Liquid ejecting head and liquid ejecting apparatus

Abstract

A liquid ejecting head and a liquid ejecting apparatus in which the occurrence of cracks in a vibration plate is suppressed while the displacement amount of the vibration plate is increased. The liquid ejecting head is configured such that a piezoelectric actuator (300) has an active portion (310) in which a piezoelectric layer (70) is sandwiched by a first electrode (60) and a second electrode (80) in a first region (P1) of a vibration plate (50) corresponding to both end portions of a pressure chamber (12) in a first direction in which the pressure chamber (12) is arranged side by side, and does not have the active portion (310) in a second region (P2) of the vibration plate (50) corresponding to a central portion of the pressure chamber (12), and the vibration plate (50) has a thick wall portion (55) having a predetermined thickness in the first region (P1) and a thin wall portion (56) having a thickness thinner than the thick wall portion (55) in the second region (P2) in the first direction.

Description

Technical Field

[0001] This invention relates to a liquid ejector head and a liquid ejection device that ejects liquid from a nozzle, and more particularly to an inkjet recording head and an inkjet recording device that ejects ink as a liquid. Background Technology

[0002] As an inkjet recording head for ejecting ink, a recording head in which a piezoelectric actuator is disposed on a flow channel forming substrate having a pressure chamber and separated by a diaphragm is known. Furthermore, as a piezoelectric actuator, a piezoelectric actuator formed by laminating a first electrode, a piezoelectric layer, and a second electrode from the diaphragm side is known. Additionally, as another type of piezoelectric actuator, there exists one in which an active portion of the piezoelectric layer, sandwiched between the first and second electrodes, is provided at both ends of the pressure chambers in a side-by-side arrangement direction, and no active portion is provided in the center of the pressure chamber (see, for example, Patent Document 1).

[0003] By configuring the piezoelectric actuator in this way, it is possible to increase the displacement of the vibrating plate driven by the piezoelectric actuator. However, if the displacement of the vibrating plate is insufficient, there is a possibility that problems such as difficulty in ejecting large ink droplets may occur. Furthermore, although the thickness of the vibrating plate has been reduced to increase the displacement, there is a possibility that this may make the vibrating plate more susceptible to cracking.

[0004] Furthermore, this problem exists not only in inkjet recorders but also in liquid ejection heads that eject liquids other than ink.

[0005] Patent Document 1: Japanese Patent Application Publication No. 2010-208204 Summary of the Invention

[0006] One aspect of the present invention that solves the above-mentioned problems is a liquid injection head, comprising: a flow channel forming substrate on which a plurality of pressure chambers communicating with nozzles are arranged side by side; a vibrating plate formed on one side of the flow channel forming substrate; and a piezoelectric actuator comprising a first electrode, a piezoelectric layer, and a second electrode laminated on the side of the vibrating plate opposite to the pressure chambers. The liquid injection head is characterized in that, in a first direction which is the side-by-side arrangement direction of the pressure chambers, the piezoelectric actuator has an active portion of the piezoelectric layer sandwiched between the first electrode and the second electrode in a first region of the vibrating plate corresponding to both ends of the pressure chambers, and does not have the active portion in a second region of the vibrating plate corresponding to the center of the pressure chambers. In the first direction, the vibrating plate has a thick-walled portion of a predetermined thickness in the first region and a thin-walled portion of a thickness thinner than the thick-walled portion in the second region.

[0007] Furthermore, another aspect of the liquid injection device of the present invention is characterized by having a liquid injection head as described above. Attached Figure Description

[0008] Figure 1 This is a plan view of the recording head according to Embodiment 1 of the present invention.

[0009] Figure 2 This is a cross-sectional view of the recording head according to Embodiment 1 of the present invention.

[0010] Figure 3 This is a plan view showing the main parts of the recording head according to Embodiment 1 of the present invention.

[0011] Figure 4 This is a cross-sectional view showing the main parts of the recording head according to Embodiment 1 of the present invention.

[0012] Figure 5 This is a cross-sectional view showing the main parts of the recording head according to Embodiment 1 of the present invention.

[0013] Figure 6 This is a cross-sectional view showing a modified example of the recording head according to Embodiment 1 of the present invention.

[0014] Figure 7 This is a cross-sectional view showing the main parts of the recording head according to Embodiment 2 of the present invention.

[0015] Figure 8 This is a cross-sectional view showing the main parts of the recording head according to Embodiment 3 of the present invention.

[0016] Figure 9 This is a cross-sectional view showing the main part of the recording head according to Embodiment 4 of the present invention.

[0017] Figure 10 This diagram illustrates a schematic structure of a recording device according to one embodiment of the present invention. Detailed Implementation

[0018] The present invention will now be described in detail based on embodiments. However, the following description is about one aspect of the invention, and the structure of the invention can be modified arbitrarily within the scope of the invention. In the accompanying drawings, the same reference numerals are used for the same parts, and repeated descriptions are omitted.

[0019] Furthermore, in each of the accompanying figures, X, Y, and Z represent three spatial axes that are orthogonal to each other. In this specification, the directions along these axes will be designated as the X direction, Y direction, and Z direction. The direction in which the arrows in each figure point will be designated as the positive (+) direction, and the opposite direction of the arrows will be designated as the negative (-) direction. Additionally, the Z direction represents the vertical direction, with +Z representing vertically downward and -Z representing vertically upward. Furthermore, the three spatial axes X, Y, and Z, whose positive and negative directions are not defined, will be referred to as the X-axis, Y-axis, and Z-axis.

[0020] Implementation Method 1

[0021] Figure 1 This is a plan view of an inkjet recording head (hereinafter also simply referred to as "recording head") as an example of a liquid jetting head according to Embodiment 1 of the present invention, viewed from the nozzle face side. Figure 2 for Figure 1 A sectional view along line AA′. Figure 3 This is an enlarged plan view of the main part of the piezoelectric actuator mounted on the recording head. Figure 4 for Figure 3 BB' line section view, Figure 5 for Figure 3 A cross-sectional view along the CC' line.

[0022] As shown in the figure, the recording head 1 includes a flow channel unit 100, a vibrating plate 50, and a piezoelectric actuator 300. In this embodiment, the flow channel unit 100 includes a flow channel forming substrate 10, a common liquid chamber substrate 30, a nozzle plate 20, and a plastic substrate 40.

[0023] The flow channel forming substrate 10 is composed of a silicon substrate, a glass substrate, an SOI substrate, and various ceramic substrates.

[0024] On the flow channel forming substrate 10, a plurality of pressure chambers 12, divided by partitions 11, are arranged side-by-side along the X-axis direction. That is, on the flow channel forming substrate 10, a plurality of pressure chambers 12 are arranged side-by-side along their short side direction and are separated by partitions 11. The plurality of pressure chambers 12 are arranged in a straight line along the X-axis direction such that their positions in the Y-axis direction are the same. Of course, the arrangement of the pressure chambers 12 is not particularly limited; for example, it can be configured as a so-called staggered arrangement, that is, the pressure chambers 12 arranged side-by-side in the X-axis direction are arranged at positions staggered in the Y-axis direction every other one.

[0025] The shape of each pressure chamber 12, viewed from the Z-axis direction, is based on a rectangle with the axial direction as the long side, and the two ends in the Y-axis direction are set as semi-circles. That is, the opening shape of each pressure chamber 12, viewed from the Z-axis direction, is a so-called rounded rectangle shape (also called a racetrack shape). In other words, each pressure chamber 12 is formed into a long strip shape with the Y-axis direction as the long side and the X-axis direction as the short side when viewed from the Z-axis direction. In this way, by setting the pressure chamber 12 into a long strip shape, it is possible to arrange multiple pressure chambers 12 close to each other side by side while ensuring the volume of each pressure chamber 12.

[0026] Of course, the shape of the pressure chamber 12 as viewed from the Z-axis is not particularly limited, and can also be, for example, a square shape, a rectangle shape, a polygon shape, a parallelogram shape, a sector shape, a circle shape, or an elongated hole shape. In addition, the elongated hole shape includes not only the rounded rectangular shape mentioned above, but also elliptical shapes, oval shapes, oblong shapes, etc.

[0027] A common liquid chamber substrate 30 is bonded to the +Z direction side of the flow channel forming substrate 10 using an adhesive. The common liquid chamber substrate 30 is a substrate having common liquid chambers 35 communicating with each pressure chamber 12. The common liquid chambers 35 are continuously arranged in the X-axis direction, spanning areas corresponding to the plurality of pressure chambers 12 arranged side-by-side. Furthermore, the common liquid chambers 35 are positioned to overlap with the ends of the pressure chambers 12 in the +Y direction direction in the Z-axis direction. These common liquid chambers 35 are provided with openings in the +Z direction side of the common liquid chamber substrate 30.

[0028] Furthermore, a first flow channel 31 is formed on the common liquid chamber substrate 30, communicating with the vicinity of the end of the pressure chamber 12 in the +Y direction direction. The first flow channel 31 is provided independently for each pressure chamber 12. The first flow channel 31 communicates the common liquid chamber 35 and the pressure chamber 12 in the Z-axis direction, and supplies the ink in the common liquid chamber 35 to the pressure chamber 12.

[0029] Furthermore, a second flow channel 32 is formed on the common liquid chamber substrate 30, communicating with the vicinity of the end of the pressure chamber 12 in the -Y direction direction. The second flow channel 32 is provided independently for each pressure chamber 12. This second flow channel 32 is a flow channel that communicates the pressure chamber 12 and the nozzle 21 and supplies ink in the pressure chamber 12 to the nozzle 21, and is configured to penetrate the common liquid chamber substrate 30 in the Z-axis direction.

[0030] As the material for such a common liquid chamber substrate 30, silicon substrates, glass substrates, SOI substrates, various ceramic substrates, stainless steel substrates, and other metal substrates can be used. Furthermore, it is preferable to use a material with a thermal expansion coefficient approximately the same as that of the flow channel forming substrate 10 as the material for the common liquid chamber substrate 30. This can suppress warping caused by heat due to the difference in thermal expansion coefficients between the flow channel forming substrate 10 and the common liquid chamber substrate 30.

[0031] The nozzle plate 20 is attached to the side of the common liquid chamber substrate 30 opposite to the flow channel forming substrate 10, i.e., the +Z direction side.

[0032] On the nozzle plate 20, a plurality of nozzles 21 are formed that eject ink in the +Z direction. In this embodiment, as... Figure 1 As shown, multiple nozzles 21 are arranged in a straight line along the X-axis. That is, multiple nozzles 21 are arranged such that their positions in the Y-axis direction are the same. Of course, the arrangement of the nozzles 21 is not particularly limited, and can be, for example, arranged in a so-called staggered configuration, that is, the nozzles 21 arranged side by side in the X-axis direction are arranged at staggered positions in the Y-axis direction every other one.

[0033] As the material for such a nozzle plate 20, silicon substrates, glass substrates, SOI substrates, various ceramic substrates, stainless steel substrates, and other metal substrates, as well as organic materials such as polyimide resins, can be used. Furthermore, it is preferable to use a material with a thermal expansion coefficient approximately the same as that of the connecting plate 15 as the nozzle plate 20. This helps to suppress warping caused by heat due to the difference in thermal expansion coefficients between the nozzle plate 20 and the connecting plate 15.

[0034] The malleable substrate 40 is joined together with the nozzle plate 20 to the side of the common liquid chamber substrate 30 opposite to the flow channel forming substrate 10. The malleable substrate 40 is joined to the opening of the common liquid chamber 35 of the common liquid chamber substrate 30, thus sealing the opening on the +Z direction side of the common liquid chamber 35. In this embodiment, the malleable substrate 40 includes a sealing film 41 made of a flexible thin film and a fixing substrate 42 made of a rigid material such as metal. The area of ​​the fixing substrate 42 opposite to the common liquid chamber 35 becomes an opening 43 completely removed in the thickness direction. Therefore, one side of the common liquid chamber 35 becomes a malleable portion 49, which is a flexible portion, sealed only by the flexible sealing film 41. Thus, by providing the malleable portion 49 on a portion of the surface of the common liquid chamber 35, pressure fluctuations of the ink within the common liquid chamber 35 can be absorbed by deformation of the malleable portion 49.

[0035] Thus, in the flow channel unit 100, an ink flow channel is formed from the common liquid chamber 35 through the first flow channel 31, the pressure chamber 12, and the second flow channel 32 to the nozzle 21. Furthermore, although not shown in the figure, the common liquid chamber 35 is configured to be supplied with ink from an external ink supply unit.

[0036] When ink is supplied from the ink supply unit to the common liquid chamber 35, the ink in the common liquid chamber 35 is appropriately supplied to each pressure chamber 12 via each first flow channel 31. Furthermore, the ink in the pressure chamber 12 is ejected from the nozzle 21 via the second flow channel 32 through the piezoelectric actuator 300 described later.

[0037] The piezoelectric actuator 300 is disposed on the side of the flow channel forming substrate 10 opposite to the nozzle plate 20, etc., with the vibrating plate 50 in between.

[0038] The vibrating plate 50 is constructed by laminating multiple films in their thickness direction. Specifically, the vibrating plate 50 according to this embodiment has two film layers: a first vibrating plate 51 and a second vibrating plate 52. These first vibrating plates 51 and second vibrating plates 52 are laminated sequentially toward the -Z direction.

[0039] The first vibrating plate 51 is a silicon oxide film and is disposed on the -Z direction side surface of the flow channel forming substrate 10. The second vibrating plate 52 is a zirconium oxide film and is disposed on the -Z direction side surface of the first vibrating plate 51. In addition, the pressure chamber 12 is disposed through the flow channel forming substrate 10, and the -Z direction side surface of the pressure chamber 12 is formed by the first vibrating plate 51 of the vibrating plate 50.

[0040] The details will be described below. The vibrating plate 50 has a thick wall portion 55 of predetermined thickness in the region corresponding to the end of the pressure chamber 12, and a thin wall portion 56 of thinner thickness than the thick wall portion 55 in the region corresponding to the center of the pressure chamber 12.

[0041] Furthermore, the structure of the vibrating plate 50 is not particularly limited. The vibrating plate 50 may be composed of either the first vibrating plate 51 or the second vibrating plate 52, or it may include other films besides the first vibrating plate 51 and the second vibrating plate 52. Examples of other film materials include silicon, silicon nitride, etc.

[0042] The piezoelectric actuator 300 is disposed on the surface of the second vibrating plate 52 side of the vibrating plate 50, that is, on the side opposite to the pressure chamber 12. The piezoelectric actuator 300 is composed of a first electrode 60, a piezoelectric layer 70 and a second electrode 80 laminated by film deposition and photolithography.

[0043] When a voltage is applied between the first electrode 60 and the second electrode 80 in the piezoelectric actuator 300, the portion of the piezoelectric layer 70 that undergoes piezoelectric deformation is called the active portion 310. That is, the portion of the piezoelectric layer 70 in the piezoelectric actuator 300 that is sandwiched between the first electrode 60 and the second electrode 80 is the active portion 310. This active portion 310 is provided independently for each pressure chamber 12.

[0044] Generally, the active part 310 is configured such that one electrode is an independent individual electrode for each active part 310, and the other electrode is a common electrode shared by multiple active parts 310. In this embodiment, the first electrode 60 constitutes the common electrode, and the second electrode 80 constitutes an individual electrode.

[0045] Here, the region in the vibrating plate 50 that undergoes flexural deformation when the piezoelectric actuator 300 is driven, that is, the region opposite to the pressure chamber 12, is called the flexible region P. Furthermore, the annular region in the flexible region P corresponding to the end (edge) of the pressure chamber 12 when viewed along the +Z direction is called the first region P1. Furthermore, the region in the flexible region P corresponding to the center of the pressure chamber 12, that is, the region further inward than the first region P1, is called the second region P2.

[0046] Furthermore, in this embodiment, the active portion 310 of the piezoelectric actuator 300 is not disposed in the second region P2 of the vibrating plate 50 when viewed in a plane along the Z-axis direction, but is disposed in the first region P1. That is, the active portion 310 of the piezoelectric actuator 300 is disposed in a ring shape along the end of each pressure chamber 12.

[0047] The result is, such as Figure 4 As shown, in the first direction which is the side-by-side arrangement direction of the pressure chambers 12, in this embodiment, in the X-axis direction, the active part 310 of the piezoelectric actuator 300 is provided in the first region P1 of the vibrating plate 50 corresponding to both ends of the pressure chamber 12, but is not provided in the second region P2 of the vibrating plate 50 corresponding to the center of the pressure chamber 12.

[0048] In addition, such as Figure 5 As shown, in the second direction intersecting the X-axis direction which is the first direction, in this embodiment, the active part 310 of the piezoelectric actuator 300 is provided in the Y-axis direction which is the long side direction of the pressure chamber 12, which is the first region P1 corresponding to both ends of the pressure chamber 12, but is not provided in the second region P2 corresponding to the center of the pressure chamber 12.

[0049] In addition, the active part 310 of the piezoelectric actuator 300 is extended to the outside of the first region P1, i.e. the outside of the pressure chamber 12, in either the X-axis direction or the Y-axis direction.

[0050] Furthermore, the first electrode 60, constituting the common electrode of the piezoelectric actuator 300, is continuously arranged across the regions corresponding to the plurality of pressure chambers 12. The first electrode 60 is arranged so that its length in the Y-axis direction is longer than the length of the pressure chamber 12 in the Y-axis direction, and it is continuously arranged across the regions corresponding to the plurality of pressure chambers 12 arranged side by side in the X-axis direction. In addition, the first electrode 60 is made of a conductive material such as gold, silver, copper, palladium, platinum, or titanium.

[0051] The piezoelectric layer 70 is continuously disposed across the X-axis in such a way that its length in the Y-axis direction is a predetermined length. The length of the piezoelectric layer 70 in the Y-axis direction is longer than the length of the pressure chamber 12 in the Y-axis direction, and in this embodiment, it is longer than the length of the first electrode 60 in the Y-axis direction. Therefore, in the Y-axis direction of the pressure chamber 12, the piezoelectric layer 70 is extended to the outside of the first electrode 60, and the end of the first electrode 60 is covered by the piezoelectric layer 70.

[0052] Furthermore, the thickness of the portion of the piezoelectric layer 70 opposite to the thin-walled portion 56 of the vibrating plate 50 is thinner than the thickness of the other portions. In this embodiment, an opening 70a is provided in the piezoelectric layer 70 at the portion corresponding to the second region P2 of the vibrating plate 50. That is, the piezoelectric layer 70 is not provided at the portion corresponding to the second region P2 of the vibrating plate 50.

[0053] In addition, although in this embodiment the piezoelectric layer 70 is continuously provided across the regions corresponding to the plurality of pressure chambers 12, it may also be provided that each pressure chamber 12 is separated on the partition wall 11 of the adjacent pressure chambers 12.

[0054] Such a piezoelectric layer 70 is composed of a piezoelectric material having a polarization structure of an oxide formed on the first electrode 60, for example, a perovskite-type oxide represented by the general formula ABO3. Furthermore, lead-based piezoelectric materials containing lead or lead-free piezoelectric materials can be used as the material for the piezoelectric layer 70.

[0055] Furthermore, the second electrode 80, which constitutes the independent electrode of the piezoelectric actuator 300, is separated for each pressure chamber 12. When viewed in a plane along the Z-axis direction, the second electrode 80 is formed in a ring shape along the end of each pressure chamber 12. That is, the outer periphery of the second electrode 80 is the same as that of the pressure chamber 12, forming a rounded rectangle with the Y-axis direction as the long side, and the second electrode 80 is configured to have an opening 80a at its center that is approximately similar in shape to the outer periphery, which communicates with the opening 70a of the piezoelectric layer 70.

[0056] Furthermore, the shape of the second electrode 80 defines the range of the active portion 310 in the piezoelectric actuator 300. That is, by forming the second electrode 80 in a ring shape along the ends of each pressure chamber 12, the active portion 310 of the piezoelectric actuator 300 is arranged in a ring shape along the ends of each pressure chamber 12. Additionally, the material of the second electrode 80 is not particularly limited, and conductive materials such as gold, silver, copper, palladium, platinum, and titanium can be used.

[0057] In addition, although the illustration is omitted, such a piezoelectric actuator is provided with a protective film made of insulating material, and a common lead electrode connected to the first electrode and individual lead electrodes connected to each of the second electrodes are provided on the protective film.

[0058] In the recording head 1 equipped with such a piezoelectric actuator 300, when a voltage is applied to the first electrode 60 and the second electrode 80 of the piezoelectric actuator 300, the active part 310 flexes and deforms. Along with the flexing and deformation of the active part 310, the vibrating plate 50 flexes and deforms, thereby applying pressure to the ink in the pressure chamber 12, and then the ink is ejected from the nozzle 21.

[0059] Furthermore, as described above, the vibrating plate 50 has a thick-walled portion 55 of predetermined thickness in the region corresponding to the end of the pressure chamber 12, and a thin-walled portion 56 of thinner thickness than the thick-walled portion 55 in the region corresponding to the center of the pressure chamber 12. That is, in a planar view along the Z-axis, the thick-walled portion 55 of predetermined thickness along the end of the pressure chamber 12 is provided in a ring shape in the first region P1 of the vibrating plate 50. In addition, a thin-walled portion 56 of thinner thickness than the thick-walled portion 55 is provided in the second region P2 of the vibrating plate 50. In other words, in the second region P2 of the vibrating plate 50, a recess 57 formed by removing a portion of the thickness direction of the vibrating plate 50 is formed into a generally oblong shape, and the portion of the vibrating plate 50 corresponding to this recess 57 becomes the thin-walled portion 56.

[0060] In this embodiment, the vibrating plate 50 has a first vibrating plate 51 made of silicon oxide film and a second vibrating plate 52 made of zirconium oxide film. The first vibrating plate 51, which is disposed on the side of the pressure chamber 12, has a recess 57 formed by removing a portion of its thickness, thereby forming a thin-walled portion 56 on the vibrating plate 50. Furthermore, the second vibrating plate 52 is formed with a substantially uniform thickness on the surface of the first vibrating plate 51 where the recess 57 is formed.

[0061] Therefore, as Figure 4 As shown, the vibrating plate 50 has a thick-walled portion 55 of predetermined thickness in the first region P1 along the X-axis direction, and a thin-walled portion 56 of thinner thickness compared to the thick-walled portion 55 in the second region P2. Additionally, as... Figure 5 As shown, the vibrating plate 50 also has a thick-walled portion 55 with a predetermined thickness in the first region P1 in the Y-axis direction, and a thin-walled portion 56 with a thinner thickness than the thick-walled portion 55 in the second region P2.

[0062] Thus, by having a thick-walled portion 55 in the first region P1 and a thin-walled portion 56 in the second region P2, the displacement of the vibrating plate 50 can be increased while suppressing the occurrence of cracks relative to the vibrating plate 50 when the piezoelectric actuator 300 is driven.

[0063] Specifically, by providing a thick-walled portion 55 of predetermined thickness in the first region P1 of the vibrating plate 50, the occurrence of cracks near the end of the pressure chamber 12 can be suppressed. In the recording head 1 according to the present invention, the piezoelectric actuator 300 has an annular active portion 310 along the end of the pressure chamber 12. Therefore, when the piezoelectric actuator 300 is driven, the vibrating plate 50 deforms relatively significantly near the end of the pressure chamber 12. In particular, the vibrating plate 50 deforms significantly near the end in the X-axis direction, which is the parallel arrangement direction of the pressure chambers 12. Therefore, cracks are easily generated on the vibrating plate 50 near the end of the pressure chamber 12. However, by providing a thick-walled portion 55 of predetermined thickness in the first region P1 of the vibrating plate 50, the rigidity of the first region P1 of the vibrating plate 50 is improved, thereby suppressing the occurrence of cracks on the vibrating plate 50 near the end of the pressure chamber 12. Furthermore, since the resonant frequency is increased due to the hardening of the first region P1 of the vibrating plate 50, the driving speed of the piezoelectric actuator 300 can also be increased.

[0064] On the other hand, by providing a thin-walled portion 56, which is thinner than the thick-walled portion 55, in the second region P2 of the vibrating plate 50, the displacement of the vibrating plate 50 achieved by the piezoelectric actuator 300 can be increased. In the recording head 1 according to the present invention, the active portion 310 of the piezoelectric actuator 300 is not provided in the center of the pressure chamber 12. Therefore, when the piezoelectric actuator 300 is driven, cracks are unlikely to occur in the second region P2 of the vibrating plate 50, but the deformation is relatively small. However, by providing the thin-walled portion 56 in the second region P2 of the vibrating plate 50, when the piezoelectric actuator 300 is driven, the deformation of the second region P2 of the vibrating plate 50 can be increased, and consequently, the overall deformation of the flexible region P of the vibrating plate 50 can be increased.

[0065] Furthermore, the Young's modulus of the vibrating plate 50 is less than that of the piezoelectric layer 70. Additionally, the Young's modulus of the vibrating plate 50 mentioned here refers to the average value, which is a weighted average proportional to the thickness of each layer constituting the vibrating plate 50. Thus, by providing the thin-walled portion 56 on the vibrating plate 50, which is made of a relatively hard material, the displacement of the vibrating plate 50 when driven by the piezoelectric actuator 300 can be increased more effectively.

[0066] Here, the preferred positions of the neutral axis are different for the first region P1 of the vibrating plate 50 of the piezoelectric actuator 300, where the active part 310 is provided, and the second region P2 of the vibrating plate 50, where the active part 310 is not provided. When the thickness of the vibrating plate 50 is approximately fixed across the flexible region P, it is difficult to set the neutral axis in a suitable position in the first region P1 and the second region P2 respectively.

[0067] However, by providing a thick-walled portion 55 and a thin-walled portion 56, the neutral axis can be set in a suitable position in the first region P1 and the second region P2 of the vibrating plate 50, respectively. That is, by adjusting the thickness of the thick-walled portion 55 and the thin-walled portion 56, the neutral axis can be set in a suitable position in the first region P1 and the second region P2 of the vibrating plate 50, respectively. This allows for a more effective increase in the displacement of the vibrating plate 50 when the piezoelectric actuator 300 is driven.

[0068] Based on the above, the diaphragm 50 has a thick-walled portion 55 in the first region P1 and a thin-walled portion 56 in the second region P2. Therefore, when the piezoelectric actuator 300 is driven, the displacement of the diaphragm 50 can be increased while suppressing the occurrence of cracks in the diaphragm 50. Thus, while suppressing breakage of the recording head 1, the jetting performance can be improved, thereby enhancing the durability and reliability of the recording head 1.

[0069] Although in this embodiment, the thick-walled portion 55 of the vibrating plate 50 only needs to be provided on at least a portion of the first region P1, it is preferable to provide it over as large a range as possible within the first region P1. In this embodiment, the thick-walled portion 55 is provided continuously across the entire first region P1. That is, the thick-walled portion 55 is provided continuously across the first region P1 in either the X-axis direction or the Y-axis direction. As a result, the rigidity of the vibrating plate 50 in the first region P1 can be adequately improved.

[0070] Furthermore, in this embodiment, the active portion 310 of the piezoelectric actuator 300 extends to the partition wall 11 that separates the pressure chamber 12 in either the X-axis or Y-axis direction. Also, the thick-walled portion 55 of the vibrating plate 50 is continuously provided from the first region P1 to the region on the partition wall 11 where the active portion 310 is provided in either the X-axis or Y-axis direction. That is, the active portion 310 of the piezoelectric actuator 300 is only provided in the portion corresponding to the thick-walled portion 55 of the vibrating plate 50.

[0071] Therefore, in the active part 310 of the piezoelectric actuator 300, the distance between the first electrode 60 and the second electrode 80 is approximately equal throughout the entire part, and the electric field strength is also approximately equal throughout the entire part. Therefore, it is possible to suppress the occurrence of burn-out in the active part 310.

[0072] On the other hand, although the thin-walled portion 56 only needs to be provided in at least a portion of the second region P2, it is preferable to provide it over as large an area as possible within the second region P2. Furthermore, while the thin-walled portion 56 may be continuously provided to the outer side of the second region P2, i.e., the first region P1, it is preferable to provide it only on the inner side of the second region P2. In this embodiment, the thin-walled portion 56 is formed on the inner side of the second region P2 at the same size as the second region P2. That is, the second region P2 of the vibrating plate 50 is substantially entirely comprised of the thin-walled portion 56. By forming the thin-walled portion 56 to such a size, it is possible to effectively increase the displacement of the vibrating plate 50 while suppressing cracks in the vibrating plate 50.

[0073] The thicknesses of the thick-walled portions 55 and the thin-walled portions 56 are not particularly limited; for example, they can be appropriately determined by considering factors such as the displacement characteristics of the piezoelectric actuator 300, the rigidity of the vibrating plate 50, and the amount of deformation. However, the thickness of the thin-walled portion 56 is preferably about half that of the thick-walled portion 55 or thinner than that. This makes it easier to increase the displacement of the vibrating plate 50.

[0074] Furthermore, although the vibrating plate 50 of this embodiment is composed of a first vibrating plate 51 and a second vibrating plate 52, the structure of the vibrating plate 50 is not particularly limited. For example, the vibrating plate 50 can be composed of a single layer or three or more layers. In order to suppress the occurrence of cracks, it is preferable to be composed of two or more layers.

[0075] Furthermore, although in this embodiment, a thin-walled portion 56 is formed on the vibrating plate 50 by providing a recess 57 on the first vibrating plate 51, which removes a portion of its thickness direction, it is also possible, for example, like... Figure 6 As shown, the first vibrating plate 51 is provided with a substantially uniform thickness across the entire surface, and a recess 57 is provided on the second vibrating plate 52, which is a zirconia film, by removing a portion of its thickness direction, thereby forming a thin-walled portion 56 of the vibrating plate 50.

[0076] Even with this structure, the vibration plate 50 can be increased in displacement while suppressing the occurrence of cracks in the vibration plate 50 when the piezoelectric actuator 300 is driven. Furthermore, by providing a recess 57 on the second vibration plate 52, which contains zirconium oxide and has a relatively large Young's modulus, it becomes easier to further increase the displacement of the vibration plate 50 when the piezoelectric actuator 300 is driven.

[0077] Furthermore, in this embodiment, an opening 70a is formed in the portion of the piezoelectric layer 70 corresponding to the second region P2, thereby further increasing the displacement of the vibrating plate 50 when the piezoelectric actuator 300 is driven. Additionally, the portion of the piezoelectric layer 70 corresponding to the second region P2 does not need to be completely removed, as long as it is thinner than the other portions. Of course, the opening 70a in the piezoelectric layer 70 is not necessarily required. That is, the piezoelectric layer 70 may also be configured to cover the portion corresponding to the flexible region P.

[0078] Implementation Method 2

[0079] Figure 7 This is a cross-sectional view showing the main parts of the recording head according to Embodiment 2. Furthermore, the same symbols are used for the same parts as in Embodiment 1, and repeated descriptions are omitted.

[0080] like Figure 7As shown, in the recording head 1A of this embodiment, the vibrating plate 50A includes a first vibrating plate 51, a second vibrating plate 52, and a third vibrating plate 53 disposed on the -Z direction side of the second vibrating plate 52. Furthermore, a recess 57A is provided on the third vibrating plate 53, and a thin-walled portion 56A is formed on the vibrating plate 50A. The recess 57A is provided so that it penetrates the third vibrating plate 53 in the thickness direction. Therefore, the thick-walled portion 55A disposed in the first region P1 of the vibrating plate 50A is composed of the first vibrating plate 51, the second vibrating plate 52, and the third vibrating plate 53, and the thin-walled portion 56A is composed of the first vibrating plate 51 and the second vibrating plate 52. As the material of the third vibrating plate 53, silicon nitride (SiN) is preferably used, for example. However, the material of the third vibrating plate 53 is not particularly limited, and it can also be, for example, an adhesive.

[0081] Even with such a structure for the vibrating plate 50A, similar to Embodiment 1, it is possible to increase the displacement of the vibrating plate 50A while suppressing the occurrence of cracks in the vibrating plate 50A when the piezoelectric actuator 300 is driven.

[0082] Furthermore, the vibratory plate 50A is composed of multiple films laminated in the thickness direction, namely, a first vibratory plate 51, a second vibratory plate 52, and a third vibratory plate 53 in this embodiment. Any one of these films, namely the third vibratory plate 53 in this embodiment, is removed across its thickness direction to form a thin-walled portion 56A. That is, the recess 57A is formed by removing the third vibratory plate 53 across its thickness direction. Therefore, it is relatively easy to form a vibratory plate 50A having both a thick-walled portion 55A and a thin-walled portion 56A, thereby improving mass production feasibility.

[0083] Furthermore, although in this embodiment the recess 57A is formed by removing the third vibrating plate 53 across its thickness direction, it can also be formed by removing other films. For example, the recess 57A can be formed by removing the second vibrating plate 52 across its thickness direction. Alternatively, the recess 57A can be formed, for example, by removing both the third vibrating plate 53 and the second vibrating plate 52 across their thickness directions.

[0084] Implementation Method 3

[0085] Figure 8 This is a cross-sectional view showing the main parts of the recording head according to Embodiment 3. Furthermore, the same symbols are used for the same parts as in Embodiment 1, and repeated descriptions are omitted.

[0086] like Figure 8As shown, in the recording head 1B according to this embodiment, the diaphragm 50B is composed of a first diaphragm 51 and a second diaphragm 52, similar to that in Embodiment 1. Furthermore, the thin-walled portion 56B is formed by removing a portion of the thickness direction of the first diaphragm 51 from the pressure chamber 12 side. That is, a recess 57B is provided on the first diaphragm 51 by removing a portion of its thickness direction from the pressure chamber 12 side, thereby forming a thick-walled portion 55B together with the thin-walled portion 56B.

[0087] Even with such a structure for the vibrating plate 50B, similar to Embodiment 1, it is possible to increase the displacement of the vibrating plate 50B while suppressing the occurrence of cracks in the vibrating plate 50B when the piezoelectric actuator 300 is driven.

[0088] Furthermore, since the thin-walled portion 56B is formed by removing a portion of the thickness direction of the first vibrating plate 51 from the pressure chamber 12 side, that is, the recess 57B is formed on the surface of the first vibrating plate 51 on the pressure chamber 12 side, the surface of the vibrating plate 50B on the piezoelectric actuator 300 side is not formed with unevenness and becomes flat. Therefore, the manufacturing of the piezoelectric actuator 300 becomes easier, thereby improving mass production capability.

[0089] However, the surface of the piezoelectric actuator 300 side of the vibrating plate 50B does not necessarily have to be flat. It can also be configured, for example, in the same manner as in Embodiment 1, to provide a recess 57 on the surface of the first electrode 60 side of the first vibrating plate 51, and to provide a recess 57B on the surface of the pressure chamber 12 side of the first vibrating plate 51.

[0090] Furthermore, the method for forming the recess 57B on the first vibrating plate 51 is not particularly limited, and any existing technology can be used. For example, when the pressure chamber 12 is formed on the flow channel forming substrate 10 by anisotropic etching or the like, after the flow channel forming substrate 10 is removed and the surface of the first vibrating plate 51 is exposed, the recess 57B can be formed by etching the first vibrating plate 51 with hydrogen fluoride (HF) or the like.

[0091] At this time, by setting the so-called correction pattern into a predetermined shape on the surface of the flow channel forming substrate 10, a mask pattern can be used to form a pressure chamber 12 on the flow channel forming substrate 10 and a recess 57B is also formed on the first vibrating plate 51.

[0092] Implementation Method 4

[0093] Figure 9 This is a cross-sectional view showing the main parts of the recording head according to Embodiment 4. Furthermore, the same symbols are used for the same parts as in Embodiment 1, and repeated descriptions are omitted.

[0094] like Figure 9 As shown, in the recording head 1C of this embodiment, the flexible region P of the vibrating plate 50C opposite the pressure chamber 12 is composed of a first vibrating plate 51, a second vibrating plate 52, and a third vibrating plate 53A disposed on the +Z direction side of the first vibrating plate 51, i.e., the pressure chamber 12 side. The third vibrating plate 53A is disposed on the surface of the first vibrating plate 51 within the pressure chamber 12. Furthermore, by providing a recess 57C on the third vibrating plate 53A, a thin-walled portion 56C and a thick-walled portion 55C are formed on the vibrating plate 50C. The recess 57C is provided to penetrate the third vibrating plate 53A in the thickness direction.

[0095] Therefore, in the structure of this embodiment, the thick-walled portion 55C provided in the first region P1 of the vibrating plate 50C is composed of a first vibrating plate 51, a second vibrating plate 52, and a third vibrating plate 53A. On the other hand, the thin-walled portion 56C provided in the second region P2 is composed of a first vibrating plate 51 and a second vibrating plate 52.

[0096] The material of the third vibrating plate 53A is not particularly limited. In this embodiment, an adhesive for bonding the common liquid chamber substrate 30 to the flow channel forming substrate 10 can be used as the material of the third vibrating plate 53A. Furthermore, the method of forming the third vibrating plate 53A is not particularly limited. For example, when joining the common liquid chamber substrate 30 and the flow channel forming substrate 10, the amount of adhesive applied for bonding the two is increased. As a result, when the common liquid chamber substrate 30 and the flow channel forming substrate 10 come into contact with each other by the adhesive, the excess adhesive flows along the corner formed in the sidewall of the pressure chamber 12 to the first vibrating plate 51, thereby forming the third vibrating plate 53A made of adhesive near the corner formed by the flow channel forming substrate 10 and the first vibrating plate 51, that is, in the first region P1 of the vibrating plate 50C.

[0097] That is, the third vibrating plate 53A is not formed in the second region P2 of the vibrating plate 50C; the third vibrating plate 53A is only formed in the first region P1 of the vibrating plate 50C. In other words, the third vibrating plate 53A is only formed in the first region P1 of the vibrating plate 50C, and a recess 57C penetrating the third vibrating plate 53A in the thickness direction is formed in the second region P2 of the vibrating plate 50C, so that the portion of the vibrating plate 50C corresponding to the recess 57C becomes a thin-walled portion 56C. In addition, as described above, the thickness of the third vibrating plate 53A formed by the adhesive flowing to the corner of the pressure chamber 12 in the Z-axis direction is the thickest at the end of the pressure chamber 12 and becomes thinner towards the center of the pressure chamber 12. Of course, the thickness of the third vibrating plate 53A can also be approximately fixed throughout the entire structure.

[0098] Even with such a structure for the vibrating plate 50C, similar to Embodiment 1, it is possible to increase the displacement of the vibrating plate 50C while suppressing the occurrence of cracks in the vibrating plate 50C when the piezoelectric actuator 300 is driven.

[0099] Furthermore, in this embodiment, since the third diaphragm 53A is formed by an adhesive, the impact on displacement caused by the provision of the thick-walled portion 55C and the thin-walled portion 56C on the diaphragm 50C can be minimized. Therefore, the diaphragm 50C can be displaced more reliably, and the reliability of the recording head 1 can be further improved.

[0100] Other implementation methods

[0101] While various embodiments of the present invention have been described above, the basic structure of the present invention is not limited to the structure described above.

[0102] For example, although in the above embodiment the vibratory plate is provided with a thick-walled portion in the first region and a thin-walled portion in the second region in both the X-axis and Y-axis directions, the structure of the vibratory plate in the Y-axis direction is not limited to this structure. That is, the vibratory plate only needs to have both thick-walled and thin-walled portions in the X-axis direction, and it is also possible to omit both thick-walled and thin-walled portions in the Y-axis direction. Even with such a structure, the effect of increasing the displacement of the vibratory plate while suppressing the occurrence of cracks in the vibratory plate can be achieved.

[0103] Furthermore, although in the above embodiments the first electrode is configured as a common electrode shared by multiple active parts, and the second electrode is configured as a separate electrode for each active part, it is also possible to configure the first electrode as a separate electrode and the second electrode as a common electrode. Even in such a case, by having both thick-walled and thin-walled portions in the vibrating plate, the same effects as in the above embodiments can be achieved.

[0104] Furthermore, the recording head 1 of these various embodiments is mounted on an inkjet recording device, which is an example of a liquid jetting device. Figure 10 This is a schematic diagram illustrating an example of an inkjet recording device as an example of a liquid jetting device according to one embodiment.

[0105] exist Figure 10 In the inkjet recording device I shown, the recording head 1 is detachably equipped with a cartridge 2 constituting an ink supply unit and is mounted on a carriage 3. The carriage 3, on which the recording head 1 is mounted, is configured to move freely in the axial direction of a carriage shaft 5 mounted on the device body 4.

[0106] Furthermore, the driving force of the drive motor 6 is transmitted to the carriage 3 via multiple gears (not shown) and a timing belt 7, thereby causing the carriage 3, which carries the recording head 1, to move along the carriage shaft 5. On the other hand, a conveyor roller 8, which serves as a conveying unit, is provided in the main body 4 of the device, and the recording sheet S, which is a recording medium such as paper, is conveyed by the conveyor roller 8. In addition, the conveying unit for conveying the recording sheet S is not limited to the conveyor roller, and may also be a belt or a roller, etc.

[0107] In such an inkjet recording device I, printing is performed by conveying the recording sheet S in the +X direction relative to the recording head 1, and by moving the carriage 3 back and forth in the Y direction relative to the recording sheet S, while ink droplets are ejected from the recording head 1, thereby spraying ink droplets across approximately the entire surface of the recording sheet S.

[0108] Furthermore, although the inkjet recording device I described above exemplifies a structure in which the recording head 1 is mounted on the carriage 3 and moves back and forth in the Y direction, which is the main scanning direction, it is not particularly limited to this. For example, the present invention can also be applied to a so-called line recording device in which the recording head 1 is fixed and printing is performed by moving only the recording sheet S, such as paper, in the X direction, which is the secondary scanning direction.

[0109] Furthermore, although the above embodiments have described an inkjet recording head as an example of a liquid ejection head and an inkjet recording device as an example of a liquid ejection apparatus, the present invention is applicable to a wide range of liquid ejection heads and liquid ejection apparatuses in general, and can of course also be applied to liquid ejection heads or liquid ejection apparatuses that eject liquids other than ink. Other examples of liquid ejection heads include, for example, various recording heads used in image recording devices such as printers, color material ejection heads used in the production of color filters for liquid crystal displays, electrode material ejection heads used in electrode formation for organic EL displays, FED (field emission displays), etc., and biological organic matter ejection heads used in biochip manufacturing, etc., and the present invention can also be applied to liquid ejection apparatuses equipped with such liquid ejection heads.

[0110] Symbol Explanation

[0111] 1…Inkjet recording device (liquid jet device); 1…Inkjet recording head (liquid jet head); 2…Case; 3…Carriage; 4…Main body; 5…Carriage shaft; 6…Drive motor; 7…Synchronous belt; 8…Conveyor roller; 10…Channel forming substrate; 11…Block; 12…Pressure chamber; 15…Connecting plate; 20…Nozzle plate; 21…Nozzle; 30…Common liquid chamber substrate; 31…First flow channel; 32…Second flow channel; 35…Common liquid chamber; 40…Plastic substrate; 41…Sealing film; 42… Fixed substrate; 43… opening; 49… malleable part; 50… vibrating plate; 51… first vibrating plate; 52… second vibrating plate; 53… third vibrating plate; 55… thick-walled part; 56… thin-walled part; 57… recess; 60… first electrode; 70… piezoelectric layer; 70a… opening; 80… second electrode; 80a… opening; 100… flow channel unit; 300… piezoelectric actuator; 310… active part; S… recording film; P… flexible region; P1… first region; P2… second region.

Claims

1. A liquid injection head, characterized in that, have: A flow channel forming substrate has multiple pressure chambers arranged side by side on it, which are in communication with nozzles; A vibrating plate is formed on one side of the flow channel forming substrate; A piezoelectric actuator comprising a first electrode, a piezoelectric layer, and a second electrode laminated on the side of the vibrating plate opposite to the pressure chamber. In a first direction, which is the side-by-side arrangement direction of the pressure chambers, the piezoelectric actuator has an active portion of the piezoelectric layer sandwiched between the first electrode and the second electrode in a first region of the vibrating plate corresponding to both ends of the pressure chambers, and no such active portion in a second region of the vibrating plate corresponding to the center of the pressure chambers. The vibrating plate has a thick-walled portion of predetermined thickness in the first region along the first direction, and a thin-walled portion of thinner thickness compared to the thick-walled portion in the second region. The active part is extended onto the partition wall that divides the pressure chamber. The piezoelectric layer has an opening in the second region that is not covered by the second electrode.

2. The liquid injection head as described in claim 1, characterized in that, The thin-walled portion is only located on the inner side of the second region.

3. The liquid injection head as described in claim 1 or 2, characterized in that, The thick-walled portion is provided continuously across the entire first region in the first direction.

4. The liquid injection head as described in claim 1, characterized in that, The thick-walled portion is continuously provided from the region opposite the pressure chamber to the region on the partition wall where the active portion is provided.

5. The liquid injection head as described in claim 1, characterized in that, The vibrating plate has a zirconium oxide film containing zirconium oxide. In the thin-walled portion, at least the thickness of the zirconium oxide film is thinner than the thickness of the thick-walled portion.

6. The liquid injection head as described in claim 1, characterized in that, The Young's modulus of the vibrating plate is less than that of the piezoelectric layer.

7. The liquid injection head as claimed in claim 1, characterized in that, The thickness of the portion of the piezoelectric layer opposite the thin-walled portion of the vibrating plate is thinner than the thickness of the other portions.

8. The liquid injection head as described in claim 1, characterized in that, The piezoelectric actuator has the active part in the first region and does not have the active part in the second region, in a second direction intersecting the parallel arrangement direction of the pressure chamber. The vibrating plate has the thick-walled portion in the first region and the thin-walled portion in the second region in the second direction.

9. The liquid injection head as claimed in claim 1, characterized in that, The vibrating plate is formed by laminating multiple membranes in the thickness direction. The thin-walled portion is formed by removing any one of the multiple membranes across its thickness direction.

10. The liquid injection head as claimed in claim 1, characterized in that, The thin-walled portion is formed by removing a portion of the pressure chamber side of the vibrating plate.

11. A liquid injection device, characterized in that, It has a liquid injection head as described in any one of claims 1 to 10.

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