elements 24. In a liquid ejection head configured so that the bonding layer 28 and the amorphous silicon layer 29 are positioned so as to individually surround each of the plurality of piezoelectric elements 24, for example, it is possible to reduce the possibility that vibrations generated in one piezoelectric element 24 will propagate to a piezoelectric element 24 adjacent to that one piezoelectric element 24.

[0082] The piezoelectric element 24 according to this embodiment is located in space A whose walls are the amorphous silicon layer 29 and the bonding layer 28. In other words, the piezoelectric element 24 according to this embodiment is located in space A that is independent from the outside of the liquid ejection head 1. In the liquid ejection head 1 according to this embodiment, the air pressure in space A is set to be lower than the air pressure outside the liquid ejection head 1, for example, standard atmospheric pressure. Therefore, the piezoelectric element 24 according to this embodiment has a smaller amount of oxygen in space A, which reduces the possibility of oxidation.

[0083] In the liquid ejection head 1 according to this embodiment, the air pressure in the space A is 1 Pa or less, which is approximately 1 / 100,000 of the standard atmospheric pressure of 101,325 Pa. The air pressure in the independent space A can be reduced, for example, by bonding the first member 2 and the second member 3 together under vacuum. Furthermore, in the liquid ejection head 1 according to this embodiment, the first member 2 and the second member 3 are bonded together by bonding between dangling bonds of silicon, i.e., by covalent bonding. Therefore, in the liquid ejection head 1 according to this embodiment, a strong bonding force is generated at the bonded portion between the first member 2 and the second member 3, which makes the independent space A highly airtight and makes it easy to maintain the air pressure in the independent space A.

[0084] In the liquid ejection head 1 according to this embodiment, the lower surface 32 of the second member 3, including the portion overlapping with the piezoelectric element 24 in a planar view, is located higher than the lower surface 33 of the portion overlapping with the amorphous silicon layer 29 in a planar view. In other words, the lower surface 32 of the second member 3, including the portion overlapping with the piezoelectric element 24 in a planar view, is located further toward the positive Z-axis direction than the lower surface 33 of the portion overlapping with the amorphous silicon layer 29 in a planar view. In other words, the second member 3 according to this embodiment forms a recess when viewed in cross section. In the liquid ejection head 1 according to this embodiment, the lower surface 32 of the second member 3, including the portion overlapping with the piezoelectric element 24 in a planar view, is located higher than the lower surface 33 of the portion overlapping with the amorphous silicon layer 29 in a planar view. This reduces the possibility that the second member 3 will come into contact with the piezoelectric element 24 and interfere with the displacement of the piezoelectric element 24.

[0085] The second member 3 according to this embodiment contains single-crystal silicon. The surface of the single-crystal silicon can be activated using an Ar ion beam under high vacuum. By bringing the activated single-crystal silicon contained in the second member 3 into contact with the activated amorphous silicon layer 29 while the activated silicon is in an activated state, the first member 2 and the second member 3 can be bonded to each other without high-temperature treatment. The first member 2 and the second member 3 can be bonded to each other by a so-called room-temperature bonding method. In the liquid ejection head 1 according to this embodiment, by bonding the first member 2 and the second member 3 by the room-temperature bonding method, the possibility of damage to the piezoelectric element 24 due to exposure to high temperatures can be reduced.

[0086] The relationship between the amorphous silicon layer 29, the individual electrode wiring 25, and the common electrode wiring 26 will be described in detail with reference to Fig. 8. Fig. 8 is a plan view showing the pressure chambers 21, the liquid chambers 22, the individual electrode wiring 25, the common electrode wiring 26, and the amorphous silicon layer 29 in the first member 2 according to this embodiment. In Fig. 8, the amorphous silicon layer 29 is shown in gray.

[0087] The individual electrode wiring 25 drawn out from the portion corresponding to the pressure chamber 21 on the positive side of the X axis passes between the pressure chambers 21 on the negative side of the X axis and between the liquid chambers 22 on the negative side of the X axis, and is drawn out to the end of the first member 2 on the negative side of the X axis.

[0088] In plan view, the amorphous silicon layer 29 partially overlaps with the individual electrode wires 25. Therefore, in the liquid ejection head 1 according to this embodiment, the positions where the amorphous silicon layer 29 partially overlaps with the individual electrode wires 25 are pressed by the second member 3, thereby reducing the possibility of the individual electrode wires 25 peeling off. Specifically, in plan view, the amorphous silicon layer 29 is positioned so as to overlap with the individual electrode wires 25 that are positioned between the pressure chambers 21 on the positive X-axis direction side and the pressure chambers 21 on the negative X-axis direction side. In addition, in plan view, the amorphous silicon layer 29 is positioned so as to overlap with the pressure chambers 21 on the negative X-axis direction side and the end of the first member 2 on the negative X-axis side.

[0089] Furthermore, in a plan view, the amorphous silicon layer 29 also partially overlaps with the common electrode wiring 26. Therefore, in the liquid ejection head 1 according to this embodiment, the positions where the amorphous silicon layer 29 partially overlaps with the common electrode wiring 26 are pressed by the second member 3, thereby reducing the possibility of peeling off of the common electrode wiring 26. Specifically, in a plan view, the amorphous silicon layer 29 is positioned so as to overlap with the common electrode wiring 26 other than the end of the first member 2 on the negative X-axis direction side. In other words, in a plan view, the amorphous silicon layer 29 is positioned so as to overlap with the common electrode wiring 26 other than the portion connected to the flexible substrate 6.

[0090] Next, a method for manufacturing the liquid ejection head 1 will be described.

[0091] First, a single crystal silicon substrate is prepared.

[0092] The vibration plate 23, piezoelectric element 24, insulator 2N, individual electrode wiring 25, common electrode wiring 26, and protective film 27 are formed on a single crystal silicon substrate by sputtering, sol-gel method, CVD, or thermal oxidation.

[0093] Next, a SiO 2 film that will become the bonding layer 28 is formed on the protective film 27. ２ is formed by sputtering. ２ is formed relatively thick on the protective film 27. ２ is formed to a thin thickness by grinding. ２ The top surface of the SiO2 is planarized by CMP. ２ is the bonding layer 28. The thickness of the bonding layer 28 is reduced to about 2 μm by grinding and polishing. Note that polishing methods other than CMP may also be used.

[0094] Next, a supply channel 31 is formed in the single crystal silicon substrate to manufacture the second member 3. An Ar ion beam is irradiated onto the second member 3 to cause amorphous silicon to scatter onto the bonding layer 28, thereby forming an amorphous silicon layer 29. When the amorphous silicon is scattered using the Ar ion beam described above under high vacuum, the surface of the second member 3 is activated.

[0095] Next, the activated portion of the single crystal silicon contained in the second member 3 is brought into contact with the activated amorphous silicon layer 29, thereby bonding the first member 2 and the second member 3 to each other. Note that the irradiation of the Ar ion beam and the bonding of the first member 2 and the second member 3 are carried out under high vacuum and at room temperature.

[0096] Next, the pressure chamber 21 and the liquid chamber 22 are formed by etching from the bottom surface of the single crystal silicon substrate of the first member 2 .

[0097] Next, the third member 4 is manufactured by forming a nozzle 41 in the single-crystal silicon substrate. The lower surface of the first member 2 and the upper surface of the third member 4 are activated by irradiating them with an Ar ion beam under high vacuum. The lower surface of the first member 2 and the upper surface of the third member 4 are then brought into contact with the upper surface of the third member 4 at room temperature under high vacuum, thereby bonding the first member 2 and the third member 4. At this time, an amorphous silicon layer is formed between the first member 2 and the third member 4. In other words, the first member 2 and the third member 4 are bonded to each other via the amorphous silicon layer.

[0098] Next, the common flow path 51 is formed in the resin member to manufacture the fourth member 5. The fourth member 5 is bonded onto the second member 3 via a resin adhesive.

[0099] Next, a flexible substrate 6 on which a driving IC 7 is mounted is prepared. The flexible substrate 6 on which the driving IC 7 is mounted is bonded to the first member 2 via an adhesive so as to be electrically connected to the individual electrode wiring 25 and the common electrode wiring 26 of the first member 2. In this way, the liquid ejection head 1 can be manufactured. Note that the order of film formation and the order of bonding are not limited in any way.

[0100] Second Embodiment A liquid ejection head 1a according to a second embodiment will be described. In the description of the liquid ejection head 1a according to this embodiment, basically, only the differences from the liquid ejection head 1 according to the first embodiment will be described. Matters not specifically mentioned may be considered to be the same as those in the first embodiment or may be inferred from those in the first embodiment.

[0101] Fig. 9 is a plan view schematically showing a first member 2a according to the second embodiment. Fig. 10 is a cross-sectional view taken along line III-III shown in Fig. 9. Note that the two wavy lines drawn vertically in Fig. 9 represent omission lines. Fig. 10 also shows a second member 3 and a third member 4.

[0102] 9, the bonding layer 28 and the first amorphous silicon layer 29a are shown in gray. Here, the first amorphous silicon layer 29a corresponds to the amorphous silicon layer 29 described in the first embodiment.

[0103] In the liquid ejection head 1a of this embodiment, an Ar ion beam is irradiated onto the second member 3 made of single crystal silicon under high vacuum, causing silicon atoms to scatter onto the bonding layer 28, thereby forming an activated first amorphous silicon layer 29a on the bonding layer 28.

[0104] The second member 3 is located on the first amorphous silicon layer 29a and is bonded to the first member 2a. Specifically, the surface of the second member 3 is activated by scattering silicon atoms using the above-mentioned Ar ion beam under high vacuum. When an activated portion of single crystal silicon contained in the second member 3 is brought into contact with the activated first amorphous silicon layer 29a, dangling bonds in the first amorphous silicon layer 29a and dangling bonds in the second member 3 bond, and the first member 2a and the second member 3 are bonded to each other.

[0105] In the liquid ejection head 1a according to this embodiment, the first member 2a and the second member 3 are bonded to each other via the first amorphous silicon layer 29a, as in the liquid ejection head 1 according to the first embodiment. Therefore, in the liquid ejection head 1a according to this embodiment, the first member 2a and the second member 3 are bonded to each other via the first amorphous silicon layer 29a, which has excellent chemical stability and thermal stability, and therefore it is possible to reduce the possibility of deterioration at the bonded portion between the first member 2a and the second member 3 due to the influence of the supplied liquid. Furthermore, the liquid ejection head 1a according to this embodiment is also possible to reduce the possibility of deterioration at the bonded portion between the first member 2a and the second member 3 due to oxidation.

[0106] The liquid ejection head 1a according to this embodiment differs from the liquid ejection head 1 according to the first embodiment in that it further includes a second amorphous silicon layer 29b. The second amorphous silicon layer 29b is located on the piezoelectric element 24 and the protective film 27. In plan view, the second amorphous silicon layer 29b is located in a portion excluding the portion including the first amorphous silicon layer 29a and in a portion excluding the end of the first member 2a on the negative X-axis direction side. In other words, in plan view, the second amorphous silicon layer 29b is located in a portion excluding the bonding layer 28 and in a portion excluding the end of the first member 2a on the negative X-axis direction side.

[0107] At the same time as forming the first amorphous silicon layer 29 a on the bonding layer 28, an Ar ion beam is irradiated to the second member 3, which is single crystal silicon, under high vacuum to scatter amorphous silicon onto a portion excluding the portion having the first amorphous silicon layer 29 a and onto a portion excluding the end of the first member 2 a on the negative side of the X-axis, thereby forming a second amorphous silicon layer 29 b.

[0108] The second amorphous silicon layer 29b is made of non-crystalline silicon, similar to the first amorphous silicon layer 29a, and has silicon atoms bonded together in a disordered manner. The thickness of the second amorphous silicon layer 29b may be, similar to the thickness of the first amorphous silicon layer 29a, for example, 1 nm to 20 nm or less.

[0109] The second amorphous silicon layer 29b according to this embodiment overlaps with the plurality of piezoelectric elements 24 in a plan view. Therefore, the second amorphous silicon layer 29b according to this embodiment functions as a protective film that protects the plurality of piezoelectric elements 24 from dust, moisture, and oxygen. Furthermore, the second amorphous silicon layer 29b has a high resistance value because silicon atoms are bonded together in a disordered manner. In the liquid ejection head 1a according to this embodiment, the second amorphous silicon layer 29b is located directly on the plurality of piezoelectric elements 24. Therefore, in the liquid ejection head 1a according to this embodiment, the possibility of one piezoelectric element 24 becoming electrically connected to another piezoelectric element 24 through the second amorphous silicon layer 29b is reduced. Furthermore, the thickness of the second amorphous silicon layer 29b is thin, at 20 nm, which reduces the possibility of a decrease in the displacement of the piezoelectric elements 24.

[0110] Furthermore, the second amorphous silicon layer 29b overlaps with the individual electrode wires 25 in a plan view. Therefore, in the liquid ejection head 1a according to this embodiment, the second amorphous silicon layer 29b functions as a protective film that protects the individual electrode wires 25 from dust, moisture, and oxygen. The second amorphous silicon layer 29b also functions as an insulator for the individual electrode wires 25. Therefore, in the liquid ejection head 1a according to this embodiment, the possibility of a short circuit occurring even if moisture or ink gets between an individual electrode wire 25 and another individual electrode wire 25 or a piezoelectric element 24 is reduced.

[0111] Furthermore, the individual electrode wiring 25 extending from the piezoelectric element 24 on the positive X-axis side passes between the piezoelectric elements 24 on the negative X-axis side and is extended to the end of the first member 2a on the negative X-axis side. The individual electrode wiring 25 located between a piezoelectric element 24 and a piezoelectric element 24 adjacent to that piezoelectric element 24 is close to the piezoelectric element 24, and therefore has a high possibility of short-circuiting. Therefore, in the liquid ejection head 1a according to this embodiment, the second amorphous silicon layer 29b overlaps with the individual electrode wiring 25 located between the piezoelectric element 24 and the piezoelectric element 24 adjacent to that piezoelectric element 24 in a plan view, thereby reducing the possibility of short-circuiting. Furthermore, in the liquid ejection head 1a according to this embodiment, the individual electrode wiring 25 is located between the piezoelectric element 24 and the piezoelectric element 24 adjacent to that piezoelectric element 24, but any wiring, such as a common electrode wiring, may be located therein.

[0112] In the liquid ejection head 1a according to this embodiment, the first amorphous silicon layer 29a is located on the bonding layer 28, so even if the thickness of the first amorphous silicon layer 29a is relatively small, the thickness can be ensured by the bonding layer 28. The thickness of the bonding layer 28 is thicker than the thickness of the first amorphous silicon layer 29a.

[0113] Furthermore, in the liquid ejection head 1a according to this embodiment, the bonding layer 28 and the first amorphous silicon layer 29a are positioned to surround the piezoelectric element 24 and the second amorphous silicon layer 29b. Therefore, in the liquid ejection head 1a according to this embodiment, the upper part of the piezoelectric element 24 can be sealed with the second amorphous silicon layer 29b, and the periphery of the piezoelectric element 24 can be sealed with the bonding layer 28 and the first amorphous silicon layer 29a. Therefore, the liquid ejection head 1a according to this embodiment can reduce the possibility of the piezoelectric element 24 being altered by moisture or oxidized by oxygen.

[0114] The first and second embodiments described above may be combined as appropriate.

[0115] REFERENCE SIGNS LIST 1, 1a Liquid ejection head 2, 2a First member 21 Pressure chamber 22 Liquid chamber 23 Vibration plate 231 Through hole 24 Piezoelectric element 241 Common electrode 242 Piezoelectric body 243 Individual electrode 25 Individual electrode wiring 26 Common electrode wiring 28 Bonding layer 29 Amorphous silicon layer 29a First amorphous silicon layer 29b Second amorphous silicon layer 3 Second member 31 Supply path 10 Printer (recording device) 109 Control unit A Space

Claims

1. A liquid ejection head comprising: a first member having a pressure chamber, a diaphragm positioned above the pressure chamber, and a piezoelectric element positioned on the diaphragm corresponding to the pressure chamber; and a second member positioned above the first member and having a supply path capable of supplying liquid to the pressure chamber, wherein the first member is provided with an amorphous silicon layer, and the first member and the second member are joined to each other via the amorphous silicon layer.

2. The liquid ejection head according to claim 1, wherein the diaphragm has a through hole at a position corresponding to the supply path, and the amorphous silicon layer is positioned to surround the through hole in a plan view.

3. The liquid ejection head according to claim 1, wherein the first member further has a liquid chamber connected to the pressure chamber, the liquid chamber is positioned between the supply path and the pressure chamber, and in a plan view, the liquid chamber includes a portion having a width smaller than the width of the pressure chamber, and the amorphous silicon layer does not overlap with the pressure chamber and overlaps with a part of the liquid chamber.

4. The liquid ejection head according to claim 1, wherein the amorphous silicon layer is positioned above the piezoelectric element in a cross-sectional view.

5. The liquid ejection head according to claim 1, wherein the first member further has a bonding layer thicker than the thickness of the amorphous silicon layer, the amorphous silicon layer is positioned on the bonding layer, and the upper surface of the bonding layer is positioned above the piezoelectric element in a cross-sectional view.

6. The liquid ejection head according to claim 5, wherein the upper surface of the bonding layer is a flat surface.

7. The amorphous silicon layer and the bonding layer are positioned to surround the piezoelectric element, and the bonding layer contains SiO ２ or SiN. The liquid ejection head according to claim 5.

8. The liquid ejection head according to claim 7, wherein the piezoelectric element is positioned in a space having the amorphous silicon layer and the bonding layer as wall surfaces, and the atmospheric pressure in the space is smaller than the standard atmospheric pressure.

9. The liquid ejection head according to claim 1, wherein the second member contains single crystal silicon, and the single crystal silicon contained in the second member is joined to the amorphous silicon layer.

10. The piezoelectric element has an individual electrode, a piezoelectric body, and a common electrode, the first member further has an individual electrode wiring electrically connected to the individual electrode, and when viewed in plan, the amorphous silicon layer partially overlaps with the individual electrode wiring. The liquid ejection head according to claim 1.

11. The piezoelectric element has an individual electrode, a piezoelectric body, and a common electrode, the first member further has a common electrode wiring electrically connected to the common electrode, and when viewed in plan, the amorphous silicon layer partially overlaps with the common electrode wiring. The liquid ejection head according to claim 1.

12. When the amorphous silicon layer is a first amorphous silicon layer, the first member further has a second amorphous silicon layer that overlaps with the piezoelectric element when viewed in plan. The liquid ejection head according to claim 1.

13. When the amorphous silicon layer is a first amorphous silicon layer, the first member further has: a wiring located between adjacent piezoelectric elements; and a second amorphous silicon layer that overlaps with the wiring when viewed in plan. The liquid ejection head according to claim 1.

14. The first member further has a bonding layer thicker than the thickness of the first amorphous silicon layer, the first amorphous silicon layer is located on the bonding layer, the upper surface of the bonding layer is located above the piezoelectric element when viewed in cross section, and the first amorphous silicon layer and the bonding layer surround the piezoelectric element and the second amorphous silicon layer. The liquid ejection head according to claim 12.

15. A recording apparatus comprising: the liquid ejection head according to any one of claims 1 to 14; a moving unit that relatively moves the liquid ejection head and a recording medium; and a control unit that controls the moving unit.

Images