Liquid discharge head, head module, and recording device

Abstract

A liquid discharge head (1) comprises: a plurality of pressure chambers (31); a plurality of nozzles (21) connected to the plurality of pressure chambers (31), respectively; a diaphragm (33) positioned on the plurality of pressure chambers (31); and a plurality of piezoelectric elements (34) corresponding to the plurality of pressure chambers (31) and positioned on the diaphragm (33). The diaphragm (33) has a first silicon oxide layer (331), a silicon layer (332) positioned on the first silicon oxide layer (331), and a second silicon oxide layer (333) positioned on the silicon layer (332). The thickness of the silicon layer (332) is 1.1-1.9 μm.

Description

Liquid ejection head, head module, and recording apparatus

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

[0002] Liquid ejection heads that eject liquid toward a recording medium are known. Such liquid ejection heads include a plurality of pressure chambers, a plurality of nozzles connected to the pressure chambers, a vibration plate located above the pressure chambers, and a plurality of piezoelectric elements located on the vibration plate corresponding to the pressure chambers. When a voltage is applied to the piezoelectric elements, the piezoelectric elements are displaced, and the vibration plate is displaced in response to the displacement of the piezoelectric elements. The displacement of the vibration plate pressurizes the liquid in the pressure chambers, causing the liquid to be ejected from the nozzles connected to the pressure chambers.

[0003] In Patent Document 1, an SOI (Silicon on Insulator) wafer is used as the material for the diaphragm, and a first silicon oxide layer and a second silicon oxide layer are formed on the upper and lower surfaces of the silicon layer. Patent Document 1 discloses that the thickness of the silicon layer is 2 μm to 20 μm, and the thicknesses of the first silicon oxide layer and the second silicon oxide layer are each 0.5 μm to 2.0 μm.

[0004] In Patent Document 2, an SOI wafer is used as a diaphragm, and a first silicon oxide layer and a second silicon oxide layer are formed on the upper and lower surfaces of a silicon layer. Patent Document 2 discloses that the thickness of the silicon layer is 3 μm or more, the thickness of the first silicon oxide layer is 0.5 μm or more, and the thickness of the second silicon oxide layer is 0.5 μm or more.

[0005] JP 2008-228458 A JP 2019-161213 A

[0006] A liquid ejection head according to one aspect of the present disclosure comprises a plurality of pressure chambers, a plurality of nozzles connected to each of the plurality of pressure chambers, a vibration plate located above the plurality of pressure chambers, and a plurality of piezoelectric elements located on the vibration plate corresponding to the plurality of pressure chambers, wherein the vibration plate has a first silicon oxide layer, a silicon layer located on the first silicon oxide layer, and a second silicon oxide layer located on the silicon layer, and the silicon layer has a thickness of 1.1 μm to 1.9 μm.

[0007] FIG. 1 is a side view schematically showing a printer according to this embodiment. FIG. 2 is a plan view schematically showing a printer according to this embodiment. FIG. 3 is a plan view schematically showing a liquid ejection head according to this embodiment. FIG. 4 is a view of the liquid ejection head shown in FIG. 3 as seen from the A direction. FIG. 5 is an enlarged view of region I shown in FIG. 3. FIG. 6 is a cross-sectional view taken along line II-II in FIG. 5. FIG. 7 is a cross-sectional view taken along line III-III in FIG. 5. FIG. 8 is a diagram showing the results of an evaluation experiment when the total thickness of the first silicon oxide layer and the second silicon oxide layer was 0.1 μm. FIG. 9 is a diagram showing the results of an evaluation experiment when the total thickness of the first silicon oxide layer and the second silicon oxide layer was 0.2 μm. FIG. 10 is a diagram showing the results of an evaluation experiment when the total thickness of the first silicon oxide layer and the second silicon oxide layer was 0.3 μm. FIG. 11 is a diagram showing the results of an evaluation experiment when the total thickness of the first silicon oxide layer and the second silicon oxide layer was 0.4 μm. Fig. 12 is a diagram showing the results of an evaluation experiment when the total thickness of the first silicon oxide layer and the second silicon oxide layer is 0.5 μm. Fig. 13 is a diagram showing the results of an evaluation experiment when the total thickness of the first silicon oxide layer and the second silicon oxide layer is 0.6 μm. Fig. 14 is a diagram showing the displacement amount of the diaphragm. Fig. 15 is an enlarged view of region IV shown in Fig. 6. Fig. 16 is an enlarged view of region V shown in Fig. 7. Fig. 17 is a block diagram showing an example configuration of a head module.

[0008] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0009] 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.

[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 printing paper P, color images can be printed. 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, a liquid such as a coating agent may be printed uniformly or in a pattern using the liquid ejection head 1 to perform surface treatment on the printing paper P. Note that instead of using the liquid ejection head 1, a coating agent may be applied using an applicator (not shown).

[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 conveyor belt. In this way, sheets of paper, cut pieces of cloth, wood, or tiles can be used as the recording medium. Furthermore, a liquid containing conductive particles may be ejected from the liquid ejection head 1 to print wiring patterns for electronic devices. Furthermore, a chemical agent may be produced by ejecting a predetermined amount of liquid chemical agent or a liquid containing a chemical agent from the liquid ejection head 1 toward 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] For ease of understanding, Fig. 3 illustrates a three-dimensional Cartesian coordinate system including an X-axis with the positive direction pointing upward on the paper surface and a Y-axis with the positive direction pointing rightward on the paper surface. This Cartesian coordinate system is also shown in other drawings used in the following explanation. For convenience, in the following explanation, the positive Z-axis side of the liquid ejection head 1 may be referred to as "up." In addition, in the liquid ejection head 1, the X-axis direction is the transport direction of the printing paper P.

[0028] The liquid ejection head 1 includes a nozzle member 2 , an actuator member 3 , a support member 4 , and a liquid supply member 5 .

[0029] The nozzle member 2 includes a plurality of nozzles 21. The nozzle member 2 is made of silicon.

[0030] The multiple nozzles 21 are through-holes that penetrate the nozzle member 2 in the Z-axis direction. The multiple nozzles 21 are positioned along the Y-axis direction to form a nozzle group 21G. The nozzle group 21G according to this embodiment has a first nozzle group 21GA on the positive side of the X-axis and a second nozzle group 21GB on the negative side of the X-axis. The liquid ejection head 1 according to this embodiment has two nozzle groups 21G, but may have only one, or three or more. The two nozzle groups 21G according to this embodiment are configured parallel to each other. The distance between the nozzles 21 in the nozzle group 21G in the Y-axis direction is 84.6 μm. In other words, the resolution of the nozzles 21 in each nozzle group 21G is 300 dpi. The nozzles 21 in the first nozzle group 21GA are each positioned between the multiple nozzles 21 in the second nozzle group 21GB in the Y-axis direction. In other words, the nozzles 21 of the first nozzle group 21GA and the nozzles 21 of the second nozzle group 21GB are shifted from each other in the Y-axis direction, and the combined resolution of the nozzles 21 of the two nozzle groups 21G is 600 dpi. The distance between the nozzles 21 of each nozzle group 21G may be set as appropriate.

[0031] The actuator member 3 is composed of a silicon substrate 30 in which a plurality of pressure chambers 31 and a plurality of first apertures 32 are formed, a vibration plate 33 located on the silicon substrate 30, and a plurality of piezoelectric elements 34 located on the vibration plate 33. The silicon substrate 30 is located on the nozzle member 2. The actuator member 3 according to this embodiment has substantially the same shape as the nozzle member 2 in a plan view.

[0032] The multiple pressure chambers 31 are through-holes that penetrate the silicon substrate 30 in the Z-axis direction and are provided so as to be connected to the multiple nozzles 21, respectively. According to this embodiment, the multiple pressure chambers 31 are each physically connected to the multiple nozzles 21, but this is not limiting. For example, the multiple pressure chambers 31 may each be fluidly connected to the multiple nozzles 21 via flow paths such as descenders. In other words, the concept of "connected" is not limited to physical connection, but also includes fluidic connection. Like the multiple nozzles 21, the multiple pressure chambers 31 are located along the Y-axis direction. Furthermore, in a plan view, the multiple pressure chambers 31 are located so that their longitudinal direction is aligned with the X-axis direction and their lateral direction is aligned with the Y-axis direction. According to this embodiment, the pressure chambers 31 have a substantially rectangular planar shape, but this is not limiting. For example, the pressure chambers 31 may have a diamond or circular planar shape. Liquid is stored in the pressure chambers 31. When pressure is applied to the liquid in the pressure chamber 31, the liquid is ejected from the nozzle 21 to the outside as droplets.

[0033] The multiple first apertures 32 are through-holes that penetrate the silicon substrate 30 in the Z-axis direction, and are each provided so as to be connected to one longitudinal end of the multiple pressure chambers 31. The first aperture 32 connected to the pressure chamber 31 located on the positive X-axis side is provided so as to be connected to the end of the pressure chamber 31 on the negative X-axis side. The first aperture 32 connected to the pressure chamber 31 located on the negative X-axis side is provided so as to be connected to the end of the pressure chamber 31 on the positive X-axis side. Liquid is stored in the first aperture 32, similar to the pressure chamber 31. When viewed in a plane, the first aperture 32 has a smaller width in the Y-axis direction, i.e., a flow path width, than the pressure chamber 31, and therefore functions as a so-called throttle.

[0034] The vibration plate 33 is located above the plurality of pressure chambers 31 and the plurality of first apertures 32 .

[0035] The plurality of piezoelectric elements 34 are positioned on the vibration plate 33 corresponding to the plurality of pressure chambers 31. The plurality of piezoelectric elements 34 are provided in a one-to-one relationship with the plurality of pressure chambers 31. When a voltage is applied to the piezoelectric elements 34, the piezoelectric elements 34 are displaced. In response to the displacement of the piezoelectric elements 34, the vibration plate 33 positioned above the pressure chambers 31 is also displaced. As a result, pressure is applied to the liquid in the pressure chambers 31. This causes the liquid to be ejected from the pressure chambers 31 through the nozzles 21.

[0036] The support member 4 is located on the actuator member 3. The support member 4 has a predetermined thickness that is thicker in the Z-axis direction than the actuator member 3, and has the function of supporting the actuator member 3. The support member 4 includes a plurality of second apertures 41. The support member 4 is made of silicon.

[0037] The multiple second apertures 41 are through holes that pass through the support member 4 in the Z-axis direction, and are provided so as to be connected to the multiple first apertures 32, respectively. The multiple second apertures 41 are connected to the multiple pressure chambers 31 via the multiple first apertures 32, respectively. The second apertures 41 function as so-called throttles, similar to the first apertures 32. Furthermore, the multiple second apertures 41 are located at the center of the support member 4 in the X-axis direction when viewed in a plan view.

[0038] The liquid supply member 5 is located on the support member 4. In a plan view, the liquid supply member 5 has substantially the same shape as the support member 4. The liquid supply member 5 includes a common flow path 51. The liquid supply member 5 is made of resin.

[0039] In a plan view, the common flow path 51 is located at the center of the liquid supply 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 second apertures 41 and is connected to the plurality of second apertures 41. Therefore, the common flow path 51 can supply liquid to the plurality of second apertures 41.

[0040] Liquid is filled in the pressure chamber 31, the first aperture 32, the second aperture 41, and the common flow path 51. When pressure is applied to the pressure chamber 31 by the piezoelectric element 34, liquid is supplied from the pressure chamber 31 to the nozzle 21, and droplets are ejected from the nozzle 21. In addition, liquid is replenished into the pressure chamber 31 from the common flow path 51 via the first aperture 32 and the second aperture 41.

[0041] In the liquid ejection head 1 according to this embodiment, two apertures, a first aperture 32 and a second aperture 41, are provided between each pressure chamber 31 and the common flow path 51. This reduces so-called crosstalk, which is the propagation of a pressure wave generated in one pressure chamber 31 to another pressure chamber 31 via the common flow path 51.

[0042] 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.

[0043] The common flow path 51 may also have a common flow path 51 that supplies liquid to the pressure chamber 31 and a common flow path 51 that recovers liquid from the pressure chamber 31. 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 21.

[0044] The configuration around the pressure chamber 31 according to this embodiment will be described in detail with reference to Figures 5, 6, and 7. Figure 5 is an enlarged view of region I shown in Figure 3. Figure 6 is a cross-sectional view taken along line II-II in Figure 5. Figure 7 is a cross-sectional view taken along line III-III in Figure 5. In addition, to make the description easier to understand, the liquid supply member 5 is not shown in Figures 5, 6, and 7.

[0045] The pressure chamber 31 has a longitudinal length 31X of 300 to 500 μm, a lateral length 31Y of 60 to 80 μm, and a depth length 31Z of 50 to 100 μm.

[0046] The diaphragm 33 has a first silicon oxide layer 331 , a silicon layer 332 located on the first silicon oxide layer 331 , and a second silicon oxide layer 333 located on the silicon layer 332 .

[0047] The first silicon oxide layer 331 functions as a protective layer. Therefore, by positioning the first silicon oxide layer 331 between the plurality of pressure chambers 31 and the silicon layer 332, corrosion resistance from the liquid inside the pressure chambers 31 can be improved.

[0048] The second silicon oxide layer 333 functions as an insulator. Therefore, by positioning the second silicon oxide layer 333 between the silicon layer 332 and the plurality of piezoelectric elements 34, it is possible to suppress current leakage from the plurality of piezoelectric elements 34 to the silicon layer 332. Therefore, the liquid ejection head 1 according to this embodiment can reduce electrical crosstalk.

[0049] The piezoelectric element 34 is composed of a common electrode 341, a piezoelectric body 342, and an individual electrode 343. Furthermore, in the piezoelectric element 34 according to this embodiment, the common electrode 341 is located on the vibration plate 33, the piezoelectric body 342 is located on the common electrode 341, and the individual electrode 343 is located on the piezoelectric body 342, but this is not limited to this. For example, the arrangement order of the common electrode 341 and the individual electrode 343 from the vibration plate 33 may be reversed. Specifically, the individual electrode 343, the piezoelectric body 342, and the common electrode 341 may be provided on the vibration plate 33 in this order. Furthermore, the piezoelectric element 34 may have an adhesive layer such as Ti between the common electrode 341 and the vibration plate 33. Furthermore, the piezoelectric element 34 may have a LaNiO layer between the common electrode 341 and the piezoelectric body 342 and between the piezoelectric body 342 and the individual electrode 343. ３ The adhesive layer may have an adhesive layer such as the above.

[0050] The common electrode 341 according to this embodiment is provided in common to the multiple pressure chambers 31. The thickness of the common electrode 341 according to this embodiment may be 0.05 μm or more and 1 μm or less. The common electrode 341 may be made of a metal material such as Pt, for example.

[0051] Although the piezoelectric body 342 according to this embodiment is individually provided corresponding to each pressure chamber 31, this is not limiting. For example, the piezoelectric body 342 may be provided in common to a plurality of pressure chambers 31, similar to the common electrode 341. The portion of the piezoelectric body 342 sandwiched between the individual electrode 343 and the common electrode 341 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 342 by the individual electrode 343 and the common electrode 341, the piezoelectric body 342 contracts in a direction along the vibration plate 33. This contraction is regulated by the vibration plate 33. As a result, the piezoelectric body 342 is displaced so as to convexly protrude toward the pressure chamber 31. As the piezoelectric body 342 displaces, the vibration plate 33 positioned above the pressure chamber 31 also displaces. As a result, pressure is applied to the liquid in the pressure chamber 31. The thickness of the piezoelectric body 342 may be 0.5 μm or more and 5 μm or less. The piezoelectric body 342 is made of, for example, Pb(Zr,Ti)O ３ system, NaNbO ３ system, BaTiO ３ system, (BiNa)NbO ３ system, BiNaNB ５ O １５ Examples of suitable materials include ceramic materials having ferroelectricity such as ferroelectric ceramics.

[0052] The individual electrodes 343 are individually provided corresponding to the pressure chambers 31. The thickness of the individual electrodes 343 may be set to 0.05 μm or more and 1 μm or less. The individual electrodes 343 may be made of a metal material such as Pt, for example.

[0053] Next, the embodiment of the vibration plate 33 of the liquid ejection head 1 of this embodiment will be described in detail.

[0054] In the liquid ejection head 1, in order to reduce the possibility of variations in ejection of the liquid ejected from the plurality of nozzles 21 or variations in the ejection voltage, it is preferable that the thickness of the silicon layer 332 is uniform across the plurality of pressure chambers 31. Here, the term "liquid ejection variations" refers to variations in the ejection speed or ejection amount of the liquid ejected from the plurality of nozzles 21, which are caused by the thickness of the silicon layer 332 being non-uniform across the plurality of pressure chambers 31, when a constant voltage value is applied to the plurality of piezoelectric elements 34. Furthermore, the term "ejection voltage variations" refers to variations in the voltage value, which are caused by the thickness of the silicon layer 332 being non-uniform across the plurality of pressure chambers 31, when the value of the voltage applied to each piezoelectric element 34 is adjusted so that the liquid is ejected from the plurality of nozzles 21 at a constant ejection speed.

[0055] It is difficult in manufacturing to make the thickness of the silicon layer 332 uniform for each of the multiple pressure chambers 31. For this reason, in conventional liquid ejection heads, the uneven thickness of the silicon layer for the multiple pressure chambers causes variations in the ejection of liquid ejected from the multiple nozzles or variations in the ejection voltage. Here, "uneven thickness of the silicon layer" means, for example, that the difference between the maximum thickness of the silicon layer and the minimum thickness of the silicon layer for the multiple pressure chambers is 0.01 μm or more.

[0056] After detailed investigation, the inventors found that if the thickness of the silicon layer 332 is too thick or if the thickness of the silicon layer 332 is too thin, there is a greater possibility that variations in the ejection of the liquid ejected from the multiple nozzles 21 or variations in the ejection voltage will occur.

[0057] Therefore, the inventors carried out an evaluation experiment using the liquid ejection head 1 according to this embodiment. The contents of the evaluation experiment are as follows.

[0058] First, the voltage values ​​that need to be applied to the piezoelectric element 34 for the liquid ejection head 1 to eject liquid at a ejection speed of 8 m / s were calculated by simulation for various thicknesses of the silicon layer 332. Furthermore, based on the calculated values, the voltage gradient was calculated for various thicknesses of the silicon layer 332. The voltage gradient indicates the voltage variation due to changes in the thickness of the silicon layer 332. Hereinafter, the voltage variation due to changes in the thickness of the silicon layer 332 will be referred to as "voltage variation." A liquid ejection head 1 with large voltage variation is more likely to cause ejection variation or ejection voltage variation in the liquid ejected from the multiple nozzles 21.

[0059] 6 to 8, the evaluation conditions were as follows: the common electrode 341 had a thickness of 0.1 μm, the piezoelectric body 342 had a thickness of 1 μm, the individual electrode 343 had a thickness of 0.1 μm, the pressure chamber 31 had a longitudinal length 31X of 500 μm, the pressure chamber 31 had a lateral length 31Y of 70 μm, and the pressure chamber 31 had a depth length 31Z of 70 μm. The liquid had a viscosity of 4.5 mPa·s. The pulse width of the applied voltage was set to AL (Acoustic Length), which is half the natural vibration period of the liquid ejection head 1.

[0060] The liquid is ejected using a so-called pull-and-shoot method. That is, the individual electrodes 343 are set to a higher potential than the common electrode 341 in advance, and at the timing of ejection, the individual electrodes 343 are temporarily set to the same low potential as the common electrode 341, and after the AL time, the individual electrodes 343 are again set to a high potential, thereby ejecting the liquid. In this case, the difference between the high potential and the low potential is the value of the voltage that needs to be applied to the piezoelectric element 34.

[0061] The results of the evaluation experiments are shown in FIGS. 8 to 13. FIG. 8 shows the results of the evaluation experiments when the total thickness of the first silicon oxide layer 331 and the second silicon oxide layer 333 is 0.1 μm. FIG. 9 shows the results of the evaluation experiments when the total thickness of the first silicon oxide layer 331 and the second silicon oxide layer 333 is 0.2 μm. FIG. 10 shows the results of the evaluation experiments when the total thickness of the first silicon oxide layer 331 and the second silicon oxide layer 333 is 0.3 μm. FIG. 11 shows the results of the evaluation experiments when the total thickness of the first silicon oxide layer 331 and the second silicon oxide layer 333 is 0.4 μm. FIG. 12 shows the results of the evaluation experiments when the total thickness of the first silicon oxide layer 331 and the second silicon oxide layer 333 is 0.5 μm. FIG. 13 shows the results of an evaluation experiment in which the total thickness of the first silicon oxide layer 331 and the second silicon oxide layer 333 is 0.6 μm.

[0062] In the evaluation experiment results, when the voltage variation was less than 5 V / μm, the evaluation of the liquid ejection variation or the ejection voltage variation was rated as "good," and when it was 5 V / μm or more, the evaluation of the liquid ejection variation or the ejection voltage variation was rated as "poor." In Figures 8 to 13, the evaluation of the liquid ejection variation or the ejection voltage variation is simply referred to as "evaluation." This is because when the voltage variation is 5 V / μm or more, the voltage variation is large, and there is a high possibility that the ejection variation or the ejection voltage variation of the liquid ejected from the multiple nozzles 21 will occur.

[0063] As shown in FIGS. 12 and 13 , when the sum of the thicknesses of the first silicon oxide layer 331 and the second silicon oxide layer 333 is 0.5 μm and 0.6 μm, respectively, the voltage variation is 4.39 V / μm and 2.97 V / μm, respectively, when the thickness of the silicon layer 332 is 0.5 μm. This is less than 5 V / μm. However, the thickness of the silicon layer 332 is 1.0 μm or less, which is relatively thin. On the other hand, the sum of the thicknesses of the first silicon oxide layer 331 and the second silicon oxide layer 333 is 0.5 μm or more, which is relatively thick. Therefore, it is not easy to stably form the first silicon oxide layer 331 and the second silicon oxide layer 333. Therefore, there is a possibility that the thicknesses of the first silicon oxide layer 331 and the second silicon oxide layer 333 may vary during manufacturing. For this reason, in a liquid ejection head 1 in which the total thickness of the first silicon oxide layer 331 and the second silicon oxide layer 333 is 0.5 μm or 0.6 μm and the thickness of the silicon layer 332 is 0.5 μm, there is a high possibility that variations in the ejection of the liquid or the ejection voltage will occur when ejected from the multiple nozzles 21. For this reason, even if the voltage variation is less than 5 V / μm, the evaluation of the liquid ejection variation or the ejection voltage variation is rated as ×.

[0064] 8 to 13, the voltage variation increases rapidly when the thickness of the silicon layer 332 changes from 1.1 μm to 0.5 μm. Furthermore, the voltage variation also increases rapidly when the thickness of the silicon layer 332 changes from 1.9 μm to 3 μm.

[0065] 9 , when the sum of the thicknesses of the first silicon oxide layer 331 and the second silicon oxide layer 333 is 0.2 μm, the voltage variation does not change significantly, from 3.74 V / μm to 3.09 V / μm, as the thickness of the silicon layer 332 increases from 1.1 μm to 1.9 μm. On the other hand, the voltage variation increases sharply, from 3.74 V / μm to 8.85 V / μm, as the thickness of the silicon layer 332 increases from 1.1 μm to 0.5 μm. Furthermore, the voltage variation increases sharply, from 3.09 V / μm to 12.47 V / μm, as the thickness of the silicon layer 332 increases from 1.9 μm to 3 μm.

[0066] The same applies to the cases where the total thickness of the first silicon oxide layer 331 and the second silicon oxide layer 333 is 0.1 μm, 0.3 μm, 0.4 μm, 0.5 μm, and 0.6 μm.

[0067] Furthermore, the diaphragm 33 having a silicon layer 332 with a thickness of 1.1 μm to 1.9 μm received a ◯ in the variation evaluation. That is, a liquid ejection head 1 having a silicon layer 332 with a thickness of 1.1 μm to 1.9 μm can reduce the possibility of variations in the ejection of liquid ejected from the plurality of nozzles 21 or variations in the ejection voltage. Furthermore, even under conditions other than the above evaluation conditions, a liquid ejection head 1 having a silicon layer 332 with a thickness of 1.1 μm to 1.9 μm can reduce the possibility of variations in the ejection of liquid ejected from the plurality of nozzles 21 or variations in the ejection voltage.

[0068] As described above, in the liquid ejection head 1 according to this embodiment, the thickness of the silicon layer 332 of the vibration plate 33 is 1.1 μm to 1.9 μm.

[0069] Here, the thickness of the silicon layer 332 refers to the average thickness of only the portions of the silicon layer 332 corresponding to each pressure chamber 31. The average thickness is the arithmetic average of measurements taken at at least three or more points on the silicon layer 332 corresponding to each pressure chamber 31. The "three or more points" may refer to the arithmetic average of measurements taken at any three points on the silicon layer 332 corresponding to each pressure chamber 31, or may refer to the arithmetic average of measurements taken at five points. In other words, this does not refer to measurements taken at ten or more points. The thicknesses of the first silicon oxide layer 331, the second silicon oxide layer 333, the diaphragm 33, and the piezoelectric element 34 are considered in the same manner as the thickness of the silicon layer 332 described above.

[0070] Here, the thickness of the silicon layer 332 being 1.1 μm to 1.9 μm includes a thickness that is 1.1 μm to 1.9 μm when rounded to one decimal place. For example, if the thickness of the silicon layer 332 is 1.09 μm, rounding to one decimal place results in 1.1 μm, which falls within the range of 1.1 μm to 1.9 μm. Furthermore, if the thickness of the silicon layer 332 is 1.92 μm, rounding to one decimal place results in 1.9 μm, which falls within the range of 1.1 μm to 1.9 μm.

[0071] Furthermore, when the thickness of the silicon layer 332 is 1.3 μm to 1.55 μm, the voltage variation is further reduced to 3 V / μm in the total thickness of the first silicon oxide layer 331 and the second silicon oxide layer 333. For this reason, in the liquid ejection head 1 according to this embodiment, it is more preferable that the thickness of the silicon layer 332 is 1.3 μm to 1.55 μm.

[0072] The inventors further conducted detailed studies on the displacement of the vibration plate 33 in the liquid ejection head 1 according to this embodiment, in addition to the variation in the ejection rate of the liquid ejected from the multiple nozzles 21 or the variation in the ejection voltage. In the above, the value of the voltage that must be applied to the piezoelectric element 34 in order for the liquid ejection head 1 to eject liquid at a ejection speed of 8 m / s was calculated through simulation. The inventors also simultaneously calculated, through simulation, the displacement of the vibration plate 33 when this voltage value is applied to the piezoelectric element 34. Here, the displacement of the vibration plate 33 was calculated when the thickness of the silicon layer 332 was 1.45 μm. Here, the displacement refers to the maximum displacement of the vibration plate 33 when a voltage is applied to the piezoelectric element 34.

[0073] The evaluation conditions were the same as those for the simulations shown in FIGS.

[0074] The calculated displacement of the diaphragm 33 is shown in Fig. 14. Fig. 14 shows the voltage and displacement of the diaphragm 33 when the total thickness of the first silicon oxide layer 331 and the second silicon oxide layer 333 is 0.1 µm, 0.2 µm, 0.3 µm, 0.4 µm, 0.5 µm, and 0.6 µm. In Fig. 14, the total thickness of the first silicon oxide layer 331 and the second silicon oxide layer 333 is simply referred to as the "total thickness."

[0075] The greater the displacement of the vibration plate 33, the greater the amount of liquid ejected from the nozzle 21. When the total thickness of the first silicon oxide layer 331 and the second silicon oxide layer 333 is 0.3 μm or less, the displacement of the vibration plate 33 is 280 nm or more, which is a relatively large displacement.

[0076] Therefore, in a liquid ejection head 1 having a vibration plate 33 in which the sum of the thicknesses of the first silicon oxide layer 331 and the second silicon oxide layer 333 is 0.3 μm or less, a large amount of liquid is ejected from the nozzle 21. Furthermore, when the sum of the thicknesses of the first silicon oxide layer 331 and the second silicon oxide layer 333 is 0.3 μm or less, the thickness of the silicon layer 332 is 1.3 μm to 1.8 μm, and the voltage variation is further reduced to 3 V / μm.

[0077] Therefore, in a liquid ejection head 1 having a diaphragm 33 in which the total thickness of the first silicon oxide layer 331 and the second silicon oxide layer 333 is 0.3 μm or less and the thickness of the silicon layer 332 is 1.3 μm to 1.8 μm, the ejection volume of liquid ejected from the plurality of nozzles 21 is large and the possibility of variations in ejection or ejection voltage of the liquid ejected from the plurality of nozzles 21 can be reduced. Therefore, in the liquid ejection head 1 according to this embodiment, it is preferable that the total thickness of the first silicon oxide layer 331 and the second silicon oxide layer 333 is 0.3 μm or less and the thickness of the silicon layer 332 is 1.3 μm to 1.8 μm. Furthermore, in a diaphragm 33 in which the total thickness of the first silicon oxide layer 331 and the second silicon oxide layer 333 is less than 0.1 μm, it is difficult to obtain effects such as corrosion resistance from the liquid in the pressure chambers 31 or reduction in electrical crosstalk. Therefore, the total thickness of the first silicon oxide layer 331 and the second silicon oxide layer 333 is preferably 0.1 μm or more.

[0078] On the other hand, in a diaphragm 33 in which the sum of the thicknesses of the first silicon oxide layer 331 and the second silicon oxide layer 333 is greater than 0.3 μm, the amount of displacement is smaller than in a diaphragm 33 in which the sum of the thicknesses of the first silicon oxide layer 331 and the second silicon oxide layer 333 is 0.3 μm or less. This means that a diaphragm 33 in which the sum of the thicknesses of the first silicon oxide layer 331 and the second silicon oxide layer 333 is greater than 0.3 μm has high rigidity. Therefore, a diaphragm 33 in which the sum of the thicknesses of the first silicon oxide layer 331 and the second silicon oxide layer 333 is greater than 0.3 μm can reduce the possibility of deterioration due to displacement. Furthermore, in a diaphragm 33 in which the sum of the thicknesses of the first silicon oxide layer 331 and the second silicon oxide layer 333 is greater than 0.3 μm, the voltage variation is further reduced to 3 V / μm when the thickness of the silicon layer 332 is 1.1 μm to 1.55 μm.

[0079] Therefore, in a liquid ejection head 1 having a vibration plate 33 in which the sum of the thicknesses of the first silicon oxide layer 331 and the second silicon oxide layer 333 is greater than 0.3 μm and the thickness of the silicon layer 332 is 1.1 μm to 1.55 μm, it is possible to reduce the possibility of deterioration of the vibration plate 33 and to reduce the possibility of variations in the ejection speed or ejection voltage of the liquid ejected from the multiple nozzles 21. Therefore, in the liquid ejection head 1 according to this embodiment, it is preferable that the sum of the thicknesses of the first silicon oxide layer 331 and the second silicon oxide layer 333 is greater than 0.3 μm and the thickness of the silicon layer 332 is 1.1 μm to 1.55 μm. Furthermore, if the total thickness of the first silicon oxide layer 331 and the second silicon oxide layer 333 is greater than 1.0 μm, it is difficult to obtain a displacement amount sufficient to eject liquid, so it is preferable that the total thickness of the first silicon oxide layer 331 and the second silicon oxide layer 333 be 1.0 μm or less.

[0080] The evaluation of voltage variation shown in Figures 8 to 13 was performed when the width 31Y of the pressure chamber 31 was 70 μm, and it was assumed that the resolution of the multiple nozzles 21 was 300 dpi. If the resolution of the multiple nozzles 21 was greater than 1200 dpi, the width 31Y of the pressure chamber 31 would be smaller, making it difficult to obtain a displacement amount sufficient for the vibration plate 33 to eject liquid. Therefore, it is preferable that the resolution of the multiple nozzles 21 be 1200 dpi or less. Furthermore, if the resolution of the multiple nozzles 21 is less than 150 dpi, the resolution is low and it is difficult to obtain good image quality. Therefore, it is preferable that the resolution of the multiple nozzles 21 be 150 dpi or more.

[0081] Furthermore, in the liquid ejection head 1, in a vibration plate 33 in which the difference between the portion where the silicon layer 332 is at its maximum thickness and the portion where the silicon layer 332 is at its minimum thickness is 0.01 μm or more, the thickness of the silicon layer 332 becomes non-uniform for the plurality of pressure chambers 31, which increases the possibility of variations in ejection of the liquid ejected from the plurality of nozzles 21 or variations in the ejection voltage. For this reason, it is more preferable that the thickness of the silicon layer 332 be 1.1 μm to 1.9 μm.

[0082] The thickness of the piezoelectric element 34 according to this embodiment is 1.2 μm. The thickness of the vibration plate 33 according to this embodiment is 1.65 μm. That is, in the liquid ejection head 1 according to this embodiment, the thickness of the piezoelectric element 34 is thinner than the thickness of the vibration plate 33. This reduces the possibility that the displacement amount of the vibration plate 33 will decrease due to the thickness of the piezoelectric element 34 being thick.

[0083] The configuration of the pressure chamber 31 and the periphery of the pressure chamber 31 according to this embodiment will be described in detail with reference to Fig. 15. Fig. 15 is an enlarged view of region IV shown in Fig. 6.

[0084] The first silicon oxide layer 331 has a central portion 3311 and end portions 3312 on both sides of the central portion 3311 in a portion corresponding to the pressure chamber 31. In the first silicon oxide layer 331, the central portion 3311 is subject to a larger amount of displacement than the end portions 3312, so there is a high possibility that deterioration of the central portion 3311 will occur. For this reason, the first silicon oxide layer 331 according to this embodiment is configured so that the thickness of the central portion 3311 is greater than the thickness of the end portions 3312. As a result, in the liquid ejection head 1 according to this embodiment, it is possible to increase the rigidity of the central portion 3311, and thereby reduce the possibility of deterioration of the central portion 3311 and, ultimately, the vibration plate 33.

[0085] Furthermore, in cross section, the central portion 3311 has a convex curved surface. Since the central portion 3311 has a convex curved surface, the convex curved surface can relieve stress, further reducing the possibility of deterioration of the diaphragm 33.

[0086] The displacement of the vibration plate 33 pressurizes the liquid in the pressure chamber 31, causing the liquid to be ejected from the nozzle 21 connected to the pressure chamber 31. In cross-sectional view, the pressure chamber 31 according to this embodiment has a pair of first and second ends 311 and 312 in the height direction, i.e., the Z-axis direction. The first end 311 contacts the vibration plate 33, and the second end 312 contacts the nozzle 21. The width W1 of the first end 311 is greater than the width W2 of the second end 312. The larger width W1 of the first end 311 allows for a larger displacement of the vibration plate 33. Furthermore, the smaller width W2 of the second end 312 allows for greater strength of the portion between the pressure chamber 31 and the adjacent pressure chamber 31. Therefore, the liquid ejection head 1 according to this embodiment can efficiently utilize the displacement of the vibration plate 33 to generate pressure waves for ejecting droplets.

[0087] Furthermore, the pressure chamber 31 includes a portion whose width gradually increases toward the first end 311. Therefore, the liquid ejection head 1 according to this embodiment can more efficiently utilize the pressure wave generated by the displacement of the vibration plate 33 to eject droplets, compared to a case in which the width increases stepwise toward the first end 311.

[0088] Furthermore, in cross-sectional view, the nozzle 21 according to this embodiment has a pair of third and fourth ends 211 and 212 in the height direction, i.e., the Z-axis direction. The third end 211 is in contact with the pressure chamber 31, and the fourth end 212 is spaced apart from the pressure chamber 31. The width of the third end 211 is greater than the width of the fourth end 212. Therefore, in the liquid ejection head 1, pressure is easily transmitted to the nozzle 21 due to the displacement of the vibration plate 33. Therefore, the liquid ejection head 1 according to this embodiment can efficiently utilize the displacement of the vibration plate 33 to generate pressure waves for ejecting droplets.

[0089] The configuration of the pressure chamber 31 and the periphery of the pressure chamber 31 according to this embodiment will be described in detail with reference to Fig. 16. Fig. 16 is an enlarged view of region V shown in Fig. 7.

[0090] As described above, the second silicon oxide layer 333 can reduce current leakage from the plurality of piezoelectric elements 34 to the silicon layer 332. The liquid ejection head 1 according to this embodiment includes a portion 3331 of the second silicon oxide layer 333 located below the common electrode 341, the thickness of which is greater than the thickness of a portion 3332 of the second silicon oxide layer 333 that is not located below the common electrode 341. Therefore, the liquid ejection head 1 according to this embodiment can reduce current leakage from the plurality of piezoelectric elements 34 to the silicon layer 332. In other words, the liquid ejection head 1 according to this embodiment can further reduce electrical crosstalk.

[0091] The thickness of a portion 3331 of the second silicon oxide layer 333 located below the common electrode 341 is preferably 1.05 times or more the thickness of a portion 3332 of the second silicon oxide layer 333 not located below the common electrode 341 .

[0092] Since the amount of displacement is large in the diaphragm 33 located above the pressure chamber 31, there is a high possibility of deterioration of the diaphragm 33. In this embodiment, the portion 3331 located below the common electrode 341 of the second silicon oxide layer 333 is located on the silicon layer 332 so as to cover the pressure chamber 31 in plan view. Therefore, since the thickness of the portion 3331 located below the common electrode 341 of the second silicon oxide layer 333 is large, the rigidity of the diaphragm 33 above the pressure chamber 31 can be increased, and therefore the possibility of deterioration of the diaphragm 33 can be reduced.

[0093] An example of the configuration of the head module 100 according to this embodiment will be described with reference to Fig. 17. Fig. 17 is a block diagram showing an example of the configuration of the head module 100.

[0094] The head module 100 includes five liquid ejection heads 1A, 1B, 1C, 1D, and 1E, and a storage unit 50. The storage unit 50 of each liquid ejection head 1A, 1B, 1C, 1D, and 1E stores the value of a voltage commonly applied to the plurality of piezoelectric elements 34. The voltage value is common to the plurality of piezoelectric elements 34 in each of the liquid ejection heads 1A, 1B, 1C, 1D, and 1E. Therefore, a common voltage value is applied to the plurality of piezoelectric elements 34 of each liquid ejection head 1A, 1B, 1C, 1D, and 1E based on data sent from the control unit 109. Furthermore, the storage unit 50 according to this embodiment stores the value of a voltage commonly applied to the plurality of piezoelectric elements 34 and a pulse width, and is capable of sending a common pulse-shaped voltage waveform to the plurality of piezoelectric elements 34 of each liquid ejection head 1A, 1B, 1C, 1D, and 1E.

[0095] Although one storage unit 50 according to the present embodiment is provided for the head module 100, multiple storage units 50 may be provided. Also, one storage unit 50 may be provided for each of the five liquid ejection heads 1A, 1B, 1C, 1D, and 1E. The storage unit 50 is provided in an IC such as a driver IC, for example.

[0096] The storage unit 50 may store one voltage value or multiple voltage values ​​for each of the liquid ejection heads 1A, 1B, 1C, 1D, and 1E. If the storage unit 50 stores multiple voltage values ​​for each of the liquid ejection heads 1A, 1B, 1C, 1D, and 1E, it is possible to adjust the ejection amount of the ejected liquid, for example. If the storage unit 50 stores multiple voltage values ​​for each of the liquid ejection heads 1A, 1B, 1C, 1D, and 1E, it is sufficient that at least one voltage value is common to the multiple piezoelectric elements 34 in each of the liquid ejection heads 1A, 1B, 1C, 1D, and 1E.

[0097] In the head module 100, a common voltage value is applied to the plurality of piezoelectric elements 34 of each of the liquid ejection heads 1A, 1B, 1C, 1D, and 1E. For this reason, it is necessary to further reduce the possibility of ejection variations occurring in the liquid ejected from the plurality of nozzles 21 in each of the liquid ejection heads 1A, 1B, 1C, 1D, and 1E. For this reason, it is more preferable that the thickness of the silicon layer 332 of each of the liquid ejection heads 1A, 1B, 1C, 1D, and 1E in the head module 100 be 1.1 μm to 1.9 μm.

[0098] Furthermore, the voltage values ​​stored in the storage unit 50 are different among the multiple liquid ejection heads 1A, 1B, 1C, 1D, and 1E. In the head module 100 according to this embodiment, the voltage values ​​stored in the storage unit 50 are adjusted so that the ejection speed of the liquid ejected from each of the liquid ejection heads 1A, 1B, 1C, 1D, and 1E is the same. Furthermore, in the head module 100, the voltage values ​​stored in the storage unit 50 may be adjusted so that the print density is the same among the liquid ejection heads 1A, 1B, 1C, 1D, and 1E. Therefore, it is necessary to further reduce the possibility of voltage variations occurring among the liquid ejection heads 1A, 1B, 1C, 1D, and 1E. Therefore, in the head module 100, it is more preferable that the thickness of the silicon layer 332 in each of the liquid ejection heads 1A, 1B, 1C, 1D, and 1E be 1.1 μm to 1.9 μm.

[0099] Furthermore, the average thickness of the silicon layer 332 differs by 0.01 μm or more among the multiple liquid ejection heads 1A, 1B, 1C, 1D, and 1E. In such a head module 100, since the thickness of the silicon layer 332 is non-uniform among the liquid ejection heads 1A, 1B, 1C, 1D, and 1E, it is necessary to reduce the possibility of variations in the ejection of the liquid ejected from the multiple nozzles 21 or variations in the ejection voltage. Therefore, it is more preferable that the thickness of the silicon layer 332 of each of the liquid ejection heads 1A, 1B, 1C, 1D, and 1E in the head module 100 be 1.1 μm to 1.9 μm.

[0100] Finally, a method for manufacturing the liquid ejection head 1 will be described.

[0101] First, the nozzle member 2, actuator member 3, support member 4, and liquid supply member 5 are prepared. Then, the support member 4 is bonded onto the actuator member 3, and the nozzle member 2 is bonded below the actuator member 3. Then, the liquid supply member 5 is bonded to the support member 4. The order of bonding is not limited. Note that examples of methods for bonding the nozzle member 2 and the actuator member 3, and the actuator member 3 and the support member 4 include room temperature bonding and metal bonding. Also, examples of methods for bonding the support member 4 and the liquid supply member 5 include a method using an adhesive.

[0102] A method for manufacturing the actuator member 3 will now be described.

[0103] The actuator member 3 can be manufactured by depositing and etching a film on an SOI wafer. An SOI wafer is a substrate formed of a silicon layer, a silicon oxide layer located on the silicon layer, and a silicon layer located on the silicon oxide layer. Here, the silicon layer located on the lower side of the SOI wafer corresponds to the silicon substrate 30. The silicon oxide layer of the SOI wafer corresponds to the first silicon oxide layer 331 of the diaphragm 33. The silicon layer located on the upper side of the SOI wafer corresponds to the silicon layer 332 of the diaphragm 33.

[0104] The diaphragm 33 is formed by depositing a silicon oxide layer corresponding to the second silicon oxide layer 333 of the diaphragm 33 on the surface of a silicon layer located on the upper side of the SOI wafer by, for example, plasma CVD or thermal oxidation. The diaphragm 33 according to this embodiment is formed so that the first silicon oxide layer 331 has a thickness of 0.1 μm, the silicon layer 332 has a thickness of 1.45 μm, and the second silicon oxide layer 333 has a thickness of 0.1 μm.

[0105] The common electrode 341 is formed on the diaphragm 33 by, for example, forming a film of Pt by sputtering and then removing unnecessary portions by etching.

[0106] The piezoelectric body 342 is, for example, Pb(Zr,Ti)O ３is formed on the common electrode 341 by forming a film by sputtering and then removing unnecessary portions by etching.

[0107] The individual electrodes 343 are formed on the piezoelectric bodies 342 by, for example, forming a Pt film by sputtering and then removing unnecessary portions by etching.

[0108] The pressure chamber 31 and the first aperture 32 are formed, for example, by etching the silicon layer located under the SOI wafer, with the silicon oxide layer of the SOI wafer serving as an etching stop layer.

[0109] In this manner, the actuator member 3 is manufactured.

[0110] 1, 1A, 1B, 1C, 1D, 1E Liquid ejection head 21 Nozzle 31 Pressure chamber 311 First end 312 Second end 33 Vibration plate 331 First silicon oxide layer 332 Silicon layer 333 Second silicon oxide layer 34 Piezoelectric element 341 Common electrode 10 Printer (recording device) 50 Storage section 100 Head module 109 Control section

Claims

1. A liquid ejection head comprising: a plurality of pressure chambers; a plurality of nozzles connected to each of the plurality of pressure chambers; a vibration plate located above the plurality of pressure chambers; and a plurality of piezoelectric elements located on the vibration plate corresponding to the plurality of pressure chambers, wherein the vibration plate has a first silicon oxide layer, a silicon layer located on the first silicon oxide layer, and a second silicon oxide layer located on the silicon layer, and the silicon layer has a thickness of 1.1 μm to 1.9 μm.

2. The liquid ejection head according to claim 1, wherein the sum of the thicknesses of said first silicon oxide layer and said second silicon oxide layer is 0.3 μm or less, and the thickness of said silicon layer is 1.3 μm to 1.8 μm.

3. The liquid ejection head according to claim 1, wherein the sum of the thicknesses of said first silicon oxide layer and said second silicon oxide layer is greater than 0.3 μm, and the thickness of said silicon layer is 1.1 μm to 1.55 μm.

4. The liquid ejection head according to claim 1, wherein the resolution of the plurality of nozzles is 150 dpi to 1200 dpi.

5. The liquid ejection head according to claim 1, wherein the difference in thickness between the maximum thickness portion and the minimum thickness portion of the silicon layer is 0.01 μm or more.

6. The liquid ejection head according to claim 1, wherein the thickness of said piezoelectric element is thinner than the thickness of said vibration plate.

7. The liquid ejection head according to claim 1, wherein the first silicon oxide layer has a thickness greater at the center than at the end in a portion corresponding to the pressure chamber.

8. A liquid ejection head as described in claim 1, wherein, when viewed in cross section, the pressure chamber has a pair of first and second ends in the height direction, the first end is in contact with the vibration plate, the second end is in contact with the nozzle, and the width of the first end is greater than the width of the second end.

9. A liquid ejection head as described in claim 1, wherein the plurality of piezoelectric elements include a common electrode on the vibration plate that is common to the plurality of piezoelectric elements, and the first silicon oxide layer includes a portion located under the common electrode whose thickness is greater than the thickness of a portion not located under the common electrode.

10. A head module comprising: the liquid ejection head according to claim 1; and a storage section in which the value of a voltage commonly applied to the plurality of piezoelectric elements in the liquid ejection head is stored.

11. The head module according to claim 10, comprising a plurality of the liquid ejection heads, and the voltage value is different between the plurality of the liquid ejection heads.

12. The head module according to claim 11, wherein the average thickness of the silicon layer differs by 0.01 μm or more among the plurality of liquid ejection heads.

13. A recording device comprising: a liquid ejection head according to any one of claims 1 to 9; a moving unit that moves the liquid ejection head and a recording medium relatively; and a control unit that controls the moving unit.

14. A recording device comprising: a head module according to any one of claims 10 to 12; a moving section that moves the head module and a recording medium relatively; and a control section that controls the moving section.

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