JP2022057159A - Liquid jet head and liquid jet device - Google Patents

Abstract

To provide a liquid jet head that can reduce occurrence of cracks or the like of a vibration plate, and a liquid jet device.SOLUTION: A liquid jet head comprises: a nozzle plate having a nozzle that jets liquid; a pressure chamber substrate having a wall surface forming a pressure chamber communicating with the nozzle; a vibration plate arranged at an opposite side of the nozzle plate with respect to the pressure chamber substrate; a piezoelectric element having a first electrode, a piezoelectric body layer and a second electrode in this order when viewed from the vibration plate; and a protective film arranged on the vibration plate and on a portion of the wall surface. A portion corresponding to 90% of a thickness of the vibration plate is a first amorphous layer having a first layer and a second layer laminated with each other, or a laminated layer having a second amorphous layer and a metal layer laminated with each other, or a laminated layer having a third amorphous layer and a carbon layer including any of diamond-like carbon, graphene and carbon nanotube laminated with each other.SELECTED DRAWING: Figure 5

Description

The present invention relates to a liquid injection head and a liquid injection device.

Conventionally, there has been proposed a technique of injecting a liquid such as ink filled in the pressure chamber from a nozzle by vibrating the diaphragm constituting the wall surface of the pressure chamber with a piezoelectric element. For example, Patent Document 1 discloses a liquid injection head including a diaphragm. The diaphragm includes an elastic membrane made of silicon dioxide and an insulator membrane made of zirconium oxide.

Japanese Unexamined Patent Publication No. 2014-837797

Zirconium oxide has a crystal structure. Therefore, when stress is applied to the insulator film, microcracks may occur at the grain boundaries of zirconium oxide. Then, the microcracks became large, and there was a possibility that cracks would occur in the diaphragm. As a result, the ejection performance may deteriorate.

In order to solve the above problems, the liquid injection head according to a preferred embodiment of the present invention includes a nozzle plate having a nozzle for injecting liquid and a pressure chamber substrate having a wall surface forming a pressure chamber communicating with the nozzle. A vibrating plate arranged opposite to the nozzle plate with respect to the pressure chamber substrate, a piezoelectric element having a first electrode, a piezoelectric layer, and a second electrode in this order from the vibrating plate, and on the vibrating plate and above. It has a protective film arranged on a part of the wall surface, and 90% of the thickness of the diaphragm is a first amorphous layer in which a first layer and a second layer are laminated, or a first. It is a laminate in which the amorphous layer 2 and the metal layer are laminated, or a laminate in which the third amorphous layer and a carbon layer containing any one of diamond-like carbon, graphene and carbon nanotubes are laminated.

The liquid injection device according to a preferred embodiment of the present invention is equipped with the above-mentioned injection head.

It is a schematic diagram which illustrates the structure of the liquid injection apparatus which concerns on 1st Embodiment. It is an exploded perspective view of a liquid injection head. It is sectional drawing of the liquid injection head. It is a top view of the piezoelectric element and its vicinity. FIG. 3 is a cross-sectional view taken along the line bb in FIG. It is a figure for demonstrating the crack in the conventional diaphragm. It is sectional drawing which shows a part of the diaphragm in 2nd Embodiment. It is sectional drawing which shows a part of the diaphragm in 3rd Embodiment. It is sectional drawing which shows a part of the diaphragm in 4th Embodiment. It is sectional drawing which shows a part of the diaphragm in 5th Embodiment. It is sectional drawing which shows the piezoelectric element of the modification.

1. 1. First Embodiment 1-1. Overall Configuration of Liquid Injection Device 100 FIG. 1 is a configuration diagram illustrating the liquid injection device 100 according to the first embodiment. In the following, for convenience of explanation, the X-axis, Y-axis, and Z-axis that are orthogonal to each other will be appropriately used. Further, in the present specification, the expression "element B is arranged on the upper part of element A" is not limited to the configuration in which element A and element B are in direct contact with each other. A configuration in which the element A and the element B are not in direct contact is also included in the concept of "the element B is arranged on the element A".

The liquid injection device 100 of the first embodiment is an inkjet printing device that injects ink, which is an example of a liquid, onto a medium 12. The medium 12 is typically printing paper, but a printing target of any material such as a resin film or a cloth is used as the medium 12. As shown in FIG. 1, a liquid container 14 for storing ink is installed in the liquid injection device 100. For example, a cartridge that can be attached to and detached from the liquid injection device 100, a bag-shaped ink pack made of a flexible film, or an ink tank that can be refilled with ink is used as the liquid container 14.

As shown in FIG. 1, the liquid injection device 100 includes a control unit 20, a transfer mechanism 22, a moving mechanism 24, and a liquid injection head 26. The control unit 20 includes one or a plurality of processing circuits such as a CPU (Central Processing Unit) or an FPGA (Field Programmable Gate Array) and one or a plurality of storage circuits such as a semiconductor memory, and each element of the liquid injection device 100. Is controlled comprehensively. The transport mechanism 22 transports the medium 12 along the Y axis under the control of the control unit 20.

The moving mechanism 24 reciprocates the liquid injection head 26 along the X axis under the control of the control unit 20. The moving mechanism 24 of the first embodiment includes a substantially box-shaped transport body 242 that accommodates the liquid injection head 26, and a transport belt 244 to which the transport body 242 is fixed. It should be noted that a configuration in which a plurality of liquid injection heads 26 are mounted on the transport body 242 or a configuration in which the liquid container 14 is mounted on the transport body 242 together with the liquid injection head 26 may be adopted.

The liquid injection head 26 ejects the ink supplied from the liquid container 14 from a plurality of nozzles onto the medium 12 under the control of the control unit 20. An image is formed on the surface of the medium 12 by each liquid injection head 26 injecting ink onto the medium 12 in parallel with the transfer of the medium 12 by the transfer mechanism 22 and the repetitive reciprocation of the transfer body 242.

1-2. Overall Configuration of Liquid Injection Head 26 FIG. 2 is an exploded perspective view of the liquid injection head 26. FIG. 3 is a cross-sectional view taken along the line aa in FIG. The cross section shown in FIG. 3 is a cross section parallel to the XX plane. The Z-axis is an axis along the ink injection direction of the liquid injection head 26. Further, one direction along the X axis is referred to as the X1 direction, and the direction opposite to the X1 direction is referred to as the X2 direction. Similarly, one direction along the Y axis is referred to as the Y1 direction, and the direction opposite to the Y1 direction is referred to as the Y2 direction. One direction along the Z axis is referred to as the Z1 direction, and the direction opposite to the Z1 direction is referred to as the Z2 direction. Further, in the following, viewing in the Z1 direction or the Z2 direction is referred to as "planar view".

As shown in FIG. 2, the liquid injection head 26 includes a plurality of nozzles N arranged along the Y axis. The plurality of nozzles N of the first embodiment are divided into a first row La and a second row Lb arranged side by side at intervals along the X axis. Each of the first row La and the second row Lb is a set of a plurality of nozzles N linearly arranged along the Y axis. The liquid injection head 26 shown in FIG. 3 has a structure in which elements related to each nozzle N in the first row La and elements related to each nozzle N in the second row Lb are arranged substantially plane-symmetrically. Therefore, in the following description, the elements corresponding to the first column La will be mainly described, and the description of the elements corresponding to the second column Lb will be omitted as appropriate.

As shown in FIGS. 2 and 3, the liquid injection head 26 includes a flow path structure 30, a plurality of piezoelectric elements 34, a sealing body 35, a housing portion 36, and a wiring board 51. The flow path structure 30 is a structure in which a flow path for supplying ink to each of the plurality of nozzles N is formed inside. The flow path structure 30 is composed of a flow path substrate 31, a pressure chamber substrate 32, a diaphragm 33, a nozzle plate 41, and a vibration absorbing body 42. Each member constituting the flow path structure 30 is a long plate-shaped member along the Y axis. The pressure chamber substrate 32 and the housing portion 36 are installed in the Z2 direction with respect to the flow path substrate 31. On the other hand, the nozzle plate 41 and the vibration absorbing body 42 are installed in the Z1 direction with respect to the flow path substrate 31. Each member is fixed, for example, with an adhesive.

The nozzle plate 41 is a plate-shaped member having a plurality of nozzles N for ejecting ink. Each of the plurality of nozzles N is generally a circular through hole for ejecting ink, but ink can be ejected even if the through hole is not circular. For example, the nozzle plate 41 is manufactured by processing a silicon (Si) single crystal substrate using semiconductor manufacturing techniques such as photolithography and etching. However, a known material or manufacturing method may be arbitrarily adopted for manufacturing the nozzle plate 41.

The flow path substrate 31 is formed with a space Ra, a plurality of supply flow paths 312, a plurality of communication flow paths 314, and a relay liquid chamber 316. Space Ra is an opening formed in a long shape along the Y axis. Each of the supply flow path 312 and the communication flow path 314 is a through hole formed for each nozzle N. The relay liquid chamber 316 is a space formed in a long shape along the Y axis over a plurality of nozzles N, and allows the space Ra and the plurality of supply flow paths 312 to communicate with each other. Each of the plurality of communication flow paths 314 overlaps one nozzle N corresponding to the communication flow path 314 in a plan view.

A plurality of pressure chambers C1 which are spaces in which ink is arranged are formed on the pressure chamber substrate 32. The plurality of pressure chambers C1 are arranged one-to-one with respect to the plurality of nozzles N. The pressure chamber substrate 32 has a wall surface 320 that forms a pressure chamber C1 corresponding to each nozzle N. The pressure chamber C1 is a long space along the X axis in a plan view. The plurality of pressure chambers C1 are arranged along the Y axis. The flow path substrate 31 and the pressure chamber substrate 32 are manufactured by processing a single crystal substrate of silicon by using, for example, a semiconductor manufacturing technique, similarly to the nozzle plate 41 described above. However, known materials and manufacturing methods can be arbitrarily adopted for manufacturing the flow path substrate 31 and the pressure chamber substrate 32. Further, although not shown in FIG. 3, a protective film 43 is arranged on the wall surface 320 of the pressure chamber substrate 32. The protective film 43 will be described in detail later with reference to FIG.

The diaphragm 33 is arranged opposite to the nozzle plate 41 with respect to the pressure chamber substrate 32. The diaphragm 33 is laminated on the pressure chamber substrate 32 and comes into contact with the surface of the pressure chamber substrate 32 opposite to the flow path substrate 31. The diaphragm 33 is a plate-shaped member formed in a long rectangular shape along the Y axis in a plan view. The diaphragm 33 is elastically deformable. The thickness direction of the diaphragm 33 is parallel to the direction along the Z axis. As shown in FIG. 3, the pressure chamber C1 is a space located between the flow path substrate 31 and the diaphragm 33. As shown in FIGS. 2 and 3, the pressure chamber C1 communicates with the communication flow path 314 and the supply flow path 312. Therefore, the pressure chamber C1 communicates with the nozzle N via the communication flow path 314 and communicates with the space Ra via the supply flow path 312 and the relay liquid chamber 316. Although the pressure chamber substrate 32 and the diaphragm 33 are shown as separate substrates in FIG. 2 for ease of explanation, they are actually laminated on one silicon substrate.

A piezoelectric element 34 is formed in each pressure chamber C1 opposite to the pressure chamber C1 in the diaphragm 33. The piezoelectric element 34 is a long passive element along the X axis in a plan view. The piezoelectric element 34 is also a drive element that is driven by applying a drive signal. The piezoelectric element 34 will be described in detail later.

The housing portion 36 is a case for storing ink supplied to a plurality of pressure chambers C1, and is formed, for example, by injection molding of a resin material. A space Rb and a supply port 361 are formed in the housing portion 36. The supply port 361 is a pipeline in which ink is supplied from the liquid container 14, and communicates with the space Rb. The space Rb of the housing portion 36 and the space Ra of the flow path substrate 31 communicate with each other. The space composed of the space Ra and the space Rb functions as a liquid storage chamber R for storing ink supplied to the plurality of pressure chambers C1. The ink supplied from the liquid container 14 and passing through the supply port 361 is stored in the liquid storage chamber R. The ink stored in the liquid storage chamber R branches from the relay liquid chamber 316 to each supply flow path 312, and is supplied and filled in parallel to the plurality of pressure chambers C1. The vibration absorber 42 is a flexible film constituting the wall surface of the liquid storage chamber R, and absorbs pressure fluctuations of ink in the liquid storage chamber R.

The sealing body 35 is a structure that protects a plurality of piezoelectric elements 34 and reinforces the mechanical strength of the pressure chamber substrate 32 and the diaphragm 33. The sealing body 35 is fixed to the surface of the diaphragm 33 with, for example, an adhesive. A plurality of piezoelectric elements 34 are housed inside the recess formed on the surface of the sealing body 35 facing the diaphragm 33. Further, a wiring board 51 is joined to the surface of the diaphragm 33. The wiring board 51 is a mounting component on which a plurality of wirings for electrically connecting the control unit 20 and the liquid injection head 26 are formed. For example, a flexible wiring board 51 such as an FPC (Flexible Printed Circuit) or an FFC (Flexible Flat Cable) is preferably adopted. A drive signal and a reference voltage for driving the piezoelectric element 34 are supplied from the wiring board 51 to each piezoelectric element 34.

1-3. Piezoelectric element 34
FIG. 4 is a plan view of the piezoelectric element 34 and its vicinity. FIG. 5 is a cross-sectional view taken along the line bb in FIG. In FIG. 4, dots are added to the second electrode 342 for convenience.

As shown in FIGS. 4 and 5, the piezoelectric element 34 generally has a first electrode 341, a piezoelectric layer 343, and a second electrode 342 in order from the diaphragm 33. The Z-axis corresponds to an axis along the direction in which the first electrode 341, the piezoelectric layer 343, and the second electrode 342 are laminated.

As shown in FIG. 5, the first electrode 341 is arranged in the Z2 direction with respect to the diaphragm 33. The first electrode 341 is an individual electrode formed so as to be separated from each other for each piezoelectric element 34. The first electrode 341 has a long shape along the X axis. The plurality of first electrodes 341 are arranged along the Y axis at intervals from each other. The first electrode 341 is made of a conductive material such as aluminum (Al), platinum (Pt) or iridium (Ir). As shown in FIG. 4, the first wiring 37 is electrically connected to the first electrode 341. The first wiring 37 is a lead wiring to which a drive signal is supplied from a drive circuit (not shown) mounted on the wiring board 51 shown in FIG. 3, and supplies the drive signal to the first electrode 341. The first wiring 37 is made of a conductive material having a lower resistance than that of the first electrode 341. For example, the first wiring 37 is a conductive pattern having a structure in which a gold (Au) conductive film is laminated on the surface of a conductive film made of nichrome (NiCr).

As shown in FIG. 5, the piezoelectric layer 343 is arranged in the Z2 direction with respect to the first electrode 341. As shown in FIG. 4, the piezoelectric layer 343 is a strip-shaped dielectric film continuous along the Y axis over a plurality of piezoelectric elements 34. The piezoelectric layer 343 is formed of a known piezoelectric material such as lead zirconate titanate (Pb (Zr _, Ti) O3). A notch G along the X axis is formed in the region of the piezoelectric layer 343 corresponding to the gap between the pressure chambers C1 adjacent to each other. The notch G is an opening that penetrates the piezoelectric layer 343. By forming the notch G, each piezoelectric element 34 is individually deformed for each pressure chamber C1, and the propagation of vibration between the piezoelectric elements 34 is suppressed. The bottomed hole from which a part of the piezoelectric layer 343 in the thickness direction is removed may be formed as the notch G.

As shown in FIG. 5, the second electrode 342 is arranged in the Z2 direction with respect to the piezoelectric layer 343. As shown in FIGS. 4 and 5, the second electrode 342 is a band-shaped common electrode extending along the Y axis so as to be continuous over the plurality of piezoelectric elements 34. A predetermined reference voltage is applied to the second electrode 342. The reference voltage is a constant voltage, and is set to a voltage higher than, for example, the ground voltage. A voltage corresponding to the difference between the reference voltage applied to the second electrode 342 and the drive signal supplied to the first electrode 341 is applied to the piezoelectric layer 343. A ground voltage may be applied to the second electrode 342. Further, the second electrode 342 is formed of a low resistance conductive material such as aluminum (Al), platinum (Pt) or iridium (Ir).

As shown in FIG. 4, a second wiring 38 electrically connected to the second electrode 342 is arranged in the Z2 direction with respect to the second electrode 342. A reference voltage (not shown) is supplied to the second wiring 38 via the wiring board 51 shown in FIG. As shown in FIG. 4, the second wiring 38 has a band-shaped first conductive layer 381 extending along the Y axis and a band-shaped second conductive layer 382 extending along the Y axis. The first conductive layer 381 and the second conductive layer 382 are arranged at predetermined intervals along the X axis. By providing the first conductive layer 381 and the second conductive layer 382, the voltage drop of the reference voltage in the second electrode 342 is suppressed. Further, the first conductive layer 381 and the second conductive layer 382 also function as weights for suppressing the vibration of the diaphragm 33. The second wiring 38 is made of a conductive material having a lower resistance than the second electrode 342. For example, the second wiring 38 is a conductive pattern having a structure in which a gold (Au) conductive film is laminated on the surface of a conductive film made of nichrome (NiCr).

In such a piezoelectric element 34, the piezoelectric layer 343 is deformed by applying a voltage between the first electrode 341 and the second electrode 342. Due to this deformation, the piezoelectric element 34 bends and deforms the diaphragm 33. Then, the pressure in the pressure chamber C1 changes due to the vibration of the diaphragm 33, and the ink in the pressure chamber C1 is ejected from the nozzle N shown in FIG.

Further, in the present embodiment, the seed layer 44 is arranged between the first electrode 341 and the piezoelectric layer 343. Further, the seed layer 44 has a portion that comes into contact with the diaphragm 33. The seed layer 44 is an orientation control layer for controlling the orientation of the crystal of the piezoelectric layer 343 by including a crystal structure that becomes a seed crystal of the piezoelectric layer 343. By providing the seed layer 44, the orientation characteristics of the piezoelectric layer 343 can be improved. Therefore, the displacement force of the piezoelectric element 34 can be increased. Therefore, the ejection performance of the liquid injection head 26 can be improved.

In the illustrated example, the seed layer 44 is arranged between the first electrode 341 and the piezoelectric layer 343, but may be arranged, for example, between the diaphragm 33 and the first electrode 341. However, by arranging the seed layer 44 between the first electrode 341 and the piezoelectric layer 343, the orientation characteristics of the piezoelectric layer 343 can be most improved.

The material of the seed layer 44 may be any material as long as it has a function as an orientation control layer, but preferably strontium titanate (SrTIO ₃ ), lanthanum nickelate (LaNiO ₃ ), titanium (Ti) or titanium oxide (Titanium oxide). It is one of TiO ₂ ). By using these materials, the orientation characteristics of the piezoelectric layer 343 can be improved as compared with the case where other materials are used.

1-4. Protective film 43
As shown in FIG. 5, the protective film 43 comes into contact with the wall surface 320 of the diaphragm 33 and the pressure chamber substrate 32. In particular, the protective film 43 covers a part of the diaphragm 33 and a part of the wall surface 320 of the pressure chamber substrate 32. The protective film 43 protects the pressure chamber substrate 32 and the diaphragm 33 so that the ink does not come into contact with the pressure chamber substrate 32 and the diaphragm 33.

The protective film 43 is, for example, a resin layer or an inorganic insulating layer having a thickness of 1/10 or less of the thickness of the diaphragm 33. By providing the protective film 43, it is possible to prevent the pressure chamber substrate 32 and the diaphragm 33 from being eroded by the ink in the pressure chamber C1.

The inorganic insulating layer is made of an inorganic material having an insulating property. Examples of the material of the inorganic insulating layer include silicon oxide (SiOx), zirconium oxide (ZrOx), tantalum pentoxide (TaOx), and aluminum oxide (AlOx). When the protective film 43 is an inorganic insulating layer, the thickness of the inorganic insulating layer may exceed 1/10 of the thickness of the diaphragm 33, but is 1/10 or less, so that the diaphragm is It is suppressed that 33 does not perform the desired deformation.

The thickness of the protective film 43 is not particularly limited, but is preferably 1 nm or more and less than 100 nm, for example. The protective film 43 is thinner than each layer of the diaphragm 33.

1-5. Diaphragm 33
As shown in FIG. 5, the diaphragm 33 forms the pressure chamber C1 together with the pressure chamber substrate 32. Further, the diaphragm 33 has a vibration region V corresponding to each of the plurality of pressure chambers C1 in a plan view. The vibration region V is a region of the diaphragm 33 that overlaps the pressure chamber C1 in a plan view, and is a region that vibrates due to the drive of the piezoelectric element 34.

90% or more of the thickness D of the diaphragm 33 is the first amorphous layer 330 in which two or more kinds of layers are laminated. That is, the diaphragm 33 is mainly composed of a first amorphous layer 330 in which two or more kinds of layers are laminated. In the example shown in FIG. 5, the diaphragm 33 is composed of a first amorphous layer 330 in which an amorphous first layer 331 and an amorphous second layer 332 are laminated. The first layer 331 comes into contact with the pressure chamber substrate 32. The second layer 332 is arranged between the first layer 331 and the first electrode 341 and comes into contact with them.

Since 90% or more of the thickness D of the diaphragm 33 is the first amorphous layer 330 in which two or more layers are laminated, there is almost no layer having a crystal structure. Alternatively, there are very few layers having a crystal structure. Therefore, it is possible to suppress the generation of cracks in the diaphragm 33 starting from the microcracks that occur at the crystal grain boundaries of the crystal structure as in the conventional case. Therefore, the diaphragm 33 is unlikely to be damaged. As a result, it is possible to provide a highly reliable liquid injection head 26 in which deterioration of discharge performance is suppressed. Further, since the occurrence of cracks can be suppressed over time, the life of the liquid injection head 26 can be extended.

In addition, less than 10% of the thickness D of the diaphragm 33 may be a layer other than the laminated layer in which the first layer 331 and the second layer 332 are laminated. Less than 10% of the thickness D of the diaphragm 33 is effective in suppressing damage to the diaphragm 33 starting from microcracks, even if it is not an amorphous layer.

FIG. 6 is a diagram for explaining the crack C0 in the conventional diaphragm 33x. The conventional diaphragm 33x shown in FIG. 6 includes, for example, an amorphous SiO ₂ layer 331x and a ZrO ₂ layer 332x having a crystal structure. For example, when stress is applied to the diaphragm 33x by driving the piezoelectric element 34, microcracks MC may occur at the grain boundaries of zirconium oxide. Then, the microcrack MC becomes large, and there is a possibility that crack C0 may occur in the ZrO ₂ layer 332x. Further, the crack C0 may penetrate into the SiO ₂ layer 331x. As a result, there is a possibility that the diaphragm 33 may be damaged in the thickness direction. On the other hand, since the diaphragm 33 of the present embodiment is composed of the first amorphous layer 330, microcracks MC are unlikely to occur. Therefore, the diaphragm 33 is unlikely to be damaged.

Further, as described above, the diaphragm 33 has two types of amorphous layers, a first layer 331 and a second layer 332. Therefore, compared to the case of having only one type of amorphous layer, for example, by adjusting the Young's modulus of the material of each amorphous layer, a diaphragm that is less likely to crack while ensuring the required amount of deformation. It is easy to form 33. For example, as compared with the case where the diaphragm 33 is made of single crystal silicon, it is easy to adjust the thickness, and therefore it is easy to form the diaphragm 33 in which cracks are unlikely to occur while ensuring a required amount of deformation.

The diaphragm 33 may be an amorphous layer composed of three or more types of layers. Therefore, the diaphragm 33 may have a layer containing other materials in addition to the first layer 331 and the second layer 332.

The material of the first layer 331 is silicon oxide (SiO ₂ ). Therefore, the diaphragm 33 has a layer containing silicon oxide. By using silicon oxide, the first layer 331 having a predetermined thickness can be most easily formed by thermal oxidation, sputtering, CVD, or the like. The first layer 331 may be a single layer or may have a plurality of layers.

The material of the second layer 332 is silicon nitride (Si _{3N 4 )} , silicon nitride (SiON), aluminum oxide (Al ₂ O ₃ ), silicon carbide (SiC), tungsten carbide (WC), aluminum nitride (AlN). , Either beryllium oxide (BeO), boron carbide ₍ B4C) or magnesium oxide (MgO), or a combination thereof. These materials are amorphous materials below 900 °. In the manufacture of the liquid injection head 26, processing such as annealing is performed at a temperature of less than 900 ° so that the oxide film grows significantly and the characteristics of the single crystal silicon substrate do not change.

These materials have a higher Young's modulus than silicon oxide. Therefore, by using these materials, the rigidity of the diaphragm 33 is increased, and it is easy to shorten the vibration cycle of the diaphragm 33. Therefore, it is possible to improve the ejection performance in a short cycle. For example, when the diaphragm 33 is composed of only the first layer 331 made of silicon oxide as a material, the Young's modulus is lower than that of the case where the diaphragm 33 is composed of the first layer 331 and the second layer 332. Become. The soft diaphragm 33 with a low Young's modulus does not easily follow the displacement at high frequencies. Therefore, it is difficult to eject high-frequency droplets.

Further, the second layer 332 is formed by, for example, sputtering, CVD or the like. Further, the second layer 332 may be a single layer or may have a plurality of layers. For example, the second layer 332 may be a stack of layers composed of Si ₃ N ₄ , SiON, Al ₂ O ₃ , SiC, WC, Al N, BeO, B ₄ C or MgO.

The Young's modulus of the material of the second layer 332 is not particularly limited, but is preferably larger than the Young's modulus of the first layer 331, specifically preferably 150 GPa or more, and more preferably 200 GPa or more and 960 GPa or less. When the Young's modulus is 150 GPa or more, the diaphragm 33 can easily follow the displacement at a high frequency. Therefore, it is easy to realize the diaphragm 33 in which cracks are unlikely to occur while ensuring the required amount of deformation.

When the material of the second layer 332 is SiON, Young's modulus can be adjusted by adjusting the composition ratio of oxygen and nitrogen. The Young's modulus can be increased by increasing the composition ratio of nitrogen, and the Young's modulus can be decreased by increasing the composition ratio of oxygen. Therefore, when SiON is used, it is easy to form the second layer 332 having a desired Young's modulus by adjusting the composition ratio of oxygen and nitrogen.

Further, the thickness D2 of the second layer 332 is larger than the thickness D1 of the first layer 331. Therefore, it is easier to realize the diaphragm 33 that can easily follow the displacement at a high frequency as compared with the case where the thickness D2 is the thickness D1 or less. Therefore, it is possible to provide the liquid injection head 26 suitable for high frequency driving. The thickness D2 may be less than the thickness D1 or may be equal to the thickness D1.

The thickness D1 of the first layer 331 is not particularly limited, but is, for example, 50 nm or more and 1000 nm or less. The thickness D2 of the second layer 332 is not particularly limited, but is, for example, 100 nm or more and 2000 nm or less.

2. 2. Second Embodiment The second embodiment will be described. In each of the following examples, for the elements having the same functions as those of the first embodiment, the reference numerals used in the description of the first embodiment will be diverted and detailed description of each will be omitted as appropriate.

FIG. 7 is a cross-sectional view showing a part of the diaphragm 33A in the second embodiment, and corresponds to FIG. 5 in the first embodiment. In this embodiment, the diaphragm 33A is used instead of the diaphragm 33 of the first embodiment. In the following, items different from the diaphragm 33 of the first embodiment will be described with respect to the diaphragm 33A, and description of similar items will be omitted as appropriate.

90% or more of the thickness D of the diaphragm 33A is a laminate in which the second amorphous layer 333 and the metal layer 334 are laminated. That is, the diaphragm 33 is mainly composed of a laminate in which a second amorphous layer 333 and a metal layer 334 are laminated. In the example shown in FIG. 7, the diaphragm 33A is composed of a laminate in which a second amorphous layer 333 and a metal layer 334 are laminated. The metal layer 334 comes into contact with the pressure chamber substrate 32. The second amorphous layer 333 is arranged between the metal layer 334 and the first electrode 341 and comes into contact with them.

90% or more of the thickness D of the diaphragm 33A is a laminate in which the second amorphous layer 333 and the metal layer 334 are laminated. That is, the metal layer 334 is used instead of the conventional layer composed of zirconium oxide. Therefore, it is possible to suppress the occurrence of cracks in the diaphragm 33A due to the occurrence of microcracks at the crystal grain boundaries of the layer composed of zirconium oxide as in the conventional case. Therefore, the diaphragm 33A is unlikely to be damaged. As a result, it is possible to provide a highly reliable liquid injection head 26 in which deterioration of discharge performance is suppressed. Further, since the occurrence of cracks can be suppressed over time, the life of the liquid injection head 26 can be extended.

Further, since the metal layer 334 is provided, the toughness of the diaphragm 33A can be increased as compared with the case where the metal layer 334 is not provided. Therefore, it is possible to provide the diaphragm 33A which is not easily damaged.

In addition, less than 10% of the thickness D of the diaphragm 33A may be a layer other than the laminated layer in which the second amorphous layer 333 and the metal layer 334 are laminated. Less than 10% of the thickness D of the diaphragm 33A exhibits the effect of suppressing damage to the diaphragm 33A originating from microcracks, even if it is not the laminated layer.

The material of the metal layer 334 is, for example, titanium (Ti), titanium nitride (TiN), nickel (Ni), lead (Pd), platinum (Pt), iridium (Ir), copper (Au), aluminum (Al), and the like. It is either ruthenium (Ru), aluminum nitride (AlN), titanium aluminum nitride (AlTiN), stainless steel, mild steel, carbon steel, marage steel, high tension steel or aluminum alloy. These materials have higher toughness than, for example, SiO ₂ and Al ₂ O ₃ . Therefore, since the metal layer 334 contains these materials, the toughness of the diaphragm 33A can be enhanced, and the damage of the diaphragm 33 can be suppressed.

The material of the second amorphous layer 333 is Si _{3N 4} , SiON, Al ₂ O ₃ , SiC, WC, AlN, BeO, B ₄ C or MgO, or a combination thereof. These materials have a higher Young's modulus than, for example, silicon oxide. Therefore, by using these materials, it is easy to shorten the vibration cycle. Therefore, it is possible to improve the ejection performance in a short cycle.

The Young's modulus of the material of the second amorphous layer 333 is not particularly limited, but is preferably 150 GPa or more, and more preferably 200 GPa or more and 960 GPa or less. When the Young's modulus is equal to or higher than the above lower limit value, it is easy to follow the displacement at a high frequency. Therefore, it is easy to realize the diaphragm 33A in which cracks are unlikely to occur while ensuring the required amount of deformation.

When the material of the second amorphous layer 333 is SiON, the second amorphous layer 333 having a desired Young's modulus can be formed by adjusting the composition ratio of oxygen and nitrogen.

The thickness D3 of the second amorphous layer 333 is not particularly limited, but is, for example, 50 nm or more and 1000 nm or less. The thickness D4 of the metal layer 334 is not particularly limited, but is, for example, 50 nm or more and 500 nm or less.

3. 3. Third Embodiment The third embodiment will be described. In each of the following examples, for the elements having the same functions as those of the first embodiment, the reference numerals used in the description of the first embodiment will be diverted and detailed description of each will be omitted as appropriate.

FIG. 8 is a cross-sectional view showing a part of the diaphragm 33B in the third embodiment, and corresponds to FIG. 5 in the first embodiment. In this embodiment, the diaphragm 33B is used instead of the diaphragm 33 of the first embodiment. In the following, items different from the diaphragm 33 of the first embodiment will be described with respect to the diaphragm 33B, and description of similar items will be omitted as appropriate.

90% or more of the thickness D of the diaphragm 33B is a laminate in which the second amorphous layer 333B and the metal layer 334 are laminated. That is, the diaphragm 33B is mainly composed of a laminate in which a second amorphous layer 333B and a metal layer 334 are laminated. In the example shown in FIG. 8, the diaphragm 33B is composed of a laminate in which a second amorphous layer 333B and a metal layer 334 are laminated. The metal layer 334 is the same as the metal layer 334 of the second embodiment.

The second amorphous layer 333B has a third layer 3331 and a fourth layer 3332. A metal layer 334 is arranged between the third layer 3331 and the fourth layer 3332. The third layer 3331, the metal layer 334, and the fourth layer 3332 are laminated from the pressure chamber substrate 32 in this order. Further, the fourth layer 3332 comes into contact with the pressure chamber substrate 32. The third layer 3331 is arranged between the metal layer 334 and the first electrode 341 and comes into contact with them.

As described above, since 90% or more of the thickness D of the diaphragm 33B is a laminate in which the second amorphous layer 333B and the metal layer 334 are laminated, the diaphragm 33B is caused by microcracks at the crystal grain boundaries. The occurrence of cracks can be suppressed. Therefore, the diaphragm 33B is unlikely to be damaged. As a result, it is possible to provide a highly reliable liquid injection head 26 in which deterioration of discharge performance is suppressed. Further, since the occurrence of cracks can be suppressed over time, the life of the liquid injection head 26 can be extended.

Further, since the metal layer 334 is provided, the toughness of the diaphragm 33B can be increased as compared with the case where the metal layer 334 is not provided. Therefore, it is possible to provide the diaphragm 33B which is not easily damaged.

In addition, less than 10% of the thickness D of the diaphragm 33B may be a layer other than the laminated layer in which the second amorphous layer 333B and the metal layer 334 are laminated. Less than 10% of the thickness D of the diaphragm 33B exhibits the effect of suppressing damage to the diaphragm 33B originating from microcracks, even if it is not the laminated layer.

Further, as described above, the metal layer 334 is arranged between the third layer 3331 and the fourth layer 3332. Therefore, the oxidation of the metal layer 334 can be suppressed as compared with the case where the metal layer 334 is not sandwiched between the amorphous layers.

The material of the _third layer 3331 is either Si 3N ₄ , SiON, Al ₂ O ₃ , SiC, WC, AlN, BeO, B ₄ C or MgO, or a combination thereof. These materials have a higher Young's modulus than, for example, silicon oxide. Therefore, by using these materials, it is easy to shorten the vibration cycle. Therefore, it is possible to improve the ejection performance in a short cycle.

The Young's modulus of the material of the third layer 3331 is not particularly limited, but is preferably 150 GPa or more, and more preferably 200 GPa or more and 960 GPa or less. When the Young's modulus is equal to or higher than the above lower limit value, it is easy to follow the displacement at a high frequency. Therefore, it is easy to realize the diaphragm 33B in which cracks are unlikely to occur while ensuring the required amount of deformation.

When the material of the third layer 3331 is SiON, the third layer 3331 having a desired Young's modulus can be formed by adjusting the composition ratio of oxygen and nitrogen. The third layer 3331 may be a single layer or may have a plurality of layers.

The material of the fourth layer 3332 is silicon oxide. Therefore, the diaphragm 33B has a layer containing silicon oxide. By using silicon oxide, the fourth layer 3332 having a predetermined thickness can be most easily formed by thermal oxidation, sputtering, CVD, or the like. The fourth layer 3332 may be a single layer or may have a plurality of layers.

The thickness D31 of the third layer 3331 is larger than the thickness D32 of the fourth layer 3332. Therefore, it is easier to realize the diaphragm 33B which is easy to follow with respect to the displacement of high frequency as compared with the case where the thickness D31 is the thickness D32 or less. Therefore, it is possible to provide the liquid injection head 26 suitable for high frequency driving. The thickness D31 may be less than the thickness D32 or may be equal to the thickness D32. Further, the thickness D4 of the metal layer 334 may be equal to or different from each of the thickness D31 and the thickness D32.

The thickness D31 of the third layer 3331 is not particularly limited, but is, for example, 50 nm or more and 1000 nm or less. The thickness D32 of the fourth layer 3332 is not particularly limited, but is, for example, 50 nm or more and 500 nm or less.

4. Fourth Embodiment The fourth embodiment will be described. In each of the following examples, for the elements having the same functions as those of the first embodiment, the reference numerals used in the description of the first embodiment will be diverted and detailed description of each will be omitted as appropriate.

FIG. 9 is a cross-sectional view showing a part of the diaphragm 33C in the fourth embodiment, and corresponds to FIG. 5 in the first embodiment. In this embodiment, the diaphragm 33C is used instead of the diaphragm 33 of the first embodiment. In the following, matters different from the diaphragm 33 of the first embodiment will be described with respect to the diaphragm 33C, and description of the same matters will be omitted as appropriate.

90% or more of the thickness D of the diaphragm 33C is a laminate in which a third amorphous layer 335 and a carbon layer 336 are laminated. That is, the diaphragm 33 is mainly composed of a laminate in which a third amorphous layer 335 and a carbon layer 336 are laminated. In the example shown in FIG. 7, the diaphragm 33A is composed of a laminate in which a third amorphous layer 335 and a carbon layer 336 are laminated. The carbon layer 336 comes into contact with the pressure chamber substrate 32. The third amorphous layer 335 is arranged between the carbon layer 336 and the first electrode 341 and comes into contact with them.

90% or more of the thickness D of the diaphragm 33C is a laminate in which the third amorphous layer 335 and the carbon layer 336 are laminated. That is, the carbon layer 336 is used instead of the conventional layer composed of zirconium oxide. Therefore, it is possible to suppress the occurrence of cracks in the diaphragm 33C due to the occurrence of microcracks at the crystal grain boundaries of the layer composed of zirconium oxide as in the conventional case. Therefore, the diaphragm 33C is unlikely to be damaged. As a result, it is possible to provide a highly reliable liquid injection head 26 in which deterioration of discharge performance is suppressed. Further, since the occurrence of cracks can be suppressed over time, the life of the liquid injection head 26 can be extended.

In addition, less than 10% of the thickness D of the diaphragm 33C may be a layer other than the laminated layer in which the third amorphous layer 335 and the carbon layer 336 are laminated. Less than 10% of the thickness D of the diaphragm 33C exhibits the effect of suppressing damage to the diaphragm 33C originating from microcracks, even if it is not the laminated layer.

Further, since the carbon layer 336 is provided, the toughness of the diaphragm 33C can be increased as compared with the case where the carbon layer 336 is not provided. Therefore, it is possible to provide the diaphragm 33C which is not easily damaged. The material of the carbon layer 336 is either diamond-like carbon, graphene and carbon nanotubes.

The material of the _third amorphous layer 335 is Si 3N ₄ , SiON, Al ₂ O ₃ , SiC, WC, AlN, BeO, B ₄ C or MgO, or a combination thereof. These materials have a higher Young's modulus than, for example, silicon oxide. Therefore, by using these materials, it is easy to shorten the vibration cycle. Therefore, it is possible to improve the ejection performance in a short cycle.

The Young's modulus of the material of the third amorphous layer 335 is not particularly limited, but is preferably 150 GPa or more, and more preferably 200 GPa or more and 960 GPa or less. When the Young's modulus is equal to or higher than the above lower limit value, it is easy to follow the displacement at a high frequency. Therefore, it is easy to realize the diaphragm 33C in which cracks are unlikely to occur while ensuring the required amount of deformation.

When the material of the third amorphous layer 335 is SiON, the third amorphous layer 335 having a desired Young's modulus can be formed by adjusting the composition ratio of oxygen and nitrogen.

The thickness D5 of the third amorphous layer 335 may be larger than the thickness D6 of the carbon layer 336, may be equal to the thickness D6, or may be smaller than the thickness D6 of the metal layer 334.

The thickness D5 of the third amorphous layer 335 is not particularly limited, but is, for example, 50 nm or more and 1000 nm or less. The thickness D6 of the carbon layer 336 is not particularly limited, but is, for example, 50 nm or more and 1000 nm or less.

Further, as shown in FIG. 9, an oxygen barrier membrane 45 is arranged between the diaphragm 33C and the first electrode 341. The oxygen barrier membrane 45 is used to prevent oxidation of the carbon layer 336. When the heat treatment is performed in an oxidizing atmosphere, the components of the carbon layer 336 may be oxidized to carbon dioxide (CO ₂ ) and vaporized. Therefore, by providing the oxygen barrier membrane 45, it is possible to prevent the carbon layer 336 from being oxidized.

Examples of the material of the oxygen barrier membrane 45 include _Al2O3 or _AlTiN . The oxygen barrier membrane 45 may be arranged, for example, between the third amorphous layer 335 and the carbon layer 336, or in the Z2 direction with respect to the piezoelectric layer 343.

5. Fifth Embodiment The fifth embodiment will be described. In each of the following examples, for the elements having the same functions as those of the first embodiment, the reference numerals used in the description of the first embodiment will be diverted and detailed description of each will be omitted as appropriate.

FIG. 10 is a cross-sectional view showing a part of the diaphragm 33D in the fifth embodiment, and corresponds to FIG. 5 in the first embodiment. In this embodiment, the diaphragm 33D is used instead of the diaphragm 33 of the first embodiment. In the following, matters different from the diaphragm 33 of the first embodiment will be described with respect to the diaphragm 33D, and the description of the same matters will be omitted as appropriate.

90% or more of the thickness D of the diaphragm 33D is a laminate in which the third amorphous layer 335D and the carbon layer 336 are laminated. That is, the diaphragm 33D is mainly composed of a laminate in which a third amorphous layer 335D and a carbon layer 336 are laminated. In the example shown in FIG. 10, the diaphragm 33D is composed of a laminate in which a third amorphous layer 335D and a carbon layer 336 are laminated. The carbon layer 336 is the same as the carbon layer 336 of the third embodiment.

The third amorphous layer 335D has a fifth layer 3351 and a sixth layer 3352. A carbon layer 336 is arranged between the fifth layer 3351 and the sixth layer 3352. The fifth layer 3351, the carbon layer 336, and the sixth layer 3352 are laminated from the pressure chamber substrate 32 in this order. Further, the sixth layer 3352 comes into contact with the pressure chamber substrate 32. The fifth layer 3351 is arranged between the carbon layer 336 and the first electrode 341 and comes into contact with them.

As described above, 90% or more of the thickness D of the diaphragm 33D is a laminate in which the third amorphous layer 335D and the carbon layer 336 are laminated. Therefore, it is possible to suppress the occurrence of cracks in the diaphragm 33D due to the occurrence of microcracks at the crystal grain boundaries. Therefore, the diaphragm 33D is unlikely to be damaged. As a result, it is possible to provide a highly reliable liquid injection head 26 in which deterioration of discharge performance is suppressed. Further, since the occurrence of cracks can be suppressed over time, the life of the liquid injection head 26 can be extended.

In addition, less than 10% of the thickness D of the diaphragm 33D may be a layer other than the laminated layer in which the third amorphous layer 335D and the carbon layer 336 are laminated. Less than 10% of the thickness D of the diaphragm 33D exhibits the effect of suppressing damage to the diaphragm 33D originating from microcracks, even if it is not the laminated layer.

Further, since the carbon layer 336 is provided, the toughness of the diaphragm 33D can be increased as compared with the case where the carbon layer 336 is not provided. Therefore, it is possible to provide the diaphragm 33D which is not easily damaged.

The material of the fifth layer 3351 is either Si 3N ₄ , SiON, Al ₂ O _{3 ,} SiC, WC, AlN, BeO, B ₄ C or MgO, or a combination thereof. These materials have a higher Young's modulus than, for example, silicon oxide. Therefore, by using these materials, it is easy to shorten the vibration cycle. Therefore, it is possible to improve the ejection performance in a short cycle.

The Young's modulus of the material of the fifth layer 3351 is not particularly limited, but is preferably 150 GPa or more, and more preferably 200 GPa or more and 960 GPa or less. When the Young's modulus is 150 GPa or more, it is easy to follow the displacement at a high frequency. Therefore, it is easy to realize the diaphragm 33D in which cracks are unlikely to occur while ensuring the required amount of deformation.

When the material of the fifth layer 3351 is SiON, the fifth layer 3351 having a desired Young's modulus can be formed by adjusting the composition ratio of oxygen and nitrogen. The fifth layer 3351 may be a single layer or may have a plurality of layers.

The material of the sixth layer 3352 is silicon oxide. Therefore, the diaphragm 33D has a layer containing silicon oxide. By using silicon oxide, the fifth layer 3351 having a predetermined thickness can be most easily formed by thermal oxidation, sputtering, CVD and the like. The sixth layer 3352 may be a single layer or may have a plurality of layers.

The thickness D51 of the fifth layer 3351 is larger than the thickness of D52 of the sixth layer 3352. Therefore, it is easier to realize the diaphragm 33D which can easily follow the displacement of high frequency as compared with the case where the thickness D51 is the thickness D52 or less. Therefore, it is possible to provide the liquid injection head 26 suitable for high frequency driving. The thickness D51 may be less than the thickness D52 or may be equal to the thickness D52. Further, the thickness D4 of the metal layer 334 may be equal to or different from each of the thickness D51 and the thickness D52.

The thickness D51 of the fifth layer 3351 is not particularly limited, but is, for example, 50 nm or more and 500 nm or less. The thickness of D52 of the sixth layer 3352 is not particularly limited, but is, for example, 50 nm or more and 500 nm or less.

Further, although not shown, for example, the oxygen barrier membrane 45 of the third embodiment may be arranged between the diaphragm 33D and the first electrode 341.

2. 2. Modifications The embodiments illustrated above can be variously modified. Specific embodiments that may be applied to the above-described embodiments are illustrated below. Two or more embodiments arbitrarily selected from the following examples can be appropriately merged to the extent that they do not contradict each other. The following modifications relating to the first embodiment can be applied to each of the second to fifth embodiments within a consistent range.

In the first embodiment, the first electrode 341 of the piezoelectric element 34 is used as an individual electrode and the second electrode 342 is used as a common electrode, but the first electrode 341 may be used as a common electrode and the second electrode 342 may be used as an individual electrode. Further, both the first electrode 341 and the second electrode 342 may be used as individual electrodes.

FIG. 11 is a diagram showing a modified example piezoelectric element 34E. The piezoelectric element 34E shown in FIG. 11 generally has a first electrode 341E, a piezoelectric layer 343, and a second electrode 342E in order from the diaphragm 33. The first electrode 341E is a band-shaped common electrode extending along the Y axis so as to be continuous over the plurality of piezoelectric elements 34. The second electrode 342E is an individual electrode formed so as to be separated from each other for each piezoelectric element 34. Further, a hydrogen barrier membrane 46 for preventing deterioration of the piezoelectric layer 343 due to hydrogen reduction is arranged on the second electrode 342E.

Since the second electrode 342 of the piezoelectric element 34 is a common electrode as in the first embodiment, the second electrode 342 functions as a hydrogen barrier membrane. Therefore, the hydrogen barrier membrane 46 shown in FIG. 11 can be omitted.

In the diaphragm 33 of the first embodiment, the first layer 331 and the second layer 332 are laminated in order from the pressure chamber substrate 32, but the second layer 332 and the first layer 331 are laminated in order from the pressure chamber substrate 32. May be done. Therefore, the second layer 332 may come into contact with the pressure chamber substrate 32.

In the first embodiment, the serial type liquid injection device 100 that reciprocates the carrier 242 equipped with the liquid injection head 26 is exemplified, but the line type liquid injection device in which a plurality of nozzles N are distributed over the entire width of the medium 12 is used. It is also possible to apply the present invention.

The liquid injection device 100 exemplified in the first embodiment can be adopted in various devices such as a facsimile machine and a copier, in addition to a device dedicated to printing. However, the application of the liquid injection device of the present invention is not limited to printing. For example, a liquid injection device that injects a solution of a coloring material is used as a manufacturing device for forming a color filter of a display device such as a liquid crystal display panel. Further, a liquid injection device for injecting a solution of a conductive material is used as a manufacturing device for forming wiring and electrodes on a wiring board. Further, a liquid injection device for injecting a solution of an organic substance related to a living body is used, for example, as a manufacturing device for manufacturing a biochip.

12 ... medium, 14 ... liquid container, 20 ... control unit, 22 ... transfer mechanism, 24 ... moving mechanism, 26 ... liquid injection head, 30 ... flow path structure, 31 ... flow path substrate, 32 ... pressure chamber substrate, 33 ... Vibrating plate, 34 ... piezoelectric element, 35 ... encapsulant, 36 ... housing, 37 ... first wiring, 38 ... second wiring, 41 ... nozzle plate, 42 ... vibration absorber, 43 ... protective film, 44 ... Seed layer, 45 ... oxygen barrier film, 51 ... wiring board, 100 ... liquid injection device, 242 ... carrier, 244 ... transport belt, 312 ... supply flow path, 314 ... communication flow path, 316 ... relay liquid chamber, 320 ... Wall surface, 330 ... 1st amorphous layer, 331 ... 1st layer, 331x ... SiO2 layer, 332 ... 2nd layer, 332x ... ZrO ₂ layer, 333 ... 2nd amorphous layer, 334 ... Metal layer, 335 ... third amorphous layer, 336 ... carbon layer, 341 ... first electrode, 342 ... second electrode, 343 ... piezoelectric layer, 361 ... supply port, 381 ... first conductive layer, 382 ... second conductive Layer, 3331 ... 3rd layer, 3332 ... 4th layer, 3351 ... 5th layer, 3352 ... 6th layer, C0 ... crack, C1 ... pressure chamber, D ... thickness, D1 ... thickness, D2 ... thickness, D3 ... thickness , D4 ... Thickness, D5 ... Thickness, D6 ... Thickness, G ... Notch, La ... 1st row, Lb ... 2nd row, MC ... Microcrack, N ... Nozzle, R ... Liquid storage chamber, Ra ... Space, Rb ... Space, V ... Vibration area.

Claims (12)

A nozzle plate with a nozzle that injects liquid,
A pressure chamber substrate having a wall surface forming a pressure chamber communicating with the nozzle,
A diaphragm arranged opposite to the nozzle plate with respect to the pressure chamber substrate,
In order from the diaphragm, a piezoelectric element having a first electrode, a piezoelectric layer, and a second electrode,
It has a diaphragm and a protective film that comes into contact with a part of the wall surface.
90% of the thickness of the diaphragm is a first amorphous layer in which a first layer and a second layer are laminated.
Alternatively, a laminate in which a second amorphous layer and a metal layer are laminated,
Alternatively, a laminate in which a third amorphous layer and a carbon layer containing any of diamond-like carbon, graphene and carbon nanotubes are laminated.
A liquid injection head characterized by being. The liquid injection head according to claim 1, wherein the material of the diaphragm contains silicon oxide. Each of the first amorphous layer, the second amorphous layer and the _third amorphous layer is Si 3N ₄ , SiON, Al ₂ O ₃ , SiC, WC, AlN, BeO, respectively. B ₄ The liquid injection head according to claim 1 or 2, wherein the liquid injection head comprises a layer containing either C or MgO, or a plurality of combinations thereof. Claims 1 to 3, wherein each of the first amorphous layer, the second amorphous layer, and the third amorphous layer contains a layer having a Young's modulus of 150 GPa or more. The liquid injection head according to any one of the above items. The liquid injection head according to any one of claims 2 to 4, wherein the thickness of the second layer is larger than the thickness of the first layer. The liquid injection head according to any one of claims 1 to 5, further comprising a seed layer arranged between the first electrode and the piezoelectric layer. The liquid injection head according to claim 6, wherein the material of the seed layer is any one of SrTiO ₃ , LaNiO ₃ , Ti or TiO ₂ . The material of the metal layer is either Ti, TiN, Ni, Pd, Pt, Ir, Au, Al, Ru, AlN, AlTiN, stainless steel, mild steel, carbon steel, marage steel, high tension steel or aluminum alloy. The liquid injection head according to any one of claims 1 to 7, wherein the liquid injection head is characterized in that. The second amorphous layer has a third layer and a fourth layer, and has a third layer and a fourth layer.
The liquid injection head according to any one of claims 1 to 8, wherein the metal layer is arranged between the third layer and the fourth layer. The material of the fourth layer is silicon oxide.
The Young's modulus of the material of the third layer is 150 GPa or more, and the Young's modulus is 150 GPa or more.
The liquid injection head according to claim 9, wherein the thickness of the third layer is larger than the thickness of the fourth layer. The liquid injection head according to any one of claims 1 to 10, wherein the protective film is a resin layer or an inorganic insulating layer having a thickness of 1/10 or less of the diaphragm. A liquid injection device comprising the liquid injection head according to any one of claims 1 to 11.

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